const express = require('express');
const db = require('../db');
const router = express.Router();

// GET /api/progress — all topics with pct calculation
router.get('/', (req, res) => {
  try {
    const rows = db.prepare('SELECT * FROM progress ORDER BY topic').all();
    const result = rows.map(r => {
      const pct = r.exercises_done > 0 ? Math.round((r.exercises_correct / r.exercises_done) * 100) : 0;
      return {
        topic: r.topic,
        exercises_done: r.exercises_done,
        exercises_correct: r.exercises_correct,
        percentage: pct,
        last_session: r.last_session,
        notes: r.notes,
      };
    });
    res.json(result);
  } catch (err) {
    console.error('[progress] list error:', err.message);
    res.status(500).json({ error: err.message });
  }
});

// PUT /api/progress/:topic — update exercises (body: { correct: bool })
router.put('/:topic', (req, res) => {
  const topic = req.params.topic;
  const { correct } = req.body;

  if (correct === undefined) {
    return res.status(400).json({ error: 'correct is required' });
  }

  try {
    const existing = db.prepare('SELECT * FROM progress WHERE topic = ?').get(topic);
    if (existing) {
      db.prepare(`
        UPDATE progress SET
          exercises_done = exercises_done + 1,
          exercises_correct = exercises_correct + ?,
          last_session = datetime('now')
        WHERE topic = ?
      `).run(correct === true ? 1 : 0, topic);
    } else {
      db.prepare(`
        INSERT INTO progress (topic, exercises_done, exercises_correct, last_session, notes)
        VALUES (?, 1, ?, datetime('now'), '[]')
      `).run(topic, correct === true ? 1 : 0);
    }

    const row = db.prepare('SELECT * FROM progress WHERE topic = ?').get(topic);
    const pct = row.exercises_done > 0 ? Math.round((row.exercises_correct / row.exercises_done) * 100) : 0;
    res.json({ ...row, percentage: pct });
  } catch (err) {
    console.error('[progress] update error:', err.message);
    res.status(500).json({ error: err.message });
  }
});

// DELETE /api/progress/:topic — reset
router.delete('/:topic', (req, res) => {
  const topic = req.params.topic;

  try {
    const info = db.prepare('DELETE FROM progress WHERE topic = ?').run(topic);
    if (info.changes === 0) {
      return res.status(404).json({ error: 'Topic not found' });
    }
    res.json({ deleted: true });
  } catch (err) {
    console.error('[progress] delete error:', err.message);
    res.status(500).json({ error: err.message });
  }
});

module.exports = router;