const express = require('express');
const db      = require('../../db');
const { authenticate } = require('../../middleware/auth');
const router  = express.Router();

// ── DB-Migration ──────────────────────────────────────────────────────────────
(function migrate() {
  const cols = db.pragma('table_info(geo_games)').map(c => c.name);
  if (!cols.length) {
    db.exec(`
      CREATE TABLE IF NOT EXISTS geo_games (
        id           INTEGER PRIMARY KEY AUTOINCREMENT,
        owner_id     INTEGER NOT NULL,
        opponent_id  INTEGER NOT NULL,
        grid         TEXT    NOT NULL,
        current_turn INTEGER NOT NULL,
        status       TEXT    NOT NULL DEFAULT 'active',
        winner_id    INTEGER,
        move_count   INTEGER NOT NULL DEFAULT 0,
        created_at   TEXT    NOT NULL DEFAULT (datetime('now','localtime')),
        updated_at   TEXT    NOT NULL DEFAULT (datetime('now','localtime'))
      );
    `);
  }
  // move_count nachrüsten falls Tabelle schon existiert
  if (!cols.includes('move_count')) {
    db.exec(`ALTER TABLE geo_games ADD COLUMN move_count INTEGER NOT NULL DEFAULT 0`);
  }
})();

const GRID = 20;

function createGrid(ownerId, oppId) {
  const grid = Array(GRID).fill(null).map(() => Array(GRID).fill(0));
  grid[0][0] = ownerId;
  grid[GRID - 1][GRID - 1] = oppId;
  return JSON.stringify(grid);
}

// Diagonal erlaubt: alle 8 Richtungen
function isAdjacent(grid, row, col, playerId) {
  const dirs = [[-1,-1],[-1,0],[-1,1],[0,-1],[0,1],[1,-1],[1,0],[1,1]];
  for (const [dr, dc] of dirs) {
    const r = row + dr, c = col + dc;
    if (r >= 0 && r < GRID && c >= 0 && c < GRID && grid[r][c] === playerId) return true;
  }
  return false;
}

function canMove(grid, playerId) {
  for (let r = 0; r < GRID; r++)
    for (let c = 0; c < GRID; c++)
      if (grid[r][c] === 0 && isAdjacent(grid, r, c, playerId)) return true;
  return false;
}

function countCells(grid, playerId) {
  let n = 0;
  for (let r = 0; r < GRID; r++)
    for (let c = 0; c < GRID; c++)
      if (grid[r][c] === playerId) n++;
  return n;
}

function sendPush(userId, title, message) {
  const cfg = db.prepare('SELECT user_key, app_token FROM pushover_settings WHERE user_id=?').get(userId);
  if (!cfg?.app_token || !cfg?.user_key) return;
  fetch('https://api.pushover.net/1/messages.json', {
    method: 'POST',
    headers: { 'Content-Type': 'application/json' },
    body: JSON.stringify({ token: cfg.app_token, user: cfg.user_key, title, message, priority: 0 }),
  }).catch(() => {});
}

// Spiel mit JOIN laden (inkl. owner_name / opp_name)
function getGame(id) {
  return db.prepare(`
    SELECT g.*, u1.username as owner_name, u2.username as opp_name
    FROM geo_games g
    JOIN users u1 ON u1.id = g.owner_id
    JOIN users u2 ON u2.id = g.opponent_id
    WHERE g.id = ?
  `).get(id);
}

const uid = req => req.user.id;

// ── Alle Spiele des Users ─────────────────────────────────────────────────────
router.get('/', authenticate, (req, res) => {
  const me = uid(req);
  const games = db.prepare(`
    SELECT g.*, u1.username as owner_name, u2.username as opp_name
    FROM geo_games g
    JOIN users u1 ON u1.id = g.owner_id
    JOIN users u2 ON u2.id = g.opponent_id
    WHERE (g.owner_id=? OR g.opponent_id=?)
      AND NOT (g.status='finished' AND g.move_count < 2)
    ORDER BY g.updated_at DESC
  `).all(me, me);
  res.json(games);
});

// ── Topliste ──────────────────────────────────────────────────────────────────
router.get('/leaderboard', authenticate, (req, res) => {
  // Nur Spiele die wirklich gespielt wurden (mind. 1 Zug pro Spieler = move_count >= 2)
  // und nicht durch Aufgeben ohne Züge beendet wurden
  const rows = db.prepare(`
    SELECT u.username, COUNT(*) as wins
    FROM geo_games g
    JOIN users u ON u.id = g.winner_id
    WHERE g.status = 'finished'
      AND g.winner_id IS NOT NULL
      AND g.move_count >= 2
    GROUP BY g.winner_id
    ORDER BY wins DESC
    LIMIT 20
  `).all();
  res.json(rows);
});

// ── Alle User (für Einladen) ──────────────────────────────────────────────────
router.get('/users', authenticate, (req, res) => {
  const me = uid(req);
  const isAdmin = req.user?.role === 'admin';
  const users = isAdmin
    ? db.prepare('SELECT id, username FROM users WHERE id != ? ORDER BY username').all(me)
    : db.prepare('SELECT id, username FROM users WHERE id != ? AND hidden != 1 ORDER BY username').all(me);
  res.json(users);
});

// ── Einzelnes Spiel ───────────────────────────────────────────────────────────
router.get('/:id', authenticate, (req, res) => {
  const me   = uid(req);
  const game = getGame(req.params.id);
  if (!game) return res.status(404).json({ error: 'Nicht gefunden' });
  if (game.owner_id !== me && game.opponent_id !== me)
    return res.status(403).json({ error: 'Kein Zugriff' });
  res.json(game);
});

// ── Neues Spiel erstellen ─────────────────────────────────────────────────────
router.post('/', authenticate, (req, res) => {
  const me = uid(req);
  const { opponent_id } = req.body;
  if (!opponent_id) return res.status(400).json({ error: 'Gegner fehlt' });
  if (opponent_id === me) return res.status(400).json({ error: 'Du kannst nicht gegen dich spielen' });

  const opp = db.prepare('SELECT id, username FROM users WHERE id=?').get(opponent_id);
  if (!opp) return res.status(404).json({ error: 'Benutzer nicht gefunden' });

  const grid   = createGrid(me, opponent_id);
  const result = db.prepare(`
    INSERT INTO geo_games (owner_id, opponent_id, grid, current_turn, move_count)
    VALUES (?, ?, ?, ?, 0)
  `).run(me, opponent_id, grid, me);

  const myName = db.prepare('SELECT username FROM users WHERE id=?').get(me)?.username || 'Jemand';
  sendPush(opponent_id, '⬡ Hex Wars', `${myName} hat dich zu einem Spiel eingeladen! Du bist zuerst dran.`);

  res.json({ id: result.lastInsertRowid });
});

// ── Zug machen ────────────────────────────────────────────────────────────────
router.post('/:id/move', authenticate, (req, res) => {
  const me = uid(req);
  const { row, col } = req.body;
  if (row === undefined || col === undefined) return res.status(400).json({ error: 'row/col fehlt' });

  const game = db.prepare('SELECT * FROM geo_games WHERE id=?').get(req.params.id);
  if (!game) return res.status(404).json({ error: 'Spiel nicht gefunden' });
  if (game.owner_id !== me && game.opponent_id !== me)
    return res.status(403).json({ error: 'Kein Zugriff' });
  if (game.status !== 'active') return res.status(400).json({ error: 'Spiel beendet' });
  if (game.current_turn !== me) return res.status(400).json({ error: 'Nicht dein Zug' });

  const grid = JSON.parse(game.grid);
  if (row < 0 || row >= GRID || col < 0 || col >= GRID)
    return res.status(400).json({ error: 'Ungültige Position' });
  if (grid[row][col] !== 0)
    return res.status(400).json({ error: 'Zelle bereits belegt' });
  if (!isAdjacent(grid, row, col, me))
    return res.status(400).json({ error: 'Zelle grenzt nicht an dein Gebiet' });

  grid[row][col] = me;
  const opponent  = game.owner_id === me ? game.opponent_id : game.owner_id;
  const newMoves  = (game.move_count || 0) + 1;
  let nextTurn    = opponent;
  let status      = 'active';
  let winnerId    = null;

  if (!canMove(grid, opponent)) {
    if (!canMove(grid, me)) {
      status   = 'finished';
      const mc = countCells(grid, me);
      const oc = countCells(grid, opponent);
      winnerId = mc > oc ? me : (oc > mc ? opponent : null);
    } else {
      nextTurn = me; // Gegner überspringen
    }
  }

  db.prepare(`
    UPDATE geo_games SET grid=?, current_turn=?, status=?, winner_id=?, move_count=?,
    updated_at=datetime('now','localtime') WHERE id=?
  `).run(JSON.stringify(grid), nextTurn, status, winnerId, newMoves, game.id);

  // Pushover
  const myName  = db.prepare('SELECT username FROM users WHERE id=?').get(me)?.username || 'Jemand';
  const oppName = db.prepare('SELECT username FROM users WHERE id=?').get(opponent)?.username || 'Jemand';

  if (status === 'finished') {
    const mc = countCells(grid, me);
    const oc = countCells(grid, opponent);
    if (winnerId === me) {
      sendPush(opponent, '⬡ Hex Wars beendet', `${myName} hat gewonnen! ${mc} vs ${oc} Felder.`);
      sendPush(me, '⬡ Hex Wars gewonnen!', `Du hast gewonnen! ${mc} vs ${oc} Felder. 🎉`);
    } else if (winnerId === opponent) {
      sendPush(me, '⬡ Hex Wars beendet', `${oppName} hat gewonnen. ${mc} vs ${oc} Felder.`);
      sendPush(opponent, '⬡ Hex Wars gewonnen!', `Du hast gewonnen! ${oc} vs ${mc} Felder. 🎉`);
    } else {
      sendPush(me,       '⬡ Hex Wars — Unentschieden!', `${mc} vs ${oc} Felder.`);
      sendPush(opponent, '⬡ Hex Wars — Unentschieden!', `${oc} vs ${mc} Felder.`);
    }
  } else if (nextTurn === opponent) {
    sendPush(opponent, '⬡ Hex Wars — Du bist dran!', `${myName} hat gezogen!`);
  }

  res.json(getGame(game.id));
});

// ── Aufgeben ──────────────────────────────────────────────────────────────────
router.post('/:id/resign', authenticate, (req, res) => {
  const me   = uid(req);
  const game = db.prepare('SELECT * FROM geo_games WHERE id=?').get(req.params.id);
  if (!game) return res.status(404).json({ error: 'Nicht gefunden' });
  if (game.owner_id !== me && game.opponent_id !== me)
    return res.status(403).json({ error: 'Kein Zugriff' });
  if (game.status !== 'active') return res.status(400).json({ error: 'Spiel bereits beendet' });

  const winner = game.owner_id === me ? game.opponent_id : game.owner_id;
  // move_count bleibt wie es ist — wird für Leaderboard/Liste genutzt
  db.prepare(`
    UPDATE geo_games SET status='finished', winner_id=?,
    updated_at=datetime('now','localtime') WHERE id=?
  `).run(winner, game.id);

  const myName = db.prepare('SELECT username FROM users WHERE id=?').get(me)?.username || 'Jemand';
  sendPush(winner, '⬡ Hex Wars gewonnen!', `${myName} hat aufgegeben. Du gewinnst! 🎉`);

  res.json({ ok: true });
});

module.exports = router;

// ── Spiel löschen (nur Admin, nur beendete/aufgegebene) ───────────────────────
router.delete('/:id', authenticate, (req, res) => {
  if (req.user?.role !== 'admin') return res.status(403).json({ error: 'Kein Zugriff' });
  const game = db.prepare('SELECT * FROM geo_games WHERE id=?').get(req.params.id);
  if (!game) return res.status(404).json({ error: 'Nicht gefunden' });
  if (game.status !== 'finished') return res.status(400).json({ error: 'Nur beendete Spiele können gelöscht werden' });
  db.prepare('DELETE FROM geo_games WHERE id=?').run(req.params.id);
  res.json({ ok: true });
});