'use strict';

const fs = require('fs');
const path = require('path');
const initSqlJs = require('sql.js');

const DATA_DIR = path.join(__dirname, 'data');
const DB_PATH = path.join(DATA_DIR, 'games.db');

let db = null;

async function init() {
  if (!fs.existsSync(DATA_DIR)) {
    fs.mkdirSync(DATA_DIR, { recursive: true });
  }

  const SQL = await initSqlJs();

  if (fs.existsSync(DB_PATH)) {
    const buf = fs.readFileSync(DB_PATH);
    db = new SQL.Database(buf);
  } else {
    db = new SQL.Database();
    db.run(`CREATE TABLE IF NOT EXISTS games (
      id         TEXT PRIMARY KEY,
      token      TEXT UNIQUE NOT NULL,
      status     TEXT NOT NULL DEFAULT 'waiting',
      board      TEXT NOT NULL DEFAULT 'null',
      turn       TEXT NOT NULL DEFAULT 'X',
      created_at TEXT NOT NULL,
      updated_at TEXT NOT NULL
    )`);
    persist();
  }
}

function createGame({ id, token }) {
  const now = new Date().toISOString();
  db.run(
    `INSERT INTO games (id, token, status, board, turn, created_at, updated_at)
     VALUES (?, ?, 'waiting', 'null', 'X', ?, ?)`,
    [id, token, now, now]
  );
  persist();
}

function getGameByToken(token) {
  const stmt = db.prepare(`SELECT * FROM games WHERE token = ?`);
  stmt.bind([token]);
  if (stmt.step()) {
    const row = stmt.getAsObject();
    stmt.free();
    return row;
  }
  stmt.free();
  return null;
}

function getGameById(id) {
  const stmt = db.prepare(`SELECT * FROM games WHERE id = ?`);
  stmt.bind([id]);
  if (stmt.step()) {
    const row = stmt.getAsObject();
    stmt.free();
    return row;
  }
  stmt.free();
  return null;
}

function updateGame(id, { status, board, turn }) {
  const now = new Date().toISOString();
  db.run(
    `UPDATE games SET status = ?, board = ?, turn = ?, updated_at = ? WHERE id = ?`,
    [status, board, turn, now, id]
  );
  persist();
}

function persist() {
  const data = db.export();
  fs.writeFileSync(DB_PATH, Buffer.from(data));
}

module.exports = { init, createGame, getGameByToken, getGameById, updateGame, persist };