import bcrypt from 'bcryptjs';
import path from 'path';
import { fileURLToPath } from 'url';

const __filename = fileURLToPath(import.meta.url);
const __dirname = path.dirname(__filename);

const DATABASE_URL = process.env.DATABASE_URL;
const isPostgres = !!(DATABASE_URL && DATABASE_URL.startsWith('postgres'));

let db;

// Convert ? placeholders to $1, $2, ... for PostgreSQL
function convertPlaceholders(sql) {
  let index = 0;
  return sql.replace(/\?/g, () => `$${++index}`);
}

// ── SQLite Adapter ──────────────────────────────────────────────────────────
class SqliteAdapter {
  async init() {
    const { default: Database } = await import('better-sqlite3');
    const dbPath = process.env.SQLITE_PATH || path.join(__dirname, '..', '..', 'redlight.db');
    this.db = Database(dbPath);
    this.db.pragma('journal_mode = WAL');
    this.db.pragma('foreign_keys = ON');
  }

  async get(sql, params = []) {
    return this.db.prepare(sql).get(...params);
  }

  async all(sql, params = []) {
    return this.db.prepare(sql).all(...params);
  }

  async run(sql, params = []) {
    const result = this.db.prepare(sql).run(...params);
    return { lastInsertRowid: Number(result.lastInsertRowid), changes: result.changes };
  }

  async exec(sql) {
    this.db.exec(sql);
  }

  async columnExists(table, column) {
    const columns = this.db.pragma(`table_info(${table})`);
    return !!columns.find(c => c.name === column);
  }

  close() {
    this.db.close();
  }
}

// ── PostgreSQL Adapter ──────────────────────────────────────────────────────
class PostgresAdapter {
  async init() {
    const pg = await import('pg');
    // Parse int8 (bigint / COUNT) as JS number instead of string
    pg.default.types.setTypeParser(20, val => parseInt(val, 10));
    this.pool = new pg.default.Pool({ connectionString: DATABASE_URL });
  }

  async get(sql, params = []) {
    const result = await this.pool.query(convertPlaceholders(sql), params);
    return result.rows[0] || undefined;
  }

  async all(sql, params = []) {
    const result = await this.pool.query(convertPlaceholders(sql), params);
    return result.rows;
  }

  async run(sql, params = []) {
    let pgSql = convertPlaceholders(sql);
    const isInsert = /^\s*INSERT/i.test(pgSql);
    if (isInsert && !/RETURNING/i.test(pgSql)) {
      pgSql += ' RETURNING id';
    }
    const result = await this.pool.query(pgSql, params);
    return {
      lastInsertRowid: isInsert ? result.rows[0]?.id : undefined,
      changes: result.rowCount,
    };
  }

  async exec(sql) {
    await this.pool.query(sql);
  }

  async columnExists(table, column) {
    const result = await this.pool.query(
      'SELECT column_name FROM information_schema.columns WHERE table_name = $1 AND column_name = $2',
      [table, column]
    );
    return result.rows.length > 0;
  }

  close() {
    this.pool?.end();
  }
}

// ── Public API ──────────────────────────────────────────────────────────────
export function getDb() {
  if (!db) {
    throw new Error('Database not initialised – call initDatabase() first');
  }
  return db;
}

export async function initDatabase() {
  // Create the right adapter
  if (isPostgres) {
    console.log('📦 Using PostgreSQL database');
    db = new PostgresAdapter();
  } else {
    console.log('📦 Using SQLite database');
    db = new SqliteAdapter();
  }
  await db.init();

  // ── Schema creation ─────────────────────────────────────────────────────
  if (isPostgres) {
    await db.exec(`
      CREATE TABLE IF NOT EXISTS users (
        id SERIAL PRIMARY KEY,
        name TEXT NOT NULL,
        email TEXT UNIQUE NOT NULL,
        password_hash TEXT NOT NULL,
        role TEXT DEFAULT 'user' CHECK(role IN ('user', 'admin')),
        language TEXT DEFAULT 'de',
        theme TEXT DEFAULT 'dark',
        avatar_color TEXT DEFAULT '#6366f1',
        avatar_image TEXT DEFAULT NULL,
        created_at TIMESTAMP DEFAULT NOW(),
        updated_at TIMESTAMP DEFAULT NOW()
      );

      CREATE TABLE IF NOT EXISTS rooms (
        id SERIAL PRIMARY KEY,
        uid TEXT UNIQUE NOT NULL,
        name TEXT NOT NULL,
        user_id INTEGER NOT NULL REFERENCES users(id) ON DELETE CASCADE,
        welcome_message TEXT DEFAULT 'Willkommen im Meeting!',
        max_participants INTEGER DEFAULT 0,
        access_code TEXT,
        mute_on_join INTEGER DEFAULT 1,
        require_approval INTEGER DEFAULT 0,
        anyone_can_start INTEGER DEFAULT 0,
        all_join_moderator INTEGER DEFAULT 0,
        record_meeting INTEGER DEFAULT 1,
        guest_access INTEGER DEFAULT 0,
        moderator_code TEXT,
        created_at TIMESTAMP DEFAULT NOW(),
        updated_at TIMESTAMP DEFAULT NOW()
      );

      CREATE INDEX IF NOT EXISTS idx_rooms_user_id ON rooms(user_id);
      CREATE INDEX IF NOT EXISTS idx_rooms_uid ON rooms(uid);
      CREATE INDEX IF NOT EXISTS idx_users_email ON users(email);
    `);
  } else {
    await db.exec(`
      CREATE TABLE IF NOT EXISTS users (
        id INTEGER PRIMARY KEY AUTOINCREMENT,
        name TEXT NOT NULL,
        email TEXT UNIQUE NOT NULL,
        password_hash TEXT NOT NULL,
        role TEXT DEFAULT 'user' CHECK(role IN ('user', 'admin')),
        language TEXT DEFAULT 'de',
        theme TEXT DEFAULT 'dark',
        avatar_color TEXT DEFAULT '#6366f1',
        avatar_image TEXT DEFAULT NULL,
        created_at DATETIME DEFAULT CURRENT_TIMESTAMP,
        updated_at DATETIME DEFAULT CURRENT_TIMESTAMP
      );

      CREATE TABLE IF NOT EXISTS rooms (
        id INTEGER PRIMARY KEY AUTOINCREMENT,
        uid TEXT UNIQUE NOT NULL,
        name TEXT NOT NULL,
        user_id INTEGER NOT NULL,
        welcome_message TEXT DEFAULT 'Willkommen im Meeting!',
        max_participants INTEGER DEFAULT 0,
        access_code TEXT,
        mute_on_join INTEGER DEFAULT 1,
        require_approval INTEGER DEFAULT 0,
        anyone_can_start INTEGER DEFAULT 0,
        all_join_moderator INTEGER DEFAULT 0,
        record_meeting INTEGER DEFAULT 1,
        guest_access INTEGER DEFAULT 0,
        moderator_code TEXT,
        created_at DATETIME DEFAULT CURRENT_TIMESTAMP,
        updated_at DATETIME DEFAULT CURRENT_TIMESTAMP,
        FOREIGN KEY (user_id) REFERENCES users(id) ON DELETE CASCADE
      );

      CREATE INDEX IF NOT EXISTS idx_rooms_user_id ON rooms(user_id);
      CREATE INDEX IF NOT EXISTS idx_rooms_uid ON rooms(uid);
      CREATE INDEX IF NOT EXISTS idx_users_email ON users(email);
    `);
  }

  // ── Migrations ──────────────────────────────────────────────────────────
  if (!(await db.columnExists('users', 'avatar_image'))) {
    await db.exec('ALTER TABLE users ADD COLUMN avatar_image TEXT DEFAULT NULL');
  }
  if (!(await db.columnExists('rooms', 'guest_access'))) {
    await db.exec('ALTER TABLE rooms ADD COLUMN guest_access INTEGER DEFAULT 0');
  }
  if (!(await db.columnExists('rooms', 'moderator_code'))) {
    await db.exec('ALTER TABLE rooms ADD COLUMN moderator_code TEXT');
  }

  // ── Default admin ───────────────────────────────────────────────────────
  const adminEmail = process.env.ADMIN_EMAIL || 'admin@example.com';
  const adminPassword = process.env.ADMIN_PASSWORD || 'admin123';

  const existingAdmin = await db.get('SELECT id FROM users WHERE email = ?', [adminEmail]);
  if (!existingAdmin) {
    const hash = bcrypt.hashSync(adminPassword, 12);
    await db.run(
      'INSERT INTO users (name, email, password_hash, role) VALUES (?, ?, ?, ?)',
      ['Administrator', adminEmail, hash, 'admin']
    );
    console.log(`✅ Default admin created: ${adminEmail}`);
  }
}