const express = require('express');
const { Pool } = require('pg');
const path    = require('path');

const app       = express();
const PORT      = parseInt(process.env.PORT || '3003');
const ADMIN_PIN = process.env.ADMIN_PIN || '1234';

// ── Database ──────────────────────────────────────────────────────────────────
// Requires env var DATABASE_URL with a valid PostgreSQL connection string.
const pool = new Pool({ connectionString: process.env.DATABASE_URL });

/**
 * Run schema migrations on startup.
 * CREATE TABLE IF NOT EXISTS is idempotent — safe to run every boot.
 */
async function initSchema() {
  await pool.query(`
    CREATE TABLE IF NOT EXISTS players (
      id         SERIAL PRIMARY KEY,
      name       TEXT    NOT NULL,
      avatar     TEXT    NOT NULL,
      created_at TIMESTAMPTZ DEFAULT NOW()
    );

    CREATE TABLE IF NOT EXISTS sessions (
      id               SERIAL PRIMARY KEY,
      player_id        INTEGER NOT NULL REFERENCES players(id) ON DELETE CASCADE,
      level            INTEGER NOT NULL,
      score            INTEGER NOT NULL,
      total            INTEGER NOT NULL,
      stars            INTEGER NOT NULL,
      duration_seconds INTEGER NOT NULL DEFAULT 0,
      created_at       TIMESTAMPTZ DEFAULT NOW()
    );

    CREATE INDEX IF NOT EXISTS idx_sessions_player ON sessions(player_id);
    CREATE INDEX IF NOT EXISTS idx_sessions_level  ON sessions(player_id, level);
  `);
  console.log('✅ Schema ready');
}

// ── Middleware ────────────────────────────────────────────────────────────────
app.use(express.json());
app.use(express.static(path.join(__dirname, 'public')));

// ── Helpers ───────────────────────────────────────────────────────────────────
/**
 * Build per-level best-score stats from a flat sessions array.
 * @param {Array} sessions
 * @returns {Object} keyed by level 1–5
 */
function buildLevelStats(sessions) {
  const stats = {};
  for (let lvl = 1; lvl <= 5; lvl++) {
    const ls = sessions.filter(s => s.level === lvl);
    if (!ls.length) continue;
    const best = ls.reduce((b, s) => (s.score / s.total > b.score / b.total ? s : b));
    stats[lvl] = {
      played:    ls.length,
      bestScore: best.score,
      bestTotal: best.total,
      bestPct:   Math.round(best.score / best.total * 100),
    };
  }
  return stats;
}

// ── Routes ────────────────────────────────────────────────────────────────────

// GET /api/health — also verifies DB connectivity
app.get('/api/health', async (_req, res) => {
  try {
    await pool.query('SELECT 1');
    res.json({ ok: true });
  } catch {
    res.status(503).json({ ok: false });
  }
});

// GET /api/players
app.get('/api/players', async (_req, res) => {
  try {
    const { rows } = await pool.query(
      'SELECT id, name, avatar, created_at FROM players ORDER BY name'
    );
    res.json(rows);
  } catch (err) {
    res.status(500).json({ error: err.message });
  }
});

// POST /api/players  { name, avatar }
app.post('/api/players', async (req, res) => {
  const { name, avatar } = req.body ?? {};
  if (!name?.trim() || !avatar) {
    return res.status(400).json({ error: 'name i avatar són obligatoris' });
  }
  try {
    // Case-insensitive duplicate check
    const dup = await pool.query(
      'SELECT id FROM players WHERE lower(name) = lower($1)',
      [name.trim()]
    );
    if (dup.rows.length) {
      return res.status(409).json({ error: 'Ja existeix un jugador amb aquest nom' });
    }
    const { rows } = await pool.query(
      'INSERT INTO players (name, avatar) VALUES ($1, $2) RETURNING id, name, avatar',
      [name.trim(), avatar]
    );
    res.status(201).json(rows[0]);
  } catch (err) {
    res.status(500).json({ error: err.message });
  }
});

// GET /api/players/:id/stats
app.get('/api/players/:id/stats', async (req, res) => {
  try {
    const playerRes = await pool.query(
      'SELECT id, name, avatar, created_at FROM players WHERE id = $1',
      [req.params.id]
    );
    if (!playerRes.rows.length) {
      return res.status(404).json({ error: 'Jugador no trobat' });
    }
    const player = playerRes.rows[0];

    const sessionRes = await pool.query(
      `SELECT level, score, total, stars, duration_seconds, created_at
       FROM sessions WHERE player_id = $1 ORDER BY created_at DESC`,
      [req.params.id]
    );
    const sessions = sessionRes.rows;

    const totalStars    = sessions.reduce((s, r) => s + r.stars, 0);
    const totalSessions = sessions.length;
    const levelStats    = buildLevelStats(sessions);
    const recent        = sessions.slice(0, 10).map(s => ({
      level: s.level, score: s.score, total: s.total,
      stars: s.stars, date: s.created_at,
    }));

    res.json({ player, totalStars, totalSessions, levelStats, recent });
  } catch (err) {
    res.status(500).json({ error: err.message });
  }
});

// POST /api/sessions  { player_id, level, score, total, stars, duration_seconds? }
app.post('/api/sessions', async (req, res) => {
  const { player_id, level, score, total, stars, duration_seconds = 0 } = req.body ?? {};
  if ([player_id, level, score, total, stars].some(v => v == null)) {
    return res.status(400).json({ error: 'Falten camps obligatoris' });
  }
  try {
    const playerRes = await pool.query(
      'SELECT id FROM players WHERE id = $1', [player_id]
    );
    if (!playerRes.rows.length) {
      return res.status(404).json({ error: 'Jugador no trobat' });
    }
    const { rows } = await pool.query(
      `INSERT INTO sessions (player_id, level, score, total, stars, duration_seconds)
       VALUES ($1, $2, $3, $4, $5, $6) RETURNING id`,
      [player_id, level, score, total, stars, duration_seconds]
    );
    res.status(201).json({ id: rows[0].id });
  } catch (err) {
    res.status(500).json({ error: err.message });
  }
});

// GET /api/admin/stats   Header: x-admin-pin
app.get('/api/admin/stats', async (req, res) => {
  if (req.headers['x-admin-pin'] !== ADMIN_PIN) {
    return res.status(401).json({ error: 'PIN incorrecte' });
  }
  try {
    const { rows: players } = await pool.query(
      'SELECT id, name, avatar, created_at FROM players ORDER BY name'
    );

    // Fetch all sessions in one query to avoid N+1
    const { rows: allSessions } = await pool.query(
      `SELECT player_id, level, score, total, stars, created_at
       FROM sessions ORDER BY created_at DESC`
    );

    const full = players.map(p => {
      const sessions     = allSessions.filter(s => s.player_id === p.id);
      const totalStars   = sessions.reduce((s, r) => s + r.stars, 0);
      const levelStats   = buildLevelStats(sessions);
      const lastActivity = sessions[0]?.created_at ?? null;
      return { ...p, totalSessions: sessions.length, totalStars, levelStats, lastActivity };
    });

    res.json(full);
  } catch (err) {
    res.status(500).json({ error: err.message });
  }
});

// ── Start ─────────────────────────────────────────────────────────────────────
initSchema()
  .then(() => app.listen(PORT, '0.0.0.0', () =>
    console.log(`🏔️  Comarques API · port ${PORT} · PostgreSQL`)
  ))
  .catch(err => {
    console.error('❌ DB init failed:', err.message);
    process.exit(1);
  });