added MD support

src/main/java/cz/kamma/kfmanager/MainApp.java

@@ -15,7 +15,7 @@ import java.io.InputStreamReader;
  */
 public class MainApp {
 
-    public static final String APP_VERSION = "1.4.6";
+    public static final String APP_VERSION = "1.4.7";
     
     public enum OS {
         WINDOWS, LINUX, MACOS, UNKNOWN

src/main/java/cz/kamma/kfmanager/ui/FileEditor.java

@@ -4,6 +4,8 @@ import cz.kamma.kfmanager.config.AppConfig;
 import cz.kamma.kfmanager.model.FileItem;
 
 import javax.swing.*;
+import javax.swing.text.html.HTMLEditorKit;
+import javax.swing.text.html.StyleSheet;
 import java.awt.*;
 import java.awt.event.KeyEvent;
 import java.awt.event.InputEvent;
@@ -20,6 +22,7 @@ import java.util.regex.Matcher;
  */
 public class FileEditor extends JFrame {
     private JTextArea textArea;
+    private JEditorPane markdownPane;
     private JScrollPane scrollPane;
     private File file;
     private String virtualPath;
@@ -55,6 +58,8 @@ public class FileEditor extends JFrame {
     private JButton prevPageBtn = null;
     private JButton nextPageBtn = null;
     private JLabel pageOffsetLabel = null;
+    private boolean markdownMode = false;
+    private JCheckBoxMenuItem markdownItem = null;
     private javax.swing.undo.UndoManager undoManager;
 
     // Search support
@@ -171,6 +176,9 @@ public class FileEditor extends JFrame {
     }
 
     private void showSearchPanel(boolean focusField) {
+        if (markdownMode) {
+            setMarkdownMode(false);
+        }
         searchPanel.setVisible(true);
         wholeWordCheckBox.setSelected(lastWholeWord);
         caseSensitiveCheckBox.setSelected(lastCaseSensitive);
@@ -210,7 +218,7 @@ public class FileEditor extends JFrame {
 
     private void hideSearchPanel() {
         searchPanel.setVisible(false);
-        textArea.requestFocusInWindow();
+        getActiveTextComponent().requestFocusInWindow();
         revalidate();
     }
 
@@ -412,6 +420,17 @@ public class FileEditor extends JFrame {
             textArea.setColumns(120);
         }
 
+        markdownPane = new JEditorPane();
+        markdownPane.setEditable(false);
+        markdownPane.setContentType("text/html");
+        markdownPane.putClientProperty(JEditorPane.HONOR_DISPLAY_PROPERTIES, Boolean.TRUE);
+        markdownPane.addHyperlinkListener(e -> {
+            if (e.getEventType() == javax.swing.event.HyperlinkEvent.EventType.ACTIVATED) {
+                openMarkdownLink(e);
+            }
+        });
+        markdownPane.addCaretListener(e -> updateStatus());
+
         // Menu bar
         createMenuBar();
         
@@ -512,6 +531,15 @@ public class FileEditor extends JFrame {
         });
 
         textArea.setComponentPopupMenu(popup);
+
+        JPopupMenu markdownPopup = new JPopupMenu();
+        JMenuItem markdownCopyItem = new JMenuItem(new javax.swing.text.DefaultEditorKit.CopyAction());
+        markdownCopyItem.setText("Copy");
+        markdownPopup.add(markdownCopyItem);
+        JMenuItem markdownSelectAllItem = new JMenuItem("Select All");
+        markdownSelectAllItem.addActionListener(e -> markdownPane.selectAll());
+        markdownPopup.add(markdownSelectAllItem);
+        markdownPane.setComponentPopupMenu(markdownPopup);
     }
     
     private void applyAppearance() {
@@ -540,6 +568,14 @@ public class FileEditor extends JFrame {
         if (readOnly) {
             textArea.getCaret().setVisible(true);
         }
+        if (markdownPane != null) {
+            markdownPane.setFont(textArea.getFont());
+            markdownPane.setBackground(textArea.getBackground());
+            markdownPane.setForeground(textArea.getForeground());
+            if (markdownMode) {
+                renderMarkdown();
+            }
+        }
     }
 
     private void applyRecursiveColors(Container container, Color bg, boolean dark) {
@@ -696,6 +732,12 @@ public class FileEditor extends JFrame {
         viewMenu.add(wrapItem);
         viewMenu.addSeparator();
 
+        markdownItem = new JCheckBoxMenuItem("Markdown preview");
+        markdownItem.setState(markdownMode);
+        markdownItem.setEnabled(readOnly && isMarkdownFile());
+        markdownItem.addActionListener(e -> setMarkdownMode(markdownItem.getState()));
+        viewMenu.add(markdownItem);
+
         JCheckBoxMenuItem hexItem = new JCheckBoxMenuItem("Hex view");
         hexItem.setState(hexMode);
         hexItem.addActionListener(e -> {
@@ -706,6 +748,262 @@ public class FileEditor extends JFrame {
         menuBar.add(viewMenu);
     }
 
+    private javax.swing.text.JTextComponent getActiveTextComponent() {
+        return markdownMode ? markdownPane : textArea;
+    }
+
+    private boolean isMarkdownFile() {
+        String name = virtualPath != null ? virtualPath : file.getName();
+        name = name.toLowerCase();
+        return name.endsWith(".md") || name.endsWith(".markdown") || name.endsWith(".mdown") || name.endsWith(".mkd");
+    }
+
+    private void setMarkdownMode(boolean on) {
+        if (on && (!readOnly || !isMarkdownFile() || hexMode || isImageFile(file))) {
+            on = false;
+        }
+
+        markdownMode = on;
+        if (markdownItem != null) {
+            markdownItem.setState(on);
+            markdownItem.setEnabled(readOnly && isMarkdownFile() && !hexMode && !isImageFile(file));
+        }
+
+        if (on) {
+            renderMarkdown();
+            scrollPane.setViewportView(markdownPane);
+            SwingUtilities.invokeLater(() -> {
+                markdownPane.setCaretPosition(0);
+                markdownPane.requestFocusInWindow();
+            });
+        } else if (scrollPane != null && scrollPane.getViewport().getView() == markdownPane) {
+            scrollPane.setViewportView(textArea);
+            SwingUtilities.invokeLater(() -> textArea.requestFocusInWindow());
+        }
+        updateStatus();
+    }
+
+    private void renderMarkdown() {
+        String raw = textArea.getText();
+        markdownPane.setEditorKit(createMarkdownEditorKit());
+        markdownPane.setText(markdownToHtml(raw));
+        markdownPane.setCaretPosition(0);
+    }
+
+    private void openMarkdownLink(javax.swing.event.HyperlinkEvent event) {
+        try {
+            if (event.getURL() != null) {
+                Desktop.getDesktop().browse(event.getURL().toURI());
+                return;
+            }
+            String description = event.getDescription();
+            if (description == null || description.isBlank()) return;
+            java.net.URI uri = new java.net.URI(description);
+            if (uri.isAbsolute()) {
+                Desktop.getDesktop().browse(uri);
+                return;
+            }
+            File baseDir = file.getParentFile();
+            if (baseDir != null) {
+                Desktop.getDesktop().open(new File(baseDir, description));
+            }
+        } catch (Exception ex) {
+            JOptionPane.showMessageDialog(this, "Cannot open link:\n" + ex.getMessage(), "Error", JOptionPane.ERROR_MESSAGE);
+        }
+    }
+
+    private HTMLEditorKit createMarkdownEditorKit() {
+        HTMLEditorKit kit = new HTMLEditorKit();
+        StyleSheet styles = kit.getStyleSheet();
+        Font font = config.getEditorFont();
+        Color bg = textArea.getBackground();
+        Color fg = textArea.getForeground();
+        String fontFamily = font != null ? font.getFamily() : "SansSerif";
+        int fontSize = font != null ? font.getSize() : 13;
+        styles.addRule("body { font-family: " + cssString(fontFamily) + "; font-size: " + fontSize + "pt; "
+                + "background: " + toCssColor(bg) + "; color: " + toCssColor(fg) + "; margin: 12px; }");
+        styles.addRule("h1 { font-size: 190%; margin: 0 0 10px 0; }");
+        styles.addRule("h2 { font-size: 155%; margin: 18px 0 8px 0; }");
+        styles.addRule("h3 { font-size: 130%; margin: 16px 0 7px 0; }");
+        styles.addRule("h4, h5, h6 { margin: 14px 0 6px 0; }");
+        styles.addRule("p { margin: 0 0 10px 0; }");
+        styles.addRule("ul, ol { margin-top: 0; margin-bottom: 10px; }");
+        styles.addRule("blockquote { margin: 0 0 10px 12px; padding-left: 10px; border-left: 3px solid #808080; }");
+        styles.addRule("pre { font-family: Monospaced; font-size: " + fontSize + "pt; margin: 0 0 10px 0; padding: 8px; }");
+        styles.addRule("code { font-family: Monospaced; }");
+        styles.addRule("a { color: #2f7ed8; }");
+        return kit;
+    }
+
+    private String markdownToHtml(String markdown) {
+        StringBuilder body = new StringBuilder();
+        String[] lines = markdown.replace("\r\n", "\n").replace('\r', '\n').split("\n", -1);
+        StringBuilder paragraph = new StringBuilder();
+        StringBuilder list = null;
+        String listTag = null;
+        boolean inFence = false;
+        StringBuilder fence = new StringBuilder();
+
+        for (String line : lines) {
+            String trimmed = line.trim();
+            if (trimmed.startsWith("```")) {
+                if (inFence) {
+                    body.append("<pre><code>").append(escapeHtml(fence.toString())).append("</code></pre>");
+                    fence.setLength(0);
+                    inFence = false;
+                } else {
+                    flushParagraph(body, paragraph);
+                    list = flushList(body, list, listTag);
+                    listTag = null;
+                    inFence = true;
+                }
+                continue;
+            }
+            if (inFence) {
+                fence.append(line).append('\n');
+                continue;
+            }
+
+            if (trimmed.isEmpty()) {
+                flushParagraph(body, paragraph);
+                list = flushList(body, list, listTag);
+                listTag = null;
+                continue;
+            }
+
+            String heading = headingHtml(trimmed);
+            if (heading != null) {
+                flushParagraph(body, paragraph);
+                list = flushList(body, list, listTag);
+                listTag = null;
+                body.append(heading);
+                continue;
+            }
+
+            if (trimmed.matches("[-*_]{3,}")) {
+                flushParagraph(body, paragraph);
+                list = flushList(body, list, listTag);
+                listTag = null;
+                body.append("<hr>");
+                continue;
+            }
+
+            Matcher unordered = Pattern.compile("^[-*+]\\s+(.+)$").matcher(trimmed);
+            Matcher ordered = Pattern.compile("^\\d+[.)]\\s+(.+)$").matcher(trimmed);
+            if (unordered.matches() || ordered.matches()) {
+                flushParagraph(body, paragraph);
+                String currentTag = unordered.matches() ? "ul" : "ol";
+                if (list != null && !currentTag.equals(listTag)) {
+                    list = flushList(body, list, listTag);
+                }
+                if (list == null) {
+                    list = new StringBuilder();
+                    listTag = currentTag;
+                }
+                String item = unordered.matches() ? unordered.group(1) : ordered.group(1);
+                list.append("<li>").append(renderInline(item)).append("</li>");
+                continue;
+            }
+
+            if (trimmed.startsWith(">")) {
+                flushParagraph(body, paragraph);
+                list = flushList(body, list, listTag);
+                listTag = null;
+                String quote = trimmed.replaceFirst("^>\\s?", "");
+                body.append("<blockquote>").append(renderInline(quote)).append("</blockquote>");
+                continue;
+            }
+
+            if (paragraph.length() > 0) {
+                paragraph.append(' ');
+            }
+            paragraph.append(trimmed);
+        }
+
+        if (inFence) {
+            body.append("<pre><code>").append(escapeHtml(fence.toString())).append("</code></pre>");
+        }
+        flushParagraph(body, paragraph);
+        flushList(body, list, listTag);
+        return "<html><body>" + body + "</body></html>";
+    }
+
+    private void flushParagraph(StringBuilder body, StringBuilder paragraph) {
+        if (paragraph.length() == 0) return;
+        body.append("<p>").append(renderInline(paragraph.toString())).append("</p>");
+        paragraph.setLength(0);
+    }
+
+    private StringBuilder flushList(StringBuilder body, StringBuilder list, String listTag) {
+        if (list == null || listTag == null) return null;
+        body.append('<').append(listTag).append('>').append(list).append("</").append(listTag).append('>');
+        return null;
+    }
+
+    private String headingHtml(String trimmed) {
+        Matcher m = Pattern.compile("^(#{1,6})\\s+(.+)$").matcher(trimmed);
+        if (!m.matches()) return null;
+        int level = m.group(1).length();
+        return "<h" + level + ">" + renderInline(m.group(2)) + "</h" + level + ">";
+    }
+
+    private String renderInline(String text) {
+        java.util.List<String> codeSpans = new java.util.ArrayList<>();
+        Matcher codeMatcher = Pattern.compile("`([^`]+)`").matcher(text);
+        StringBuffer protectedText = new StringBuffer();
+        while (codeMatcher.find()) {
+            String token = "{{KF_MD_CODE_" + codeSpans.size() + "}}";
+            codeSpans.add("<code>" + escapeHtml(codeMatcher.group(1)) + "</code>");
+            codeMatcher.appendReplacement(protectedText, Matcher.quoteReplacement(token));
+        }
+        codeMatcher.appendTail(protectedText);
+
+        String html = escapeHtml(protectedText.toString());
+        html = html.replaceAll("\\*\\*([^*]+)\\*\\*", "<strong>$1</strong>");
+        html = html.replaceAll("__([^_]+)__", "<strong>$1</strong>");
+        html = html.replaceAll("(?<!\\*)\\*([^*]+)\\*(?!\\*)", "<em>$1</em>");
+        html = html.replaceAll("(?<!_)_([^_]+)_(?!_)", "<em>$1</em>");
+        html = replaceLinks(html);
+
+        for (int i = 0; i < codeSpans.size(); i++) {
+            html = html.replace("{{KF_MD_CODE_" + i + "}}", codeSpans.get(i));
+        }
+        return html;
+    }
+
+    private String replaceLinks(String html) {
+        Matcher m = Pattern.compile("\\[([^\\]]+)]\\(([^\\s)]+)\\)").matcher(html);
+        StringBuffer sb = new StringBuffer();
+        while (m.find()) {
+            String label = m.group(1);
+            String href = m.group(2);
+            String replacement = "<a href=\"" + escapeAttribute(href) + "\">" + label + "</a>";
+            m.appendReplacement(sb, Matcher.quoteReplacement(replacement));
+        }
+        m.appendTail(sb);
+        return sb.toString();
+    }
+
+    private String escapeHtml(String text) {
+        return text.replace("&", "&amp;")
+                .replace("<", "&lt;")
+                .replace(">", "&gt;")
+                .replace("\"", "&quot;");
+    }
+
+    private String escapeAttribute(String text) {
+        return escapeHtml(text).replace("'", "&#39;");
+    }
+
+    private String toCssColor(Color color) {
+        if (color == null) return "#ffffff";
+        return "#%02x%02x%02x".formatted(color.getRed(), color.getGreen(), color.getBlue());
+    }
+
+    private String cssString(String value) {
+        return "'" + value.replace("\\", "\\\\").replace("'", "\\'") + "'";
+    }
+
     private void ensureHexControls() {
         if (hexControlPanel != null) return;
         hexControlPanel = new JPanel(new FlowLayout(FlowLayout.LEFT));
@@ -746,7 +1044,7 @@ public class FileEditor extends JFrame {
                 showSearchPanel(false);
             }
             findNext();
-            textArea.requestFocusInWindow();
+            getActiveTextComponent().requestFocusInWindow();
         },
                 KeyStroke.getKeyStroke(KeyEvent.VK_F3, 0),
                 JComponent.WHEN_IN_FOCUSED_WINDOW);
@@ -821,14 +1119,20 @@ public class FileEditor extends JFrame {
 
         rootPane.registerKeyboardAction(e -> {
             findPrevious();
-            textArea.requestFocusInWindow();
+            getActiveTextComponent().requestFocusInWindow();
         },
                 KeyStroke.getKeyStroke(KeyEvent.VK_F3, InputEvent.SHIFT_DOWN_MASK),
                 JComponent.WHEN_IN_FOCUSED_WINDOW);
     }
 
     private void setHexMode(boolean on) {
+        if (on && markdownMode) {
+            setMarkdownMode(false);
+        }
         this.hexMode = on;
+        if (markdownItem != null) {
+            markdownItem.setEnabled(readOnly && isMarkdownFile() && !on && !isImageFile(file));
+        }
         if (on) {
             // ensure bytes loaded
             try {
@@ -1009,7 +1313,7 @@ public class FileEditor extends JFrame {
         if (virtualPath != null && ftpProfile == null) {
             try {
                 fileBytes = cz.kamma.kfmanager.service.FileOperations.readFileFromArchive(file, virtualPath);
-                boolean binary = isBinary(fileBytes);
+                boolean binary = isBinaryForCurrentFile(fileBytes);
                 if (binary && readOnly) {
                     hexMode = true;
                     buildHexViewText(0L);
@@ -1029,6 +1333,7 @@ public class FileEditor extends JFrame {
                 }
                 if (undoManager != null) undoManager.discardAllEdits();
                 modified = false;
+                updateMarkdownPreviewAfterLoad();
                 updateTitle();
                 updateStatus();
                 return;
@@ -1058,7 +1363,7 @@ public class FileEditor extends JFrame {
                 }
             }
 
-            boolean binaryProbe = isBinary(probe);
+            boolean binaryProbe = isBinaryForCurrentFile(probe);
 
             if (binaryProbe && readOnly && size > maxFullLoadBytes) {
                 // Open RAF and stream pages
@@ -1077,7 +1382,7 @@ public class FileEditor extends JFrame {
             } else {
                 // Small or text file: load fully
                 fileBytes = readFileBytesWithChunking(file, size);
-                boolean binary = isBinary(fileBytes);
+                boolean binary = isBinaryForCurrentFile(fileBytes);
                 if (binary && readOnly) {
                     hexMode = true;
                     buildHexViewText(0L);
@@ -1098,6 +1403,7 @@ public class FileEditor extends JFrame {
             }
             if (undoManager != null) undoManager.discardAllEdits();
             modified = false;
+            updateMarkdownPreviewAfterLoad();
             updateTitle();
             updateStatus();
         } catch (IOException e) {
@@ -1105,6 +1411,26 @@ public class FileEditor extends JFrame {
         }
     }
 
+    private void updateMarkdownPreviewAfterLoad() {
+        boolean shouldPreview = readOnly && isMarkdownFile() && !hexMode && !isImageFile(file);
+        setMarkdownMode(shouldPreview);
+    }
+
+    private boolean isBinaryForCurrentFile(byte[] bytes) {
+        if (isMarkdownFile()) {
+            return containsNulByte(bytes);
+        }
+        return isBinary(bytes);
+    }
+
+    private boolean containsNulByte(byte[] bytes) {
+        if (bytes == null) return false;
+        for (byte b : bytes) {
+            if (b == 0) return true;
+        }
+        return false;
+    }
+
     private boolean isBinary(byte[] bytes) {
         if (bytes == null || bytes.length == 0) return false;
         int nonPrintable = 0;
@@ -1499,6 +1825,26 @@ public class FileEditor extends JFrame {
                         statusSelLabel.setText(" ");
                     }
                 
+                } else if (markdownMode) {
+                    String text = textArea.getText();
+                    int chars = text != null ? text.length() : 0;
+                    int bytes = 0;
+                    try {
+                        bytes = text != null ? text.getBytes("UTF-8").length : 0;
+                    } catch (Exception ignore) {}
+                    statusPosLabel.setText("Markdown preview  |  %d chars / %d bytes".formatted(chars, bytes));
+
+                    String selected = markdownPane.getSelectedText();
+                    int selChars = selected != null ? selected.length() : 0;
+                    if (selChars > 0) {
+                        int selBytes = 0;
+                        try {
+                            selBytes = selected.getBytes("UTF-8").length;
+                        } catch (Exception ignore) {}
+                        statusSelLabel.setText("Selected: %d chars / %d bytes".formatted(selChars, selBytes));
+                    } else {
+                        statusSelLabel.setText(" ");
+                    }
                 } else {
                     int caret = textArea.getCaretPosition();
                     String text = textArea.getText();