feat(exam-prep F10): план по дате экзамена — виджет на дашборде + модалка + GET/PUT/DELETE /plan

backend/src/routes/exam-prep.js

@@ -227,6 +227,34 @@ const SQL = {
      ORDER BY started_at DESC
      LIMIT ?
   `),
+
+  /* ── Study plan (F10) ───────────────────────────────────────── */
+  getPlan: db.prepare(`
+    SELECT exam_date, daily_target, weak_focus, created_at, updated_at
+      FROM exam_user_plan
+     WHERE user_id = ? AND exam_key = ?
+  `),
+  upsertPlan: db.prepare(`
+    INSERT INTO exam_user_plan
+      (user_id, exam_key, exam_date, daily_target, weak_focus, created_at, updated_at)
+    VALUES (?, ?, ?, ?, ?, ?, ?)
+    ON CONFLICT(user_id, exam_key) DO UPDATE SET
+      exam_date    = excluded.exam_date,
+      daily_target = excluded.daily_target,
+      weak_focus   = excluded.weak_focus,
+      updated_at   = excluded.updated_at
+  `),
+  deletePlan: db.prepare(`DELETE FROM exam_user_plan WHERE user_id = ? AND exam_key = ?`),
+
+  /* Tasks solved today (distinct, mc+open+long); used by "today" progress. */
+  tasksSolvedToday: db.prepare(`
+    SELECT COUNT(DISTINCT a.exam_task_id) AS solved
+      FROM exam_attempts a
+      JOIN exam_tasks t ON t.id = a.exam_task_id
+     WHERE a.user_id = ? AND t.exam_key = ?
+       AND a.is_correct = 1
+       AND DATE(a.created_at / 1000, 'unixepoch') = DATE('now')
+  `),
 };
 
 /* ── GET /api/exam-prep/tracks ──
@@ -505,6 +533,110 @@ function stripPreview(html) {
   return text.length > 100 ? text.slice(0, 100) + '…' : text;
 }
 
+/* ──────────────────────────────────────────────────────────────────
+   Study plan (F10) — by exam date
+   ────────────────────────────────────────────────────────────────── */
+
+function isIsoDate(s) {
+  return typeof s === 'string' && /^\d{4}-\d{2}-\d{2}$/.test(s);
+}
+
+function daysBetween(yyyymmdd) {
+  // Calendar days from today to yyyymmdd (UTC). Negative if in past.
+  const [y, m, d] = yyyymmdd.split('-').map(Number);
+  const target = Date.UTC(y, m - 1, d);
+  const today  = new Date();
+  const todayStart = Date.UTC(today.getUTCFullYear(), today.getUTCMonth(), today.getUTCDate());
+  return Math.round((target - todayStart) / 86400000);
+}
+
+function buildPlanPayload(row, userId, examKey) {
+  if (!row) return { plan: null };
+
+  const counts = SQL.countTasks.get(examKey);
+  const progress = SQL.userProgress.get(userId, examKey);
+  const todayRow = SQL.tasksSolvedToday.get(userId, examKey);
+
+  const daysLeft  = daysBetween(row.exam_date);
+  const tasksLeft = Math.max(0, counts.total - progress.tasks_solved);
+
+  // Auto daily target if user hasn't customized: ceil(left / days)
+  let dailyTarget = row.daily_target;
+  if (!dailyTarget && daysLeft > 0) {
+    dailyTarget = Math.max(5, Math.min(50, Math.ceil(tasksLeft / daysLeft)));
+  }
+
+  return {
+    plan: {
+      exam_date:    row.exam_date,
+      daily_target: dailyTarget,
+      weak_focus:   !!row.weak_focus,
+      created_at:   row.created_at,
+      updated_at:   row.updated_at,
+      days_left:    daysLeft,
+      tasks_left:   tasksLeft,
+      today: {
+        solved: todayRow.solved,
+        target: dailyTarget,
+      },
+    },
+  };
+}
+
+/* ── GET /api/exam-prep/:examKey/plan ──
+   Returns { plan: null } if user has no plan for this track. */
+// @public-by-design: router-level authMiddleware (line 6) covers this route
+router.get('/:examKey/plan', (req, res) => {
+  const { examKey } = req.params;
+  if (!SQL.getTrack.get(examKey)) return res.status(404).json({ error: 'Unknown exam track' });
+  const row = SQL.getPlan.get(req.user.id, examKey);
+  res.json(buildPlanPayload(row, req.user.id, examKey));
+});
+
+/* ── PUT /api/exam-prep/:examKey/plan ──
+   Body: { exam_date: 'YYYY-MM-DD', daily_target?: int 5-50, weak_focus?: 0|1 }
+   Upserts the plan. exam_date is required; the other fields are optional. */
+// @public-by-design: router-level authMiddleware (line 6) covers this route
+router.put('/:examKey/plan', (req, res) => {
+  const { examKey } = req.params;
+  if (!SQL.getTrack.get(examKey)) return res.status(404).json({ error: 'Unknown exam track' });
+
+  const examDate = req.body?.exam_date;
+  if (!isIsoDate(examDate)) return res.status(400).json({ error: 'exam_date must be YYYY-MM-DD' });
+
+  let dailyTarget = req.body?.daily_target;
+  if (dailyTarget != null) {
+    dailyTarget = Number(dailyTarget);
+    if (!Number.isInteger(dailyTarget) || dailyTarget < 5 || dailyTarget > 50) {
+      return res.status(400).json({ error: 'daily_target must be integer 5-50' });
+    }
+  } else {
+    dailyTarget = 10;       // sensible default; client can override
+  }
+
+  const weakFocus = req.body?.weak_focus ? 1 : 0;
+
+  const existing = SQL.getPlan.get(req.user.id, examKey);
+  const now = Date.now();
+  SQL.upsertPlan.run(
+    req.user.id, examKey, examDate, dailyTarget, weakFocus,
+    existing ? existing.created_at : now, now
+  );
+
+  const row = SQL.getPlan.get(req.user.id, examKey);
+  res.json(buildPlanPayload(row, req.user.id, examKey));
+});
+
+/* ── DELETE /api/exam-prep/:examKey/plan ──
+   Remove the user's plan for this track. */
+// @public-by-design: router-level authMiddleware (line 6) covers this route
+router.delete('/:examKey/plan', (req, res) => {
+  const { examKey } = req.params;
+  if (!SQL.getTrack.get(examKey)) return res.status(404).json({ error: 'Unknown exam track' });
+  SQL.deletePlan.run(req.user.id, examKey);
+  res.json({ ok: true });
+});
+
 /* ──────────────────────────────────────────────────────────────────
    Mock exam (F9)
    ────────────────────────────────────────────────────────────────── */