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>
2026-04-12 10:10:37 +03:00
commit be4d43105e
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+const db = require('../db/db');
+
+/* ── SM-2 algorithm ───────────────────────────────────────────────────────
+   quality: 0 = blackout, 1 = wrong, 2 = wrong but familiar,
+            3 = correct with difficulty, 4 = correct, 5 = perfect
+   ─────────────────────────────────────────────────────────────────────── */
+function sm2(easeFactor, intervalDays, repetitions, quality) {
+  let ef  = easeFactor;
+  let n   = repetitions;
+  let iv  = intervalDays;
+
+  if (quality < 3) {
+    n  = 0;
+    iv = 1;
+  } else {
+    if (n === 0)      iv = 1;
+    else if (n === 1) iv = 6;
+    else              iv = Math.round(iv * ef);
+    n++;
+  }
+  ef = Math.max(1.3, ef + 0.1 - (5 - quality) * (0.08 + (5 - quality) * 0.02));
+  const due = new Date(Date.now() + iv * 86400000).toISOString();
+  return { easeFactor: ef, intervalDays: iv, repetitions: n, dueAt: due };
+}
+
+/* ── GET /api/flashcards/decks ─────────────────────────────────────────── */
+function listDecks(req, res) {
+  const uid = req.user.id;
+  const decks = db.prepare(`
+    SELECT d.*,
+      (SELECT COUNT(*) FROM flashcard_cards c WHERE c.deck_id = d.id) AS card_count,
+      (SELECT COUNT(*) FROM flashcard_cards c
+       LEFT JOIN flashcard_reviews r ON r.card_id = c.id AND r.user_id = ?
+       WHERE c.deck_id = d.id AND (r.id IS NULL OR r.due_at <= datetime('now'))) AS due_count
+    FROM flashcard_decks d
+    WHERE d.user_id = ?
+    ORDER BY d.created_at DESC
+  `).all(uid, uid);
+  res.json({ decks });
+}
+
+/* ── POST /api/flashcards/decks ────────────────────────────────────────── */
+function createDeck(req, res) {
+  const uid  = req.user.id;
+  const { title, description = '', color = '#9B5DE5' } = req.body;
+  if (!title?.trim()) return res.status(400).json({ error: 'Title required' });
+  const r = db.prepare(
+    `INSERT INTO flashcard_decks (user_id, title, description, color) VALUES (?,?,?,?)`
+  ).run(uid, title.trim(), description, color);
+  res.json({ id: r.lastInsertRowid, title: title.trim(), description, color, card_count: 0, due_count: 0 });
+}
+
+/* ── PUT /api/flashcards/decks/:id ─────────────────────────────────────── */
+function updateDeck(req, res) {
+  const uid = req.user.id;
+  const { title, description, color } = req.body;
+  const deck = db.prepare(`SELECT * FROM flashcard_decks WHERE id = ? AND user_id = ?`)
+                  .get(req.params.id, uid);
+  if (!deck) return res.status(404).json({ error: 'Not found' });
+  db.prepare(`UPDATE flashcard_decks SET title=?, description=?, color=? WHERE id=?`)
+    .run(title ?? deck.title, description ?? deck.description, color ?? deck.color, deck.id);
+  res.json({ ok: true });
+}
+
+/* ── DELETE /api/flashcards/decks/:id ──────────────────────────────────── */
+function deleteDeck(req, res) {
+  const uid = req.user.id;
+  const deck = db.prepare(`SELECT id FROM flashcard_decks WHERE id = ? AND user_id = ?`)
+                  .get(req.params.id, uid);
+  if (!deck) return res.status(404).json({ error: 'Not found' });
+  db.prepare(`DELETE FROM flashcard_decks WHERE id = ?`).run(deck.id);
+  res.json({ ok: true });
+}
+
+/* ── GET /api/flashcards/decks/:id/cards ───────────────────────────────── */
+function getCards(req, res) {
+  const uid = req.user.id;
+  const deck = db.prepare(`SELECT id FROM flashcard_decks WHERE id = ? AND user_id = ?`)
+                  .get(req.params.id, uid);
+  if (!deck) return res.status(404).json({ error: 'Not found' });
+  const cards = db.prepare(`
+    SELECT c.*, r.ease_factor, r.interval_days, r.repetitions, r.due_at, r.last_reviewed
+    FROM flashcard_cards c
+    LEFT JOIN flashcard_reviews r ON r.card_id = c.id AND r.user_id = ?
+    WHERE c.deck_id = ?
+    ORDER BY c.order_idx, c.id
+  `).all(uid, deck.id);
+  res.json({ cards });
+}
+
+/* ── POST /api/flashcards/decks/:id/cards ──────────────────────────────── */
+function addCard(req, res) {
+  const uid = req.user.id;
+  const deck = db.prepare(`SELECT id FROM flashcard_decks WHERE id = ? AND user_id = ?`)
+                  .get(req.params.id, uid);
+  if (!deck) return res.status(404).json({ error: 'Not found' });
+  const { front = '', back = '' } = req.body;
+  const maxIdx = db.prepare(`SELECT MAX(order_idx) AS m FROM flashcard_cards WHERE deck_id = ?`)
+                    .get(deck.id)?.m ?? -1;
+  const r = db.prepare(`INSERT INTO flashcard_cards (deck_id, front, back, order_idx) VALUES (?,?,?,?)`)
+               .run(deck.id, front, back, maxIdx + 1);
+  res.json({ id: r.lastInsertRowid, deck_id: deck.id, front, back, order_idx: maxIdx + 1 });
+}
+
+/* ── POST /api/flashcards/decks/:id/cards/bulk ──────────────────────────── */
+function addCardsBulk(req, res) {
+  const uid = req.user.id;
+  const deck = db.prepare(`SELECT id FROM flashcard_decks WHERE id = ? AND user_id = ?`)
+                  .get(req.params.id, uid);
+  if (!deck) return res.status(404).json({ error: 'Not found' });
+  const { cards } = req.body;
+  if (!Array.isArray(cards) || !cards.length) return res.status(400).json({ error: 'cards[] required' });
+  const maxIdx = db.prepare(`SELECT MAX(order_idx) AS m FROM flashcard_cards WHERE deck_id = ?`)
+                    .get(deck.id)?.m ?? -1;
+  const stmt = db.prepare(`INSERT INTO flashcard_cards (deck_id, front, back, order_idx) VALUES (?,?,?,?)`);
+  const inserted = [];
+  const ins = db.transaction(() => {
+    cards.forEach((c, i) => {
+      const r = stmt.run(deck.id, c.front || '', c.back || '', maxIdx + 1 + i);
+      inserted.push({ id: r.lastInsertRowid, front: c.front, back: c.back });
+    });
+  });
+  ins();
+  res.json({ inserted });
+}
+
+/* ── PUT /api/flashcards/cards/:id ─────────────────────────────────────── */
+function updateCard(req, res) {
+  const uid  = req.user.id;
+  const card = db.prepare(`
+    SELECT c.* FROM flashcard_cards c
+    JOIN flashcard_decks d ON d.id = c.deck_id
+    WHERE c.id = ? AND d.user_id = ?
+  `).get(req.params.id, uid);
+  if (!card) return res.status(404).json({ error: 'Not found' });
+  const { front, back } = req.body;
+  db.prepare(`UPDATE flashcard_cards SET front=?, back=? WHERE id=?`)
+    .run(front ?? card.front, back ?? card.back, card.id);
+  res.json({ ok: true });
+}
+
+/* ── DELETE /api/flashcards/cards/:id ──────────────────────────────────── */
+function deleteCard(req, res) {
+  const uid  = req.user.id;
+  const card = db.prepare(`
+    SELECT c.id FROM flashcard_cards c
+    JOIN flashcard_decks d ON d.id = c.deck_id
+    WHERE c.id = ? AND d.user_id = ?
+  `).get(req.params.id, uid);
+  if (!card) return res.status(404).json({ error: 'Not found' });
+  db.prepare(`DELETE FROM flashcard_cards WHERE id = ?`).run(card.id);
+  res.json({ ok: true });
+}
+
+/* ── GET /api/flashcards/decks/:id/study ───────────────────────────────── */
+function getStudySession(req, res) {
+  const uid = req.user.id;
+  const deck = db.prepare(`SELECT id FROM flashcard_decks WHERE id = ? AND user_id = ?`)
+                  .get(req.params.id, uid);
+  if (!deck) return res.status(404).json({ error: 'Not found' });
+  // due cards first, then new cards (no review yet), limit 20
+  const cards = db.prepare(`
+    SELECT c.id, c.front, c.back,
+      COALESCE(r.ease_factor, 2.5) AS ease_factor,
+      COALESCE(r.interval_days, 1) AS interval_days,
+      COALESCE(r.repetitions, 0)   AS repetitions,
+      COALESCE(r.due_at, datetime('now')) AS due_at,
+      r.last_reviewed,
+      CASE WHEN r.id IS NULL THEN 0 ELSE 1 END AS seen
+    FROM flashcard_cards c
+    LEFT JOIN flashcard_reviews r ON r.card_id = c.id AND r.user_id = ?
+    WHERE c.deck_id = ?
+      AND (r.id IS NULL OR r.due_at <= datetime('now'))
+    ORDER BY seen ASC, r.due_at ASC
+    LIMIT 20
+  `).all(uid, deck.id);
+  const total_due = db.prepare(`
+    SELECT COUNT(*) AS n FROM flashcard_cards c
+    LEFT JOIN flashcard_reviews r ON r.card_id = c.id AND r.user_id = ?
+    WHERE c.deck_id = ? AND (r.id IS NULL OR r.due_at <= datetime('now'))
+  `).get(uid, deck.id).n;
+  res.json({ cards, total_due });
+}
+
+/* ── POST /api/flashcards/cards/:id/review ─────────────────────────────── */
+function submitReview(req, res) {
+  const uid     = req.user.id;
+  const { quality } = req.body;   // 0..5
+  if (quality === undefined || quality < 0 || quality > 5)
+    return res.status(400).json({ error: 'quality 0-5 required' });
+
+  const card = db.prepare(`
+    SELECT c.id FROM flashcard_cards c
+    JOIN flashcard_decks d ON d.id = c.deck_id
+    WHERE c.id = ? AND d.user_id = ?
+  `).get(req.params.id, uid);
+  if (!card) return res.status(404).json({ error: 'Not found' });
+
+  const existing = db.prepare(
+    `SELECT * FROM flashcard_reviews WHERE user_id = ? AND card_id = ?`
+  ).get(uid, card.id);
+
+  const prev = existing || { ease_factor: 2.5, interval_days: 1, repetitions: 0 };
+  const next = sm2(prev.ease_factor, prev.interval_days, prev.repetitions, quality);
+
+  if (existing) {
+    db.prepare(`
+      UPDATE flashcard_reviews
+      SET ease_factor=?, interval_days=?, repetitions=?, due_at=?, last_reviewed=datetime('now')
+      WHERE user_id=? AND card_id=?
+    `).run(next.easeFactor, next.intervalDays, next.repetitions, next.dueAt, uid, card.id);
+  } else {
+    db.prepare(`
+      INSERT INTO flashcard_reviews (user_id, card_id, ease_factor, interval_days, repetitions, due_at, last_reviewed)
+      VALUES (?,?,?,?,?,?,datetime('now'))
+    `).run(uid, card.id, next.easeFactor, next.intervalDays, next.repetitions, next.dueAt);
+  }
+  res.json({ ok: true, next_review: next.dueAt, interval_days: next.intervalDays });
+}
+
+/* ── GET /api/flashcards/stats ─────────────────────────────────────────── */
+function getStats(req, res) {
+  const uid = req.user.id;
+  const decks_count = db.prepare(`SELECT COUNT(*) AS n FROM flashcard_decks WHERE user_id=?`).get(uid).n;
+  const cards_count = db.prepare(`
+    SELECT COUNT(*) AS n FROM flashcard_cards c
+    JOIN flashcard_decks d ON d.id = c.deck_id WHERE d.user_id=?
+  `).get(uid).n;
+  const due_count = db.prepare(`
+    SELECT COUNT(*) AS n FROM flashcard_cards c
+    JOIN flashcard_decks d ON d.id = c.deck_id
+    LEFT JOIN flashcard_reviews r ON r.card_id = c.id AND r.user_id = ?
+    WHERE d.user_id = ? AND (r.id IS NULL OR r.due_at <= datetime('now'))
+  `).get(uid, uid).n;
+  const reviewed_today = db.prepare(`
+    SELECT COUNT(*) AS n FROM flashcard_reviews
+    WHERE user_id = ? AND date(last_reviewed) = date('now')
+  `).get(uid).n;
+  res.json({ decks_count, cards_count, due_count, reviewed_today });
+}
+
+module.exports = {
+  listDecks, createDeck, updateDeck, deleteDeck,
+  getCards, addCard, addCardsBulk, updateCard, deleteCard,
+  getStudySession, submitReview, getStats,
+};