added database dirty state monitor

Co-authored-by: Copilot <copilot@github.com>

src/main/java/cz/kamma/jkeepass/KeepassApp.java

@@ -84,6 +84,8 @@ public class KeepassApp extends JFrame {
     private static final int MAX_RECENT_FILES = 5;
     private File currentFile;
     private String currentPassword;
+    private boolean hasUnsavedChanges;
+    private final List<String> changedItems = new ArrayList<>();
     
     // Menu items that need state management
     private JMenuItem menuSave;
@@ -117,9 +119,7 @@ public class KeepassApp extends JFrame {
         addWindowListener(new WindowAdapter() {
             @Override
             public void windowClosing(WindowEvent e) {
-                saveWindowState();
+                requestCloseApplication();
-                saveComponentState();
-                System.exit(0);
             }
         });
 
@@ -182,7 +182,7 @@ public class KeepassApp extends JFrame {
         menuChangeMasterPassword.addActionListener(e -> changeMasterPassword());
         minimizeItem.addActionListener(e -> minimizeToCustomTray());
         menuLock.addActionListener(e -> lockDatabase());
-        exitItem.addActionListener(e -> System.exit(0));
+        exitItem.addActionListener(e -> requestCloseApplication());
 
         fileMenu.add(openItem);
         fileMenu.add(recentMenu);
@@ -464,7 +464,7 @@ public class KeepassApp extends JFrame {
         boolean hasEntrySelected = entryTable != null && entryTable.getSelectedRow() >= 0;
         
         // File menu items
-        menuSave.setEnabled(dbIsLoaded);
+        menuSave.setEnabled(dbIsLoaded && hasUnsavedChanges);
         menuChangeMasterPassword.setEnabled(dbIsLoaded);
         menuLock.setEnabled(dbIsLoaded);
         
@@ -554,6 +554,7 @@ public class KeepassApp extends JFrame {
                 this.database = CustomDatabaseFormat.convertJkpToDatabase(selectedFile, password);
                 this.currentFile = selectedFile;
                 this.currentPassword = password;
+                setUnsavedChanges(false);
                 updateTree(this.database.getRootGroup());
                 saveRecentFile(selectedFile.getAbsolutePath());
                 statusLabel.setText(" Database loaded: " + selectedFile.getName());
@@ -584,21 +585,102 @@ public class KeepassApp extends JFrame {
         }
     }
 
-    private void saveDatabase() {
+    private boolean saveDatabase() {
         if (database == null || currentFile == null || currentPassword == null) {
             JOptionPane.showMessageDialog(this, "No database open to save.", "Warning", JOptionPane.WARNING_MESSAGE);
-            return;
+            return false;
         }
         try {
             // Save as custom JKP format
             CustomDatabaseFormat.saveDatabase(currentFile, database, currentPassword);
+            setUnsavedChanges(false);
             statusLabel.setText(" Database saved successfully.");
+            return true;
         } catch (Exception ex) {
             JOptionPane.showMessageDialog(this, "Error saving database: " + ex.getMessage(), "Error", JOptionPane.ERROR_MESSAGE);
             ex.printStackTrace();
+            return false;
         }
     }
 
+    private void requestCloseApplication() {
+        if (!confirmSaveIfNeeded()) {
+            return;
+        }
+
+        saveWindowState();
+        saveComponentState();
+        System.exit(0);
+    }
+
+    private boolean confirmSaveIfNeeded() {
+        if (!hasUnsavedChanges) {
+            return true;
+        }
+
+        JTextArea changedItemsArea = new JTextArea(buildChangedItemsText());
+        changedItemsArea.setEditable(false);
+        changedItemsArea.setLineWrap(false);
+        changedItemsArea.setRows(8);
+
+        JScrollPane changedItemsScroll = new JScrollPane(changedItemsArea);
+        changedItemsScroll.setPreferredSize(new Dimension(420, 160));
+        changedItemsScroll.setBorder(BorderFactory.createTitledBorder("Changed items"));
+
+        JPanel panel = new JPanel(new BorderLayout(0, 8));
+        panel.add(new JLabel("Database has unsaved changes. Save before closing?"), BorderLayout.NORTH);
+        panel.add(changedItemsScroll, BorderLayout.CENTER);
+
+        int choice = JOptionPane.showConfirmDialog(
+                this,
+            panel,
+                "Unsaved Changes",
+                JOptionPane.YES_NO_CANCEL_OPTION,
+                JOptionPane.WARNING_MESSAGE
+        );
+
+        if (choice == JOptionPane.YES_OPTION) {
+            return saveDatabase();
+        }
+
+        if (choice == JOptionPane.NO_OPTION) {
+            return true;
+        }
+
+        return false;
+    }
+
+    private void setUnsavedChanges(boolean hasUnsavedChanges) {
+        this.hasUnsavedChanges = hasUnsavedChanges;
+        if (!hasUnsavedChanges) {
+            changedItems.clear();
+        }
+        updateMenuState();
+    }
+
+    private void markDataChanged(String description) {
+        this.hasUnsavedChanges = true;
+        changedItems.add(description);
+        updateMenuState();
+    }
+
+    private String buildChangedItemsText() {
+        if (changedItems.isEmpty()) {
+            return "No item-level details available.";
+        }
+
+        StringBuilder sb = new StringBuilder();
+        int maxItems = 25;
+        int limit = Math.min(changedItems.size(), maxItems);
+        for (int i = 0; i < limit; i++) {
+            sb.append(i + 1).append(". ").append(changedItems.get(i)).append('\n');
+        }
+        if (changedItems.size() > maxItems) {
+            sb.append("... and ").append(changedItems.size() - maxItems).append(" more change(s)");
+        }
+        return sb.toString();
+    }
+
     private void changeMasterPassword() {
         if (database == null || currentFile == null || currentPassword == null) {
             JOptionPane.showMessageDialog(this, "Database must be unlocked to change master password.", "Warning", JOptionPane.WARNING_MESSAGE);
@@ -656,6 +738,7 @@ public class KeepassApp extends JFrame {
         try {
             CustomDatabaseFormat.saveDatabase(currentFile, database, newPassword);
             currentPassword = newPassword;
+            setUnsavedChanges(false);
             statusLabel.setText(" Master password changed successfully.");
         } catch (Exception ex) {
             JOptionPane.showMessageDialog(this, "Error changing master password: " + ex.getMessage(), "Error", JOptionPane.ERROR_MESSAGE);
@@ -697,6 +780,7 @@ public class KeepassApp extends JFrame {
             Entry entry = currentGroup.addEntry(database.newEntry());
             updateEntryFromDialog(entry, dialog);
             displayEntriesInGroup(currentGroup);
+            markDataChanged("Entry added: " + safeItemName(entry.getTitle()));
             statusLabel.setText(" Entry added. Remember to Save.");
             updateMenuState();
         }
@@ -709,8 +793,10 @@ public class KeepassApp extends JFrame {
             Entry entry = currentEntries.get(modelRow);
             EntryDialog dialog = new EntryDialog(this, "Edit Entry", entry);
             if (dialog.showDialog()) {
+                String oldTitle = entry.getTitle();
                 updateEntryFromDialog(entry, dialog);
                 displayEntriesInGroup(currentGroup);
+                markDataChanged("Entry edited: " + safeItemName(oldTitle) + " -> " + safeItemName(entry.getTitle()));
                 statusLabel.setText(" Entry updated. Remember to Save.");
                 updateMenuState();
             }
@@ -726,8 +812,10 @@ public class KeepassApp extends JFrame {
             if (confirm == JOptionPane.YES_OPTION) {
                 int modelRow = entryTable.convertRowIndexToModel(selectedRow);
                 Entry entry = currentEntries.get(modelRow);
+                String entryTitle = entry.getTitle();
                 currentGroup.removeEntry(entry);
                 displayEntriesInGroup(currentGroup);
+                markDataChanged("Entry deleted: " + safeItemName(entryTitle));
                 statusLabel.setText(" Entry deleted. Remember to Save.");
                 updateMenuState();
             }
@@ -749,6 +837,7 @@ public class KeepassApp extends JFrame {
         if (name != null && !name.trim().isEmpty()) {
             parentGroup.addGroup(database.newGroup(name.trim()));
             updateTree(database.getRootGroup());
+            markDataChanged("Category added: " + safeItemName(name.trim()));
             statusLabel.setText(" Category added. Remember to Save.");
             updateMenuState();
         }
@@ -785,11 +874,19 @@ public class KeepassApp extends JFrame {
             Group parentGroup = ((GroupWrapper) parentNode.getUserObject()).getGroup();
             parentGroup.removeGroup(group);
             updateTree(database.getRootGroup());
+            markDataChanged("Category deleted: " + safeItemName(group.getName()));
             statusLabel.setText(" Category deleted. Remember to Save.");
             updateMenuState();
         }
     }
 
+    private String safeItemName(String value) {
+        if (value == null || value.trim().isEmpty()) {
+            return "(unnamed)";
+        }
+        return value.trim();
+    }
+
     private void displayEntriesInGroup(Group group) {
         this.currentGroup = group;
         tableModel.setRowCount(0);