LearnSpace: full-stack educational whiteboard platform

Node.js/Express backend + vanilla JS frontend.
Features: real-time collaborative whiteboard (SSE), multi-page support,
LaTeX formulas, shapes/connectors, coordinate systems, number lines,
compass, zoom/pan, Catmull-Rom pencil smoothing, ruler/protractor with
rotation & resize controls, minimap navigation overlay, auto-measurements,
multi-page thumbnails sidebar, PNG export, page templates.
Student/teacher workflows: classes, assignments, library, dashboard.
Mobile responsive. SQLite (better-sqlite3).

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

backend/src/controllers/collectionController.js

@@ -0,0 +1,69 @@
+'use strict';
+const db = require('../db/db');
+
+function _tier(total, correct) {
+  if (total === 0) return 'locked';
+  const pct = correct / total * 100;
+  if (total >= 10 && pct >= 90) return 'platinum';
+  if (total >= 5  && pct >= 80) return 'gold';
+  if (total >= 3  && pct >= 50) return 'silver';
+  if (correct >= 1)             return 'bronze';
+  return 'locked';
+}
+
+/* ── GET /api/collection ──────────────────────────────────────────────── */
+function getCollection(req, res) {
+  const rows = db.prepare(`
+    SELECT
+      t.id   AS topic_id,
+      t.name AS topic_name,
+      s.name AS subject_name,
+      s.slug AS subject_slug,
+      s.icon AS subject_icon,
+      COALESCE(agg.total_attempts, 0)  AS total_attempts,
+      COALESCE(agg.correct_count, 0)   AS correct_count,
+      agg.first_seen_at
+    FROM topics t
+    JOIN subjects s ON s.id = t.subject_id
+    LEFT JOIN (
+      SELECT q.topic_id,
+             COUNT(ua.id)                       AS total_attempts,
+             SUM(CASE WHEN ua.is_correct=1 THEN 1 ELSE 0 END) AS correct_count,
+             MIN(ua.answered_at)                AS first_seen_at
+      FROM user_answers ua
+      JOIN questions q ON q.id = ua.question_id
+      WHERE ua.session_id IN (
+        SELECT id FROM test_sessions WHERE user_id = ? AND status = 'completed'
+      )
+      GROUP BY q.topic_id
+    ) agg ON agg.topic_id = t.id
+    ORDER BY s.slug, t.order_index, t.name
+  `).all(req.user.id);
+
+  const cards = rows.map(r => ({
+    topicId:      r.topic_id,
+    topicName:    r.topic_name,
+    subjectName:  r.subject_name,
+    subjectSlug:  r.subject_slug,
+    subjectIcon:  r.subject_icon,
+    tier:         _tier(r.total_attempts, r.correct_count),
+    totalAttempts: r.total_attempts,
+    correctCount:  r.correct_count,
+    masteryPct:   r.total_attempts > 0 ? Math.round(r.correct_count / r.total_attempts * 100) : 0,
+    firstSeenAt:  r.first_seen_at || null,
+  }));
+
+  const unlocked = cards.filter(c => c.tier !== 'locked').length;
+
+  res.json({
+    totalTopics:    cards.length,
+    unlockedTopics: unlocked,
+    platinumCount:  cards.filter(c => c.tier === 'platinum').length,
+    goldCount:      cards.filter(c => c.tier === 'gold').length,
+    silverCount:    cards.filter(c => c.tier === 'silver').length,
+    bronzeCount:    cards.filter(c => c.tier === 'bronze').length,
+    cards,
+  });
+}
+
+module.exports = { getCollection };