feat: add activity discussion/comments system with threaded replies

public/course.html

@@ -223,11 +223,130 @@ <h2 class="font-bold text-slate-800 text-lg mb-3">Welcome!</h2>
     }
   }
 
+
+  // Comments
+  let replyToId = null;
+  function escHtml(s) { const d = document.createElement('div'); d.textContent = s||''; return d.innerHTML; }
+  async function loadComments() {
+    try {
+      const res  = await fetch('/api/activities/' + actId + '/comments');
+      const data = await res.json();
+      if (res.ok) renderComments(data.data || []);
+    } catch(e) { console.error('loadComments', e); }
+  }
+  function renderComments(comments) {
+    const top = comments.filter(c => !c.parent_id);
+    const byParent = {};
+    comments.filter(c => c.parent_id).forEach(c => {
+      byParent[c.parent_id] = byParent[c.parent_id] || [];
+      byParent[c.parent_id].push(c);
+    });
+    const list = document.getElementById('comments-list');
+    if (top.length === 0) {
+      list.innerHTML = '<p class="text-slate-400 text-sm">No comments yet. Be the first!</p>';
+      return;
+    }
+    list.innerHTML = top.map(c => renderComment(c, byParent)).join('');
+  }
+  function renderComment(c, byParent) {
+    const replies = (byParent[c.id] || []).map(r => renderComment(r, byParent)).join('');
+    const initial = (c.author || '?')[0].toUpperCase();
+    const date = new Date(c.created_at).toLocaleDateString();
+    const replyBtn = token
+      ? '<button type="button" class="reply-btn text-xs text-indigo-500 hover:underline" data-id="' + c.id + '" data-author="' + escHtml(c.author) + '">Reply</button>'
+      : '';
+    const replyThread = replies
+      ? '<div class="mt-3 pl-4 border-l-2 border-slate-100 space-y-3">' + replies + '</div>'
+      : '';
+    return '<div class="flex gap-3" id="comment-' + c.id + '">' +
+      '<div class="w-8 h-8 rounded-full bg-indigo-100 flex items-center justify-center text-indigo-600 font-bold text-sm flex-shrink-0">' + initial + '</div>' +
+      '<div class="flex-1">' +
+        '<div class="flex items-center gap-2 mb-1">' +
+          '<span class="font-semibold text-slate-800 text-sm">' + escHtml(c.author) + '</span>' +
+          '<span class="text-xs text-slate-400">' + date + '</span>' +
+        '</div>' +
+        '<p class="text-slate-700 text-sm mb-1">' + escHtml(c.body) + '</p>' +
+        replyBtn + replyThread +
+      '</div></div>';
+  }
+  function startReply(commentId, author) {
+    replyToId = commentId;
+    const ind = document.getElementById('reply-indicator');
+    ind.classList.remove('hidden');
+    ind.innerHTML = 'Replying to <strong>' + escHtml(author) + '</strong> &mdash; <button type="button" onclick="cancelReply()" class="underline">cancel</button>';
+    document.getElementById('comment-input').focus();
+  }
+  function cancelReply() {
+    replyToId = null;
+    document.getElementById('reply-indicator').classList.add('hidden');
+  }
+  async function postComment() {
+    const input = document.getElementById('comment-input');
+    const body  = input.value.trim();
+    if (body.length === 0) return;
+    const btn = document.querySelector('#comment-form button[onclick="postComment()"]');
+    btn.textContent = 'Posting...'; btn.disabled = true;
+    try {
+      const payload = { body };
+      if (replyToId) payload.parent_id = replyToId;
+      const res  = await fetch('/api/activities/' + actId + '/comments', {
+        method: 'POST',
+        headers: { 'Content-Type': 'application/json', Authorization: 'Bearer ' + token },
+        body: JSON.stringify(payload)
+      });
+      const data = await res.json();
+      if (res.ok) {
+        input.value = '';
+        cancelReply();
+        await loadComments();
+      } else {
+        alert(data.error || 'Failed to post comment');
+      }
+    } catch (e) { alert(e.message); }
+    finally { btn.textContent = 'Post Comment'; btn.disabled = false; }
+  }
+  document.addEventListener('click', function(e) {
+    if (e.target.classList.contains('reply-btn')) {
+      startReply(e.target.dataset.id, e.target.dataset.author);
+    }
+  });
+
+  document.addEventListener('DOMContentLoaded', function() {
+    if (token) {
+      const cf = document.getElementById('comment-form');
+      if (cf) cf.classList.remove('hidden');
+    } else {
+      const cl = document.getElementById('comment-login-cta');
+      if (cl) cl.classList.remove('hidden');
+    }
+    if (actId) loadComments();
+  });
   if (!actId) {
     document.getElementById('act-title').textContent = 'No activity selected';
   } else {
     loadActivity().catch(e => { document.getElementById('act-title').textContent = 'Error: ' + e.message; });
   }
 </script>
+
+  <!-- Comments Section -->
+  <div class="mt-8 bg-white rounded-2xl shadow-sm border border-slate-100 p-6" id="comments-section">
+    <h2 class="font-bold text-slate-800 text-lg mb-4">&#128172; Discussion</h2>
+    <div id="comments-list" class="space-y-4 mb-6"></div>
+    <div id="comment-form" class="hidden">
+      <div id="reply-indicator" class="hidden text-xs text-indigo-600 mb-2">
+        Replying to a comment &mdash; <button type="button" onclick="cancelReply()" class="underline">cancel</button>
+      </div>
+      <textarea id="comment-input" rows="3" placeholder="Write a comment..."
+        class="w-full border border-slate-200 rounded-xl px-4 py-2 text-sm text-slate-700 focus:outline-none focus:ring-2 focus:ring-indigo-300 resize-none"></textarea>
+      <label for="comment-input" class="sr-only">Write a comment</label>
+      <button type="button" onclick="postComment()"
+        class="mt-2 bg-indigo-600 hover:bg-indigo-700 text-white font-semibold px-5 py-2 rounded-xl text-sm transition">
+        Post Comment
+      </button>
+    </div>
+    <div id="comment-login-cta" class="hidden text-sm text-slate-500">
+      <a href="/login.html" class="text-indigo-600 font-semibold hover:underline">Login</a> to join the discussion.
+    </div>
+  </div>
 </body>
 </html>

schema.sql

@@ -93,3 +93,21 @@ CREATE INDEX IF NOT EXISTS idx_sessions_activity    ON sessions(activity_id);
 CREATE INDEX IF NOT EXISTS idx_sa_session           ON session_attendance(session_id);
 CREATE INDEX IF NOT EXISTS idx_sa_user              ON session_attendance(user_id);
 CREATE INDEX IF NOT EXISTS idx_at_activity          ON activity_tags(activity_id);
+
+-- COMMENTS (discussion threads on activities)
+CREATE TABLE IF NOT EXISTS comments (
+    id          TEXT PRIMARY KEY,
+    activity_id TEXT NOT NULL,
+    user_id     TEXT NOT NULL,
+    body        TEXT NOT NULL,          -- encrypted
+    parent_id   TEXT,                   -- NULL = top-level, else reply
+    created_at  TEXT NOT NULL DEFAULT (datetime('now')),
+    updated_at  TEXT,
+    FOREIGN KEY (activity_id) REFERENCES activities(id),
+    FOREIGN KEY (user_id)     REFERENCES users(id),
+    FOREIGN KEY (parent_id)   REFERENCES comments(id) ON DELETE CASCADE
+);
+
+CREATE INDEX IF NOT EXISTS idx_comments_activity ON comments(activity_id);
+CREATE INDEX IF NOT EXISTS idx_comments_parent   ON comments(parent_id);
+CREATE INDEX IF NOT EXISTS idx_comments_user     ON comments(user_id);

src/worker.py

@@ -14,6 +14,9 @@
   POST /api/sessions          – add a session to activity    [host]
   GET  /api/tags              – list all tags
   POST /api/activity-tags     – add tags to an activity      [host]
+  GET  /api/activities/:id/comments – list comments for an activity
+  POST /api/activities/:id/comments – post a comment            [auth]
+  DELETE /api/comments/:id         – delete a comment           [owner|host]
 
 Security model
   * ALL user PII (username, email, display name, role) is encrypted with a
@@ -361,6 +364,22 @@ def _is_basic_auth_valid(req, env) -> bool:
     "CREATE INDEX IF NOT EXISTS idx_sa_session           ON session_attendance(session_id)",
     "CREATE INDEX IF NOT EXISTS idx_sa_user              ON session_attendance(user_id)",
     "CREATE INDEX IF NOT EXISTS idx_at_activity          ON activity_tags(activity_id)",
+    # Comments
+    """CREATE TABLE IF NOT EXISTS comments (
+        id          TEXT PRIMARY KEY,
+        activity_id TEXT NOT NULL,
+        user_id     TEXT NOT NULL,
+        body        TEXT NOT NULL,
+        parent_id   TEXT,
+        created_at  TEXT NOT NULL DEFAULT (datetime('now')),
+        updated_at  TEXT,
+        FOREIGN KEY (activity_id) REFERENCES activities(id),
+        FOREIGN KEY (user_id)     REFERENCES users(id),
+        FOREIGN KEY (parent_id)   REFERENCES comments(id) ON DELETE CASCADE
+    )""",
+    "CREATE INDEX IF NOT EXISTS idx_comments_activity ON comments(activity_id)",
+    "CREATE INDEX IF NOT EXISTS idx_comments_parent   ON comments(parent_id)",
+    "CREATE INDEX IF NOT EXISTS idx_comments_user     ON comments(user_id)",
 ]
 
 
@@ -1203,6 +1222,111 @@ async def _dispatch(request, env):
     return await serve_static(path, env)
 
 
+
+# ---------------------------------------------------------------------------
+# Comments API
+# ---------------------------------------------------------------------------
+
+async def api_get_comments(_req, env, activity_id: str, enc_key: str):
+    """GET /api/activities/:id/comments — list comments for an activity."""
+    # Check activity exists
+    act = await env.DB.prepare(
+        "SELECT id FROM activities WHERE id = ?"
+    ).bind(activity_id).first()
+    if not act:
+        return err("Activity not found", 404)
+
+    rows = await env.DB.prepare(
+        "SELECT c.id, c.body, c.parent_id, c.created_at, c.updated_at, "
+        "c.user_id, u.name AS author_name "
+        "FROM comments c "
+        "JOIN users u ON u.id = c.user_id "
+        "WHERE c.activity_id = ? "
+        "ORDER BY c.created_at ASC"
+    ).bind(activity_id).all()
+
+    comments = [
+        {
+            "id": r["id"],
+            "body": decrypt(r["body"], enc_key),
+            "parent_id": r["parent_id"],
+            "created_at": r["created_at"],
+            "updated_at": r["updated_at"],
+            "user_id": r["user_id"],
+            "author": decrypt(r["author_name"], enc_key),
+        }
+        for r in (rows.results or [])
+    ]
+    return ok(comments)
+
+
+async def api_post_comment(req, env, activity_id: str, user, enc_key: str):
+    """POST /api/activities/:id/comments — post a comment (auth required)."""
+    if not user:
+        return err("Authentication required", 401)
+
+    # Check activity exists
+    act = await env.DB.prepare(
+        "SELECT id FROM activities WHERE id = ?"
+    ).bind(activity_id).first()
+    if not act:
+        return err("Activity not found", 404)
+
+    body, parse_err = await parse_json_object(req)
+    if parse_err:
+        return parse_err
+
+    text = (body.get("body") or "").strip()
+    if not text:
+        return err("Comment body is required")
+    if len(text) > 2000:
+        return err("Comment must be 2000 characters or fewer")
+
+    parent_id = body.get("parent_id") or None
+    if parent_id:
+        parent = await env.DB.prepare(
+            "SELECT id FROM comments WHERE id = ? AND activity_id = ?"
+        ).bind(parent_id, activity_id).first()
+        if not parent:
+            return err("Parent comment not found", 404)
+
+    cid = new_id()
+    try:
+        await env.DB.prepare(
+            "INSERT INTO comments (id, activity_id, user_id, body, parent_id) "
+            "VALUES (?, ?, ?, ?, ?)"
+        ).bind(cid, activity_id, user["id"], encrypt(text, enc_key), parent_id).run()
+    except Exception as exc:
+        capture_exception(exc, where="api_post_comment")
+        return err("Failed to save comment", 500)
+
+    return ok({"id": cid, "body": text, "parent_id": parent_id,
+               "user_id": user["id"], "activity_id": activity_id}, "Comment posted")
+
+
+async def api_delete_comment(_req, env, comment_id: str, user):
+    """DELETE /api/comments/:id — delete own comment (or host deletes any)."""
+    if not user:
+        return err("Authentication required", 401)
+
+    comment = await env.DB.prepare(
+        "SELECT c.id, c.user_id, a.host_id "
+        "FROM comments c JOIN activities a ON a.id = c.activity_id "
+        "WHERE c.id = ?"
+    ).bind(comment_id).first()
+    if not comment:
+        return err("Comment not found", 404)
+
+    is_owner = comment["user_id"] == user["id"]
+    is_host = comment["host_id"] == user["id"]
+
+    if not (is_owner or is_host):
+        return err("Permission denied", 403)
+
+    await env.DB.prepare("DELETE FROM comments WHERE id = ?").bind(comment_id).run()
+    return ok(msg="Comment deleted")
+
+
 async def on_fetch(request, env):
     try:
         return await _dispatch(request, env)