import mysql from 'mysql2/promise';

const host = process.env.MYSQL_HOST || '127.0.0.1';
const port = parseInt(process.env.MYSQL_PORT || '3306', 10);
const user = process.env.MYSQL_USER || 'root';
const password = process.env.MYSQL_PASSWORD || '';

let pool: mysql.Pool | null = null;

async function ensureColumn(
  db: mysql.PoolConnection,
  tableName: string,
  columnName: string,
  definition: string
): Promise<void> {
  const [rows] = await db.execute<mysql.RowDataPacket[]>(
    `
      SELECT COLUMN_NAME
      FROM INFORMATION_SCHEMA.COLUMNS
      WHERE TABLE_SCHEMA = DATABASE()
        AND TABLE_NAME = ?
        AND COLUMN_NAME = ?
    `,
    [tableName, columnName]
  );

  if (Array.isArray(rows) && rows.length > 0) {
    return;
  }

  await db.execute(`ALTER TABLE \`${tableName}\` ADD COLUMN \`${columnName}\` ${definition}`);
}

export function getPool(): mysql.Pool {
  if (!pool) {
    throw new Error('Database pool not initialized. Call initDatabase() first.');
  }
  return pool;
}

export function isPoolReady(): boolean {
  return pool !== null;
}

export async function initDatabase(): Promise<void> {
  // Create database if it doesn't exist
  const tmpConn = await mysql.createConnection({ host, port, user, password });
  await tmpConn.execute('CREATE DATABASE IF NOT EXISTS hermes_oauth');
  await tmpConn.end();

  pool = mysql.createPool({
    host,
    port,
    user,
    password,
    database: 'hermes_oauth',
    waitForConnections: true,
    connectionLimit: 10,
    queueLimit: 0,
    timezone: 'Z',
  });

  const db = await pool.getConnection();
  try {
    await db.execute(`
      CREATE TABLE IF NOT EXISTS oauth_clients (
        client_id VARCHAR(255) PRIMARY KEY,
        client_secret VARCHAR(255) NOT NULL,
        client_name VARCHAR(255),
        redirect_urls JSON,
        grant_types JSON,
        created_at TIMESTAMP DEFAULT CURRENT_TIMESTAMP,
        last_used TIMESTAMP NULL,
        is_static BOOLEAN DEFAULT FALSE,
        INDEX idx_last_used (last_used)
      )
    `);

    await db.execute(`
      CREATE TABLE IF NOT EXISTS oauth_auth_codes (
        code VARCHAR(255) PRIMARY KEY,
        client_id VARCHAR(255),
        redirect_uri TEXT,
        scope TEXT NULL,
        code_challenge TEXT NULL,
        code_challenge_method VARCHAR(20) NULL,
        expires_at TIMESTAMP,
        used BOOLEAN DEFAULT FALSE,
        INDEX idx_expires (expires_at)
      )
    `);

    await ensureColumn(db, 'oauth_auth_codes', 'scope', 'TEXT NULL');
    await ensureColumn(db, 'oauth_auth_codes', 'code_challenge', 'TEXT NULL');
    await ensureColumn(db, 'oauth_auth_codes', 'code_challenge_method', 'VARCHAR(20) NULL');

    await db.execute(`
      CREATE TABLE IF NOT EXISTS oauth_tokens (
        token VARCHAR(255) PRIMARY KEY,
        client_id VARCHAR(255),
        token_type ENUM('access', 'refresh') DEFAULT 'access',
        expires_at TIMESTAMP,
        created_at TIMESTAMP DEFAULT CURRENT_TIMESTAMP,
        INDEX idx_expires (expires_at)
      )
    `);

    await db.execute(`
      CREATE TABLE IF NOT EXISTS customers (
        id VARCHAR(255) PRIMARY KEY,
        api_key VARCHAR(255) NOT NULL UNIQUE,
        plan ENUM('free', 'starter', 'growth', 'enterprise') DEFAULT 'free',
        active BOOLEAN DEFAULT TRUE,
        email VARCHAR(255) NOT NULL,
        created_at TIMESTAMP DEFAULT CURRENT_TIMESTAMP,
        INDEX idx_api_key (api_key)
      )
    `);
  } finally {
    db.release();
  }

  console.log('[db] MySQL connected and schema initialized');
}