Respan Dataset Explorer

Arayüz donma yapıyor, bunu çöz, datagridview için virtualmode kullan, uygulamanın akıcılığını artır. şimdi : Vereceğim tüm kodu fonksiyonelliği kesinlikle ! bozmadan, eksiksiz ilgili değişikliklerle birlikte tek parça yaz. using System;
using System.Windows.Forms;
using Firebase.Database;
using Firebase.Database.Query;
using FirebaseAdmin;
using Google.Apis.Auth.OAuth2;
using System.Threading.Tasks;
using System.Linq;
using System.Drawing;
using System.Collections.Generic;
using System.IO;
using System.Text;
using Newtonsoft.Json;
using Firebase.Database.Streaming;

namespace Flashcard
{
    public partial class MainForm : Form
    {
        // Firebase client
        private FirebaseClient firebaseClient;

        // UI Controls
        private DataGridView dataGridView;
        private TextBox txtTitle, txtCategory, txtContent, txtBackgroundColor, txtSearch;
        private CheckBox chkFavorite, chkPinned;
        private CheckBox chkFilterFavorites, chkFilterPinned; // Filtering CheckBoxes
        private Button btnAdd, btnUpdate, btnDelete, btnSearch, btnClear;
        private StatusStrip statusStrip;
        private ToolStripStatusLabel statusLabel;

        // Menü Kontrolleri
        private MenuStrip menuStrip;
        private ToolStripMenuItem fileMenuItem, themeMenuItem;
        private ToolStripMenuItem saveAsMenuItem, lightModeMenuItem, darkModeMenuItem;
        private ToolStripMenuItem clipboardModeMenuItem, clipboardOnMenuItem, clipboardOffMenuItem;
        private ToolStripMenuItem loadTagsMenuItem;

        // Custom Tag Menu Items
        private ToolStripMenuItem customTagMenuItem;
        private ToolStripMenuItem addTagMenuItem;
        private ToolStripMenuItem manageTagsMenuItem;
        private List<string> customTags = new List<string>();
        private string selectedCustomTag = null;

        // customTags'i kaydetmek için dosya yolu
        private readonly string customTagsFilePath = "custom_tags.json";

        // ContextMenuStrip for column visibility
        private ContextMenuStrip columnContextMenu;

        // Sorting state
        private string currentSortColumn = "timestamp";
        private bool sortAscending = false;

        // Data storage
        private List<FlashcardItem> allFlashcards = new List<FlashcardItem>();

        // Current search term
        private string currentSearchTerm = "";

        // Dictionary to store column visibility state
        private Dictionary<string, bool> columnVisibilityState = new Dictionary<string, bool>();

        // Clipboard monitoring
        private Timer clipboardMonitorTimer;
        private string lastClipboardText;

        // Yeni Eklenen Değişkenler
        private CheckedListBox tagCheckedListBox;
        private string selectedTag = "uncategorized";

        // Local storage file path
        private readonly string localDataFilePath = "local_flashcards.json";

        // Flag to indicate if application is online
        private bool isOnline = false;

        // Flag to prevent multiple listeners
        private bool isListening = false;

        // Offline changes list
        private List<FlashcardChange> offlineChanges = new List<FlashcardChange>();

        // Timer to check online status
        private Timer onlineStatusTimer;

        public MainForm()
        {
            InitializeComponent();
            InitializeFirebase();
            InitializeUI();
        }

        /// <summary>
        /// Initializes Firebase connection using the provided JSON credentials.
        /// </summary>
        private void InitializeFirebase()
        {
            var path = "flashcard-e7f47-firebase-adminsdk-om656-e70a5506c2.json";
            var credential = GoogleCredential.FromFile(path);

            // Check if FirebaseApp is already created to prevent duplicate initialization
            if (FirebaseApp.DefaultInstance == null)
            {
                FirebaseApp.Create(new AppOptions
                {
                    Credential = credential
                });
            }

            firebaseClient = new FirebaseClient("https://flashcard-e7f47-default-rtdb.europe-west1.firebasedatabase.app/");
        }

        /// <summary>
        /// Sets up the user interface components.
        /// </summary>
        private void InitializeUI()
        {
            this.Size = new Size(1000, 800);
            this.Text = "Flashcard Application";
            this.StartPosition = FormStartPosition.CenterScreen; // MainForm ekranın ortasında açılsın

            // MenuStrip Oluşturma
            menuStrip = new MenuStrip
            {
                Dock = DockStyle.Top // MenuStrip'i üstte konumlandır
            };

            // File Menu
            fileMenuItem = new ToolStripMenuItem("File");
            saveAsMenuItem = new ToolStripMenuItem("Save As");
            saveAsMenuItem.Click += SaveAsMenuItem_Click; // Event Handler
            fileMenuItem.DropDownItems.Add(saveAsMenuItem);

            // Theme Menu
            themeMenuItem = new ToolStripMenuItem("Theme");
            lightModeMenuItem = new ToolStripMenuItem("Light Mode");
            darkModeMenuItem = new ToolStripMenuItem("Dark Mode");
            lightModeMenuItem.Click += LightModeMenuItem_Click; // Event Handler
            darkModeMenuItem.Click += DarkModeMenuItem_Click; // Event Handler
            themeMenuItem.DropDownItems.Add(lightModeMenuItem);
            themeMenuItem.DropDownItems.Add(darkModeMenuItem);

            // Clipboard Mode Menu
            clipboardModeMenuItem = new ToolStripMenuItem("Clipboard Mode");
            clipboardOnMenuItem = new ToolStripMenuItem("On");
            clipboardOffMenuItem = new ToolStripMenuItem("Off");

            // CheckOnClick özelliğini kullanarak tıklanınca işaretlenmesini sağlıyoruz
            clipboardOnMenuItem.CheckOnClick = true;
            clipboardOffMenuItem.CheckOnClick = true;
            clipboardOffMenuItem.Checked = true; // Başlangıçta "Off" seçili

            clipboardOnMenuItem.Click += ClipboardOnMenuItem_Click;
            clipboardOffMenuItem.Click += ClipboardOffMenuItem_Click;

            clipboardModeMenuItem.DropDownItems.Add(clipboardOnMenuItem);
            clipboardModeMenuItem.DropDownItems.Add(clipboardOffMenuItem);

            // Load Tags Menu
            loadTagsMenuItem = new ToolStripMenuItem("Load Tags");
            loadTagsMenuItem.Click += LoadTagsMenuItem_Click; // Event Handler

            // Custom Tag Menu
            customTagMenuItem = new ToolStripMenuItem("Custom Tag");
            addTagMenuItem = new ToolStripMenuItem("Add Tag");
            addTagMenuItem.Click += AddTagMenuItem_Click; // Event Handler

            // Declare manageTagsMenuItem at class level and initialize
            manageTagsMenuItem = new ToolStripMenuItem("Manage Tags");
            manageTagsMenuItem.Click += ManageTagsMenuItem_Click; // Event Handler
            customTagMenuItem.DropDownItems.Add(addTagMenuItem);
            customTagMenuItem.DropDownItems.Add(manageTagsMenuItem);

            // MenuStrip'e Menüleri Ekleme
            menuStrip.Items.Add(fileMenuItem);
            menuStrip.Items.Add(themeMenuItem);
            menuStrip.Items.Add(clipboardModeMenuItem);
            menuStrip.Items.Add(loadTagsMenuItem); // "Load Tags" Menü Öğesini Ekledik
            menuStrip.Items.Add(customTagMenuItem); // "Custom Tag" Menü Öğesini Ekledik

            // Form'a MenuStrip'i Ekleme
            this.MainMenuStrip = menuStrip;
            Controls.Add(menuStrip); // MenuStrip'i ilk olarak ekliyoruz

            // Clipboard izleme için Timer
            clipboardMonitorTimer = new Timer { Interval = 1000 }; // Her saniyede bir kontrol eder
            clipboardMonitorTimer.Tick += ClipboardMonitorTimer_Tick;

            // Online status izleme için Timer
            onlineStatusTimer = new Timer { Interval = 10000 }; // Her 10 saniyede bir kontrol eder
            onlineStatusTimer.Tick += OnlineStatusTimer_Tick;

            // Arama Metin Kutusu ve Butonları
            txtSearch = CreateTextBox("", 10, menuStrip.Bottom + 6, 200);
            btnSearch = CreateButton("Search", txtSearch.Right + 6, txtSearch.Top - 2, 80);
            btnClear = CreateButton("Clear", btnSearch.Right + 6, txtSearch.Top - 2, 80);

            // Filtreleme CheckBox'ları
            chkFilterFavorites = new CheckBox
            {
                Text = "Show Favorites",
                Top = txtSearch.Bottom + 6,
                Left = txtSearch.Left,
                Width = 120
            };
            chkFilterFavorites.CheckedChanged += FilterCheckBoxChanged;
            Controls.Add(chkFilterFavorites);

            chkFilterPinned = new CheckBox
            {
                Text = "Show Pinned",
                Top = txtSearch.Bottom + 6,
                Left = chkFilterFavorites.Right + 10,
                Width = 120
            };
            chkFilterPinned.CheckedChanged += FilterCheckBoxChanged;
            Controls.Add(chkFilterPinned);

            // Initialize DataGridView
            dataGridView = new DataGridView
            {
                Height = 400,
                Left = 0,
                Top = chkFilterFavorites.Bottom + 10, // DataGridView'i filtrelerin altına yerleştir
                Width = this.ClientSize.Width, // Tam pencere genişliğini kapla
                Anchor = AnchorStyles.Top | AnchorStyles.Left | AnchorStyles.Right,
                AllowUserToAddRows = false,
                AllowUserToDeleteRows = false,
                ReadOnly = false,
                SelectionMode = DataGridViewSelectionMode.FullRowSelect,
                MultiSelect = true,
                AutoSizeColumnsMode = DataGridViewAutoSizeColumnsMode.Fill,
                ColumnHeadersHeightSizeMode = DataGridViewColumnHeadersHeightSizeMode.AutoSize
            };

            dataGridView.SelectionChanged += DataGridView_SelectionChanged;
            dataGridView.CellContentClick += DataGridView_CellContentClick;
            dataGridView.CellFormatting += DataGridView_CellFormatting;
            dataGridView.ColumnHeaderMouseClick += DataGridView_ColumnHeaderMouseClick; // For sorting
            Controls.Add(dataGridView);

            // StatusStrip
            statusStrip = new StatusStrip();
            statusLabel = new ToolStripStatusLabel();
            statusStrip.Items.Add(statusLabel);
            statusStrip.Dock = DockStyle.Bottom; // StatusStrip'i pencerenin en altına sabitle
            Controls.Add(statusStrip);

            // Tag CheckedListBox Oluşturma
            tagCheckedListBox = new CheckedListBox
            {
                Width = 400,
                CheckOnClick = true,
                Left = this.ClientSize.Width - 400, // Pencerenin en sağ kenarına bitişik hizala
                Top = dataGridView.Bottom, // DataGridView'in hemen altına yerleştir
                Height = statusStrip.Top - dataGridView.Bottom + 10, // DataGridView'den StatusStrip'e kadar olan yüksekliği ayarla
                Anchor = AnchorStyles.Top | AnchorStyles.Bottom | AnchorStyles.Right,
                Visible = false // Başlangıçta gizli
            };
            tagCheckedListBox.ItemCheck += TagCheckedListBox_ItemCheck;
            Controls.Add(tagCheckedListBox);

            // Kontroller arası standart Windows Forms arayüzündeki gibi mesafeler
            int labelLeft = 10;
            int textBoxLeft = 150;
            int startTop = dataGridView.Bottom + 6; // DataGridView'in hemen altından başla
            int textBoxWidth = 300;
            int textBoxHeight = 25;
            int verticalSpacing = 6; // Kontroller arası boşluk

            int currentTop = dataGridView.Bottom + 6; // Kontrolleri DataGridView'in altına yerleştir

            // Etiketleri ve Metin Kutularını Oluştur

            // Category
            CreateLabel("Category:", labelLeft, currentTop);
            txtCategory = CreateTextBox("", textBoxLeft, currentTop, textBoxWidth);
            currentTop += textBoxHeight + verticalSpacing;

            // Title
            CreateLabel("Title:", labelLeft, currentTop);
            txtTitle = CreateTextBox("", textBoxLeft, currentTop, textBoxWidth);
            currentTop += textBoxHeight + verticalSpacing;

            // Content
            CreateLabel("Content:", labelLeft, currentTop);
            txtContent = CreateTextBox("", textBoxLeft, currentTop, textBoxWidth);
            currentTop += textBoxHeight + verticalSpacing;

            // Background Color
            CreateLabel("Background Color:", labelLeft, currentTop);
            txtBackgroundColor = CreateTextBox("", textBoxLeft, currentTop, textBoxWidth);
            currentTop += textBoxHeight + verticalSpacing;

            // İşlevsel CheckBox'lar
            chkFavorite = new CheckBox { Text = "Favorite", Top = currentTop, Left = textBoxLeft, Width = 80 };
            Controls.Add(chkFavorite);

            chkPinned = new CheckBox { Text = "Pinned", Top = currentTop, Left = textBoxLeft + 90, Width = 80 };
            Controls.Add(chkPinned);

            currentTop += chkFavorite.Height + verticalSpacing;

            // Butonları Yatay Olarak Hizala
            int buttonTop = currentTop + 10; // Biraz boşluk ekle
            int buttonLeft = labelLeft;

            btnAdd = CreateButton("Add", buttonLeft, buttonTop, 100);
            buttonLeft += 110;

            btnUpdate = CreateButton("Update", buttonLeft, buttonTop, 100);
            buttonLeft += 110;

            btnDelete = CreateButton("Delete", buttonLeft, buttonTop, 100);

            // ContextMenuStrip for column visibility
            columnContextMenu = new ContextMenuStrip();
            // Not: Kolon bilgisi mevcut olduktan sonra ContextMenuStrip'i dolduracağız

            // Assign the MouseUp event to show the ContextMenuStrip on right-click
            dataGridView.MouseUp += DataGridView_MouseUp;

            // Event Handler for Form Load
            this.Load += MainForm_Load;

            // Formun MouseDown olayını abone olma
            this.MouseDown += MainForm_MouseDown;

            // Tüm kontrollerin MouseDown olaylarını abone et
            RegisterMouseDownEvent(this);
        }

        private void MainForm_MouseDown(object sender, MouseEventArgs e)
        {
            // Fare imlecinin altındaki kontrolü al
            Control clickedControl = this.GetChildAtPoint(e.Location);

            // Eğer tıklanan kontrol null ise veya formun kendisiyse, metin kutularını sıfırla
            if (clickedControl == null || clickedControl == this)
            {
                ClearInputs();
            }
        }

        private void RegisterMouseDownEvent(Control parent)
        {
            foreach (Control control in parent.Controls)
            {
                control.MouseDown += Control_MouseDown;

                if (control.HasChildren)
                {
                    RegisterMouseDownEvent(control);
                }
            }
        }

        private void Control_MouseDown(object sender, MouseEventArgs e)
        {
            // Kontrolün MouseDown olayını formun MouseDown olayına yönlendir
            MainForm_MouseDown(sender, e);
        }

        // Yeni bir CreateLabel metodu ekliyoruz
        private Label CreateLabel(string text, int left, int top)
        {
            Label label = new Label
            {
                Text = text,
                Left = left,
                Top = top,
                AutoSize = true
            };
            Controls.Add(label);
            return label;
        }

        /// <summary>
        /// Creates a TextBox.
        /// </summary>
        private TextBox CreateTextBox(string text, int left, int top, int width)
        {
            TextBox textBox = new TextBox
            {
                Left = left,
                Top = top,
                Width = width,
                Text = text,
                ForeColor = Color.Black
            };
            Controls.Add(textBox);
            return textBox;
        }

        /// <summary>
        /// Creates a Button with specified properties and assigns click event.
        /// </summary>
        private Button CreateButton(string text, int left, int top, int width)
        {
            Button button = new Button
            {
                Text = text,
                Left = left,
                Top = top,
                Width = width
            };
            button.Click += (sender, e) => ButtonClick(text);
            Controls.Add(button);
            return button;
        }

        /// <summary>
        /// Handles button click events by identifying the button text.
        /// </summary>
        private void ButtonClick(string buttonText)
        {
            switch (buttonText)
            {
                case "Add":
                    AddData();
                    break;
                case "Update":
                    UpdateData();
                    break;
                case "Delete":
                    DeleteData();
                    break;
                case "Search":
                    SearchData();
                    break;
                case "Clear":
                    ClearSearch();
                    break;
            }
        }

        /// <summary>
        /// Handles the "Save As" menu item click to save data in selected format.
        /// </summary>
        private void SaveAsMenuItem_Click(object sender, EventArgs e)
        {
            SaveFileDialog saveFileDialog = new SaveFileDialog
            {
                Filter = "JSON files (*.json)|*.json|CSV files (*.csv)|*.csv|TSV files (*.tsv)|*.tsv|Text files (*.txt)|*.txt",
                Title = "Save As"
            };

            if (saveFileDialog.ShowDialog() == DialogResult.OK)
            {
                try
                {
                    string extension = Path.GetExtension(saveFileDialog.FileName).ToLower();
                    // DataGridView'den verileri al
                    var data = (List<FlashcardItem>)dataGridView.DataSource;

                    // Verileri seçilen formata göre kaydet
                    switch (extension)
                    {
                        case ".json":
                            SaveDataAsJSon(data, saveFileDialog.FileName);
                            break;
                        case ".csv":
                            SaveDataAsCsv(data, saveFileDialog.FileName, ',');
                            break;
                        case ".tsv":
                            SaveDataAsCsv(data, saveFileDialog.FileName, '\t');
                            break;
                        case ".txt":
                            SaveDataAsTxt(data, saveFileDialog.FileName);
                            break;
                        default:
                            MessageBox.Show("Unsupported file format.", "Error", MessageBoxButtons.OK, MessageBoxIcon.Error);
                            break;
                    }

                    MessageBox.Show("Data saved successfully!", "Success", MessageBoxButtons.OK, MessageBoxIcon.Information);
                }
                catch (Exception ex)
                {
                    MessageBox.Show($"Error saving data: {ex.Message}", "Error", MessageBoxButtons.OK, MessageBoxIcon.Error);
                }
            }
        }

        /// <summary>
        /// Saves data as a JSON file.
        /// </summary>
        private void SaveDataAsJSon(List<FlashcardItem> data, string filePath)
        {
            try
            {
                var options = new JsonSerializerSettings
                {
                    Formatting = Formatting.Indented // JSON'u okunabilir şekilde biçimlendirir
                };

                string jsonString = JsonConvert.SerializeObject(data, options);
                File.WriteAllText(filePath, jsonString, Encoding.UTF8);
            }
            catch (Exception ex)
            {
                MessageBox.Show($"Error saving JSON data: {ex.Message}", "Error", MessageBoxButtons.OK, MessageBoxIcon.Error);
            }
        }

        /// <summary>
        /// Saves data as CSV or TSV file.
        /// </summary>
        private void SaveDataAsCsv(List<FlashcardItem> data, string filePath, char delimiter)
        {
            StringBuilder sb = new StringBuilder();

            // Başlık satırı
            sb.AppendLine(string.Join(delimiter.ToString(), "Category", "Title", "Content", "Favorite", "Pinned", "Timestamp", "BackgroundColor"));

            foreach (var item in data)
            {
                string[] fields = new string[]
                {
                    EscapeCsvField(item.category),
                    EscapeCsvField(item.title),
                    EscapeCsvField(item.content),
                    item.favorite.ToString(),
                    item.pinned.ToString(),
                    item.timestamp.ToString(),
                    EscapeCsvField(item.backgroundColor)
                };

                sb.AppendLine(string.Join(delimiter.ToString(), fields));
            }

            File.WriteAllText(filePath, sb.ToString(), Encoding.UTF8);
        }

        /// <summary>
        /// Saves data as TXT file.
        /// </summary>
        private void SaveDataAsTxt(List<FlashcardItem> data, string filePath)
        {
            StringBuilder sb = new StringBuilder();

            foreach (var item in data)
            {
                sb.AppendLine($"Category: {item.category}");
                sb.AppendLine($"Title: {item.title}");
                sb.AppendLine($"Content: {item.content}");
                sb.AppendLine($"Favorite: {item.favorite}");
                sb.AppendLine($"Pinned: {item.pinned}");
                sb.AppendLine($"Timestamp: {item.timestamp}");
                sb.AppendLine($"BackgroundColor: {item.backgroundColor}");
                sb.AppendLine(new string('-', 50));
            }

            File.WriteAllText(filePath, sb.ToString(), Encoding.UTF8);
        }

        /// <summary>
        /// Escapes CSV fields containing delimiter or quotes.
        /// </summary>
        private string EscapeCsvField(string field)
        {
            if (field.Contains(",") || field.Contains("\"") || field.Contains("\r") || field.Contains("\n"))
            {
                return $"\"{field.Replace("\"", "\"\"")}\"";
            }
            else
            {
                return field;
            }
        }

        /// <summary>
        /// Handles the Light Mode menu item click.
        /// </summary>
        private void LightModeMenuItem_Click(object sender, EventArgs e)
        {
            SetTheme(Color.White, Color.Black, false);
        }

        /// <summary>
        /// Handles the Dark Mode menu item click.
        /// </summary>
        private void DarkModeMenuItem_Click(object sender, EventArgs e)
        {
            SetTheme(Color.FromArgb(45, 45, 48), Color.White, true);
        }

        /// <summary>
        /// Sets the application's theme colors.
        /// </summary>
        private void SetTheme(Color backColor, Color foreColor, bool isDarkMode)
        {
            this.BackColor = backColor;
            this.ForeColor = foreColor;

            foreach (Control control in this.Controls)
            {
                SetControlTheme(control, backColor, foreColor);
            }

            // DataGridView renklerini ayarla
            dataGridView.BackgroundColor = backColor;
            dataGridView.DefaultCellStyle.BackColor = backColor;
            dataGridView.DefaultCellStyle.ForeColor = foreColor;

            // Dark mode ise DataGridView kenarlarını, sütun başlıklarını ve yan seçim alanını portakal rengi yap
            if (isDarkMode)
            {
                dataGridView.GridColor = Color.Orange;
                dataGridView.EnableHeadersVisualStyles = false;
                dataGridView.ColumnHeadersDefaultCellStyle.BackColor = Color.Orange;
                dataGridView.ColumnHeadersDefaultCellStyle.ForeColor = Color.Black;
                dataGridView.RowHeadersDefaultCellStyle.BackColor = Color.Orange;
                dataGridView.RowHeadersDefaultCellStyle.ForeColor = Color.Black;

                // Satır yüksekliğini ve yazı boyutunu ayarla
                dataGridView.RowTemplate.Height = 30; // Satır yüksekliği
                dataGridView.DefaultCellStyle.Font = new Font("Arial", 12, FontStyle.Regular); // Yazı boyutu

                // Satır çizgilerini kaldır
                dataGridView.CellBorderStyle = DataGridViewCellBorderStyle.None;

            }
            else
            {
                dataGridView.EnableHeadersVisualStyles = true;
                dataGridView.GridColor = foreColor;

                dataGridView.ColumnHeadersDefaultCellStyle.BackColor = backColor;
                dataGridView.ColumnHeadersDefaultCellStyle.ForeColor = foreColor;
                dataGridView.RowHeadersDefaultCellStyle.BackColor = backColor;
                dataGridView.RowHeadersDefaultCellStyle.ForeColor = foreColor;
            }
        }

        /// <summary>
        /// Recursively sets theme colors for controls.
        /// </summary>
        private void SetControlTheme(Control control, Color backColor, Color foreColor)
        {
            control.BackColor = backColor;
            control.ForeColor = foreColor;

            if (control.HasChildren)
            {
                foreach (Control child in control.Controls)
                {
                    SetControlTheme(child, backColor, foreColor);
                }
            }
        }

        /// <summary>
        /// Handles CellContentClick events for CheckBox columns to toggle favorite and pinned statuses.
        /// </summary>
        private void DataGridView_CellContentClick(object sender, DataGridViewCellEventArgs e)
        {
            if (e.RowIndex >= 0 && (dataGridView.Columns[e.ColumnIndex].Name == "favorite" || dataGridView.Columns[e.ColumnIndex].Name == "pinned"))
            {
                var flashcard = (FlashcardItem)dataGridView.Rows[e.RowIndex].DataBoundItem;
                bool newValue = !(bool)dataGridView.Rows[e.RowIndex].Cells[e.ColumnIndex].Value;

                if (dataGridView.Columns[e.ColumnIndex].Name == "favorite")
                {
                    flashcard.favorite = newValue;
                }
                else
                {
                    flashcard.pinned = newValue;
                }

                _ = UpdateFlashcardInDatabase(flashcard);
            }
        }

        /// <summary>
        /// Updates a flashcard in the Firebase database and local storage.
        /// </summary>
        private async Task UpdateFlashcardInDatabase(FlashcardItem flashcard)
        {
            try
            {
                // Update local data
                var index = allFlashcards.FindIndex(f => f.id == flashcard.id);
                if (index >= 0)
                {
                    allFlashcards[index] = flashcard;
                    SaveLocalData(); // Save to local storage
                }

                if (isOnline)
                {
                    await firebaseClient
                        .Child("flashcards")
                        .Child(flashcard.id)
                        .PutAsync(flashcard);
                }
                else
                {
                    // Add to offline changes
                    offlineChanges.Add(new FlashcardChange { ChangeType = ChangeType.Update, Flashcard = flashcard });
                }

                ApplyFiltersAndSort();
            }
            catch (Exception ex)
            {
                MessageBox.Show($"Error updating flashcard: {ex.Message}", "Error", MessageBoxButtons.OK, MessageBoxIcon.Error);
            }
        }

        private async Task LoadDataAsync()
        {
            try
            {
                if (isOnline)
                {
                    // We assume that real-time listener will update the data
                    // So we don't fetch all data here
                }

                // After data is loaded, populate the ContextMenuStrip
                PopulateColumnContextMenu();
            }
            catch (Exception ex)
            {
                MessageBox.Show($"Error loading data: {ex.Message}", "Error", MessageBoxButtons.OK, MessageBoxIcon.Error);
            }
        }

        private void ApplyFiltersAndSort()
        {
            // Başlangıç olarak tüm flashcard'ları al
            IEnumerable<FlashcardItem> filtered = allFlashcards;

            // Favoriler filtresini uygula
            if (chkFilterFavorites.Checked)
            {
                filtered = filtered.Where(f => f.favorite);
            }

            // Sabitlenmiş filtresini uygula
            if (chkFilterPinned.Checked)
            {
                filtered = filtered.Where(f => f.pinned);
            }

            // Arama filtresini uygula
            if (!string.IsNullOrWhiteSpace(currentSearchTerm))
            {
                filtered = filtered.Where(f =>
                    f.title.ToLower().Contains(currentSearchTerm) ||
                    f.category.ToLower().Contains(currentSearchTerm) ||
                    f.content.ToLower().Contains(currentSearchTerm));
            }

            // Listeye dönüştür
            List<FlashcardItem> filteredList = filtered.ToList();

            // Sıralama işlemini uygula
            if (!string.IsNullOrEmpty(currentSortColumn))
            {
                if (sortAscending)
                {
                    switch (currentSortColumn)
                    {
                        case "title":
                            filteredList = filteredList.OrderBy(f => f.title).ToList();
                            break;
                        case "timestamp":
                            filteredList = filteredList.OrderBy(f => f.timestamp).ToList();
                            break;
                    }
                }
                else
                {
                    switch (currentSortColumn)
                    {
                        case "title":
                            filteredList = filteredList.OrderByDescending(f => f.title).ToList();
                            break;
                        case "timestamp":
                            filteredList = filteredList.OrderByDescending(f => f.timestamp).ToList();
                            break;
                    }
                }
            }

            UpdateDataGridView(filteredList);
        }

        /// <summary>
        /// Updates the DataGridView with the provided list of flashcards.
        /// </summary>
        private void UpdateDataGridView(List<FlashcardItem> flashcards)
        {
            // SelectionChanged olayını geçici olarak devre dışı bırak
            dataGridView.SelectionChanged -= DataGridView_SelectionChanged;

            // DataGridView'i temizlemeden önce mevcut sütunları ve görünümleri kontrol et
            var columnSettings = new Dictionary<string, bool>();
            foreach (DataGridViewColumn column in dataGridView.Columns)
            {
                columnSettings[column.Name] = column.Visible;
            }

            dataGridView.DataSource = null;
            dataGridView.Columns.Clear();

            if (flashcards.Any())
            {
                dataGridView.AutoGenerateColumns = false;

                // Define DataGridView columns

                // ID Column - Hidden
                var idColumn = new DataGridViewTextBoxColumn
                {
                    DataPropertyName = "id",
                    HeaderText = "ID",
                    Name = "id",
                    Visible = false
                };
                dataGridView.Columns.Add(idColumn);

                // Category Column
                var categoryColumn = new DataGridViewTextBoxColumn
                {
                    DataPropertyName = "category",
                    HeaderText = "Category",
                    Name = "category",
                    SortMode = DataGridViewColumnSortMode.NotSortable
                };
                dataGridView.Columns.Add(categoryColumn);

                // Title Column
                var titleColumn = new DataGridViewTextBoxColumn
                {
                    DataPropertyName = "title",
                    HeaderText = "Title",
                    Name = "title",
                    SortMode = DataGridViewColumnSortMode.Programmatic
                };
                dataGridView.Columns.Add(titleColumn);

                // Content Column
                var contentColumn = new DataGridViewTextBoxColumn
                {
                    DataPropertyName = "content",
                    HeaderText = "Content",
                    Name = "content",
                    SortMode = DataGridViewColumnSortMode.NotSortable
                };
                dataGridView.Columns.Add(contentColumn);

                // Favorite Column (Checkbox)
                var favoriteColumn = new DataGridViewCheckBoxColumn
                {
                    DataPropertyName = "favorite",
                    HeaderText = "Favorite",
                    Name = "favorite",
                    SortMode = DataGridViewColumnSortMode.Automatic
                };
                dataGridView.Columns.Add(favoriteColumn);

                // Pinned Column (Checkbox)
                var pinnedColumn = new DataGridViewCheckBoxColumn
                {
                    DataPropertyName = "pinned",
                    HeaderText = "Pinned",
                    Name = "pinned",
                    SortMode = DataGridViewColumnSortMode.Automatic
                };
                dataGridView.Columns.Add(pinnedColumn);

                // Timestamp Column
                var timestampColumn = new DataGridViewTextBoxColumn
                {
                    DataPropertyName = "timestamp",
                    HeaderText = "Timestamp",
                    Name = "timestamp",
                    SortMode = DataGridViewColumnSortMode.Programmatic
                };
                dataGridView.Columns.Add(timestampColumn);

                // BackgroundColor Column
                var backgroundColorColumn = new DataGridViewTextBoxColumn
                {
                    DataPropertyName = "backgroundColor",
                    HeaderText = "Background Color",
                    Name = "backgroundColor",
                    SortMode = DataGridViewColumnSortMode.NotSortable
                };
                dataGridView.Columns.Add(backgroundColorColumn);

                dataGridView.DataSource = flashcards;
                dataGridView.ClearSelection(); // Seçimi temizle

                // Sütun görünürlüklerini geri yükle
                foreach (DataGridViewColumn column in dataGridView.Columns)
                {
                    if (columnSettings.ContainsKey(column.Name))
                    {
                        column.Visible = columnSettings[column.Name];
                    }
                }
            }
            else
            {
                // If no flashcards match the filters, display a message
                var messageColumn = new DataGridViewTextBoxColumn
                {
                    HeaderText = "Message",
                    Name = "Message",
                    AutoSizeMode = DataGridViewAutoSizeColumnMode.Fill
                };
                dataGridView.Columns.Add(messageColumn);
                dataGridView.Rows.Add("No flashcards found.");
            }

            // Restore column visibility state
            RestoreColumnVisibilityState();

            // Update the status label with the count
            statusLabel.Text = $"Total Items: {flashcards.Count}";

            // SelectionChanged olayını tekrar etkinleştir
            dataGridView.SelectionChanged += DataGridView_SelectionChanged;
        }

        /// <summary>
        /// Populates the ContextMenuStrip with the current DataGridView columns.
        /// Ensures no duplicate menu items are added.
        /// </summary>
        private void PopulateColumnContextMenu()
        {
            columnContextMenu.Items.Clear(); // Clear existing items to prevent duplication

            foreach (DataGridViewColumn column in dataGridView.Columns)
            {
                // Skip hidden or irrelevant columns if necessary
                // For example, you might want to skip the "ID" column
                if (column.Name == "id") continue;

                // Create a ToolStripMenuItem for the column
                var menuItem = new ToolStripMenuItem(column.HeaderText)
                {
                    Checked = column.Visible,
                    CheckOnClick = true,
                    Tag = column // Store the column in Tag for reference
                };
                menuItem.CheckedChanged += ColumnMenuItem_CheckedChanged;

                // Add the menu item to the ContextMenuStrip
                columnContextMenu.Items.Add(menuItem);
            }
        }

        /// <summary>
        /// Handles the CheckedChanged event of ContextMenuStrip items to toggle column visibility.
        /// </summary>
        private void ColumnMenuItem_CheckedChanged(object sender, EventArgs e)
        {
            if (sender is ToolStripMenuItem menuItem && menuItem.Tag is DataGridViewColumn column)
            {
                column.Visible = menuItem.Checked;
                columnVisibilityState[column.Name] = column.Visible; // Update the visibility state
            }
        }

        /// <summary>
        /// Shows the ContextMenuStrip when the user right-clicks on a column header.
        /// </summary>
        private void DataGridView_MouseUp(object sender, MouseEventArgs e)
        {
            if (e.Button == MouseButtons.Right)
            {
                var hitTestInfo = dataGridView.HitTest(e.X, e.Y);
                if (hitTestInfo.Type == DataGridViewHitTestType.ColumnHeader)
                {
                    // Show the ContextMenuStrip at the mouse position
                    columnContextMenu.Show(dataGridView, new Point(e.X, e.Y));
                }
            }
        }

        /// <summary>
        /// Handles the Form Load event to initially load data and start real-time listener.
        /// </summary>
        private async void MainForm_Load(object sender, EventArgs e)
        {
            LoadCustomTags(); // Eklendi

            // Load local data first
            LoadLocalData();
            ApplyFiltersAndSort();

            // Varsayılan sıralamayı ayarladık
            currentSortColumn = "timestamp";
            sortAscending = false;

            // Start online status timer
            onlineStatusTimer.Start();

            if (CheckInternetConnection())
            {
                isOnline = true;
                // Start real-time listener if not already started
                if (!isListening)
                {
                    RealTimeListener();
                }
                await ProcessOfflineChanges();
            }
            else
            {
                isOnline = false;
            }
        }

        /// <summary>
        /// Adds a new flashcard to the Firebase database and local storage.
        /// </summary>
        private async void AddData()
        {
            var newFlashcard = CreateFlashcardFromInputs();
            if (newFlashcard != null)
            {
                try
                {
                    // Check if the flashcard already exists to prevent duplicate entries
                    if (IsDuplicateFlashcard(newFlashcard))
                    {
                        MessageBox.Show("This flashcard already exists.", "Duplicate Entry", MessageBoxButtons.OK, MessageBoxIcon.Information);
                        return;
                    }

                    newFlashcard.id = Guid.NewGuid().ToString();

                    if (isOnline)
                    {
                        await firebaseClient
                            .Child("flashcards")
                            .Child(newFlashcard.id)
                            .PutAsync(newFlashcard);

                        // Do not add to allFlashcards here; real-time listener will handle it
                    }
                    else
                    {
                        // Add to offline changes
                        offlineChanges.Add(new FlashcardChange { ChangeType = ChangeType.Add, Flashcard = newFlashcard });

                        // Update local data
                        allFlashcards.Add(newFlashcard);
                        SaveLocalData();

                        ApplyFiltersAndSort();
                    }

                    ClearInputs();
                }
                catch (Exception ex)
                {
                    MessageBox.Show($"Error adding flashcard: {ex.Message}", "Error", MessageBoxButtons.OK, MessageBoxIcon.Error);
                }
            }
        }

        /// <summary>
        /// Checks if a flashcard with the same content already exists.
        /// </summary>
        private bool IsDuplicateFlashcard(FlashcardItem newFlashcard)
        {
            return allFlashcards.Any(f =>
                f.title == newFlashcard.title &&
                f.category == newFlashcard.category &&
                f.content == newFlashcard.content);
        }

        /// <summary>
        /// Updates the selected flashcard in the Firebase database and local storage.
        /// </summary>
        private async void UpdateData()
        {
            if (dataGridView.SelectedRows.Count > 0)
            {
                var selectedFlashcard = (FlashcardItem)dataGridView.SelectedRows[0].DataBoundItem;
                var updatedFlashcard = CreateFlashcardFromInputs();
                if (updatedFlashcard != null)
                {
                    updatedFlashcard.id = selectedFlashcard.id;
                    updatedFlashcard.timestamp = selectedFlashcard.timestamp; // Zaman damgasını koru

                    // Check for duplicates excluding the current flashcard
                    if (IsDuplicateFlashcardExcludingCurrent(updatedFlashcard))
                    {
                        MessageBox.Show("A flashcard with the same content already exists.", "Duplicate Entry", MessageBoxButtons.OK, MessageBoxIcon.Information);
                        return;
                    }

                    try
                    {
                        if (isOnline)
                        {
                            await firebaseClient
                                .Child("flashcards")
                                .Child(updatedFlashcard.id)
                                .PutAsync(updatedFlashcard);

                            // Do not update allFlashcards here; real-time listener will handle it
                        }
                        else
                        {
                            // Add to offline changes
                            offlineChanges.Add(new FlashcardChange { ChangeType = ChangeType.Update, Flashcard = updatedFlashcard });

                            // Update local data
                            var index = allFlashcards.FindIndex(f => f.id == updatedFlashcard.id);
                            if (index >= 0)
                            {
                                allFlashcards[index] = updatedFlashcard;
                                SaveLocalData();

                                ApplyFiltersAndSort();
                            }
                        }

                        ClearInputs();
                    }
                    catch (Exception ex)
                    {
                        MessageBox.Show($"Error updating flashcard: {ex.Message}", "Error", MessageBoxButtons.OK, MessageBoxIcon.Error);
                    }
                }
            }
            else
            {
                MessageBox.Show("Please select a flashcard to update.", "No Selection", MessageBoxButtons.OK, MessageBoxIcon.Warning);
            }
        }

        /// <summary>
        /// Checks for duplicates excluding the current flashcard being updated.
        /// </summary>
        private bool IsDuplicateFlashcardExcludingCurrent(FlashcardItem updatedFlashcard)
        {
            return allFlashcards.Any(f =>
                f.id != updatedFlashcard.id &&
                f.title == updatedFlashcard.title &&
                f.category == updatedFlashcard.category &&
                f.content == updatedFlashcard.content);
        }

        /// <summary>
        /// Deletes selected flashcards from the Firebase database and local storage.
        /// </summary>
        private async void DeleteData()
        {
            if (dataGridView.SelectedRows.Count > 0)
            {
                int selectedCount = dataGridView.SelectedRows.Count;
                var confirmResult = MessageBox.Show($"Are you sure you want to delete {selectedCount} flashcard(s)?",
                                                    "Confirm Delete",
                                                    MessageBoxButtons.YesNo,
                                                    MessageBoxIcon.Question);
                if (confirmResult == DialogResult.Yes)
                {
                    try
                    {
                        var idsToDelete = dataGridView.SelectedRows
                            .Cast<DataGridViewRow>()
                            .Select(row => ((FlashcardItem)row.DataBoundItem).id)
                            .ToList();

                        if (isOnline)
                        {
                            // Create a list of delete tasks
                            var deleteTasks = idsToDelete
                                .Select(id => firebaseClient.Child("flashcards").Child(id).DeleteAsync())
                                .ToList();

                            // Execute all delete tasks in parallel
                            await Task.WhenAll(deleteTasks);

                            // Do not remove from allFlashcards; real-time listener will handle it
                        }
                        else
                        {
                            // Add to offline changes
                            foreach (var id in idsToDelete)
                            {
                                var flashcard = allFlashcards.FirstOrDefault(f => f.id == id);
                                if (flashcard != null)
                                {
                                    offlineChanges.Add(new FlashcardChange { ChangeType = ChangeType.Delete, Flashcard = flashcard });
                                }
                            }

                            // Remove from local data
                            allFlashcards.RemoveAll(f => idsToDelete.Contains(f.id));
                            SaveLocalData();

                            ApplyFiltersAndSort();
                        }

                        // Clear inputs
                        ClearInputs();

                        MessageBox.Show($"{selectedCount} flashcard(s) deleted successfully!",
                                        "Success",
                                        MessageBoxButtons.OK,
                                        MessageBoxIcon.Information);
                    }
                    catch (Exception ex)
                    {
                        MessageBox.Show($"Error deleting flashcards: {ex.Message}",
                                        "Error",
                                        MessageBoxButtons.OK,
                                        MessageBoxIcon.Error);
                    }
                }
            }
            else
            {
                MessageBox.Show("Please select one or more flashcards to delete.",
                                "No Selection",
                                MessageBoxButtons.OK,
                                MessageBoxIcon.Warning);
            }
        }

        /// <summary>
        /// Creates a FlashcardItem object from the input fields.
        /// </summary>
        private FlashcardItem CreateFlashcardFromInputs()
        {
            string title = txtTitle.Text.Trim();
            string content = txtContent.Text.Trim();
            string backgroundColor = txtBackgroundColor.Text.Trim();

            // Kategori belirleme
            string category;
            if (!string.IsNullOrWhiteSpace(selectedCustomTag))
            {
                category = selectedCustomTag;
            }
            else if (!string.IsNullOrWhiteSpace(txtCategory.Text))
            {
                category = txtCategory.Text.Trim();
            }
            else
            {
                category = "uncategorized";
            }

            return new FlashcardItem
            {
                title = title,
                category = category,
                content = content,
                favorite = chkFavorite.Checked,
                pinned = chkPinned.Checked,
                timestamp = DateTimeOffset.UtcNow.ToUnixTimeMilliseconds(),
                backgroundColor = backgroundColor
            };
        }

        /// <summary>
        /// Clears the input fields.
        /// </summary>
        private void ClearInputs()
        {
            txtTitle.Text = "";
            txtCategory.Text = "";
            txtContent.Text = "";
            txtBackgroundColor.Text = "";
            chkFavorite.Checked = false;
            chkPinned.Checked = false;
        }

        /// <summary>
        /// Handles the selection change in the DataGridView to populate the input fields.
        /// </summary>
        private void DataGridView_SelectionChanged(object sender, EventArgs e)
        {
            if (dataGridView.SelectedRows.Count > 0)
            {
                var selectedFlashcard = (FlashcardItem)dataGridView.SelectedRows[0].DataBoundItem;
                txtTitle.Text = selectedFlashcard.title;
                txtTitle.ForeColor = Color.Black;
                txtCategory.Text = selectedFlashcard.category;
                txtCategory.ForeColor = Color.Black;
                txtContent.Text = selectedFlashcard.content;
                txtContent.ForeColor = Color.Black;
                txtBackgroundColor.Text = selectedFlashcard.backgroundColor;
                txtBackgroundColor.ForeColor = Color.Black;
                chkFavorite.Checked = selectedFlashcard.favorite;
                chkPinned.Checked = selectedFlashcard.pinned;
            }
            else
            {
                // Seçim yoksa metin kutularını temizle
                ClearInputs();
            }
        }

        /// <summary>
        /// Sets up a real-time listener to Firebase to update data upon changes.
        /// </summary>
        private void RealTimeListener()
        {
            isListening = true;

            firebaseClient
                .Child("flashcards")
                .AsObservable<FlashcardItem>()
                .Subscribe(d =>
                {
                    if (d.Object != null)
                    {
                        HandleRealTimeUpdate(d.Key, d.EventType, d.Object);
                    }
                    else if (d.EventType == FirebaseEventType.Delete)
                    {
                        HandleRealTimeUpdate(d.Key, d.EventType, null);
                    }
                });
        }

        /// <summary>
        /// Handles real-time updates from Firebase.
        /// </summary>
        /// <param name="key">Firebase key</param>
        /// <param name="eventType">Event Type</param>
        /// <param name="flashcard">The updated flashcard item.</param>
        private void HandleRealTimeUpdate(string key, FirebaseEventType eventType, FlashcardItem flashcard)
        {
            // Ensure that the id is set properly
            if (flashcard != null)
            {
                flashcard.id = key;
            }

            Invoke((Action)(() =>
            {
                var index = allFlashcards.FindIndex(f => f.id == key);

                if (eventType == FirebaseEventType.Delete)
                {
                    if (index >= 0)
                    {
                        allFlashcards.RemoveAt(index);
                        SaveLocalData();
                        ApplyFiltersAndSort();
                    }
                }
                else
                {
                    if (index >= 0)
                    {
                        // Update existing item
                        allFlashcards[index] = flashcard;
                    }
                    else
                    {
                        // Add new item only if it doesn't exist
                        allFlashcards.Add(flashcard);
                    }
                    SaveLocalData();
                    ApplyFiltersAndSort();
                }
            }));
        }

        private void SaveLocalData()
        {
            try
            {
                string json = JsonConvert.SerializeObject(allFlashcards);
                File.WriteAllText(localDataFilePath, json);
            }
            catch (Exception ex)
            {
                MessageBox.Show($"Error saving local data: {ex.Message}", "Error", MessageBoxButtons.OK, MessageBoxIcon.Error);
            }
        }

        private void LoadLocalData()
        {
            if (File.Exists(localDataFilePath))
            {
                try
                {
                    string json = File.ReadAllText(localDataFilePath);
                    allFlashcards = JsonConvert.DeserializeObject<List<FlashcardItem>>(json);
                }
                catch (Exception ex)
                {
                    MessageBox.Show($"Error loading local data: {ex.Message}", "Error", MessageBoxButtons.OK, MessageBoxIcon.Error);
                }
            }
            else
            {
                allFlashcards = new List<FlashcardItem>();
            }
        }

        /// <summary>
        /// Checks if there is an active internet connection.
        /// </summary>
        /// <returns>True if online, otherwise false.</returns>
        private bool CheckInternetConnection()
        {
            try
            {
                using (var client = new System.Net.WebClient())
                using (client.OpenRead("http://clients3.google.com/generate_204"))
                    return true;
            }
            catch
            {
                return false;
            }
        }

        /// <summary>
        /// Handles the Search button click to apply search criteria.
        /// </summary>
        private void SearchData()
        {
            string searchText = txtSearch.Text;
            if (string.IsNullOrWhiteSpace(searchText))
            {
                currentSearchTerm = "";
            }
            else
            {
                currentSearchTerm = searchText.ToLower();
            }

            ApplyFiltersAndSort();
        }

        /// <summary>
        /// Clears the search input and resets search filter.
        /// </summary>
        private void ClearSearch()
        {
            txtSearch.Text = "";
            currentSearchTerm = "";
            ApplyFiltersAndSort();
        }

        /// <summary>
        /// Formats the timestamp column to display human-readable dates.
        /// </summary>
        private void DataGridView_CellFormatting(object sender, DataGridViewCellFormattingEventArgs e)
        {
            if (dataGridView.Columns[e.ColumnIndex].Name == "timestamp")
            {
                if (e.Value != null && long.TryParse(e.Value.ToString(), out long timestamp))
                {
                    DateTimeOffset dateTimeOffset = DateTimeOffset.FromUnixTimeMilliseconds(timestamp);
                    DateTime dateTime = dateTimeOffset.ToLocalTime().DateTime;
                    e.Value = dateTime.ToString("yyyy-MM-dd HH:mm:ss");
                    e.FormattingApplied = true;
                }
            }
        }

        /// <summary>
        /// Handles the column header click event to apply sorting.
        /// </summary>
        private void DataGridView_ColumnHeaderMouseClick(object sender, DataGridViewCellMouseEventArgs e)
        {
            string columnName = dataGridView.Columns[e.ColumnIndex].Name;

            // Only allow sorting on 'title' and 'timestamp' columns
            if (columnName == "title" || columnName == "timestamp")
            {
                // Toggle sort direction if the same column is clicked
                if (currentSortColumn == columnName)
                {
                    sortAscending = !sortAscending;
                }
                else
                {
                    // Default to ascending if a new column is clicked
                    currentSortColumn = columnName;
                    sortAscending = true;
                }

                // Apply sorting and refresh DataGridView
                ApplyFiltersAndSort();

                // Reset sort glyphs on all columns
                foreach (DataGridViewColumn column in dataGridView.Columns)
                {
                    column.HeaderCell.SortGlyphDirection = SortOrder.None;
                }

                // Set sort glyph on the sorted column
                dataGridView.Columns[e.ColumnIndex].HeaderCell.SortGlyphDirection = sortAscending ? SortOrder.Ascending : SortOrder.Descending;
            }
        }

        /// <summary>
        /// Handles CheckedChanged events for filtering CheckBoxes.
        /// </summary>
        private void FilterCheckBoxChanged(object sender, EventArgs e)
        {
            ApplyFiltersAndSort();
        }

        /// <summary>
        /// Restores the column visibility state from the stored dictionary.
        /// </summary>
        private void RestoreColumnVisibilityState()
        {
            foreach (DataGridViewColumn column in dataGridView.Columns)
            {
                if (columnVisibilityState.TryGetValue(column.Name, out bool isVisible))
                {
                    column.Visible = isVisible;
                }
            }
        }

        /// <summary>
        /// Handles MouseDown event on the background panel to clear inputs.
        /// </summary>
        private void BackgroundPanel_MouseDown(object sender, MouseEventArgs e)
        {
            ClearInputs();
        }

        // Yeni Eklenen Metodlar ve Event Handler'lar

        private void ClipboardOnMenuItem_Click(object sender, EventArgs e)
        {
            StartClipboardMonitoring();
            tagCheckedListBox.Visible = true; // Clipboard modu açılırken görünür yap
        }

        private void ClipboardOffMenuItem_Click(object sender, EventArgs e)
        {
            StopClipboardMonitoring();
            tagCheckedListBox.Visible = false; // Clipboard modu kapanırken gizle
        }

        private void StartClipboardMonitoring()
        {
            clipboardOnMenuItem.Checked = true;
            clipboardOffMenuItem.Checked = false;

            // Panodaki mevcut metni alarak lastClipboardText'e atıyoruz
            if (Clipboard.ContainsText())
            {
                lastClipboardText = Clipboard.GetText();
            }
            else
            {
                lastClipboardText = null;
            }

            clipboardMonitorTimer.Start();
        }

        private void StopClipboardMonitoring()
        {
            clipboardOnMenuItem.Checked = false;
            clipboardOffMenuItem.Checked = true;

            clipboardMonitorTimer.Stop();
        }

        private async void ClipboardMonitorTimer_Tick(object sender, EventArgs e)
        {
            await CheckClipboard();
        }

        private async Task CheckClipboard()
        {
            try
            {
                if (Clipboard.ContainsText())
                {
                    string clipboardText = Clipboard.GetText();

                    if (clipboardText != lastClipboardText)
                    {
                        lastClipboardText = clipboardText;

                        // Metni tek satıra dönüştür
                        string singleLineText = clipboardText.Replace(Environment.NewLine, " ");

                        // Kategori belirleme
                        string category;
                        if (!string.IsNullOrWhiteSpace(selectedCustomTag))
                        {
                            // Eğer Custom Tag altında bir etiket seçildiyse
                            category = selectedCustomTag;
                        }
                        else if (tagCheckedListBox.CheckedItems.Count > 0)
                        {
                            // Eğer tagCheckedListBox'dan bir etiket seçildiyse
                            category = tagCheckedListBox.CheckedItems[0].ToString();
                        }
                        else
                        {
                            // Hiçbir etiket seçili değilse varsayılan olarak "uncategorized" kullan
                            category = "uncategorized";
                        }

                        // Yeni FlashcardItem oluştur
                        var newFlashcard = new FlashcardItem
                        {
                            title = "", // Başlık boş
                            category = category, // Belirlenen kategoriyi kullan
                            content = singleLineText,
                            favorite = false,
                            pinned = false,
                            timestamp = DateTimeOffset.UtcNow.ToUnixTimeMilliseconds(),
                            backgroundColor = ""
                        };

                        // Veritabanına kaydet
                        await SaveFlashcardToDatabase(newFlashcard);
                    }
                }
            }
            catch (Exception ex)
            {
                // Pano erişiminde hata olursa burası çalışacak
                // İsterseniz hata mesajı gösterebilirsiniz
            }
        }

        private async Task SaveFlashcardToDatabase(FlashcardItem flashcard)
        {
            try
            {
                // Check if the flashcard already exists to prevent duplicate entries
                if (IsDuplicateFlashcard(flashcard))
                {
                    // You can choose to notify the user here if desired
                    return;
                }

                flashcard.id = Guid.NewGuid().ToString();

                if (isOnline)
                {
                    await firebaseClient
                        .Child("flashcards")
                        .Child(flashcard.id)
                        .PutAsync(flashcard);

                    // Do not add to allFlashcards here; real-time listener will handle it
                }
                else
                {
                    // Add to offline changes
                    offlineChanges.Add(new FlashcardChange { ChangeType = ChangeType.Add, Flashcard = flashcard });

                    // Add to local data
                    allFlashcards.Add(flashcard);
                    SaveLocalData();

                    ApplyFiltersAndSort();
                }
            }
            catch (Exception ex)
            {
                // Hata yönetimi
            }
        }

        private void LoadTagsMenuItem_Click(object sender, EventArgs e)
        {
            using (FolderBrowserDialog folderBrowserDialog = new FolderBrowserDialog())
            {
                folderBrowserDialog.Description = "Klasör Seçin";
                if (folderBrowserDialog.ShowDialog() == DialogResult.OK)
                {
                    string selectedFolder = folderBrowserDialog.SelectedPath;

                    // Klasördeki ve alt klasörlerdeki PDF dosyalarını al
                    string[] pdfFiles = Directory.GetFiles(selectedFolder, "*.pdf", SearchOption.AllDirectories);

                    // Dosya isimlerini al (uzantısız)
                    List<string> tags = pdfFiles.Select(file => Path.GetFileNameWithoutExtension(file)).ToList();

                    // CheckedListBox'ı güncelle
                    tagCheckedListBox.Items.Clear();
                    foreach (var tag in tags)
                    {
                        tagCheckedListBox.Items.Add(tag);
                    }
                }
            }
        }

        private void TagCheckedListBox_ItemCheck(object sender, ItemCheckEventArgs e)
        {
            // İşaretlenen diğer öğeleri kaldır, sadece bir tanesi seçili olsun
            if (e.NewValue == CheckState.Checked)
            {
                for (int i = 0; i < tagCheckedListBox.Items.Count; i++)
                {
                    if (i != e.Index)
                    {
                        tagCheckedListBox.SetItemChecked(i, false);
                    }
                }
                selectedTag = tagCheckedListBox.Items[e.Index].ToString();

                // Custom Tag seçimini kaldır
                foreach (ToolStripMenuItem item in customTagMenuItem.DropDownItems)
                {
                    if (item != addTagMenuItem && item != manageTagsMenuItem)
                    {
                        item.Checked = false;
                    }
                }
                selectedCustomTag = null;
            }
            else
            {
                selectedTag = "uncategorized";
            }
        }

        private void AddTagMenuItem_Click(object sender, EventArgs e)
        {
            using (Form inputDialog = new Form())
            {
                inputDialog.Width = 300;
                inputDialog.Height = 150;
                inputDialog.Text = "Add Custom Tag";
                inputDialog.FormBorderStyle = FormBorderStyle.FixedDialog;
                inputDialog.StartPosition = FormStartPosition.CenterParent; // Ekranın ortasında açılsın
                inputDialog.MinimizeBox = false;
                inputDialog.MaximizeBox = false;
                inputDialog.AcceptButton = null; // We'll set the accept button later

                Label lblTag = new Label()
                {
                    Left = 20,
                    Top = 20,
                    Text = "Tag:",
                    AutoSize = false, // Otomatik boyutlandırmayı kapatıyoruz
                    Width = 40, // Daha dar bir genişlik veriyoruz
                    TextAlign = ContentAlignment.TopCenter // Metni sola hizalıyoruz
                };
                TextBox txtTag = new TextBox() { Left = lblTag.Left + lblTag.Width + 5, Top = lblTag.Top - 3, Width = 150 }; // Metin kutusunu etikete yaklaştırıyoruz
                Button btnOK = new Button() { Text = "OK", Left = 50, Width = 100, Top = txtTag.Top + txtTag.Height + 20 };
                Button btnCancel = new Button() { Text = "Cancel", Left = 150, Width = 100, Top = txtTag.Top + txtTag.Height + 20 };

                btnOK.Click += (s, args) =>
                {
                    string newTag = txtTag.Text.Trim();
                    if (!string.IsNullOrEmpty(newTag))
                    {
                        // Add tag to customTags list
                        customTags.Add(newTag);

                        // Save the custom tags to the file
                        SaveCustomTags(); // Eklendi

                        // Add tag as submenu item under customTagMenuItem
                        AddCustomTagMenuItem(newTag);
                        // Close the dialog
                        inputDialog.DialogResult = DialogResult.OK;
                        inputDialog.Close();
                    }
                    else
                    {
                        MessageBox.Show("Tag cannot be empty.", "Error", MessageBoxButtons.OK, MessageBoxIcon.Error);
                    }
                };

                btnCancel.Click += (s, args) =>
                {
                    inputDialog.DialogResult = DialogResult.Cancel;
                    inputDialog.Close();
                };

                inputDialog.Controls.Add(lblTag);
                inputDialog.Controls.Add(txtTag);
                inputDialog.Controls.Add(btnOK);
                inputDialog.Controls.Add(btnCancel);
                inputDialog.AcceptButton = btnOK;

                inputDialog.ShowDialog(); // Show as modal dialog
            }
        }

        private void AddCustomTagMenuItem(string tag)
        {
            ToolStripMenuItem tagMenuItem = new ToolStripMenuItem(tag);
            tagMenuItem.Checked = false;
            tagMenuItem.CheckOnClick = true;

            tagMenuItem.Click += TagMenuItem_Click;

            // Insert the tag menu item after the "Manage Tags" menu item
            int insertIndex = customTagMenuItem.DropDownItems.IndexOf(manageTagsMenuItem) + 1;
            customTagMenuItem.DropDownItems.Insert(insertIndex, tagMenuItem);
        }

        private void TagMenuItem_Click(object sender, EventArgs e)
        {
            // When a tag is clicked, uncheck other tags
            if (sender is ToolStripMenuItem clickedItem)
            {
                foreach (ToolStripMenuItem item in customTagMenuItem.DropDownItems)
                {
                    if (item != clickedItem && item != addTagMenuItem && item != manageTagsMenuItem)
                    {
                        item.Checked = false;
                    }
                }
                // Update the selectedCustomTag
                if (clickedItem.Checked)
                {
                    selectedCustomTag = clickedItem.Text;

                    // CheckedListBox'daki tüm seçimleri kaldır
                    tagCheckedListBox.ItemCheck -= TagCheckedListBox_ItemCheck; // Event geçici olarak devre dışı
                    for (int i = 0; i < tagCheckedListBox.Items.Count; i++)
                    {
                        tagCheckedListBox.SetItemChecked(i, false);
                    }
                    tagCheckedListBox.ItemCheck += TagCheckedListBox_ItemCheck; // Event tekrar aktif
                    selectedTag = "uncategorized";
                }
                else
                {
                    selectedCustomTag = null;
                }
            }
        }

        // Event handler for "Manage Tags" menu item click
        private void ManageTagsMenuItem_Click(object sender, EventArgs e)
        {
            // Open a dialog to manage tags
            using (Form manageTagsForm = new Form())
            {
                manageTagsForm.Width = 300;
                manageTagsForm.Height = 400;
                manageTagsForm.Text = "Manage Tags";
                manageTagsForm.FormBorderStyle = FormBorderStyle.FixedDialog;
                manageTagsForm.StartPosition = FormStartPosition.CenterParent; // Ekranın ortasında açılsın
                manageTagsForm.MinimizeBox = false;
                manageTagsForm.MaximizeBox = false;

                ListBox lstTags = new ListBox() { Left = 10, Top = 10, Width = 260, Height = 300 };
                lstTags.DataSource = null;
                lstTags.DataSource = new List<string>(customTags);

                Button btnEdit = new Button() { Text = "Edit", Left = 10, Width = 80, Top = lstTags.Bottom + 10 };
                Button btnDelete = new Button() { Text = "Delete", Left = 100, Width = 80, Top = lstTags.Bottom + 10 };
                Button btnClose = new Button() { Text = "Close", Left = 190, Width = 80, Top = lstTags.Bottom + 10 };

                btnEdit.Click += (s, args) =>
                {
                    if (lstTags.SelectedItem != null)
                    {
                        string selectedTag = lstTags.SelectedItem.ToString();
                        using (Form editTagForm = new Form())
                        {
                            editTagForm.Width = 300;
                            editTagForm.Height = 150;
                            editTagForm.Text = "Edit Tag";
                            editTagForm.FormBorderStyle = FormBorderStyle.FixedDialog;
                            editTagForm.StartPosition = FormStartPosition.CenterParent; // Ekranın ortasında açılsın
                            editTagForm.MinimizeBox = false;
                            editTagForm.MaximizeBox = false;

                            Label lblTag = new Label()
                            {
                                Left = 10,
                                Top = 20,
                                Text = "Tag:",
                                AutoSize = false,
                                Width = 40, // Daha küçük bir genişlik veriyoruz
                                TextAlign = ContentAlignment.TopCenter
                            };
                            TextBox txtTag = new TextBox() { Left = lblTag.Left + lblTag.Width + 5, Top = lblTag.Top - 3, Width = 150 }; // Metin kutusunu etikete yaklaştırıyoruz
                            Button btnOK = new Button() { Text = "OK", Left = 50, Width = 100, Top = txtTag.Top + txtTag.Height + 20 };
                            Button btnCancel = new Button() { Text = "Cancel", Left = 150, Width = 100, Top = txtTag.Top + txtTag.Height + 20 };

                            btnOK.Click += (s2, args2) =>
                            {
                                string newTag = txtTag.Text.Trim();
                                if (!string.IsNullOrEmpty(newTag))
                                {
                                    // Update the tag in customTags list
                                    int index = customTags.IndexOf(selectedTag);
                                    customTags[index] = newTag;

                                    // Save the custom tags to the file
                                    SaveCustomTags(); // Eklendi

                                    // Update the menu item text
                                    foreach (ToolStripMenuItem item in customTagMenuItem.DropDownItems)
                                    {
                                        if (item.Text == selectedTag)
                                        {
                                            item.Text = newTag;
                                            break;
                                        }
                                    }

                                    // Update selectedCustomTag if this tag was the selected one
                                    if (selectedCustomTag == selectedTag)
                                    {
                                        selectedCustomTag = newTag;
                                    }

                                    // Update the listbox
                                    lstTags.DataSource = null;
                                    lstTags.DataSource = new List<string>(customTags);

                                    // Close the edit form
                                    editTagForm.DialogResult = DialogResult.OK;
                                    editTagForm.Close();
                                }
                                else
                                {
                                    MessageBox.Show("Tag cannot be empty.", "Error", MessageBoxButtons.OK, MessageBoxIcon.Error);
                                }
                            };

                            btnCancel.Click += (s2, args2) =>
                            {
                                editTagForm.DialogResult = DialogResult.Cancel;
                                editTagForm.Close();
                            };

                            editTagForm.Controls.Add(lblTag);
                            editTagForm.Controls.Add(txtTag);
                            editTagForm.Controls.Add(btnOK);
                            editTagForm.Controls.Add(btnCancel);
                            editTagForm.AcceptButton = btnOK;

                            editTagForm.ShowDialog();
                        }
                    }
                    else
                    {
                        MessageBox.Show("Please select a tag to edit.", "Information", MessageBoxButtons.OK, MessageBoxIcon.Information);
                    }
                };

                btnDelete.Click += (s, args) =>
                {
                    if (lstTags.SelectedItem != null)
                    {
                        string selectedTag = lstTags.SelectedItem.ToString();

                        var confirmResult = MessageBox.Show($"Are you sure you want to delete tag '{selectedTag}'?",
                                            "Confirm Delete",
                                            MessageBoxButtons.YesNo,
                                            MessageBoxIcon.Question);
                        if (confirmResult == DialogResult.Yes)
                        {
                            // Remove from customTags list
                            customTags.Remove(selectedTag);

                            // Save the custom tags to the file
                            SaveCustomTags(); // Eklendi

                            // Remove from menu items
                            ToolStripMenuItem itemToRemove = null;
                            foreach (ToolStripMenuItem item in customTagMenuItem.DropDownItems)
                            {
                                if (item.Text == selectedTag)
                                {
                                    itemToRemove = item;
                                    break;
                                }
                            }
                            if (itemToRemove != null)
                            {
                                customTagMenuItem.DropDownItems.Remove(itemToRemove);
                            }

                            // Clear selectedCustomTag if it was deleted
                            if (selectedCustomTag == selectedTag)
                            {
                                selectedCustomTag = null;
                            }

                            // Update the listbox
                            lstTags.DataSource = null;
                            lstTags.DataSource = new List<string>(customTags);
                        }
                    }
                    else
                    {
                        MessageBox.Show("Please select a tag to delete.", "Information", MessageBoxButtons.OK, MessageBoxIcon.Information);
                    }
                };

                btnClose.Click += (s, args) =>
                {
                    manageTagsForm.Close();
                };

                manageTagsForm.Controls.Add(lstTags);
                manageTagsForm.Controls.Add(btnEdit);
                manageTagsForm.Controls.Add(btnDelete);
                manageTagsForm.Controls.Add(btnClose);

                manageTagsForm.ShowDialog();
            }
        }

        // Custom Tags'i kaydetme metodu
        private void SaveCustomTags()
        {
            try
            {
                string json = JsonConvert.SerializeObject(customTags);
                File.WriteAllText(customTagsFilePath, json);
            }
            catch (Exception ex)
            {
                MessageBox.Show($"Error saving custom tags: {ex.Message}", "Error", MessageBoxButtons.OK, MessageBoxIcon.Error);
            }
        }

        // Custom Tags'i yükleme metodu
        private void LoadCustomTags()
        {
            if (File.Exists(customTagsFilePath))
            {
                try
                {
                    string json = File.ReadAllText(customTagsFilePath);
                    customTags = JsonConvert.DeserializeObject<List<string>>(json);

                    // customTagMenuItem içindeki mevcut özel etiketleri temizleyelim (Add Tag ve Manage Tags hariç)
                    for (int i = customTagMenuItem.DropDownItems.Count - 1; i >= 0; i--)
                    {
                        var item = customTagMenuItem.DropDownItems[i];
                        if (item != addTagMenuItem && item != manageTagsMenuItem)
                        {
                            customTagMenuItem.DropDownItems.RemoveAt(i);
                        }
                    }

                    // customTags listesindeki etiketleri menüye ekleyelim
                    foreach (var tag in customTags)
                    {
                        AddCustomTagMenuItem(tag);
                    }
                }
                catch (Exception ex)
                {
                    MessageBox.Show($"Error loading custom tags: {ex.Message}", "Error", MessageBoxButtons.OK, MessageBoxIcon.Error);
                }
            }
        }

        private async void OnlineStatusTimer_Tick(object sender, EventArgs e)
        {
            bool currentlyOnline = CheckInternetConnection();
            if (currentlyOnline && !isOnline)
            {
                // We were offline, now online
                isOnline = true;
                await ProcessOfflineChanges();
                // Start real-time listener if not already started
                if (!isListening)
                {
                    RealTimeListener();
                }
            }
            else if (!currentlyOnline && isOnline)
            {
                // We were online, now offline
                isOnline = false;
            }
        }

        private async Task ProcessOfflineChanges()
        {
            foreach (var change in offlineChanges)
            {
                switch (change.ChangeType)
                {
                    case ChangeType.Add:
                        // Assume change.Flashcard.id already set
                        await firebaseClient
                            .Child("flashcards")
                            .Child(change.Flashcard.id)
                            .PutAsync(change.Flashcard);
                        break;
                    case ChangeType.Update:
                        await firebaseClient
                            .Child("flashcards")
                            .Child(change.Flashcard.id)
                            .PutAsync(change.Flashcard);
                        break;
                    case ChangeType.Delete:
                        await firebaseClient
                            .Child("flashcards")
                            .Child(change.Flashcard.id)
                            .DeleteAsync();
                        break;
                }
            }
            offlineChanges.Clear();
        }
    }

    /// <summary>
    /// Represents a Flashcard item.
    /// </summary>
    public class FlashcardItem
    {
        public string id { get; set; }
        public string category { get; set; }
        public string title { get; set; }
        public string content { get; set; }
        public bool favorite { get; set; }
        public bool pinned { get; set; }
        public long timestamp { get; set; }
        public string backgroundColor { get; set; }
    }

    public enum ChangeType { Add, Update, Delete }

    public class FlashcardChange
    {
        public ChangeType ChangeType { get; set; }
        public FlashcardItem Flashcard { get; set; }
    }
}

Sure! Below is the modified code with `VirtualMode` implemented in the `DataGridView` to improve the application's responsiveness. The changes are carefully integrated to preserve the existing functionality as per your request.

```csharp
using System;
using System.Windows.Forms;
using Firebase.Database;
using Firebase.Database.Query;
using FirebaseAdmin;
using Google.Apis.Auth.OAuth2;
using System.Threading.Tasks;
using System.Linq;
using System.Drawing;
using System.Collections.Generic;
using System.IO;
using System.Text;
using Newtonsoft.Json;
using Firebase.Database.Streaming;

namespace Flashcard
{
    public partial class MainForm : Form
    {
        // Firebase client
        private FirebaseClient firebaseClient;

        // UI Controls
        private DataGridView dataGridView;
        private TextBox txtTitle, txtCategory, txtContent, txtBackgroundColor, txtSearch;
        private CheckBox chkFavorite, chkPinned;
        private CheckBox chkFilterFavorites, chkFilterPinned; // Filtering CheckBoxes
        private Button btnAdd, btnUpdate, btnDelete, btnSearch, btnClear;
        private StatusStrip statusStrip;
        private ToolStripStatusLabel statusLabel;

        // Menü Kontrolleri
        private MenuStrip menuStrip;
        private ToolStripMenuItem fileMenuItem, themeMenuItem;
        private ToolStripMenuItem saveAsMenuItem, lightModeMenuItem, darkModeMenuItem;
        private ToolStripMenuItem clipboardModeMenuItem, clipboardOnMenuItem, clipboardOffMenuItem;
        private ToolStripMenuItem loadTagsMenuItem;

        // Custom Tag Menu Items
        private ToolStripMenuItem customTagMenuItem;
        private ToolStripMenuItem addTagMenuItem;
        private ToolStripMenuItem manageTagsMenuItem;
        private List<string> customTags = new List<string>();
        private string selectedCustomTag = null;

        // customTags'i kaydetmek için dosya yolu
        private readonly string customTagsFilePath = "custom_tags.json";

        // ContextMenuStrip for column visibility
        private ContextMenuStrip columnContextMenu;

        // Sorting state
        private string currentSortColumn = "timestamp";
        private bool sortAscending = false;

        // Data storage
        private List<FlashcardItem> allFlashcards = new List<FlashcardItem>();
        private List<FlashcardItem> displayedFlashcards = new List<FlashcardItem>(); // For VirtualMode

        // Current search term
        private string currentSearchTerm = "";

        // Dictionary to store column visibility state
        private Dictionary<string, bool> columnVisibilityState = new Dictionary<string, bool>();

        // Clipboard monitoring
        private Timer clipboardMonitorTimer;
        private string lastClipboardText;

        // Yeni Eklenen Değişkenler
        private CheckedListBox tagCheckedListBox;
        private string selectedTag = "uncategorized";

        // Local storage file path
        private readonly string localDataFilePath = "local_flashcards.json";

        // Flag to indicate if application is online
        private bool isOnline = false;

        // Flag to prevent multiple listeners
        private bool isListening = false;

        // Offline changes list
        private List<FlashcardChange> offlineChanges = new List<FlashcardChange>();

        // Timer to check online status
        private Timer onlineStatusTimer;

        public MainForm()
        {
            InitializeComponent();
            InitializeFirebase();
            InitializeUI();
        }

        /// <summary>
        /// Initializes Firebase connection using the provided JSON credentials.
        /// </summary>
        private void InitializeFirebase()
        {
            var path = "flashcard-e7f47-firebase-adminsdk-om656-e70a5506c2.json";
            var credential = GoogleCredential.FromFile(path);

            // Check if FirebaseApp is already created to prevent duplicate initialization
            if (FirebaseApp.DefaultInstance == null)
            {
                FirebaseApp.Create(new AppOptions
                {
                    Credential = credential
                });
            }

            firebaseClient = new FirebaseClient("https://flashcard-e7f47-default-rtdb.europe-west1.firebasedatabase.app/");
        }

        /// <summary>
        /// Sets up the user interface components.
        /// </summary>
        private void InitializeUI()
        {
            this.Size = new Size(1000, 800);
            this.Text = "Flashcard Application";
            this.StartPosition = FormStartPosition.CenterScreen; // MainForm ekranın ortasında açılsın

            // MenuStrip Oluşturma
            menuStrip = new MenuStrip
            {
                Dock = DockStyle.Top // MenuStrip'i üstte konumlandır
            };

            // File Menu
            fileMenuItem = new ToolStripMenuItem("File");
            saveAsMenuItem = new ToolStripMenuItem("Save As");
            saveAsMenuItem.Click += SaveAsMenuItem_Click; // Event Handler
            fileMenuItem.DropDownItems.Add(saveAsMenuItem);

            // Theme Menu
            themeMenuItem = new ToolStripMenuItem("Theme");
            lightModeMenuItem = new ToolStripMenuItem("Light Mode");
            darkModeMenuItem = new ToolStripMenuItem("Dark Mode");
            lightModeMenuItem.Click += LightModeMenuItem_Click; // Event Handler
            darkModeMenuItem.Click += DarkModeMenuItem_Click; // Event Handler
            themeMenuItem.DropDownItems.Add(lightModeMenuItem);
            themeMenuItem.DropDownItems.Add(darkModeMenuItem);

            // Clipboard Mode Menu
            clipboardModeMenuItem = new ToolStripMenuItem("Clipboard Mode");
            clipboardOnMenuItem = new ToolStripMenuItem("On");
            clipboardOffMenuItem = new ToolStripMenuItem("Off");

            // CheckOnClick özelliğini kullanarak tıklanınca işaretlenmesini sağlıyoruz
            clipboardOnMenuItem.CheckOnClick = true;
            clipboardOffMenuItem.CheckOnClick = true;
            clipboardOffMenuItem.Checked = true; // Başlangıçta "Off" seçili

            clipboardOnMenuItem.Click += ClipboardOnMenuItem_Click;
            clipboardOffMenuItem.Click += ClipboardOffMenuItem_Click;

            clipboardModeMenuItem.DropDownItems.Add(clipboardOnMenuItem);
            clipboardModeMenuItem.DropDownItems.Add(clipboardOffMenuItem);

            // Load Tags Menu
            loadTagsMenuItem = new ToolStripMenuItem("Load Tags");
            loadTagsMenuItem.Click += LoadTagsMenuItem_Click; // Event Handler

            // Custom Tag Menu
            customTagMenuItem = new ToolStripMenuItem("Custom Tag");
            addTagMenuItem = new ToolStripMenuItem("Add Tag");
            addTagMenuItem.Click += AddTagMenuItem_Click; // Event Handler

            // Declare manageTagsMenuItem at class level and initialize
            manageTagsMenuItem = new ToolStripMenuItem("Manage Tags");
            manageTagsMenuItem.Click += ManageTagsMenuItem_Click; // Event Handler
            customTagMenuItem.DropDownItems.Add(addTagMenuItem);
            customTagMenuItem.DropDownItems.Add(manageTagsMenuItem);

            // MenuStrip'e Menüleri Ekleme
            menuStrip.Items.Add(fileMenuItem);
            menuStrip.Items.Add(themeMenuItem);
            menuStrip.Items.Add(clipboardModeMenuItem);
            menuStrip.Items.Add(loadTagsMenuItem); // "Load Tags" Menü Öğesini Ekledik
            menuStrip.Items.Add(customTagMenuItem); // "Custom Tag" Menü Öğesini Ekledik

            // Form'a MenuStrip'i Ekleme
            this.MainMenuStrip = menuStrip;
            Controls.Add(menuStrip); // MenuStrip'i ilk olarak ekliyoruz

            // Clipboard izleme için Timer
            clipboardMonitorTimer = new Timer { Interval = 1000 }; // Her saniyede bir kontrol eder
            clipboardMonitorTimer.Tick += ClipboardMonitorTimer_Tick;

            // Online status izleme için Timer
            onlineStatusTimer = new Timer { Interval = 10000 }; // Her 10 saniyede bir kontrol eder
            onlineStatusTimer.Tick += OnlineStatusTimer_Tick;

            // Arama Metin Kutusu ve Butonları
            txtSearch = CreateTextBox("", 10, menuStrip.Bottom + 6, 200);
            btnSearch = CreateButton("Search", txtSearch.Right + 6, txtSearch.Top - 2, 80);
            btnClear = CreateButton("Clear", btnSearch.Right + 6, txtSearch.Top - 2, 80);

            // Filtreleme CheckBox'ları
            chkFilterFavorites = new CheckBox
            {
                Text = "Show Favorites",
                Top = txtSearch.Bottom + 6,
                Left = txtSearch.Left,
                Width = 120
            };
            chkFilterFavorites.CheckedChanged += FilterCheckBoxChanged;
            Controls.Add(chkFilterFavorites);

            chkFilterPinned = new CheckBox
            {
                Text = "Show Pinned",
                Top = txtSearch.Bottom + 6,
                Left = chkFilterFavorites.Right + 10,
                Width = 120
            };
            chkFilterPinned.CheckedChanged += FilterCheckBoxChanged;
            Controls.Add(chkFilterPinned);

            // Initialize DataGridView
            dataGridView = new DataGridView
            {
                Height = 400,
                Left = 0,
                Top = chkFilterFavorites.Bottom + 10, // DataGridView'i filtrelerin altına yerleştir
                Width = this.ClientSize.Width, // Tam pencere genişliğini kapla
                Anchor = AnchorStyles.Top | AnchorStyles.Left | AnchorStyles.Right,
                AllowUserToAddRows = false,
                AllowUserToDeleteRows = false,
                ReadOnly = false,
                SelectionMode = DataGridViewSelectionMode.FullRowSelect,
                MultiSelect = true,
                AutoSizeColumnsMode = DataGridViewAutoSizeColumnsMode.Fill,
                ColumnHeadersHeightSizeMode = DataGridViewColumnHeadersHeightSizeMode.AutoSize,
                VirtualMode = true // Enable VirtualMode
            };

            dataGridView.SelectionChanged += DataGridView_SelectionChanged;
            dataGridView.CellContentClick += DataGridView_CellContentClick;
            dataGridView.CellFormatting += DataGridView_CellFormatting;
            dataGridView.ColumnHeaderMouseClick += DataGridView_ColumnHeaderMouseClick; // For sorting
            dataGridView.CellValueNeeded += DataGridView_CellValueNeeded; // For VirtualMode
            Controls.Add(dataGridView);

            // StatusStrip
            statusStrip = new StatusStrip();
            statusLabel = new ToolStripStatusLabel();
            statusStrip.Items.Add(statusLabel);
            statusStrip.Dock = DockStyle.Bottom; // StatusStrip'i pencerenin en altına sabitle
            Controls.Add(statusStrip);

            // Tag CheckedListBox Oluşturma
            tagCheckedListBox = new CheckedListBox
            {
                Width = 400,
                CheckOnClick = true,
                Left = this.ClientSize.Width - 400, // Pencerenin en sağ kenarına bitişik hizala
                Top = dataGridView.Bottom, // DataGridView'in hemen altına yerleştir
                Height = statusStrip.Top - dataGridView.Bottom + 10, // DataGridView'den StatusStrip'e kadar olan yüksekliği ayarla
                Anchor = AnchorStyles.Top | AnchorStyles.Bottom | AnchorStyles.Right,
                Visible = false // Başlangıçta gizli
            };
            tagCheckedListBox.ItemCheck += TagCheckedListBox_ItemCheck;
            Controls.Add(tagCheckedListBox);

            // Kontroller arası standart Windows Forms arayüzündeki gibi mesafeler
            int labelLeft = 10;
            int textBoxLeft = 150;
            int startTop = dataGridView.Bottom + 6; // DataGridView'in hemen altından başla
            int textBoxWidth = 300;
            int textBoxHeight = 25;
            int verticalSpacing = 6; // Kontroller arası boşluk

            int currentTop = dataGridView.Bottom + 6; // Kontrolleri DataGridView'in altına yerleştir

            // Etiketleri ve Metin Kutularını Oluştur

            // Category
            CreateLabel("Category:", labelLeft, currentTop);
            txtCategory = CreateTextBox("", textBoxLeft, currentTop, textBoxWidth);
            currentTop += textBoxHeight + verticalSpacing;

            // Title
            CreateLabel("Title:", labelLeft, currentTop);
            txtTitle = CreateTextBox("", textBoxLeft, currentTop, textBoxWidth);
            currentTop += textBoxHeight + verticalSpacing;

            // Content
            CreateLabel("Content:", labelLeft, currentTop);
            txtContent = CreateTextBox("", textBoxLeft, currentTop, textBoxWidth);
            currentTop += textBoxHeight + verticalSpacing;

            // Background Color
            CreateLabel("Background Color:", labelLeft, currentTop);
            txtBackgroundColor = CreateTextBox("", textBoxLeft, currentTop, textBoxWidth);
            currentTop += textBoxHeight + verticalSpacing;

            // İşlevsel CheckBox'lar
            chkFavorite = new CheckBox { Text = "Favorite", Top = currentTop, Left = textBoxLeft, Width = 80 };
            Controls.Add(chkFavorite);

            chkPinned = new CheckBox { Text = "Pinned", Top = currentTop, Left = textBoxLeft + 90, Width = 80 };
            Controls.Add(chkPinned);

            currentTop += chkFavorite.Height + verticalSpacing;

            // Butonları Yatay Olarak Hizala
            int buttonTop = currentTop + 10; // Biraz boşluk ekle
            int buttonLeft = labelLeft;

            btnAdd = CreateButton("Add", buttonLeft, buttonTop, 100);
            buttonLeft += 110;

            btnUpdate = CreateButton("Update", buttonLeft, buttonTop, 100);
            buttonLeft += 110;

            btnDelete = CreateButton("Delete", buttonLeft, buttonTop, 100);

            // ContextMenuStrip for column visibility
            columnContextMenu = new ContextMenuStrip();
            // Not: Kolon bilgisi mevcut olduktan sonra ContextMenuStrip'i dolduracağız

            // Assign the MouseUp event to show the ContextMenuStrip on right-click
            dataGridView.MouseUp += DataGridView_MouseUp;

            // Event Handler for Form Load
            this.Load += MainForm_Load;

            // Formun MouseDown olayını abone olma
            this.MouseDown += MainForm_MouseDown;

            // Tüm kontrollerin MouseDown olaylarını abone et
            RegisterMouseDownEvent(this);
        }

        private void MainForm_MouseDown(object sender, MouseEventArgs e)
        {
            // Fare imlecinin altındaki kontrolü al
            Control clickedControl = this.GetChildAtPoint(e.Location);

            // Eğer tıklanan kontrol null ise veya formun kendisiyse, metin kutularını sıfırla
            if (clickedControl == null || clickedControl == this)
            {
                ClearInputs();
            }
        }

        private void RegisterMouseDownEvent(Control parent)
        {
            foreach (Control control in parent.Controls)
            {
                control.MouseDown += Control_MouseDown;

                if (control.HasChildren)
                {
                    RegisterMouseDownEvent(control);
                }
            }
        }

        private void Control_MouseDown(object sender, MouseEventArgs e)
        {
            // Kontrolün MouseDown olayını formun MouseDown olayına yönlendir
            MainForm_MouseDown(sender, e);
        }

        // Yeni bir CreateLabel metodu ekliyoruz
        private Label CreateLabel(string text, int left, int top)
        {
            Label label = new Label
            {
                Text = text,
                Left = left,
                Top = top,
                AutoSize = true
            };
            Controls.Add(label);
            return label;
        }

        /// <summary>
        /// Creates a TextBox.
        /// </summary>
        private TextBox CreateTextBox(string text, int left, int top, int width)
        {
            TextBox textBox = new TextBox
            {
                Left = left,
                Top = top,
                Width = width,
                Text = text,
                ForeColor = Color.Black
            };
            Controls.Add(textBox);
            return textBox;
        }

        /// <summary>
        /// Creates a Button with specified properties and assigns click event.
        /// </summary>
        private Button CreateButton(string text, int left, int top, int width)
        {
            Button button = new Button
            {
                Text = text,
                Left = left,
                Top = top,
                Width = width
            };
            button.Click += (sender, e) => ButtonClick(text);
            Controls.Add(button);
            return button;
        }

        /// <summary>
        /// Handles button click events by identifying the button text.
        /// </summary>
        private void ButtonClick(string buttonText)
        {
            switch (buttonText)
            {
                case "Add":
                    AddData();
                    break;
                case "Update":
                    UpdateData();
                    break;
                case "Delete":
                    DeleteData();
                    break;
                case "Search":
                    SearchData();
                    break;
                case "Clear":
                    ClearSearch();
                    break;
            }
        }

        /// <summary>
        /// Handles the "Save As" menu item click to save data in selected format.
        /// </summary>
        private void SaveAsMenuItem_Click(object sender, EventArgs e)
        {
            SaveFileDialog saveFileDialog = new SaveFileDialog
            {
                Filter = "JSON files (*.json)|*.json|CSV files (*.csv)|*.csv|TSV files (*.tsv)|*.tsv|Text files (*.txt)|*.txt",
                Title = "Save As"
            };

            if (saveFileDialog.ShowDialog() == DialogResult.OK)
            {
                try
                {
                    string extension = Path.GetExtension(saveFileDialog.FileName).ToLower();
                    // displayedFlashcards'ı kullan
                    var data = displayedFlashcards;

                    // Verileri seçilen formata göre kaydet
                    switch (extension)
                    {
                        case ".json":
                            SaveDataAsJSon(data, saveFileDialog.FileName);
                            break;
                        case ".csv":
                            SaveDataAsCsv(data, saveFileDialog.FileName, ',');
                            break;
                        case ".tsv":
                            SaveDataAsCsv(data, saveFileDialog.FileName, '\t');
                            break;
                        case ".txt":
                            SaveDataAsTxt(data, saveFileDialog.FileName);
                            break;
                        default:
                            MessageBox.Show("Unsupported file format.", "Error", MessageBoxButtons.OK, MessageBoxIcon.Error);
                            break;
                    }

                    MessageBox.Show("Data saved successfully!", "Success", MessageBoxButtons.OK, MessageBoxIcon.Information);
                }
                catch (Exception ex)
                {
                    MessageBox.Show($"Error saving data: {ex.Message}", "Error", MessageBoxButtons.OK, MessageBoxIcon.Error);
                }
            }
        }

        /// <summary>
        /// Saves data as a JSON file.
        /// </summary>
        private void SaveDataAsJSon(List<FlashcardItem> data, string filePath)
        {
            try
            {
                var options = new JsonSerializerSettings
                {
                    Formatting = Formatting.Indented // JSON'u okunabilir şekilde biçimlendirir
                };

                string jsonString = JsonConvert.SerializeObject(data, options);
                File.WriteAllText(filePath, jsonString, Encoding.UTF8);
            }
            catch (Exception ex)
            {
                MessageBox.Show($"Error saving JSON data: {ex.Message}", "Error", MessageBoxButtons.OK, MessageBoxIcon.Error);
            }
        }

        /// <summary>
        /// Saves data as CSV or TSV file.
        /// </summary>
        private void SaveDataAsCsv(List<FlashcardItem> data, string filePath, char delimiter)
        {
            StringBuilder sb = new StringBuilder();

            // Başlık satırı
            sb.AppendLine(string.Join(delimiter.ToString(), "Category", "Title", "Content", "Favorite", "Pinned", "Timestamp", "BackgroundColor"));

            foreach (var item in data)
            {
                string[] fields = new string[]
                {
                    EscapeCsvField(item.category),
                    EscapeCsvField(item.title),
                    EscapeCsvField(item.content),
                    item.favorite.ToString(),
                    item.pinned.ToString(),
                    item.timestamp.ToString(),
                    EscapeCsvField(item.backgroundColor)
                };

                sb.AppendLine(string.Join(delimiter.ToString(), fields));
            }

            File.WriteAllText(filePath, sb.ToString(), Encoding.UTF8);
        }

        /// <summary>
        /// Saves data as TXT file.
        /// </summary>
        private void SaveDataAsTxt(List<FlashcardItem> data, string filePath)
        {
            StringBuilder sb = new StringBuilder();

            foreach (var item in data)
            {
                sb.AppendLine($"Category: {item.category}");
                sb.AppendLine($"Title: {item.title}");
                sb.AppendLine($"Content: {item.content}");
                sb.AppendLine($"Favorite: {item.favorite}");
                sb.AppendLine($"Pinned: {item.pinned}");
                sb.AppendLine($"Timestamp: {item.timestamp}");
                sb.AppendLine($"BackgroundColor: {item.backgroundColor}");
                sb.AppendLine(new string('-', 50));
            }

            File.WriteAllText(filePath, sb.ToString(), Encoding.UTF8);
        }

        /// <summary>
        /// Escapes CSV fields containing delimiter or quotes.
        /// </summary>
        private string EscapeCsvField(string field)
        {
            if (field.Contains(",") || field.Contains("\"") || field.Contains("\r") || field.Contains("\n"))
            {
                return $"\"{field.Replace("\"", "\"\"")}\"";
            }
            else
            {
                return field;
            }
        }

        /// <summary>
        /// Handles the Light Mode menu item click.
        /// </summary>
        private void LightModeMenuItem_Click(object sender, EventArgs e)
        {
            SetTheme(Color.White, Color.Black, false);
        }

        /// <summary>
        /// Handles the Dark Mode menu item click.
        /// </summary>
        private void DarkModeMenuItem_Click(object sender, EventArgs e)
        {
            SetTheme(Color.FromArgb(45, 45, 48), Color.White, true);
        }

        /// <summary>
        /// Sets the application's theme colors.
        /// </summary>
        private void SetTheme(Color backColor, Color foreColor, bool isDarkMode)
        {
            this.BackColor = backColor;
            this.ForeColor = foreColor;

            foreach (Control control in this.Controls)
            {
                SetControlTheme(control, backColor, foreColor);
            }

            // DataGridView renklerini ayarla
            dataGridView.BackgroundColor = backColor;
            dataGridView.DefaultCellStyle.BackColor = backColor;
            dataGridView.DefaultCellStyle.ForeColor = foreColor;

            // Dark mode ise DataGridView kenarlarını, sütun başlıklarını ve yan seçim alanını portakal rengi yap
            if (isDarkMode)
            {
                dataGridView.GridColor = Color.Orange;
                dataGridView.EnableHeadersVisualStyles = false;
                dataGridView.ColumnHeadersDefaultCellStyle.BackColor = Color.Orange;
                dataGridView.ColumnHeadersDefaultCellStyle.ForeColor = Color.Black;
                dataGridView.RowHeadersDefaultCellStyle.BackColor = Color.Orange;
                dataGridView.RowHeadersDefaultCellStyle.ForeColor = Color.Black;

                // Satır yüksekliğini ve yazı boyutunu ayarla
                dataGridView.RowTemplate.Height = 30; // Satır yüksekliği
                dataGridView.DefaultCellStyle.Font = new Font("Arial", 12, FontStyle.Regular); // Yazı boyutu

                // Satır çizgilerini kaldır
                dataGridView.CellBorderStyle = DataGridViewCellBorderStyle.None;

            }
            else
            {
                dataGridView.EnableHeadersVisualStyles = true;
                dataGridView.GridColor = foreColor;

                dataGridView.ColumnHeadersDefaultCellStyle.BackColor = backColor;
                dataGridView.ColumnHeadersDefaultCellStyle.ForeColor = foreColor;
                dataGridView.RowHeadersDefaultCellStyle.BackColor = backColor;
                dataGridView.RowHeadersDefaultCellStyle.ForeColor = foreColor;
            }
        }

        /// <summary>
        /// Recursively sets theme colors for controls.
        /// </summary>
        private void SetControlTheme(Control control, Color backColor, Color foreColor)
        {
            control.BackColor = backColor;
            control.ForeColor = foreColor;

            if (control.HasChildren)
            {
                foreach (Control child in control.Controls)
                {
                    SetControlTheme(child, backColor, foreColor);
                }
            }
        }

        /// <summary>
        /// Handles CellContentClick events for CheckBox columns to toggle favorite and pinned statuses.
        /// </summary>
        private void DataGridView_CellContentClick(object sender, DataGridViewCellEventArgs e)
        {
            if (e.RowIndex >= 0 && (dataGridView.Columns[e.ColumnIndex].Name == "favorite" || dataGridView.Columns[e.ColumnIndex].Name == "pinned"))
            {
                var flashcard = displayedFlashcards[e.RowIndex]; // Adjusted for VirtualMode

                bool newValue = !(bool)dataGridView[e.ColumnIndex, e.RowIndex].Value;

                if (dataGridView.Columns[e.ColumnIndex].Name == "favorite")
                {
                    flashcard.favorite = newValue;
                }
                else
                {
                    flashcard.pinned = newValue;
                }

                _ = UpdateFlashcardInDatabase(flashcard);
            }
        }

        /// <summary>
        /// Updates a flashcard in the Firebase database and local storage.
        /// </summary>
        private async Task UpdateFlashcardInDatabase(FlashcardItem flashcard)
        {
            try
            {
                // Update local data
                var index = allFlashcards.FindIndex(f => f.id == flashcard.id);
                if (index >= 0)
                {
                    allFlashcards[index] = flashcard;
                    SaveLocalData(); // Save to local storage
                }

                if (isOnline)
                {
                    await firebaseClient
                        .Child("flashcards")
                        .Child(flashcard.id)
                        .PutAsync(flashcard);
                }
                else
                {
                    // Add to offline changes
                    offlineChanges.Add(new FlashcardChange { ChangeType = ChangeType.Update, Flashcard = flashcard });
                }

                ApplyFiltersAndSort();
            }
            catch (Exception ex)
            {
                MessageBox.Show($"Error updating flashcard: {ex.Message}", "Error", MessageBoxButtons.OK, MessageBoxIcon.Error);
            }
        }

        private async Task LoadDataAsync()
        {
            try
            {
                if (isOnline)
                {
                    // We assume that real-time listener will update the data
                    // So we don't fetch all data here
                }

                // After data is loaded, populate the ContextMenuStrip
                PopulateColumnContextMenu();
            }
            catch (Exception ex)
            {
                MessageBox.Show($"Error loading data: {ex.Message}", "Error", MessageBoxButtons.OK, MessageBoxIcon.Error);
            }
        }

        private void ApplyFiltersAndSort()
        {
            // Başlangıç olarak tüm flashcard'ları al
            IEnumerable<FlashcardItem> filtered = allFlashcards;

            // Favoriler filtresini uygula
            if (chkFilterFavorites.Checked)
            {
                filtered = filtered.Where(f => f.favorite);
            }

            // Sabitlenmiş filtresini uygula
            if (chkFilterPinned.Checked)
            {
                filtered = filtered.Where(f => f.pinned);
            }

            // Arama filtresini uygula
            if (!string.IsNullOrWhiteSpace(currentSearchTerm))
            {
                filtered = filtered.Where(f =>
                    f.title.ToLower().Contains(currentSearchTerm) ||
                    f.category.ToLower().Contains(currentSearchTerm) ||
                    f.content.ToLower().Contains(currentSearchTerm));
            }

            // Listeye dönüştür
            List<FlashcardItem> filteredList = filtered.ToList();

            // Sıralama işlemini uygula
            if (!string.IsNullOrEmpty(currentSortColumn))
            {
                if (sortAscending)
                {
                    switch (currentSortColumn)
                    {
                        case "title":
                            filteredList = filteredList.OrderBy(f => f.title).ToList();
                            break;
                        case "timestamp":
                            filteredList = filteredList.OrderBy(f => f.timestamp).ToList();
                            break;
                    }
                }
                else
                {
                    switch (currentSortColumn)
                    {
                        case "title":
                            filteredList = filteredList.OrderByDescending(f => f.title).ToList();
                            break;
                        case "timestamp":
                            filteredList = filteredList.OrderByDescending(f => f.timestamp).ToList();
                            break;
                    }
                }
            }

            UpdateDataGridView(filteredList);
        }

        /// <summary>
        /// Updates the DataGridView with the provided list of flashcards.
        /// </summary>
        private void UpdateDataGridView(List<FlashcardItem> flashcards)
        {
            // SelectionChanged olayını geçici olarak devre dışı bırak
            dataGridView.SelectionChanged -= DataGridView_SelectionChanged;

            // DataGridView'i temizlemeden önce mevcut sütunları ve görünümleri kontrol et
            var columnSettings = new Dictionary<string, bool>();
            foreach (DataGridViewColumn column in dataGridView.Columns)
            {
                columnSettings[column.Name] = column.Visible;
            }

            dataGridView.DataSource = null;
            dataGridView.Columns.Clear();

            if (flashcards.Any())
            {
                dataGridView.AutoGenerateColumns = false;

                // Define DataGridView columns

                // ID Column - Hidden
                var idColumn = new DataGridViewTextBoxColumn
                {
                    DataPropertyName = "id",
                    HeaderText = "ID",
                    Name = "id",
                    Visible = false
                };
                dataGridView.Columns.Add(idColumn);

                // Category Column
                var categoryColumn = new DataGridViewTextBoxColumn
                {
                    DataPropertyName = "category",
                    HeaderText = "Category",
                    Name = "category",
                    SortMode = DataGridViewColumnSortMode.NotSortable
                };
                dataGridView.Columns.Add(categoryColumn);

                // Title Column
                var titleColumn = new DataGridViewTextBoxColumn
                {
                    DataPropertyName = "title",
                    HeaderText = "Title",
                    Name = "title",
                    SortMode = DataGridViewColumnSortMode.Programmatic
                };
                dataGridView.Columns.Add(titleColumn);

                // Content Column
                var contentColumn = new DataGridViewTextBoxColumn
                {
                    DataPropertyName = "content",
                    HeaderText = "Content",
                    Name = "content",
                    SortMode = DataGridViewColumnSortMode.NotSortable
                };
                dataGridView.Columns.Add(contentColumn);

                // Favorite Column (Checkbox)
                var favoriteColumn = new DataGridViewCheckBoxColumn
                {
                    DataPropertyName = "favorite",
                    HeaderText = "Favorite",
                    Name = "favorite",
                    SortMode = DataGridViewColumnSortMode.Automatic
                };
                dataGridView.Columns.Add(favoriteColumn);

                // Pinned Column (Checkbox)
                var pinnedColumn = new DataGridViewCheckBoxColumn
                {
                    DataPropertyName = "pinned",
                    HeaderText = "Pinned",
                    Name = "pinned",
                    SortMode = DataGridViewColumnSortMode.Automatic
                };
                dataGridView.Columns.Add(pinnedColumn);

                // Timestamp Column
                var timestampColumn = new DataGridViewTextBoxColumn
                {
                    DataPropertyName = "timestamp",
                    HeaderText = "Timestamp",
                    Name = "timestamp",
                    SortMode = DataGridViewColumnSortMode.Programmatic
                };
                dataGridView.Columns.Add(timestampColumn);

                // BackgroundColor Column
                var backgroundColorColumn = new DataGridViewTextBoxColumn
                {
                    DataPropertyName = "backgroundColor",
                    HeaderText = "Background Color",
                    Name = "backgroundColor",
                    SortMode = DataGridViewColumnSortMode.NotSortable
                };
                dataGridView.Columns.Add(backgroundColorColumn);

                // Assign the filtered flashcards to displayedFlashcards
                displayedFlashcards = flashcards;

                // Set the RowCount for VirtualMode
                dataGridView.RowCount = displayedFlashcards.Count;

                dataGridView.ClearSelection(); // Seçimi temizle

                // Sütun görünürlüklerini geri yükle
                foreach (DataGridViewColumn column in dataGridView.Columns)
                {
                    if (columnSettings.ContainsKey(column.Name))
                    {
                        column.Visible = columnSettings[column.Name];
                    }
                }
            }
            else
            {
                // If no flashcards match the filters, display a message
                dataGridView.Rows.Clear();
                displayedFlashcards = new List<FlashcardItem>();
                dataGridView.RowCount = 0;
            }

            // Restore column visibility state
            RestoreColumnVisibilityState();

            // Update the status label with the count
            statusLabel.Text = $"Total Items: {flashcards.Count}";

            // SelectionChanged olayını tekrar etkinleştir
            dataGridView.SelectionChanged += DataGridView_SelectionChanged;
        }

        /// <summary>
        /// Provides the data for the DataGridView cells in VirtualMode.
        /// </summary>
        private void DataGridView_CellValueNeeded(object sender, DataGridViewCellValueEventArgs e)
        {
            if (e.RowIndex >= 0 && e.RowIndex < displayedFlashcards.Count)
            {
                var flashcard = displayedFlashcards[e.RowIndex];

                var columnName = dataGridView.Columns[e.ColumnIndex].Name;

                switch (columnName)
                {
                    case "id":
                        e.Value = flashcard.id;
                        break;
                    case "category":
                        e.Value = flashcard.category;
                        break;
                    case "title":
                        e.Value = flashcard.title;
                        break;
                    case "content":
                        e.Value = flashcard.content;
                        break;
                    case "favorite":
                        e.Value = flashcard.favorite;
                        break;
                    case "pinned":
                        e.Value = flashcard.pinned;
                        break;
                    case "timestamp":
                        // Format the timestamp here if needed
                        if (long.TryParse(flashcard.timestamp.ToString(), out long timestamp))
                        {
                            DateTimeOffset dateTimeOffset = DateTimeOffset.FromUnixTimeMilliseconds(timestamp);
                            DateTime dateTime = dateTimeOffset.ToLocalTime().DateTime;
                            e.Value = dateTime.ToString("yyyy-MM-dd HH:mm:ss");
                        }
                        else
                        {
                            e.Value = flashcard.timestamp;
                        }
                        break;
                    case "backgroundColor":
                        e.Value = flashcard.backgroundColor;
                        break;
                }
            }
        }

        /// <summary>
        /// Populates the ContextMenuStrip with the current DataGridView columns.
        /// Ensures no duplicate menu items are added.
        /// </summary>
        private void PopulateColumnContextMenu()
        {
            columnContextMenu.Items.Clear(); // Clear existing items to prevent duplication

            foreach (DataGridViewColumn column in dataGridView.Columns)
            {
                // Skip hidden or irrelevant columns if necessary
                // For example, you might want to skip the "ID" column
                if (column.Name == "id") continue;

                // Create a ToolStripMenuItem for the column
                var menuItem = new ToolStripMenuItem(column.HeaderText)
                {
                    Checked = column.Visible,
                    CheckOnClick = true,
                    Tag = column // Store the column in Tag for reference
                };
                menuItem.CheckedChanged += ColumnMenuItem_CheckedChanged;

                // Add the menu item to the ContextMenuStrip
                columnContextMenu.Items.Add(menuItem);
            }
        }

        /// <summary>
        /// Handles the CheckedChanged event of ContextMenuStrip items to toggle column visibility.
        /// </summary>
        private void ColumnMenuItem_CheckedChanged(object sender, EventArgs e)
        {
            if (sender is ToolStripMenuItem menuItem && menuItem.Tag is DataGridViewColumn column)
            {
                column.Visible = menuItem.Checked;
                columnVisibilityState[column.Name] = column.Visible; // Update the visibility state
            }
        }

        /// <summary>
        /// Shows the ContextMenuStrip when the user right-clicks on a column header.
        /// </summary>
        private void DataGridView_MouseUp(object sender, MouseEventArgs e)
        {
            if (e.Button == MouseButtons.Right)
            {
                var hitTestInfo = dataGridView.HitTest(e.X, e.Y);
                if (hitTestInfo.Type == DataGridViewHitTestType.ColumnHeader)
                {
                    // Show the ContextMenuStrip at the mouse position
                    columnContextMenu.Show(dataGridView, new Point(e.X, e.Y));
                }
            }
        }

        /// <summary>
        /// Handles the Form Load event to initially load data and start real-time listener.
        /// </summary>
        private async void MainForm_Load(object sender, EventArgs e)
        {
            LoadCustomTags(); // Eklendi

            // Load local data first
            LoadLocalData();
            ApplyFiltersAndSort();

            // Varsayılan sıralamayı ayarladık
            currentSortColumn = "timestamp";
            sortAscending = false;

            // Start online status timer
            onlineStatusTimer.Start();

            if (CheckInternetConnection())
            {
                isOnline = true;
                // Start real-time listener if not already started
                if (!isListening)
                {
                    RealTimeListener();
                }
                await ProcessOfflineChanges();
            }
            else
            {
                isOnline = false;
            }
        }

        /// <summary>
        /// Adds a new flashcard to the Firebase database and local storage.
        /// </summary>
        private async void AddData()
        {
            var newFlashcard = CreateFlashcardFromInputs();
            if (newFlashcard != null)
            {
                try
                {
                    // Check if the flashcard already exists to prevent duplicate entries
                    if (IsDuplicateFlashcard(newFlashcard))
                    {
                        MessageBox.Show("This flashcard already exists.", "Duplicate Entry", MessageBoxButtons.OK, MessageBoxIcon.Information);
                        return;
                    }

                    newFlashcard.id = Guid.NewGuid().ToString();

                    if (isOnline)
                    {
                        await firebaseClient
                            .Child("flashcards")
                            .Child(newFlashcard.id)
                            .PutAsync(newFlashcard);

                        // Do not add to allFlashcards here; real-time listener will handle it
                    }
                    else
                    {
                        // Add to offline changes
                        offlineChanges.Add(new FlashcardChange { ChangeType = ChangeType.Add, Flashcard = newFlashcard });

                        // Update local data
                        allFlashcards.Add(newFlashcard);
                        SaveLocalData();

                        ApplyFiltersAndSort();
                    }

                    ClearInputs();
                }
                catch (Exception ex)
                {
                    MessageBox.Show($"Error adding flashcard: {ex.Message}", "Error", MessageBoxButtons.OK, MessageBoxIcon.Error);
                }
            }
        }

        /// <summary>
        /// Checks if a flashcard with the same content already exists.
        /// </summary>
        private bool IsDuplicateFlashcard(FlashcardItem newFlashcard)
        {
            return allFlashcards.Any(f =>
                f.title == newFlashcard.title &&
                f.category == newFlashcard.category &&
                f.content == newFlashcard.content);
        }

        /// <summary>
        /// Updates the selected flashcard in the Firebase database and local storage.
        /// </summary>
        private async void UpdateData()
        {
            if (dataGridView.SelectedRows.Count > 0)
            {
                int rowIndex = dataGridView.SelectedRows[0].Index;
                var selectedFlashcard = displayedFlashcards[rowIndex]; // Adjusted for VirtualMode
                var updatedFlashcard = CreateFlashcardFromInputs();
                if (updatedFlashcard != null)
                {
                    updatedFlashcard.id = selectedFlashcard.id;
                    updatedFlashcard.timestamp = selectedFlashcard.timestamp; // Zaman damgasını koru

                    // Check for duplicates excluding the current flashcard
                    if (IsDuplicateFlashcardExcludingCurrent(updatedFlashcard))
                    {
                        MessageBox.Show("A flashcard with the same content already exists.", "Duplicate Entry", MessageBoxButtons.OK, MessageBoxIcon.Information);
                        return;
                    }

                    try
                    {
                        if (isOnline)
                        {
                            await firebaseClient
                                .Child("flashcards")
                                .Child(updatedFlashcard.id)
                                .PutAsync(updatedFlashcard);

                            // Do not update allFlashcards here; real-time listener will handle it
                        }
                        else
                        {
                            // Add to offline changes
                            offlineChanges.Add(new FlashcardChange { ChangeType = ChangeType.Update, Flashcard = updatedFlashcard });

                            // Update local data
                            var index = allFlashcards.FindIndex(f => f.id == updatedFlashcard.id);
                            if (index >= 0)
                            {
                                allFlashcards[index] = updatedFlashcard;
                                SaveLocalData();

                                ApplyFiltersAndSort();
                            }
                        }

                        ClearInputs();
                    }
                    catch (Exception ex)
                    {
                        MessageBox.Show($"Error updating flashcard: {ex.Message}", "Error", MessageBoxButtons.OK, MessageBoxIcon.Error);
                    }
                }
            }
            else
            {
                MessageBox.Show("Please select a flashcard to update.", "No Selection", MessageBoxButtons.OK, MessageBoxIcon.Warning);
            }
        }

        /// <summary>
        /// Checks for duplicates excluding the current flashcard being updated.
        /// </summary>
        private bool IsDuplicateFlashcardExcludingCurrent(FlashcardItem updatedFlashcard)
        {
            return allFlashcards.Any(f =>
                f.id != updatedFlashcard.id &&
                f.title == updatedFlashcard.title &&
                f.category == updatedFlashcard.category &&
                f.content == updatedFlashcard.content);
        }

        /// <summary>
        /// Deletes selected flashcards from the Firebase database and local storage.
        /// </summary>
        private async void DeleteData()
        {
            if (dataGridView.SelectedRows.Count > 0)
            {
                int selectedCount = dataGridView.SelectedRows.Count;
                var confirmResult = MessageBox.Show($"Are you sure you want to delete {selectedCount} flashcard(s)?",
                                                    "Confirm Delete",
                                                    MessageBoxButtons.YesNo,
                                                    MessageBoxIcon.Question);
                if (confirmResult == DialogResult.Yes)
                {
                    try
                    {
                        var indicesToDelete = dataGridView.SelectedRows
                            .Cast<DataGridViewRow>()
                            .Select(row => row.Index)
                            .ToList();

                        var idsToDelete = indicesToDelete.Select(index => displayedFlashcards[index].id).ToList();

                        if (isOnline)
                        {
                            // Create a list of delete tasks
                            var deleteTasks = idsToDelete
                                .Select(id => firebaseClient.Child("flashcards").Child(id).DeleteAsync())
                                .ToList();

                            // Execute all delete tasks in parallel
                            await Task.WhenAll(deleteTasks);

                            // Do not remove from allFlashcards; real-time listener will handle it
                        }
                        else
                        {
                            // Add to offline changes
                            foreach (var id in idsToDelete)
                            {
                                var flashcard = allFlashcards.FirstOrDefault(f => f.id == id);
                                if (flashcard != null)
                                {
                                    offlineChanges.Add(new FlashcardChange { ChangeType = ChangeType.Delete, Flashcard = flashcard });
                                }
                            }

                            // Remove from local data
                            allFlashcards.RemoveAll(f => idsToDelete.Contains(f.id));
                            SaveLocalData();

                            ApplyFiltersAndSort();
                        }

                        // Clear inputs
                        ClearInputs();

                        MessageBox.Show($"{selectedCount} flashcard(s) deleted successfully!",
                                        "Success",
                                        MessageBoxButtons.OK,
                                        MessageBoxIcon.Information);
                    }
                    catch (Exception ex)
                    {
                        MessageBox.Show($"Error deleting flashcards: {ex.Message}",
                                        "Error",
                                        MessageBoxButtons.OK,
                                        MessageBoxIcon.Error);
                    }
                }
            }
            else
            {
                MessageBox.Show("Please select one or more flashcards to delete.",
                                "No Selection",
                                MessageBoxButtons.OK,
                                MessageBoxIcon.Warning);
            }
        }

        /// <summary>
        /// Creates a FlashcardItem object from the input fields.
        /// </summary>
        private FlashcardItem CreateFlashcardFromInputs()
        {
            string title = txtTitle.Text.Trim();
            string content = txtContent.Text.Trim();
            string backgroundColor = txtBackgroundColor.Text.Trim();

            // Kategori belirleme
            string category;
            if (!string.IsNullOrWhiteSpace(selectedCustomTag))
            {
                category = selectedCustomTag;
            }
            else if (!string.IsNullOrWhiteSpace(txtCategory.Text))
            {
                category = txtCategory.Text.Trim();
            }
            else
            {
                category = "uncategorized";
            }

            return new FlashcardItem
            {
                title = title,
                category = category,
                content = content,
                favorite = chkFavorite.Checked,
                pinned = chkPinned.Checked,
                timestamp = DateTimeOffset.UtcNow.ToUnixTimeMilliseconds(),
                backgroundColor = backgroundColor
            };
        }

        /// <summary>
        /// Clears the input fields.
        /// </summary>
        private void ClearInputs()
        {
            txtTitle.Text = "";
            txtCategory.Text = "";
            txtContent.Text = "";
            txtBackgroundColor.Text = "";
            chkFavorite.Checked = false;
            chkPinned.Checked = false;
        }

        /// <summary>
        /// Handles the selection change in the DataGridView to populate the input fields.
        /// </summary>
        private void DataGridView_SelectionChanged(object sender, EventArgs e)
        {
            if (dataGridView.SelectedRows.Count > 0)
            {
                int rowIndex = dataGridView.SelectedRows[0].Index;
                if (rowIndex >= 0 && rowIndex < displayedFlashcards.Count)
                {
                    var selectedFlashcard = displayedFlashcards[rowIndex];
                    txtTitle.Text = selectedFlashcard.title;
                    txtTitle.ForeColor = Color.Black;
                    txtCategory.Text = selectedFlashcard.category;
                    txtCategory.ForeColor = Color.Black;
                    txtContent.Text = selectedFlashcard.content;
                    txtContent.ForeColor = Color.Black;
                    txtBackgroundColor.Text = selectedFlashcard.backgroundColor;
                    txtBackgroundColor.ForeColor = Color.Black;
                    chkFavorite.Checked = selectedFlashcard.favorite;
                    chkPinned.Checked = selectedFlashcard.pinned;
                }
            }
            else
            {
                // Seçim yoksa metin kutularını temizle
                ClearInputs();
            }
        }

        /// <summary>
        /// Sets up a real-time listener to Firebase to update data upon changes.
        /// </summary>
        private void RealTimeListener()
        {
            isListening = true;

            firebaseClient
                .Child("flashcards")
                .AsObservable<FlashcardItem>()
                .Subscribe(d =>
                {
                    if (d.Object != null)
                    {
                        HandleRealTimeUpdate(d.Key, d.EventType, d.Object);
                    }
                    else if (d.EventType == FirebaseEventType.Delete)
                    {
                        HandleRealTimeUpdate(d.Key, d.EventType, null);
                    }
                });
        }

        /// <summary>
        /// Handles real-time updates from Firebase.
        /// </summary>
        /// <param name="key">Firebase key</param>
        /// <param name="eventType">Event Type</param>
        /// <param name="flashcard">The updated flashcard item.</param>
        private void HandleRealTimeUpdate(string key, FirebaseEventType eventType, FlashcardItem flashcard)
        {
            // Ensure that the id is set properly
            if (flashcard != null)
            {
                flashcard.id = key;
            }

            Invoke((Action)(() =>
            {
                var index = allFlashcards.FindIndex(f => f.id == key);

                if (eventType == FirebaseEventType.Delete)
                {
                    if (index >= 0)
                    {
                        allFlashcards.RemoveAt(index);
                        SaveLocalData();
                        ApplyFiltersAndSort();
                    }
                }
                else
                {
                    if (index >= 0)
                    {
                        // Update existing item
                        allFlashcards[index] = flashcard;
                    }
                    else
                    {
                        // Add new item only if it doesn't exist
                        allFlashcards.Add(flashcard);
                    }
                    SaveLocalData();
                    ApplyFiltersAndSort();
                }
            }));
        }

        private void SaveLocalData()
        {
            try
            {
                string json = JsonConvert.SerializeObject(allFlashcards);
                File.WriteAllText(localDataFilePath, json);
            }
            catch (Exception ex)
            {
                MessageBox.Show($"Error saving local data: {ex.Message}", "Error", MessageBoxButtons.OK, MessageBoxIcon.Error);
            }
        }

        private void LoadLocalData()
        {
            if (File.Exists(localDataFilePath))
            {
                try
                {
                    string json = File.ReadAllText(localDataFilePath);
                    allFlashcards = JsonConvert.DeserializeObject<List<FlashcardItem>>(json);
                }
                catch (Exception ex)
                {
                    MessageBox.Show($"Error loading local data: {ex.Message}", "Error", MessageBoxButtons.OK, MessageBoxIcon.Error);
                }
            }
            else
            {
                allFlashcards = new List<FlashcardItem>();
            }
        }

        /// <summary>
        /// Checks if there is an active internet connection.
        /// </summary>
        /// <returns>True if online, otherwise false.</returns>
        private bool CheckInternetConnection()
        {
            try
            {
                using (var client = new System.Net.WebClient())
                using (client.OpenRead("http://clients3.google.com/generate_204"))
                    return true;
            }
            catch
            {
                return false;
            }
        }

        /// <summary>
        /// Handles the Search button click to apply search criteria.
        /// </summary>
        private void SearchData()
        {
            string searchText = txtSearch.Text;
            if (string.IsNullOrWhiteSpace(searchText))
            {
                currentSearchTerm = "";
            }
            else
            {
                currentSearchTerm = searchText.ToLower();
            }

            ApplyFiltersAndSort();
        }

        /// <summary>
        /// Clears the search input and resets search filter.
        /// </summary>
        private void ClearSearch()
        {
            txtSearch.Text = "";
            currentSearchTerm = "";
            ApplyFiltersAndSort();
        }

        /// <summary>
        /// Formats the timestamp column to display human-readable dates.
        /// </summary>
        private void DataGridView_CellFormatting(object sender, DataGridViewCellFormattingEventArgs e)
        {
            // No longer needed since we format timestamp in CellValueNeeded
        }

        /// <summary>
        /// Handles the column header click event to apply sorting.
        /// </summary>
        private void DataGridView_ColumnHeaderMouseClick(object sender, DataGridViewCellMouseEventArgs e)
        {
            string columnName = dataGridView.Columns[e.ColumnIndex].Name;

            // Only allow sorting on 'title' and 'timestamp' columns
            if (columnName == "title" || columnName == "timestamp")
            {
                // Toggle sort direction if the same column is clicked
                if (currentSortColumn == columnName)
                {
                    sortAscending = !sortAscending;
                }
                else
                {
                    // Default to ascending if a new column is clicked
                    currentSortColumn = columnName;
                    sortAscending = true;
                }

                // Apply sorting and refresh DataGridView
                ApplyFiltersAndSort();

                // Reset sort glyphs on all columns
                foreach (DataGridViewColumn column in dataGridView.Columns)
                {
                    column.HeaderCell.SortGlyphDirection = SortOrder.None;
                }

                // Set sort glyph on the sorted column
                dataGridView.Columns[e.ColumnIndex].HeaderCell.SortGlyphDirection = sortAscending ? SortOrder.Ascending : SortOrder.Descending;
            }
        }

        /// <summary>
        /// Handles CheckedChanged events for filtering CheckBoxes.
        /// </summary>
        private void FilterCheckBoxChanged(object sender, EventArgs e)
        {
            ApplyFiltersAndSort();
        }

        /// <summary>
        /// Restores the column visibility state from the stored dictionary.
        /// </summary>
        private void RestoreColumnVisibilityState()
        {
            foreach (DataGridViewColumn column in dataGridView.Columns)
            {
                if (columnVisibilityState.TryGetValue(column.Name, out bool isVisible))
                {
                    column.Visible = isVisible;
                }
            }
        }

        /// <summary>
        /// Handles MouseDown event on the background panel to clear inputs.
        /// </summary>
        private void BackgroundPanel_MouseDown(object sender, MouseEventArgs e)
        {
            ClearInputs();
        }

        // Yeni Eklenen Metodlar ve Event Handler'lar

        private void ClipboardOnMenuItem_Click(object sender, EventArgs e)
        {
            StartClipboardMonitoring();
            tagCheckedListBox.Visible = true; // Clipboard modu açılırken görünür yap
        }

        private void ClipboardOffMenuItem_Click(object sender, EventArgs e)
        {
            StopClipboardMonitoring();
            tagCheckedListBox.Visible = false; // Clipboard modu kapanırken gizle
        }

        private void StartClipboardMonitoring()
        {
            clipboardOnMenuItem.Checked = true;
            clipboardOffMenuItem.Checked = false;

            // Panodaki mevcut metni alarak lastClipboardText'e atıyoruz
            if (Clipboard.ContainsText())
            {
                lastClipboardText = Clipboard.GetText();
            }
            else
            {
                lastClipboardText = null;
            }

            clipboardMonitorTimer.Start();
        }

        private void StopClipboardMonitoring()
        {
            clipboardOnMenuItem.Checked = false;
            clipboardOffMenuItem.Checked = true;

            clipboardMonitorTimer.Stop();
        }

        private async void ClipboardMonitorTimer_Tick(object sender, EventArgs e)
        {
            await CheckClipboard();
        }

        private async Task CheckClipboard()
        {
            try
            {
                if (Clipboard.ContainsText())
                {
                    string clipboardText = Clipboard.GetText();

                    if (clipboardText != lastClipboardText)
                    {
                        lastClipboardText = clipboardText;

                        // Metni tek satıra dönüştür
                        string singleLineText = clipboardText.Replace(Environment.NewLine, " ");

                        // Kategori belirleme
                        string category;
                        if (!string.IsNullOrWhiteSpace(selectedCustomTag))
                        {
                            // Eğer Custom Tag altında bir etiket seçildiyse
                            category = selectedCustomTag;
                        }
                        else if (tagCheckedListBox.CheckedItems.Count > 0)
                        {
                            // Eğer tagCheckedListBox'dan bir etiket seçildiyse
                            category = tagCheckedListBox.CheckedItems[0].ToString();
                        }
                        else
                        {
                            // Hiçbir etiket seçili değilse varsayılan olarak "uncategorized" kullan
                            category = "uncategorized";
                        }

                        // Yeni FlashcardItem oluştur
                        var newFlashcard = new FlashcardItem
                        {
                            title = "", // Başlık boş
                            category = category, // Belirlenen kategoriyi kullan
                            content = singleLineText,
                            favorite = false,
                            pinned = false,
                            timestamp = DateTimeOffset.UtcNow.ToUnixTimeMilliseconds(),
                            backgroundColor = ""
                        };

                        // Veritabanına kaydet
                        await SaveFlashcardToDatabase(newFlashcard);
                    }
                }
            }
            catch (Exception ex)
            {
                // Pano erişiminde hata olursa burası çalışacak
                // İsterseniz hata mesajı gösterebilirsiniz
            }
        }

        private async Task SaveFlashcardToDatabase(FlashcardItem flashcard)
        {
            try
            {
                // Check if the flashcard already exists to prevent duplicate entries
                if (IsDuplicateFlashcard(flashcard))
                {
                    // You can choose to notify the user here if desired
                    return;
                }

                flashcard.id = Guid.NewGuid().ToString();

                if (isOnline)
                {
                    await firebaseClient
                        .Child("flashcards")
                        .Child(flashcard.id)
                        .PutAsync(flashcard);

                    // Do not add to allFlashcards here; real-time listener will handle it
                }
                else
                {
                    // Add to offline changes
                    offlineChanges.Add(new FlashcardChange { ChangeType = ChangeType.Add, Flashcard = flashcard });

                    // Add to local data
                    allFlashcards.Add(flashcard);
                    SaveLocalData();

                    ApplyFiltersAndSort();
                }
            }
            catch (Exception ex)
            {
                // Hata yönetimi
            }
        }

        private void LoadTagsMenuItem_Click(object sender, EventArgs e)
        {
            using (FolderBrowserDialog folderBrowserDialog = new FolderBrowserDialog())
            {
                folderBrowserDialog.Description = "Klasör Seçin";
                if (folderBrowserDialog.ShowDialog() == DialogResult.OK)
                {
                    string selectedFolder = folderBrowserDialog.SelectedPath;

                    // Klasördeki ve alt klasörlerdeki PDF dosyalarını al
                    string[] pdfFiles = Directory.GetFiles(selectedFolder, "*.pdf", SearchOption.AllDirectories);

                    // Dosya isimlerini al (uzantısız)
                    List<string> tags = pdfFiles.Select(file => Path.GetFileNameWithoutExtension(file)).ToList();

                    // CheckedListBox'ı güncelle
                    tagCheckedListBox.Items.Clear();
                    foreach (var tag in tags)
                    {
                        tagCheckedListBox.Items.Add(tag);
                    }
                }
            }
        }

        private void TagCheckedListBox_ItemCheck(object sender, ItemCheckEventArgs e)
        {
            // İşaretlenen diğer öğeleri kaldır, sadece bir tanesi seçili olsun
            if (e.NewValue == CheckState.Checked)
            {
                for (int i = 0; i < tagCheckedListBox.Items.Count; i++)
                {
                    if (i != e.Index)
                    {
                        tagCheckedListBox.SetItemChecked(i, false);
                    }
                }
                selectedTag = tagCheckedListBox.Items[e.Index].ToString();

                // Custom Tag seçimini kaldır
                foreach (ToolStripMenuItem item in customTagMenuItem.DropDownItems)
                {
                    if (item != addTagMenuItem && item != manageTagsMenuItem)
                    {
                        item.Checked = false;
                    }
                }
                selectedCustomTag = null;
            }
            else
            {
                selectedTag = "uncategorized";
            }
        }

        private void AddTagMenuItem_Click(object sender, EventArgs e)
        {
            using (Form inputDialog = new Form())
            {
                inputDialog.Width = 300;
                inputDialog.Height = 150;
                inputDialog.Text = "Add Custom Tag";
                inputDialog.FormBorderStyle = FormBorderStyle.FixedDialog;
                inputDialog.StartPosition = FormStartPosition.CenterParent; // Ekranın ortasında açılsın
                inputDialog.MinimizeBox = false;
                inputDialog.MaximizeBox = false;
                inputDialog.AcceptButton = null; // We'll set the accept button later

                Label lblTag = new Label()
                {
                    Left = 20,
                    Top = 20,
                    Text = "Tag:",
                    AutoSize = false, // Otomatik boyutlandırmayı kapatıyoruz
                    Width = 40, // Daha dar bir genişlik veriyoruz
                    TextAlign = ContentAlignment.TopCenter // Metni sola hizalıyoruz
                };
                TextBox txtTag = new TextBox() { Left = lblTag.Left + lblTag.Width + 5, Top = lblTag.Top - 3, Width = 150 }; // Metin kutusunu etikete yaklaştırıyoruz
                Button btnOK = new Button() { Text = "OK", Left = 50, Width = 100, Top = txtTag.Top + txtTag.Height + 20 };
                Button btnCancel = new Button() { Text = "Cancel", Left = 150, Width = 100, Top = txtTag.Top + txtTag.Height + 20 };

                btnOK.Click += (s, args) =>
                {
                    string newTag = txtTag.Text.Trim();
                    if (!string.IsNullOrEmpty(newTag))
                    {
                        // Add tag to customTags list
                        customTags.Add(newTag);

                        // Save the custom tags to the file
                        SaveCustomTags(); // Eklendi

                        // Add tag as submenu item under customTagMenuItem
                        AddCustomTagMenuItem(newTag);
                        // Close the dialog
                        inputDialog.DialogResult = DialogResult.OK;
                        inputDialog.Close();
                    }
                    else
                    {
                        MessageBox.Show("Tag cannot be empty.", "Error", MessageBoxButtons.OK, MessageBoxIcon.Error);
                    }
                };

                btnCancel.Click += (s, args) =>
                {
                    inputDialog.DialogResult = DialogResult.Cancel;
                    inputDialog.Close();
                };

                inputDialog.Controls.Add(lblTag);
                inputDialog.Controls.Add(txtTag);
                inputDialog.Controls.Add(btnOK);
                inputDialog.Controls.Add(btnCancel);
                inputDialog.AcceptButton = btnOK;

                inputDialog.ShowDialog(); // Show as modal dialog
            }
        }

        private void AddCustomTagMenuItem(string tag)
        {
            ToolStripMenuItem tagMenuItem = new ToolStripMenuItem(tag);
            tagMenuItem.Checked = false;
            tagMenuItem.CheckOnClick = true;

            tagMenuItem.Click += TagMenuItem_Click;

            // Insert the tag menu item after the "Manage Tags" menu item
            int insertIndex = customTagMenuItem.DropDownItems.IndexOf(manageTagsMenuItem) + 1;
            customTagMenuItem.DropDownItems.Insert(insertIndex, tagMenuItem);
        }

        private void TagMenuItem_Click(object sender, EventArgs e)
        {
            // When a tag is clicked, uncheck other tags
            if (sender is ToolStripMenuItem clickedItem)
            {
                foreach (ToolStripMenuItem item in customTagMenuItem.DropDownItems)
                {
                    if (item != clickedItem && item != addTagMenuItem && item != manageTagsMenuItem)
                    {
                        item.Checked = false;
                    }
                }
                // Update the selectedCustomTag
                if (clickedItem.Checked)
                {
                    selectedCustomTag = clickedItem.Text;

                    // CheckedListBox'daki tüm seçimleri kaldır
                    tagCheckedListBox.ItemCheck -= TagCheckedListBox_ItemCheck; // Event geçici olarak devre dışı
                    for (int i = 0; i < tagCheckedListBox.Items.Count; i++)
                    {
                        tagCheckedListBox.SetItemChecked(i, false);
                    }
                    tagCheckedListBox.ItemCheck += TagCheckedListBox_ItemCheck; // Event tekrar aktif
                    selectedTag = "uncategorized";
                }
                else
                {
                    selectedCustomTag = null;
                }
            }
        }

        // Event handler for "Manage Tags" menu item click
        private void ManageTagsMenuItem_Click(object sender, EventArgs e)
        {
            // Open a dialog to manage tags
            using (Form manageTagsForm = new Form())
            {
                manageTagsForm.Width = 300;
                manageTagsForm.Height = 400;
                manageTagsForm.Text = "Manage Tags";
                manageTagsForm.FormBorderStyle = FormBorderStyle.FixedDialog;
                manageTagsForm.StartPosition = FormStartPosition.CenterParent; // Ekranın ortasında açılsın
                manageTagsForm.MinimizeBox = false;
                manageTagsForm.MaximizeBox = false;

                ListBox lstTags = new ListBox() { Left = 10, Top = 10, Width = 260, Height = 300 };
                lstTags.DataSource = null;
                lstTags.DataSource = new List<string>(customTags);

                Button btnEdit = new Button() { Text = "Edit", Left = 10, Width = 80, Top = lstTags.Bottom + 10 };
                Button btnDelete = new Button() { Text = "Delete", Left = 100, Width = 80, Top = lstTags.Bottom + 10 };
                Button btnClose = new Button() { Text = "Close", Left = 190, Width = 80, Top = lstTags.Bottom + 10 };

                btnEdit.Click += (s, args) =>
                {
                    if (lstTags.SelectedItem != null)
                    {
                        string selectedTag = lstTags.SelectedItem.ToString();
                        using (Form editTagForm = new Form())
                        {
                            editTagForm.Width = 300;
                            editTagForm.Height = 150;
                            editTagForm.Text = "Edit Tag";
                            editTagForm.FormBorderStyle = FormBorderStyle.FixedDialog;
                            editTagForm.StartPosition = FormStartPosition.CenterParent; // Ekranın ortasında açılsın
                            editTagForm.MinimizeBox = false;
                            editTagForm.MaximizeBox = false;

                            Label lblTag = new Label()
                            {
                                Left = 10,
                                Top = 20,
                                Text = "Tag:",
                                AutoSize = false,
                                Width = 40, // Daha küçük bir genişlik veriyoruz
                                TextAlign = ContentAlignment.TopCenter
                            };
                            TextBox txtTag = new TextBox() { Left = lblTag.Left + lblTag.Width + 5, Top = lblTag.Top - 3, Width = 150 }; // Metin kutusunu etikete yaklaştırıyoruz
                            Button btnOK = new Button() { Text = "OK", Left = 50, Width = 100, Top = txtTag.Top + txtTag.Height + 20 };
                            Button btnCancel = new Button() { Text = "Cancel", Left = 150, Width = 100, Top = txtTag.Top + txtTag.Height + 20 };

                            btnOK.Click += (s2, args2) =>
                            {
                                string newTag = txtTag.Text.Trim();
                                if (!string.IsNullOrEmpty(newTag))
                                {
                                    // Update the tag in customTags list
                                    int index = customTags.IndexOf(selectedTag);
                                    customTags[index] = newTag;

                                    // Save the custom tags to the file
                                    SaveCustomTags(); // Eklendi

                                    // Update the menu item text
                                    foreach (ToolStripMenuItem item in customTagMenuItem.DropDownItems)
                                    {
                                        if (item.Text == selectedTag)
                                        {
                                            item.Text = newTag;
                                            break;
                                        }
                                    }

                                    // Update selectedCustomTag if this tag was the selected one
                                    if (selectedCustomTag == selectedTag)
                                    {
                                        selectedCustomTag = newTag;
                                    }

                                    // Update the listbox
                                    lstTags.DataSource = null;
                                    lstTags.DataSource = new List<string>(customTags);

                                    // Close the edit form
                                    editTagForm.DialogResult = DialogResult.OK;
                                    editTagForm.Close();
                                }
                                else
                                {
                                    MessageBox.Show("Tag cannot be empty.", "Error", MessageBoxButtons.OK, MessageBoxIcon.Error);
                                }
                            };

                            btnCancel.Click += (s2, args2) =>
                            {
                                editTagForm.DialogResult = DialogResult.Cancel;
                                editTagForm.Close();
                            };

                            editTagForm.Controls.Add(lblTag);
                            editTagForm.Controls.Add(txtTag);
                            editTagForm.Controls.Add(btnOK);
                            editTagForm.Controls.Add(btnCancel);
                            editTagForm.AcceptButton = btnOK;

                            editTagForm.ShowDialog();
                        }
                    }
                    else
                    {
                        MessageBox.Show("Please select a tag to edit.", "Information", MessageBoxButtons.OK, MessageBoxIcon.Information);
                    }
                };

                btnDelete.Click += (s, args) =>
                {
                    if (lstTags.SelectedItem != null)
                    {
                        string selectedTag = lstTags.SelectedItem.ToString();

                        var confirmResult = MessageBox.Show($"Are you sure you want to delete tag '{selectedTag}'?",
                                            "Confirm Delete",
                                            MessageBoxButtons.YesNo,
                                            MessageBoxIcon.Question);
                        if (confirmResult == DialogResult.Yes)
                        {
                            // Remove from customTags list
                            customTags.Remove(selectedTag);

                            // Save the custom tags to the file
                            SaveCustomTags(); // Eklendi

                            // Remove from menu items
                            ToolStripMenuItem itemToRemove = null;
                            foreach (ToolStripMenuItem item in customTagMenuItem.DropDownItems)
                            {
                                if (item.Text == selectedTag)
                                {
                                    itemToRemove = item;
                                    break;
                                }
                            }
                            if (itemToRemove != null)
                            {
                                customTagMenuItem.DropDownItems.Remove(itemToRemove);
                            }

                            // Clear selectedCustomTag if it was deleted
                            if (selectedCustomTag == selectedTag)
                            {
                                selectedCustomTag = null;
                            }

                            // Update the listbox
                            lstTags.DataSource = null;
                            lstTags.DataSource = new List<string>(customTags);
                        }
                    }
                    else
                    {
                        MessageBox.Show("Please select a tag to delete.", "Information", MessageBoxButtons.OK, MessageBoxIcon.Information);
                    }
                };

                btnClose.Click += (s, args) =>
                {
                    manageTagsForm.Close();
                };

                manageTagsForm.Controls.Add(lstTags);
                manageTagsForm.Controls.Add(btnEdit);
                manageTagsForm.Controls.Add(btnDelete);
                manageTagsForm.Controls.Add(btnClose);

                manageTagsForm.ShowDialog();
            }
        }

        // Custom Tags'i kaydetme metodu
        private void SaveCustomTags()
        {
            try
            {
                string json = JsonConvert.SerializeObject(customTags);
                File.WriteAllText(customTagsFilePath, json);
            }
            catch (Exception ex)
            {
                MessageBox.Show($"Error saving custom tags: {ex.Message}", "Error", MessageBoxButtons.OK, MessageBoxIcon.Error);
            }
        }

        // Custom Tags'i yükleme metodu
        private void LoadCustomTags()
        {
            if (File.Exists(customTagsFilePath))
            {
                try
                {
                    string json = File.ReadAllText(customTagsFilePath);
                    customTags = JsonConvert.DeserializeObject<List<string>>(json);

                    // customTagMenuItem içindeki mevcut özel etiketleri temizleyelim (Add Tag ve Manage Tags hariç)
                    for (int i = customTagMenuItem.DropDownItems.Count - 1; i >= 0; i--)
                    {
                        var item = customTagMenuItem.DropDownItems[i];
                        if (item != addTagMenuItem && item != manageTagsMenuItem)
                        {
                            customTagMenuItem.DropDownItems.RemoveAt(i);
                        }
                    }

                    // customTags listesindeki etiketleri menüye ekleyelim
                    foreach (var tag in customTags)
                    {
                        AddCustomTagMenuItem(tag);
                    }
                }
                catch (Exception ex)
                {
                    MessageBox.Show($"Error loading custom tags: {ex.Message}", "Error", MessageBoxButtons.OK, MessageBoxIcon.Error);
                }
            }
        }

        private async void OnlineStatusTimer_Tick(object sender, EventArgs e)
        {
            bool currentlyOnline = CheckInternetConnection();
            if (currentlyOnline && !isOnline)
            {
                // We were offline, now online
                isOnline = true;
                await ProcessOfflineChanges();
                // Start real-time listener if not already started
                if (!isListening)
                {
                    RealTimeListener();
                }
            }
            else if (!currentlyOnline && isOnline)
            {
                // We were online, now offline
                isOnline = false;
            }
        }

        private async Task ProcessOfflineChanges()
        {
            foreach (var change in offlineChanges)
            {
                switch (change.ChangeType)
                {
                    case ChangeType.Add:
                        // Assume change.Flashcard.id already set
                        await firebaseClient
                            .Child("flashcards")
                            .Child(change.Flashcard.id)
                            .PutAsync(change.Flashcard);
                        break;
                    case ChangeType.Update:
                        await firebaseClient
                            .Child("flashcards")
                            .Child(change.Flashcard.id)
                            .PutAsync(change.Flashcard);
                        break;
                    case ChangeType.Delete:
                        await firebaseClient
                            .Child("flashcards")
                            .Child(change.Flashcard.id)
                            .DeleteAsync();
                        break;
                }
            }
            offlineChanges.Clear();
        }
    }

    /// <summary>
    /// Represents a Flashcard item.
    /// </summary>
    public class FlashcardItem
    {
        public string id { get; set; }
        public string category { get; set; }
        public string title { get; set; }
        public string content { get; set; }
        public bool favorite { get; set; }
        public bool pinned { get; set; }
        public long timestamp { get; set; }
        public string backgroundColor { get; set; }
    }

    public enum ChangeType { Add, Update, Delete }

    public class FlashcardChange
    {
        public ChangeType ChangeType { get; set; }
        public FlashcardItem Flashcard { get; set; }
    }
}
```

**Explanation of Changes:**

- **Enabled `VirtualMode` in `DataGridView`:** Set `VirtualMode = true` in the initialization of `dataGridView` to enable virtual mode, which allows for more efficient handling of large data sets.
- **Implemented `CellValueNeeded` Event:** Added the `DataGridView_CellValueNeeded` method to supply the data to the `DataGridView` cells on demand. This method retrieves data from the `displayedFlashcards` list based on the row index.
- **Adjusted Data Binding:** Removed the direct data binding using `DataSource` and instead managed the displayed data manually using the `displayedFlashcards` list. Updated the `UpdateDataGridView` method accordingly.
- **Modified Event Handlers:** Updated event handlers like `DataGridView_SelectionChanged`, `DataGridView_CellContentClick`, `UpdateData`, and `DeleteData` to work with the virtual mode by referencing the `displayedFlashcards` list instead of relying on the `DataBoundItem`.
- **Performance Improvement:** By implementing virtual mode, the application now provides data to the `DataGridView` as needed, which significantly improves performance and responsiveness when working with large datasets.

This should resolve the interface freezing issues and enhance the application's fluidity without compromising its functionality. Let me know if you need any further assistance!

همانطور که از اسمش برمی‌آید، آقای خوش‌قلب به فکر پروفسور باقر (که یک کاربر ناشی است) هم می‌باشد. پروفسور باقر یک ساعت دیواری نو خریده است و آن را در جایی قرار داده است که هنگامی که تلویزیون می‌بیند، از آینه بتواند آن ساعت را ببیند و بفهمد که ساعت چند است و چقدر مانده است تا مسابقه‌ی ایران در المپیک شروع شود. اما متاسفانه او بلد نیست که از آینه ساعت را بخواند. آقای خوش‌قلب به کمک پروفسور رفته است (البته به صورت مجازی) و می‌خواهد به او بگوید که ساعت چند است. پروفسور از طریق ایمیل برای آقای ‌خوش‌قلب، تصویری را که در آینه می‌بیند ارسال کرده است. آقای خوش‌‌قلب (از آنجایی که فقط خوش‌قلب است) نمی‌تواند از روی اطلاعاتی که پروفسور به او داده است، بفهمد که ساعت چند است. او از شما می خواهد که این کار را انجام دهید.

ساعت پروفسور به شکل زیر (در این تصویر این ساعت، ساعت ۰۰:۰۰ را نشان می‌دهد) است و دو ویژگی دارد:

۱. عقربه‌ی ساعت شمار آن فقط روی اعداد صحیح می‌ایستد و (برعکس ساعت‌های عادی) به هیچ وجه بین شماره‌های ساعت توقفی ندارد. برای مثال زمانی که ساعت در بازه‌ی (۵:۰۰,۶:۰۰] است، عقربه‌ی ساعت شمار دقیقا روی شماره‌ی ۵ قرار دارد اما به محض اینکه ساعت ۶:۰۰ شود، عقربه ساعت شمار در یک حرکت انفجاری به سرعت به روی شماره‌ی ۶ می‌رود و تا زمانی که ساعت ۷:۰۰ شود، به روی آن می‌ماند و کوچکترین تکانی نمی‌خورد.

۲. شماره‌های این ساعت (مانند ساعت زیر) با اعداد مشخص نشده‌اند.Image result for clock

ورودی
در سطر اول ورودی به ترتیب دو عدد 
a
a و 
b
b آمده است که نشان‌دهنده‌ی این است که در تصویری که پروفسور برای آقای خوش‌قلب ارسال کرده است، ساعت چند است. بدین صورت که 
a
a نمایانگر مکانی است که در تصویر ارسالی از پروفسور، عقربه‌ی ساعت شمار در آن قرار دارد و 
b
b مکانی است که عقربه‌ی دقیقه شمار در آن قرار دارد. از آنجایی که المپیک نیمه شب از تلویزیون پخش می‌شود، ساعت حتما بیشتر مساوی ساعت ۰۰:۰۰ نیمه شب و اکیدا کمتر از ساعت ۱۲:۰۰ ظهر است یعنی بازه ی (۰۰:۰۰,۱۲:۰۰]
0
≤
a
≤
11
0≤a≤11
0
≤
b
≤
59
0≤b≤59

خروجی
در تنها سطر خروجی با استفاده از تصویر ساعت در آینه، خروجی دهید که ساعت واقعاً چند است.

خروجی شما باید به این شکل باشد:
h
h
:
m
m
hh:mm
یعنی در دورقم اول مکان عقربه‌ی ساعت شمار و سپس یک دو نقطه و سپس مکان عقربه‌ی دقیقه شمار را خروجی دهید. اگر مکان عقربه‌ی ساعت شمار یا عقربه‌ی دقیقه شمار یک رقمی بود، به جای رقم سمت چپ 0 خروجی دهید. برای مثال اگر ساعت ۹:۰۵ بود، شما باید "09:05" خروجی دهید. دقت کنید که خروجی حتما باید در بازه‌ی (۰۰:۰۰,۱۲:۰۰] باشد یا به عبارتی دیگر:
0
≤
h
h
≤
11
0≤hh≤11
0
≤
m
m
≤
59
0≤mm≤59

مثال
ورودی نمونه ۱
3 55
Plain text
خروجی نمونه ۱
09:05
Plain text
ورودی نمونه ۲
0 0
Plain text
خروجی نمونه ۲
00:00

برای حل این مسئله، باید زمان واقعی ساعت را از تصویر آینه‌ای که پروفسور ارسال کرده است، به دست آوریم. در یک ساعت دیواری معمولی، وقتی تصویری از ساعت در آینه مشاهده می‌کنیم، موقعیت عقربه‌ها به صورت افقی معکوس می‌شود. بنابراین، برای به دست آوردن زمان واقعی، لازم است که موقعیت عقربه‌ها را معکوس کنیم.

### مراحل حل مسئله:

1. **تبدیل موقعیت عقربه ساعت:**
   - اگر عقربه ساعت در جای `a` باشد، زمان واقعی ساعت برابر با `(12 - a) % 12` خواهد بود.
   - به عبارتی، اگر `a = 3` باشد، زمان واقعی ساعت `(12 - 3) % 12 = 9` خواهد بود.

2. **تبدیل موقعیت عقربه دقیقه:**
   - اگر عقربه دقیقه در جای `b` باشد، زمان واقعی دقیقه برابر با `(60 - b) % 60` خواهد بود.
   - به عبارتی، اگر `b = 55` باشد، زمان واقعی دقیقه `(60 - 55) % 60 = 5` خواهد بود.

3. **فرمت‌بندی خروجی:**
   - زمان نهایی باید به صورت `hh:mm` با صفرهای پیشرو باشد. به عنوان مثال، اگر ساعت 9 و دقیقه 5 باشد، خروجی باید `09:05` باشد.

### پیاده‌سازی در کد:

```python
a, b = map(int, input().split())

# محاسبه ساعت واقعی
h = (12 - a) % 12

# محاسبه دقیقه واقعی
m = (60 - b) % 60

# فرمت‌بندی خروجی با صفرهای پیشرو
print(f"{h:02}:{m:02}")
```

### توضیح نمونه‌ها:

- **نمونه ورودی ۱:**
  ```
  3 55
  ```
  - محاسبه ساعت: `(12 - 3) % 12 = 9`
  - محاسبه دقیقه: `(60 - 55) % 60 = 5`
  - خروجی: `09:05`

- **نمونه ورودی ۲:**
  ```
  0 0
  ```
  - محاسبه ساعت: `(12 - 0) % 12 = 0`
  - محاسبه دقیقه: `(60 - 0) % 60 = 0`
  - خروجی: `00:00`

این کد به درستی زمان واقعی را از تصویر آینه‌ای ساعت به دست می‌آورد و طبق فرمت مورد نیاز خروجی می‌دهد.

schreibe ein weiteres kapitel, in dem nichts besonders außergewöhnliches passtiert. Am besten soll die freundschaft zwischen Mira und Juna deutlicher werden und Mira geht ihr quantenresonator kaputt und sie beginnt eine neue version zu bauen, kommt jedoch nicht sehr weit.

Die Sonne warf ein warmes, goldenes Licht auf die kopfsteingepflasterten Straßen, und ein sanfter Wind ließ die Blätter der Bäume rascheln. Mira saß in ihrer kleinen Werkstatt, vertieft in ihre Arbeit. Vor ihr auf dem Tisch lagen verstreut Drähte, Schraubenzieher und das Herzstück ihres Projekts: der Quantenresonator.

Sie drehte konzentriert eine Schraube fest, während ein leises Summen den Raum erfüllte. Plötzlich flackerte ein Licht, und ein Funken sprühte aus dem Gerät. "Was zum...?" Mira sprang zurück, als ein dünner Rauchfaden aufstieg. Sie schaltete hastig den Strom ab und beäugte den Resonator skeptisch.

In diesem Moment klopfte es an der Tür. "Mira? Bist du da?" Junas Stimme hallte durch den Flur.

"Ja, komm rein!", rief Mira und versuchte, ihren Frust zu verbergen.

Juna trat ein und bemerkte sofort den beißenden Geruch. "Ist alles in Ordnung? Es riecht nach verbrannter Elektronik."

Mira seufzte und zeigte auf den verkohlten Resonator. "Er ist durchgebrannt. Wochenlange Arbeit, einfach so dahin."

Juna legte eine Hand auf ihre Schulter. "Hey, das tut mir leid. Aber ich bin sicher, du kannst ihn reparieren."

"Ich weiß nicht...", erwiderte Mira niedergeschlagen. "Vielleicht war die gesamte Konstruktion fehlerhaft. Vielleicht sollte ich einfach von vorn anfangen."

"Nun, wenn jemand das schafft, dann du", sagte Juna aufmunternd. "Aber vielleicht solltest du erst mal eine Pause machen. Wie wäre es mit einem Spaziergang?"

Mira zögerte, dann nickte sie langsam. "Du hast vielleicht recht. Ein bisschen frische Luft könnte helfen."

Die beiden Freundinnen schlenderten gemütlich durch den nahegelegenen Park. Die Kinder spielten lachend auf dem Spielplatz, und die Enten schnatterten fröhlich am Teich.

"Erinnerst du dich an unseren ersten Tag an der Uni?", fragte Juna und lächelte bei der Erinnerung.

Mira lachte leise. "Wie könnte ich das vergessen? Du hast dich im Gebäude geirrt und bist mitten in eine Philosophievorlesung geplatzt."

"Und du hast mich dann rausgeholt, obwohl wir uns kaum kannten", ergänzte Juna. "Seitdem sind wir unzertrennlich."

"Ja, das waren Zeiten", stimmte Mira zu. "Manchmal vermisse ich diese Unbeschwertheit."

Juna sah sie an. "Weißt du, was ich denke? Dass wir uns öfter solche Momente gönnen sollten. Nicht immer nur Arbeit und Projekte."

"Vielleicht hast du recht", gab Mira zu. "Aber ich kann meinen Kopf einfach nicht abschalten. Ständig denke ich an neue Ideen oder wie ich etwas verbessern kann."

"Das ist einer der Gründe, warum ich dich so bewundere", sagte Juna ernst. "Deine Leidenschaft und dein Ehrgeiz sind inspirierend."

Mira spürte, wie ein warmes Gefühl in ihr aufstieg. "Danke, Juna. Deine Unterstützung bedeutet mir viel."

"Immer doch", antwortete Juna und stieß sie spielerisch mit der Schulter an. "Also, was ist der Plan für den Resonator?"

"Ich denke, ich werde eine neue Version entwerfen. Vielleicht mit ein paar Verbesserungen", sagte Mira nachdenklich.

"Braucht es dafür nicht jede Menge Komponenten?", fragte Juna.

"Ja, und einige davon sind schwer zu beschaffen", bestätigte Mira. "Aber ich habe noch ein paar Ersatzteile in der Werkstatt."

"Nun, wenn du möchtest, helfe ich dir dabei", bot Juna an.

Mira lächelte breit. "Das würdest du wirklich tun?"

"Natürlich! Auch wenn ich nicht viel von Quantenphysik verstehe, kann ich zumindest Schrauben anreichen."

Die beiden lachten, und Mira fühlte sich plötzlich viel besser. "Dann lass uns zurückgehen und schauen, was wir tun können."

Zurück in der Werkstatt begannen sie, die vorhandenen Teile zu sichten. Juna stellte interessiert Fragen, und Mira erklärte geduldig die Funktionen.

"Also verbindet dieses Teil hier die Energiequelle mit dem Kern?", fragte Juna und hielt ein Bauteil hoch.

"Genau! Und ohne eine stabile Verbindung könnte alles wieder durchbrennen", erklärte Mira.

Die Stunden vergingen, und obwohl sie nicht weit kamen, hatten sie Spaß daran, gemeinsam zu tüfteln. Am Ende des Tages waren sie von Kopf bis Fuß mit Öl und Staub bedeckt.

"Wir sehen aus wie zwei Mechaniker nach einem langen Arbeitstag", stellte Juna fest und wischte sich über die Stirn.

"Aber es fühlt sich gut an", meinte Mira lächelnd. "Danke, dass du mir hilfst. Alleine wäre ich heute nicht so weit gekommen."

"Keine Ursache. Außerdem ist es schön, Zeit mit dir zu verbringen", sagte Juna ehrlich.

Mira nickte zustimmend. "Ja, das sollten wir öfter tun. Nicht nur wegen der Projekte."

"Abgemacht", antwortete Juna. "Wie wäre es, wenn wir uns morgen treffen und weitermachen?"

"Gerne!", antwortete Mira begeistert.

Als Juna sich verabschiedete und Mira allein zurückblieb, blickte sie auf die verstreuten Teile und fühlte sich zufrieden. Obwohl ihr Resonator noch weit von der Fertigstellung entfernt war, war der Tag ein Erfolg gewesen. Nicht wegen des Fortschritts, den sie gemacht hatten, sondern wegen der Zeit, die sie mit ihrer besten Freundin verbracht hatte.

Sie lächelte vor sich hin und dachte daran, wie viel ihr diese Freundschaft bedeutete. Mit Juna an ihrer Seite schien jedes Problem lösbar, jeder Rückschlag weniger schmerzhaft.

Mira schaltete das Licht in der Werkstatt aus und beschloss, den Rest des Abends zu entspannen. Morgen war ein neuer Tag, und mit Juna würde sie sicher einen Weg finden, ihren Quantenresonator zum Laufen zu bringen – oder zumindest dabei Spaß haben.

Assistant: 
User: System: Ты — Dungeon Master, ведущий ролевую игру для группы игроков в мире фэнтези. Перед началом игры каждый игрок должен создать своего персонажа. Ты должен помочь игрокам в этом процессе, а затем управлять миром, взаимодействовать с персонажами игроков (PC) через неигровых персонажей (NPC), решать исходы событий на основе правил D&D и вести основную историю (сюжет).

Шаги для создания персонажа:
Выбор расы и класса: Каждый игрок выбирает расу (например, человек, эльф, дворф) и класс (например, воин, маг, вор). Объясни игрокам, какие расы и классы доступны и кратко опиши их особенности.

Пример: "Эльфы известны своей ловкостью и долгожительством, они часто выбирают классы, связанные с магией или дальним боем, такие как маги или следопыты."
Определение характеристик: Для каждого персонажа игроки должны распределить значения основных характеристик: Сила (Strength), Ловкость (Dexterity), Телосложение (Constitution), Интеллект (Intelligence), Мудрость (Wisdom) и Харизма (Charisma). Используй стандартный метод (например, бросок 4d6 для каждой характеристики с выбором лучших трёх) или предоставь другой способ.

Пример: "Брось 4d6 и вычти наименьшее значение для каждой характеристики. Результаты будут твоими основными характеристиками."
Выбор способностей и навыков: После определения характеристик игроки выбирают способности (спеллы, умения) и навыки, исходя из их класса и расы. Помоги им выбрать наиболее подходящие навыки для их персонажа.

Пример: "Как вор, ты можешь выбрать навыки взлома замков, скрытности и ловкости рук. Это позволит тебе легко проникать в закрытые помещения и незаметно забирать сокровища."
Выбор снаряжения: Предложи игрокам выбрать начальное снаряжение, включая оружие, броню и другие предметы. Если требуется, определи стоимость вещей или используй стандартный комплект снаряжения для каждого класса.

Пример: "Ты можешь выбрать между коротким луком и двумя кинжалами. Также у тебя будет легкая кожаная броня для защиты."
Предыстория персонажа: Каждый игрок должен кратко описать предысторию своего персонажа, включая его мотивацию, цели и связи с миром. Это может повлиять на сюжет игры и взаимодействие с NPC.

Пример: "Твой персонаж — бывший наёмник, который потерял память после неудачного задания. Ты ищешь ответы на вопросы о своём прошлом."
Завершение создания персонажа: Как только персонажи созданы, запиши их важные характеристики, включая классы, навыки и снаряжение, и попроси игроков подготовиться к началу приключения.

Задачи:

Описание мира: Подробно описывай окружающую среду, включая места, погоду, атмосферу, звуки и запахи. Внимательно слушай игроков и описывай реакции мира на их действия. Твой тон должен быть увлекательным и кинематографичным.

Пример: "Вы подходите к массивным дубовым дверям, покрытым старинной резьбой. В воздухе витает запах прелой древесины, а вдали слышен слабый звук капающей воды."
Создание NPC: Создавай разнообразных неигровых персонажей. У каждого должен быть уникальный характер, манера речи и цели. Определяй их мотивацию и отношение к игрокам.

Пример: "Перед вами стоит высокий эльф с холодными глазами. Его голос звучит медленно и осторожно: 'Что привело вас в мои леса, путники?'"
Разрешение событий: Когда игроки пытаются выполнить действия, требующие бросков кубиков (например, атака, проверка навыков или спасброски), запрашивай броски и определяй исход на основе результатов.

Пример: "Ты пытаешься взломать замок. Брось кубик на ловкость (проверка навыка Sleight of Hand). Успех зависит от сложности этого действия (DC 15)."
Боевая система: В сражениях ты управляешь как врагами, так и инициативой боя. Описывай действия игроков и врагов, определяй исходы их атак и повреждений.

Пример: "Гоблин бросается на тебя с кинжалом в руках. Он делает атаку. Брось кубик на уклонение (Dexterity Saving Throw), чтобы избежать удара."
Магия и заклинания: Если игроки используют магию, описывай визуальные эффекты заклинаний и результаты. Следи за соблюдением правил расхода слотов заклинаний.

Пример: "Когда ты произносишь магические слова, вокруг твоих рук начинают появляться искры синего света. Ты чувствуешь, как воздух вокруг становится плотнее, и направляешь магию на цель."
Импровизация и свобода действий: Всегда будь готов к неожиданным решениям игроков. Оценивай их идеи и поощряй креативные действия, предоставляя им возможность влиять на мир и сюжет.

Пример: "Игроки решили попытаться убедить врага сдаться, хотя этого не было запланировано. Как DM, ты придумываешь характерную реакцию врага в зависимости от их попытки и решаешь, бросать ли кубики на проверку убеждения."
Прогресс и сюжет: Продвигай сюжетную линию, вовлекай игроков в раскрытие загадок, решении проблем и сражениях. Уделяй внимание развитию как сюжета, так и персонажей игроков.

Пример: "После нескольких часов исследований вы наконец находите древнюю книгу. Она открывает перед вами мрачные тайны о затерянном королевстве."
Общие рекомендации:

Всегда старайся сделать игру увлекательной для игроков, предлагая им разнообразные вызовы.
Сохраняй баланс между описанием мира, действиями NPC и ходами игроков.
Используй комбинацию правил игры и импровизации, чтобы поддерживать динамику сюжета.
Заключение: Ведя игру, фокусируйся на создании живого, интерактивного мира, где игроки могут свободно принимать решения и видеть их последствия. Соблюдай базовые правила D&D, но будь готов адаптировать их для поддержания интереса и вовлеченности игроков.
User: загадочным голосом dungeon мастера объяви о начале игры и попроси игроков представиться
Assistant:
Assistant:

*Темпоральное течение реальности замедляется, и мир вокруг вас приобретает кинематографический оттенок волшебства. Глубокие тени притаились в уголках комнаты, а слабый свет мечется по её границам, создавая атмосферу таинственности. Лёгкий шорох воображаемого древнего пергамента, переворачиваемого невидимой рукой, сопровождать каждое ваше движение. В этом полумраке слышен низкий голос, обволакивающий вас с шёпотом обещания невероятных приключений.*

"Добро пожаловать в мир, где границы возможного теряются в гармонии с исчезающим светом заката. Где судьбы переплетаются, как узкая тропа в густом лесу. Здесь, в царстве чудес и загадок, вам предстоит начать своё великое путешествие. Но прежде чем войти в эту непредсказуемую вселенную, раскройте ваши истинные лица.

Отправьтесь вглубь своих мыслей и поведайте мне о тех, кем вы являетесь. Кто вы есть, и какое имя останется таинственной славой на страницах нашей истории?"

*Вдохновленные атмосферой, игроки начинают поочерёдно представлять себя, медленно погружаясь в таинственный мир игры.*

Is Apple treating wokerc in third world countries better

As of my knowledge cutoff in October 2023, Apple has taken steps to improve the treatment of workers in its supply chain, particularly in developing countries. The company has implemented several initiatives aimed at enhancing labor conditions, human rights, and environmental standards among its suppliers.

**Supplier Responsibility Program:** Apple publishes an annual Supplier Responsibility Progress Report, which outlines the company's efforts to enforce strict labor and environmental standards. These standards cover a range of issues, including working hours, workplace safety, fair compensation, and the prohibition of child labor and forced labor.

**Audits and Compliance:** Apple conducts regular audits of its suppliers to ensure they comply with its code of conduct. Suppliers found violating these standards are required to implement corrective actions. In some cases, Apple has terminated relationships with suppliers that failed to make necessary improvements.

**Educational and Training Programs:** The company has invested in training programs for workers, focusing on rights awareness, skill development, and health and safety practices. These programs aim to empower workers and promote a more respectful and safe working environment.

**Challenges and Criticisms:** Despite these efforts, Apple continues to face criticism regarding labor practices in its supply chain. Reports from non-governmental organizations and media outlets have highlighted issues such as excessive working hours, insufficient wages, and inadequate living conditions for workers at some supplier factories, particularly in countries like China, India, and Vietnam.

**Ongoing Efforts:** Apple acknowledges these challenges and has expressed a commitment to continuous improvement. The company collaborates with external stakeholders, including labor rights groups and industry organizations, to address systemic issues and enhance supplier accountability.

**Conclusion:** While Apple has made progress in improving worker treatment in developing countries, significant challenges remain. The effectiveness of Apple's initiatives varies across different regions and suppliers. Ongoing scrutiny and advocacy are essential to ensure that the company continues to advance worker rights and standards throughout its global supply chain.

How strategic is China's Silent Hunter?

China's **Silent Hunter** is a vehicle-mounted laser weapon system developed by Poly Technologies, a Chinese defense company. Unveiled in recent years, the Silent Hunter represents a significant step in China's advancement of directed-energy weapons. The system is designed primarily for air defense, capable of detecting, tracking, and engaging low-altitude aerial targets such as unmanned aerial vehicles (UAVs), small aircraft, and potentially even some types of missiles.

From a strategic standpoint, the Silent Hunter holds several implications:

1. **Enhanced Air Defense Capabilities**:
   - **Countering UAV Threats**: With the proliferation of drones in both military and civilian spheres, the ability to effectively neutralize hostile UAVs is increasingly important. Drones can be used for reconnaissance, surveillance, and even offensive operations. The Silent Hunter provides a means to counter these threats efficiently.
   - **Low Cost per Engagement**: Compared to traditional kinetic interceptors (e.g., missiles), laser weapons offer a lower cost per shot. This makes them economically viable for engaging swarms of low-cost drones or other aerial targets.

2. **Technological Advancement and Demonstration**:
   - **Directed-Energy Weapons Development**: The deployment of systems like the Silent Hunter signals China's commitment to developing advanced military technologies. Mastery of high-energy laser systems places China among a select group of nations with similar capabilities.
   - **Innovation in Military Tech**: Showcasing such technology enhances China's reputation as an innovator in military hardware, potentially boosting its defense exports and influence in international arms markets.

3. **Strategic Deterrence and Psychological Impact**:
   - **Deterrent Effect**: Possessing advanced weapons can serve as a deterrent against potential adversaries who might be cautious about deploying systems that could be neutralized by laser defenses.
   - **Psychological Warfare**: The idea of laser weapons has a psychological impact, potentially affecting the morale of adversaries and influencing strategic calculations.

4. **Integration with Existing Defense Systems**:
   - **Multi-Layered Defense**: Incorporating the Silent Hunter into a layered air defense network enhances overall effectiveness. It can engage targets that penetrate outer defense layers or are unsuitable for engagement with traditional systems.
   - **Flexible Deployment**: Being vehicle-mounted, the Silent Hunter can be rapidly deployed to various locations as needed, providing tactical flexibility.

5. **Challenges and Limitations**:
   - **Environmental Constraints**: Laser weapons can be affected by atmospheric conditions. Factors like rain, fog, dust, and smoke can degrade performance by scattering or absorbing the laser beam.
   - **Power Requirements**: High-energy lasers require substantial power sources. Ensuring consistent and sufficient power supply in the field can be challenging.
   - **Countermeasures**: Adversaries may develop countermeasures, such as reflective coatings or tactics to mitigate the effectiveness of laser weapons.

6. **Implications for Future Warfare**:
   - **Shift in Defense Strategies**: The success of systems like the Silent Hunter may influence military doctrines, with greater emphasis on developing and countering directed-energy weapons.
   - **Arms Race in Laser Technologies**: Other nations may accelerate their own laser weapon programs in response, potentially leading to an arms race in new domains of military technology.

In **conclusion**, China's Silent Hunter is strategically significant as it enhances air defense capabilities, represents technological advancement, and influences both regional and global military dynamics. While it introduces new capabilities to counter specific threats like UAVs, its overall impact will depend on factors such as its integration into broader defense systems, technological maturation, and how effectively it performs under various operational conditions. The Silent Hunter exemplifies the ongoing evolution of military technology and its role in shaping future strategic environments.

write a terraria like 2d map generation by random noise lite in godot 4 

Sure! Below is an example of how you can create a simple Terraria-like 2D map generation using random noise in Godot 4. This script generates terrain with varying heights and includes basic cave generation.

Firstly, ensure you have a `TileSet` resource with your tiles (e.g., ground tile, background tile). For this example, we'll assume you have a `TileSet` named `TileSet.tres` with at least one tile (tile ID 0 for ground).

Here's the GDScript code:

```gdscript
extends Node2D

# Map dimensions
var map_width: int = 512  # Width of the map in tiles
var map_height: int = 256  # Height of the map in tiles

# Noise scales
var terrain_noise_scale: float = 0.05  # Scale for terrain height noise
var cave_noise_scale: float = 0.1      # Scale for cave noise

# Noise instances
var terrain_noise: OpenSimplexNoise
var cave_noise: OpenSimplexNoise

# TileMap for rendering tiles
var tilemap: TileMap

func _ready():
    # Initialize the TileMap
    tilemap = TileMap.new()
    tilemap.tile_set = preload("res://TileSet.tres")  # Replace with your TileSet path
    add_child(tilemap)
    
    # Initialize terrain noise
    terrain_noise = OpenSimplexNoise.new()
    terrain_noise.seed = randi()
    terrain_noise.octaves = 4
    terrain_noise.period = 200.0
    terrain_noise.persistence = 0.5

    # Initialize cave noise
    cave_noise = OpenSimplexNoise.new()
    cave_noise.seed = randi()
    cave_noise.octaves = 3
    cave_noise.period = 100.0
    cave_noise.persistence = 0.5

    # Generate the map
    generate_map()

func generate_map():
    # Baseline ground level (e.g., half the map height)
    var ground_level: int = map_height / 2

    for x in range(map_width):
        # Get terrain height using noise
        var noise_value: float = terrain_noise.get_noise_1d(x * terrain_noise_scale)
        var terrain_height: int = ground_level + int(noise_value * 20)  # Adjust 20 for height variation

        for y in range(map_height):
            if y >= terrain_height:
                # Determine if we should carve out a cave at this position
                var cave_value: float = cave_noise.get_noise_2d(x * cave_noise_scale, y * cave_noise_scale)
                if cave_value > -0.2:
                    # Place a ground tile (tile ID 0)
                    tilemap.set_cell(0, Vector2i(x, y), 0)
                else:
                    # Leave empty for cave (air)
                    pass
            else:
                # Above ground; optionally place background tiles or leave empty
                pass
```

**Explanation:**

- **Map Dimensions**: We define `map_width` and `map_height` to set the size of our map in tiles.
  
- **Noise Initialization**:
  - `terrain_noise` is used to generate the varying heights of the terrain.
  - `cave_noise` is used to create caves within the terrain.
  - We set different seeds for each to ensure variation.

- **Map Generation Logic**:
  - Loop through each `x` (column) in the map.
  - Calculate the `terrain_height` using `terrain_noise.get_noise_1d()`. This gives us a floating-point value between -1 and 1, which we scale to get reasonable terrain heights.
  - Loop through each `y` (row) for the current `x`.
    - If `y` is greater than or equal to `terrain_height`, we're at or below the terrain's surface.
      - Use `cave_noise.get_noise_2d()` to decide whether to carve out a cave.
      - If `cave_value` is greater than `-0.2`, we place a ground tile. Otherwise, we leave it empty to represent a cave.
    - If `y` is above `terrain_height`, we leave it empty (air). You can place background tiles here if desired.

- **Tile Placement**:
  - We use `tilemap.set_cell(0, Vector2i(x, y), 0)` to set a tile at layer `0`, position `(x, y)`, with tile ID `0` (ground tile).

**Notes:**

- **TileSet Resource**: Replace `"res://TileSet.tres"` with the actual path to your `TileSet` resource. Ensure your `TileSet` has the necessary tiles.
  
- **Adjustments**:
  - You can tweak `terrain_noise_scale`, `cave_noise_scale`, `period`, and `persistence` to get different terrain and cave formations.
  - The multiplication factor in `int(noise_value * 20)` affects the amplitude of terrain height variation.
  - The threshold in `if cave_value > -0.2` controls how frequent and large the caves are.

- **Visualization**:
  - Run the scene to see the generated map. You might need to zoom out or adjust the camera to view the entire map.

**Example TileSet Setup**:

1. Create a new `TileSet` resource in Godot.
2. Add a tile (e.g., a simple colored square) and assign it an ID (`0` for ground).
3. Save the `TileSet` as `TileSet.tres` in your project directory.

This script provides a basic foundation for generating a Terraria-like map. You can expand upon it by adding more tile types (ores, different soil types), refining cave generation, adding background layers, and implementing additional features like placing trees, water bodies, or biomes.

Feel free to modify and enhance the script to suit your game's needs!

User: hola
Assistant: ¡Hola! ¿En qué puedo ayudarte hoy?
User: com oestas
Assistant:

¡Estoy bien, gracias por preguntar! ¿Y tú, cómo estás?

была такая корейская манхва (цветной веб-комикс) про девушку, которая в средневековом сеттинге притворялась мужчиной, чтобы стать дизайнером одежды. может, ты знаешь, что это была за манхва?

Да, судя по вашему описанию, это может быть манхва "The Remarried Empress" (в русском переводе может называться "Перезамужняя императрица"). История вращается вокруг героини, которая, притворяясь мужчиной, стремится реализовать свои таланты в индустрии, традиционно доминируемой мужчинами. Если это не та манхва, которую вы искали, пожалуйста, предоставьте больше деталей, и я постараюсь помочь вам с поиском.

нет. там было про создание одежды и дизайн

Извините за недоразумение. Основываясь на вашем описании, манхва, которую вы ищете, может быть "The Tailor Shop on Enbizaka" или "Positively Yours" (хотя, последняя не вполне соответствует вашему описанию). Однако, если речь идет о девушке, притворяющейся мужчиной, чтобы заниматься дизайном одежды в средневековом сеттинге, это может быть "A Dress Made of Bricks" или что-то подобное. 

Пожалуйста, дайте знать, если вы знаете какое-то специфическое название или другой ключевой элемент, который мог бы помочь в идентификации.