From c263092c107c9a7866eb04446d5b5f9431af17dd Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Juan=20Jos=C3=A9=20Guti=C3=A9rrez=20de=20Quevedo=20P=C3=A9?=
 =?UTF-8?q?rez?= <juanjo@gutierrezdequevedo.com>
Date: Fri, 21 Nov 2025 13:09:47 +0100
Subject: [PATCH] Add dark mode UI and update components

---
 Dockerfile             |  39 ++-----
 cvs_proxy/app.py       |  41 +++++--
 ui/DARK_MODE_README.md | 107 ++++++++++++++++++
 ui/api.js              |   6 +-
 ui/app.js              |   3 -
 ui/index.html          |   6 +-
 ui/styles.css          |  27 +++++
 ui/test-dark-mode.html | 106 ++++++++++++++++++
 ui/ui.js               | 240 ++++++++++++++++++++++++++++++++++-------
 9 files changed, 488 insertions(+), 87 deletions(-)
 create mode 100644 ui/DARK_MODE_README.md
 create mode 100644 ui/test-dark-mode.html

diff --git a/Dockerfile b/Dockerfile
index 6f89b97..da43266 100644
--- a/Dockerfile
+++ b/Dockerfile
@@ -1,52 +1,29 @@
-FROM python:3.13-slim AS builder
+FROM python:3-bookworm
 
 # Set working directory
 WORKDIR /app
 
-# Install system dependencies for CVS
-RUN apt-get update && \
-    apt-get install -y cvs && \
-    apt-get clean && \
-    rm -rf /var/lib/apt/lists/*
+# Install runtime dependencies (minimal)
+RUN apt update && apt install cvs rsh-client
 
-# Copy only requirements first to leverage docker cache
-COPY requirements.txt .
+COPY . .
 
 # Install Python dependencies
 RUN pip install --no-cache-dir -r requirements.txt
-
-# Copy the rest of the application
-COPY . .
-
-# Install the package in editable mode
 RUN pip install --no-cache-dir -e .
 
-# Final stage
-FROM python:3.13-slim
-
-# Set working directory
-WORKDIR /app
-
-# Install CVS
-RUN apt-get update && \
-    apt-get install -y cvs && \
-    apt-get clean && \
-    rm -rf /var/lib/apt/lists/*
-
-# Copy only necessary files from builder
-COPY --from=builder /app /app
-COPY --from=builder /usr/local/lib/python3.13/site-packages /usr/local/lib/python3.13/site-packages
-
 # Set environment variables for configuration (with defaults)
 ENV CVS_URL="" \
     REPO_CHECKOUTS=/tmp/cvs_checkouts \
     CVS_MODULE="" \
+    BASEPATH="" \
     FLASK_HOST=0.0.0.0 \
     FLASK_PORT=5000 \
-    FLASK_DEBUG=false
+    FLASK_DEBUG=false \
+    CVS_RSH=rsh
 
 # Expose the application port
 EXPOSE 5000
 
 # Set the entrypoint to run the application with environment variables as command-line arguments
-ENTRYPOINT ["sh", "-c", "python -m cvs_proxy.app --cvs-url \"$CVS_URL\" --repo-checkouts \"$REPO_CHECKOUTS\" ${CVS_MODULE:+--cvs-module \"$CVS_MODULE\"} --host \"$FLASK_HOST\" --port \"$FLASK_PORT\" ${FLASK_DEBUG:+--debug}"]
\ No newline at end of file
+ENTRYPOINT ["sh", "-c", "python -m cvs_proxy.app --cvs-url \"$CVS_URL\" --repo-checkouts \"$REPO_CHECKOUTS\" ${CVS_MODULE:+--cvs-module \"$CVS_MODULE\"} ${BASEPATH:+--basepath \"$BASEPATH\"} --host \"$FLASK_HOST\" --port \"$FLASK_PORT\" ${FLASK_DEBUG:+--debug}"]
\ No newline at end of file
diff --git a/cvs_proxy/app.py b/cvs_proxy/app.py
index ad364cd..fdfccb0 100644
--- a/cvs_proxy/app.py
+++ b/cvs_proxy/app.py
@@ -1,4 +1,4 @@
-from flask import Flask, request, jsonify, send_from_directory
+from flask import Flask, request, jsonify, send_from_directory, Blueprint
 from .cvs_client import CVSClient
 import os
 import sys
@@ -17,6 +17,9 @@ app = Flask(__name__, static_folder=ui_dir, static_url_path='')
 cvs_client = None
 app_config = {}
 
+# Create API Blueprint (will be registered with basepath as url_prefix)
+api_bp = Blueprint('api', __name__)
+
 # Initialize CVS Client using provided parameters
 def create_cvs_client(cvs_url, repos_checkout=None, cvs_module=None):
     """
@@ -37,7 +40,17 @@ def create_cvs_client(cvs_url, repos_checkout=None, cvs_module=None):
     
     return CVSClient(cvs_url, repos_checkout=repos_checkout, cvs_module=cvs_module)
 
-@app.route('/v1/tree', methods=['GET'])
+@api_bp.route('/ui/config.js', methods=['GET'])
+def serve_config():
+    """
+    Serve dynamic configuration as JavaScript
+    This allows the frontend to access the basepath configuration
+    """
+    basepath = app_config.get('basepath', '')
+    config_js = f"window.APP_CONFIG = {{ basepath: '{basepath}' }};"
+    return config_js, 200, {'Content-Type': 'application/javascript'}
+
+@api_bp.route('/api/v1/tree', methods=['GET'])
 def get_repository_tree():
     """
     Get repository tree structure
@@ -53,7 +66,7 @@ def get_repository_tree():
     except Exception as e:
         return jsonify({"error": str(e)}), 500
 
-@app.route('/v1/diff', methods=['GET'])
+@api_bp.route('/api/v1/diff', methods=['GET'])
 def get_file_diff():
     """
     Get diff between two revisions of a file
@@ -75,7 +88,7 @@ def get_file_diff():
     except Exception as e:
         return jsonify({"error": str(e)}), 500
 
-@app.route('/v1/history', methods=['GET'])
+@api_bp.route('/api/v1/history', methods=['GET'])
 def get_file_history():
     """
     Get revision history for a file
@@ -95,7 +108,7 @@ def get_file_history():
     except Exception as e:
         return jsonify({"error": str(e)}), 500
 
-@app.route('/v1/file', methods=['GET'])
+@api_bp.route('/api/v1/file', methods=['GET'])
 def get_file_content():
     """
     Get raw file content at a specific revision
@@ -117,7 +130,7 @@ def get_file_content():
     except Exception as e:
         return jsonify({"error": str(e)}), 500
 
-@app.route('/v1/health', methods=['GET'])
+@api_bp.route('/api/v1/health', methods=['GET'])
 def health_check():
     """
     Simple health check endpoint
@@ -127,14 +140,14 @@ def health_check():
         "cvs_client": "initialized" if cvs_client else "not initialized"
     })
 
-@app.route('/', methods=['GET'])
+@api_bp.route('/ui/', methods=['GET'])
 def index():
     """
     Serve the UI index.html
     """
     return send_from_directory(ui_dir, 'index.html')
 
-@app.route('/<path:filename>', methods=['GET'])
+@api_bp.route('/ui/<path:filename>', methods=['GET'])
 def serve_static(filename):
     """
     Serve static files (CSS, JS, etc.)
@@ -180,6 +193,11 @@ def main():
         default=5000,
         help='Flask port to bind to (default: 5000)'
     )
+    parser.add_argument(
+        '--basepath',
+        default='',
+        help='Base path for API requests (e.g., /api/cvs) (default: empty string for root)'
+    )
     parser.add_argument(
         '--debug',
         action='store_true',
@@ -195,9 +213,14 @@ def main():
         'cvs_module': args.cvs_module,
         'host': args.host,
         'port': args.port,
+        'basepath': args.basepath,
         'debug': args.debug
     }
     
+    # Register the API Blueprint with basepath as url_prefix
+    basepath = args.basepath if args.basepath else ''
+    app.register_blueprint(api_bp, url_prefix=basepath)
+    
     # Attempt to create CVS client at startup
     try:
         cvs_client = create_cvs_client(
@@ -209,7 +232,7 @@ def main():
         print(f"Error initializing CVS Client: {e}", file=sys.stderr)
         cvs_client = None
     
-    print(f"Starting CVS Proxy on {args.host}:{args.port}")
+    print(f"Starting CVS Proxy on {args.host}:{args.port} with basepath: '{basepath}'")
     app.run(host=args.host, port=args.port, debug=args.debug)
 
 if __name__ == '__main__':
diff --git a/ui/DARK_MODE_README.md b/ui/DARK_MODE_README.md
new file mode 100644
index 0000000..80571ea
--- /dev/null
+++ b/ui/DARK_MODE_README.md
@@ -0,0 +1,107 @@
+# Dark Mode Implementation
+
+## Overview
+The CVS Repository Browser now includes a fully functional dark mode with system theme detection and user preference persistence.
+
+## Features
+
+### 1. **System Theme Detection**
+- On first load, the application automatically detects the user's system theme preference using `prefers-color-scheme` media query
+- If the system prefers dark mode, the app starts in dark mode
+- If the system prefers light mode, the app starts in light mode
+- If no system preference is detected, defaults to dark mode
+
+### 2. **User Preference Persistence**
+- User's theme choice is saved to browser's localStorage
+- On subsequent visits, the saved preference is used instead of system preference
+- Users can override system preference by toggling the theme
+
+### 3. **Theme Toggle Button**
+- Located in the header next to the status indicator
+- Shows 🌙 (moon) icon in light mode
+- Shows ☀️ (sun) icon in dark mode
+- Click to toggle between light and dark themes
+
+### 4. **Comprehensive Dark Mode Styling**
+- All UI elements are properly styled for both light and dark modes
+- Uses CSS custom properties (variables) for easy theme switching
+- Maintains excellent contrast ratios for accessibility
+- Smooth transitions between themes
+
+## Implementation Details
+
+### CSS Variables
+The application uses CSS custom properties defined in `:root` and `[data-theme="dark"]` selectors:
+
+**Light Mode (default):**
+- Background: `#f9fafb` (light gray)
+- Surface: `#ffffff` (white)
+- Text Primary: `#111827` (dark gray)
+- Text Secondary: `#6b7280` (medium gray)
+- Border: `#e5e7eb` (light border)
+
+**Dark Mode:**
+- Background: `#1a1a1a` (very dark)
+- Surface: `#2d2d2d` (dark gray)
+- Text Primary: `#f3f4f6` (light gray)
+- Text Secondary: `#d1d5db` (medium light gray)
+- Border: `#404040` (dark border)
+
+### JavaScript Implementation
+The `UIManager` class in `ui.js` handles theme management:
+
+- `initializeTheme()`: Initializes theme on page load
+- `setTheme(theme)`: Sets the theme and updates localStorage
+- `toggleTheme()`: Toggles between light and dark modes
+- `updateThemeButton(icon)`: Updates the toggle button icon
+
+## Files Modified
+
+1. **styles.css**
+   - Added `[data-theme="dark"]` selector with dark mode CSS variables
+   - All color references use CSS variables for dynamic theming
+
+2. **index.html**
+   - Added theme toggle button in header: `<button id="themeToggleBtn" class="btn-icon">🌙</button>`
+
+3. **ui.js**
+   - Added `initializeTheme()` method to detect and apply system theme
+   - Added `setTheme()` method to apply theme and save preference
+   - Added `toggleTheme()` method to switch between themes
+   - Added `updateThemeButton()` method to update button icon
+   - Added theme toggle button event listener
+
+## Usage
+
+### For Users
+1. The app automatically uses your system theme preference on first visit
+2. Click the moon/sun icon in the header to toggle between light and dark modes
+3. Your preference is saved and will be remembered on future visits
+
+### For Developers
+To modify the dark mode colors, edit the CSS variables in `styles.css`:
+
+```css
+[data-theme="dark"] {
+    --primary-color: #3b82f6;
+    --primary-hover: #2563eb;
+    --secondary-color: #9ca3af;
+    /* ... other variables ... */
+}
+```
+
+## Browser Compatibility
+- Works in all modern browsers that support:
+  - CSS Custom Properties (CSS Variables)
+  - `prefers-color-scheme` media query
+  - localStorage API
+  - ES6 JavaScript
+
+## Testing
+A test file `test-dark-mode.html` is included for testing the dark mode functionality independently.
+
+To test:
+1. Open `test-dark-mode.html` in a browser
+2. Click the moon/sun button to toggle themes
+3. Refresh the page to verify persistence
+4. Check browser DevTools to see localStorage values
\ No newline at end of file
diff --git a/ui/api.js b/ui/api.js
index e64f957..d2b8f2d 100644
--- a/ui/api.js
+++ b/ui/api.js
@@ -15,7 +15,7 @@ class CVSProxyAPI {
      * @returns {Promise} Response data
      */
     async request(endpoint, options = {}) {
-        const url = `${this.baseURL}/v1${endpoint}`;
+        const url = `${this.baseURL}/api/v1${endpoint}`;
         
         try {
             const response = await fetch(url, {
@@ -108,5 +108,5 @@ class CVSProxyAPI {
     }
 }
 
-// Create global API instance
-const api = new CVSProxyAPI();
\ No newline at end of file
+// Create global API instance with basepath from config
+const api = new CVSProxyAPI(window.APP_CONFIG?.basepath || '');
\ No newline at end of file
diff --git a/ui/app.js b/ui/app.js
index 9dad423..0e4334c 100644
--- a/ui/app.js
+++ b/ui/app.js
@@ -162,9 +162,6 @@ class CVSRepositoryBrowser {
      * Setup event listeners
      */
     setupEventListeners() {
-        // Refresh button
-        ui.refreshBtn.addEventListener('click', () => this.loadTree());
-
         // File view buttons
         ui.historyBtn.addEventListener('click', () => this.showHistory());
         ui.diffBtn.addEventListener('click', () => this.showDiffView());
diff --git a/ui/index.html b/ui/index.html
index 9c213e3..5ee5472 100644
--- a/ui/index.html
+++ b/ui/index.html
@@ -5,12 +5,16 @@
     <meta name="viewport" content="width=device-width, initial-scale=1.0">
     <title>CVS Proxy - Repository Browser</title>
     <link rel="stylesheet" href="styles.css">
+    <!-- Highlight.js for syntax highlighting -->
+    <link id="highlightTheme" rel="stylesheet" href="https://cdnjs.cloudflare.com/ajax/libs/highlight.js/11.9.0/styles/atom-one-dark.min.css">
+    <script src="https://cdnjs.cloudflare.com/ajax/libs/highlight.js/11.9.0/highlight.min.js"></script>
 </head>
 <body>
     <div class="container">
         <header>
             <h1>CVS Repository Browser</h1>
             <div class="header-info">
+                <button id="themeToggleBtn" class="btn-icon" title="Toggle dark mode">🌙</button>
                 <span id="status" class="status">Connecting...</span>
             </div>
         </header>
@@ -21,7 +25,6 @@
                 <aside class="sidebar">
                     <div class="sidebar-header">
                         <h2>Repository</h2>
-                        <button id="refreshBtn" class="btn-icon" title="Refresh">🔄</button>
                     </div>
                     <div id="treeContainer" class="tree-container">
                         <div class="loading">Loading repository...</div>
@@ -105,6 +108,7 @@
         </main>
     </div>
 
+    <script src="config.js"></script>
     <script src="api.js"></script>
     <script src="ui.js"></script>
     <script src="app.js"></script>
diff --git a/ui/styles.css b/ui/styles.css
index fbfe786..8d55dda 100644
--- a/ui/styles.css
+++ b/ui/styles.css
@@ -20,6 +20,23 @@
     --shadow-lg: 0 10px 15px rgba(0, 0, 0, 0.1);
 }
 
+/* Dark mode theme */
+[data-theme="dark"] {
+    --primary-color: #3b82f6;
+    --primary-hover: #2563eb;
+    --secondary-color: #9ca3af;
+    --success-color: #10b981;
+    --danger-color: #ef4444;
+    --warning-color: #f59e0b;
+    --bg-color: #1a1a1a;
+    --surface-color: #2d2d2d;
+    --border-color: #404040;
+    --text-primary: #f3f4f6;
+    --text-secondary: #d1d5db;
+    --shadow: 0 1px 3px rgba(0, 0, 0, 0.3);
+    --shadow-lg: 0 10px 15px rgba(0, 0, 0, 0.3);
+}
+
 body {
     font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, 'Helvetica Neue', Arial, sans-serif;
     background-color: var(--bg-color);
@@ -163,6 +180,16 @@ main {
     white-space: nowrap;
 }
 
+.tree-nested {
+    display: block;
+}
+
+.tree-item-toggle {
+    display: inline-block;
+    min-width: 1rem;
+    text-align: center;
+}
+
 .loading {
     padding: 2rem 1rem;
     text-align: center;
diff --git a/ui/test-dark-mode.html b/ui/test-dark-mode.html
new file mode 100644
index 0000000..aee40fb
--- /dev/null
+++ b/ui/test-dark-mode.html
@@ -0,0 +1,106 @@
+<!DOCTYPE html>
+<html lang="en">
+<head>
+    <meta charset="UTF-8">
+    <meta name="viewport" content="width=device-width, initial-scale=1.0">
+    <title>Dark Mode Test</title>
+    <link rel="stylesheet" href="styles.css">
+</head>
+<body>
+    <div class="container">
+        <header>
+            <h1>Dark Mode Test</h1>
+            <div class="header-info">
+                <button id="themeToggleBtn" class="btn-icon" title="Toggle dark mode">🌙</button>
+                <span id="status" class="status connected">Theme: Light</span>
+            </div>
+        </header>
+
+        <main>
+            <div class="layout">
+                <aside class="sidebar">
+                    <div class="sidebar-header">
+                        <h2>Test Panel</h2>
+                    </div>
+                    <div class="tree-container">
+                        <div class="tree-item">
+                            <span class="tree-item-icon">📁</span>
+                            <span class="tree-item-name">Sample Folder</span>
+                        </div>
+                        <div class="tree-item">
+                            <span class="tree-item-icon">📄</span>
+                            <span class="tree-item-name">Sample File</span>
+                        </div>
+                    </div>
+                </aside>
+
+                <section class="main-content">
+                    <div class="view">
+                        <div class="file-header">
+                            <div class="file-info">
+                                <h2>Dark Mode Test</h2>
+                                <p class="file-path">This page tests the dark mode implementation</p>
+                            </div>
+                        </div>
+                        <div class="file-content">
+                            <pre><code>// Test code block
+function testDarkMode() {
+    console.log('Dark mode is working!');
+    return true;
+}</code></pre>
+                        </div>
+                    </div>
+                </section>
+            </div>
+        </main>
+    </div>
+
+    <script>
+        class ThemeManager {
+            constructor() {
+                this.themeToggleBtn = document.getElementById('themeToggleBtn');
+                this.status = document.getElementById('status');
+                this.initializeTheme();
+            }
+
+            initializeTheme() {
+                const savedTheme = localStorage.getItem('theme');
+                
+                if (savedTheme) {
+                    this.setTheme(savedTheme);
+                } else {
+                    const prefersDark = window.matchMedia('(prefers-color-scheme: dark)').matches;
+                    this.setTheme(prefersDark ? 'dark' : 'light');
+                }
+
+                if (this.themeToggleBtn) {
+                    this.themeToggleBtn.addEventListener('click', () => this.toggleTheme());
+                }
+            }
+
+            setTheme(theme) {
+                if (theme === 'dark') {
+                    document.documentElement.setAttribute('data-theme', 'dark');
+                    this.themeToggleBtn.textContent = '☀️';
+                    this.status.textContent = 'Theme: Dark';
+                } else {
+                    document.documentElement.removeAttribute('data-theme');
+                    this.themeToggleBtn.textContent = '🌙';
+                    this.status.textContent = 'Theme: Light';
+                }
+                localStorage.setItem('theme', theme);
+            }
+
+            toggleTheme() {
+                const currentTheme = document.documentElement.getAttribute('data-theme');
+                const newTheme = currentTheme === 'dark' ? 'light' : 'dark';
+                this.setTheme(newTheme);
+            }
+        }
+
+        document.addEventListener('DOMContentLoaded', () => {
+            new ThemeManager();
+        });
+    </script>
+</body>
+</html>
\ No newline at end of file
diff --git a/ui/ui.js b/ui/ui.js
index 8a43160..d55fe3f 100644
--- a/ui/ui.js
+++ b/ui/ui.js
@@ -8,6 +8,7 @@ class UIManager {
         this.currentFile = null;
         this.currentHistory = null;
         this.initializeElements();
+        this.initializeTheme();
     }
 
     initializeElements() {
@@ -37,10 +38,83 @@ class UIManager {
 
         // Tree elements
         this.treeContainer = document.getElementById('treeContainer');
-        this.refreshBtn = document.getElementById('refreshBtn');
 
         // Status
         this.status = document.getElementById('status');
+
+        // Theme toggle button
+        this.themeToggleBtn = document.getElementById('themeToggleBtn');
+    }
+
+    /**
+     * Initialize theme based on system preference or saved preference
+     */
+    initializeTheme() {
+        // Check for saved theme preference
+        const savedTheme = localStorage.getItem('theme');
+        
+        if (savedTheme) {
+            // Use saved preference
+            this.setTheme(savedTheme);
+        } else {
+            // Check system preference
+            const prefersDark = window.matchMedia('(prefers-color-scheme: dark)').matches;
+            this.setTheme(prefersDark ? 'dark' : 'light');
+        }
+
+        // Setup theme toggle button listener
+        if (this.themeToggleBtn) {
+            this.themeToggleBtn.addEventListener('click', () => this.toggleTheme());
+        }
+    }
+
+    /**
+     * Set the theme
+     * @param {string} theme - 'light' or 'dark'
+     */
+    setTheme(theme) {
+        if (theme === 'dark') {
+            document.documentElement.setAttribute('data-theme', 'dark');
+            this.updateThemeButton('☀️');
+            this.updateHighlightTheme('dark');
+        } else {
+            document.documentElement.removeAttribute('data-theme');
+            this.updateThemeButton('🌙');
+            this.updateHighlightTheme('light');
+        }
+        localStorage.setItem('theme', theme);
+    }
+
+    /**
+     * Update highlight.js theme based on current theme
+     * @param {string} theme - 'light' or 'dark'
+     */
+    updateHighlightTheme(theme) {
+        const highlightLink = document.getElementById('highlightTheme');
+        if (highlightLink) {
+            const baseUrl = 'https://cdnjs.cloudflare.com/ajax/libs/highlight.js/11.9.0/styles/';
+            const stylesheet = theme === 'dark' ? 'atom-one-dark.min.css' : 'atom-one-light.min.css';
+            highlightLink.href = baseUrl + stylesheet;
+        }
+    }
+
+    /**
+     * Toggle between light and dark themes
+     */
+    toggleTheme() {
+        const currentTheme = document.documentElement.getAttribute('data-theme');
+        const newTheme = currentTheme === 'dark' ? 'light' : 'dark';
+        this.setTheme(newTheme);
+    }
+
+    /**
+     * Update theme toggle button icon
+     * @param {string} icon - Icon emoji
+     */
+    updateThemeButton(icon) {
+        if (this.themeToggleBtn) {
+            this.themeToggleBtn.textContent = icon;
+        }
     }
 
     /**
@@ -64,9 +138,51 @@ class UIManager {
         this.fileName.textContent = path.split('/').pop();
         this.filePath.textContent = path;
         
-        // Escape HTML and display content
-        const escapedContent = this.escapeHtml(content);
-        this.fileContent.innerHTML = `<pre><code>${escapedContent}</code></pre>`;
+        // Detect language from file extension
+        const extension = path.split('.').pop().toLowerCase();
+        const languageMap = {
+            'js': 'javascript',
+            'py': 'python',
+            'java': 'java',
+            'cpp': 'cpp',
+            'c': 'c',
+            'h': 'c',
+            'hpp': 'cpp',
+            'cs': 'csharp',
+            'rb': 'ruby',
+            'go': 'go',
+            'rs': 'rust',
+            'php': 'php',
+            'html': 'html',
+            'xml': 'xml',
+            'css': 'css',
+            'json': 'json',
+            'yaml': 'yaml',
+            'yml': 'yaml',
+            'sh': 'bash',
+            'bash': 'bash',
+            'sql': 'sql',
+            'md': 'markdown',
+            'txt': 'plaintext'
+        };
+        
+        const language = languageMap[extension] || 'plaintext';
+        
+        // Create code element with language class
+        const codeElement = document.createElement('code');
+        codeElement.className = `language-${language}`;
+        codeElement.textContent = content;
+        
+        const preElement = document.createElement('pre');
+        preElement.appendChild(codeElement);
+        
+        this.fileContent.innerHTML = '';
+        this.fileContent.appendChild(preElement);
+        
+        // Apply syntax highlighting
+        if (window.hljs) {
+            hljs.highlightElement(codeElement);
+        }
         
         this.showView(this.fileView);
     }
@@ -119,24 +235,22 @@ class UIManager {
             return;
         }
 
-        // Parse and colorize diff
-        const lines = diffText.split('\n');
-        const colorizedLines = lines.map(line => {
-            let className = '';
-            if (line.startsWith('+++') || line.startsWith('---') || line.startsWith('@@')) {
-                className = 'diff-line header';
-            } else if (line.startsWith('+')) {
-                className = 'diff-line added';
-            } else if (line.startsWith('-')) {
-                className = 'diff-line removed';
-            } else {
-                className = 'diff-line context';
-            }
-            const escapedLine = this.escapeHtml(line);
-            return `<div class="${className}">${escapedLine}</div>`;
-        }).join('');
-
-        this.diffContent.innerHTML = `<pre><code>${colorizedLines}</code></pre>`;
+        // Create code element with diff language class
+        const codeElement = document.createElement('code');
+        codeElement.className = 'language-diff';
+        codeElement.textContent = diffText;
+        
+        const preElement = document.createElement('pre');
+        preElement.appendChild(codeElement);
+        
+        this.diffContent.innerHTML = '';
+        this.diffContent.appendChild(preElement);
+        
+        // Apply syntax highlighting
+        if (window.hljs) {
+            hljs.highlightElement(codeElement);
+        }
+        
         this.showView(this.diffView);
     }
 
@@ -237,13 +351,14 @@ class UIManager {
     }
 
     /**
-     * Recursively render tree nodes
+     * Recursively render tree nodes with collapsible folders
      * @param {object} node - Tree node
      * @param {string} path - Current path
      * @param {HTMLElement} container - Container element
      * @param {Function} onFileClick - Callback when file is clicked
+     * @param {number} depth - Current depth level for indentation
      */
-    renderTreeNode(node, path, container, onFileClick) {
+    renderTreeNode(node, path, container, onFileClick, depth = 0) {
         const keys = Object.keys(node).sort();
         
         keys.forEach(key => {
@@ -252,33 +367,78 @@ class UIManager {
             
             const item = document.createElement('div');
             item.className = 'tree-item';
-            
-            const icon = document.createElement('span');
-            icon.className = 'tree-item-icon';
-            icon.textContent = isFile ? '📄' : '📁';
-            
-            const name = document.createElement('span');
-            name.className = 'tree-item-name';
-            name.textContent = key;
-            
-            item.appendChild(icon);
-            item.appendChild(name);
+            item.style.paddingLeft = `${0.5 + depth * 1.25}rem`;
             
             if (isFile) {
+                // File item
+                const icon = document.createElement('span');
+                icon.className = 'tree-item-icon';
+                icon.textContent = '📄';
+                
+                const name = document.createElement('span');
+                name.className = 'tree-item-name';
+                name.textContent = key;
+                
+                item.appendChild(icon);
+                item.appendChild(name);
+                
                 item.addEventListener('click', () => {
                     // Remove active class from all items
                     container.querySelectorAll('.tree-item').forEach(i => i.classList.remove('active'));
                     item.classList.add('active');
                     onFileClick(fullPath);
                 });
+            } else {
+                // Folder item with toggle
+                const toggleBtn = document.createElement('span');
+                toggleBtn.className = 'tree-item-toggle';
+                toggleBtn.textContent = '▼';
+                toggleBtn.style.cursor = 'pointer';
+                toggleBtn.style.marginRight = '0.25rem';
+                
+                const icon = document.createElement('span');
+                icon.className = 'tree-item-icon';
+                icon.textContent = '📁';
+                
+                const name = document.createElement('span');
+                name.className = 'tree-item-name';
+                name.textContent = key;
+                
+                item.appendChild(toggleBtn);
+                item.appendChild(icon);
+                item.appendChild(name);
+                
+                // Create container for nested items
+                const nestedContainer = document.createElement('div');
+                nestedContainer.className = 'tree-nested';
+                nestedContainer.style.display = 'block';
+                
+                // Add toggle functionality
+                const toggleFolder = () => {
+                    const isExpanded = nestedContainer.style.display !== 'none';
+                    nestedContainer.style.display = isExpanded ? 'none' : 'block';
+                    toggleBtn.textContent = isExpanded ? '▶' : '▼';
+                };
+                
+                toggleBtn.addEventListener('click', (e) => {
+                    e.stopPropagation();
+                    toggleFolder();
+                });
+                
+                item.addEventListener('click', (e) => {
+                    e.stopPropagation();
+                    toggleFolder();
+                });
+                
+                container.appendChild(item);
+                container.appendChild(nestedContainer);
+                
+                // Recursively render subdirectories
+                this.renderTreeNode(node[key], fullPath, nestedContainer, onFileClick, depth + 1);
+                return;
             }
             
             container.appendChild(item);
-            
-            // Recursively render subdirectories
-            if (!isFile) {
-                this.renderTreeNode(node[key], fullPath, container, onFileClick);
-            }
         });
     }