fix: sync admin UI schema with plugin (UUID keys, lesson_media table)

Schema now matches plugin Data/LessonStore.cs exactly:
- id TEXT PRIMARY KEY (UUIDs)
- lesson_media table (not media_items)
- Full column set with NOT NULL constraints matching plugin

Addresses PR #14 review feedback.

admin-ui/server.js

@@ -16,26 +16,35 @@ fs.mkdirSync(path.dirname(DB_PATH), { recursive: true });
 
 const db = new Database(DB_PATH);
 
-// Initialize schema if needed
+// UUID helper
+function generateId() {
+  return 'xxxxxxxx-xxxx-4xxx-yxxx-xxxxxxxxxxxx'.replace(/[xy]/g, c => {
+    const r = Math.random() * 16 | 0;
+    return (c === 'x' ? r : (r & 0x3 | 0x8)).toString(16);
+  });
+}
+
+// Initialize schema — must match plugin Data/LessonStore.cs
+const now = () => new Date().toISOString();
 db.exec(`
   CREATE TABLE IF NOT EXISTS lessons (
-    id INTEGER PRIMARY KEY AUTOINCREMENT,
+    id TEXT PRIMARY KEY,
     title TEXT NOT NULL,
-    grade INTEGER,
-    subject TEXT,
-    lesson_date TEXT,
+    grade INTEGER NOT NULL,
+    subject TEXT NOT NULL,
+    lesson_date TEXT NOT NULL,
     description TEXT,
-    source_path TEXT,
+    source_path TEXT NOT NULL,
     compiled_html TEXT,
-    created_at TEXT DEFAULT (datetime('now')),
-    updated_at TEXT DEFAULT (datetime('now'))
+    created_at TEXT NOT NULL,
+    updated_at TEXT NOT NULL
   );
 
-  CREATE TABLE IF NOT EXISTS media_items (
-    id INTEGER PRIMARY KEY AUTOINCREMENT,
-    lesson_id INTEGER NOT NULL,
+  CREATE TABLE IF NOT EXISTS lesson_media (
+    lesson_id TEXT NOT NULL,
     jellyfin_item_id TEXT NOT NULL,
-    sort_order INTEGER DEFAULT 0,
+    sort_order INTEGER NOT NULL DEFAULT 0,
+    PRIMARY KEY (lesson_id, jellyfin_item_id),
     FOREIGN KEY (lesson_id) REFERENCES lessons(id) ON DELETE CASCADE
   );
 `);
@@ -68,7 +77,7 @@ app.get('/api/lessons/:id', (req, res) => {
   try {
     const lesson = db.prepare('SELECT * FROM lessons WHERE id = ?').get(req.params.id);
     if (!lesson) return res.status(404).json({ error: 'Lesson not found' });
-    const mediaItems = db.prepare('SELECT * FROM media_items WHERE lesson_id = ? ORDER BY sort_order').all(req.params.id);
+    const mediaItems = db.prepare('SELECT * FROM lesson_media WHERE lesson_id = ? ORDER BY sort_order').all(req.params.id);
     res.json({ ...lesson, mediaItems });
   } catch (err) {
     res.status(500).json({ error: err.message });
@@ -83,31 +92,30 @@ app.post('/api/lessons', (req, res) => {
     if (!title) return res.status(400).json({ error: 'Title is required' });
 
     const upsertLesson = db.transaction(() => {
-      let lessonId = id;
-      if (lessonId) {
-        // Update existing
-        db.prepare(`
-          UPDATE lessons
-          SET title = ?, grade = ?, subject = ?, lesson_date = ?, description = ?,
-              source_path = ?, compiled_html = ?, updated_at = datetime('now')
-          WHERE id = ?
-        `).run(title, grade || null, subject || null, lessonDate || null, description || null,
-               sourcePath || null, compiledHtml || null, lessonId);
-        // Replace media items
-        db.prepare('DELETE FROM media_items WHERE lesson_id = ?').run(lessonId);
-      } else {
-        // Create new
-        const result = db.prepare(`
-          INSERT INTO lessons (title, grade, subject, lesson_date, description, source_path, compiled_html)
-          VALUES (?, ?, ?, ?, ?, ?, ?)
-        `).run(title, grade || null, subject || null, lessonDate || null, description || null,
-               sourcePath || null, compiledHtml || null);
-        lessonId = result.lastInsertRowid;
-      }
+      let lessonId = id || generateId();
+      const ts = now();
+      const existing = id ? db.prepare('SELECT created_at FROM lessons WHERE id = ?').get(id) : null;
+      const createdAt = existing ? existing.created_at : ts;
 
-      // Insert media items
+      db.prepare(`
+        INSERT INTO lessons (id, title, grade, subject, lesson_date, description, source_path, compiled_html, created_at, updated_at)
+        VALUES (@id, @title, @grade, @subject, @lesson_date, @description, @source_path, @compiled_html, @created_at, @updated_at)
+        ON CONFLICT(id) DO UPDATE SET
+          title = excluded.title, grade = excluded.grade, subject = excluded.subject,
+          lesson_date = excluded.lesson_date, description = excluded.description,
+          source_path = excluded.source_path, compiled_html = excluded.compiled_html,
+          updated_at = excluded.updated_at
+      `).run({
+        id: lessonId, title, grade: grade || 0,
+        subject: subject || '', lesson_date: lessonDate || new Date().toISOString().split('T')[0],
+        description: description || null, source_path: sourcePath || '',
+        compiled_html: compiledHtml || null, created_at: createdAt, updated_at: ts
+      });
+
+      // Replace media items
+      db.prepare('DELETE FROM lesson_media WHERE lesson_id = ?').run(lessonId);
       if (mediaItems && Array.isArray(mediaItems)) {
-        const insertMedia = db.prepare('INSERT INTO media_items (lesson_id, jellyfin_item_id, sort_order) VALUES (?, ?, ?)');
+        const insertMedia = db.prepare('INSERT INTO lesson_media (lesson_id, jellyfin_item_id, sort_order) VALUES (?, ?, ?)');
         for (const item of mediaItems) {
           insertMedia.run(lessonId, item.jellyfinItemId, item.sortOrder || 0);
         }
@@ -118,7 +126,7 @@ app.post('/api/lessons', (req, res) => {
 
     const lessonId = upsertLesson();
     const lesson = db.prepare('SELECT * FROM lessons WHERE id = ?').get(lessonId);
-    const media = db.prepare('SELECT * FROM media_items WHERE lesson_id = ? ORDER BY sort_order').all(lessonId);
+    const media = db.prepare('SELECT * FROM lesson_media WHERE lesson_id = ? ORDER BY sort_order').all(lessonId);
     res.json({ ...lesson, mediaItems: media });
   } catch (err) {
     res.status(500).json({ error: err.message });