import mysql, { Pool, PoolConnection, ResultSetHeader, RowDataPacket } from 'mysql2/promise';
import { config } from '../config.js';

let pool: Pool | null = null;

export function initializePool(): Pool {
  if (pool) return pool;

  const socketPath = config.DB_HOST.startsWith('/') ? config.DB_HOST : undefined;

  pool = mysql.createPool({
    ...(socketPath ? { socketPath } : { host: config.DB_HOST, port: config.DB_PORT }),
    user: config.DB_USER,
    password: config.DB_PASSWORD,
    database: config.DB_NAME,
    waitForConnections: true,
    connectionLimit: config.MAX_CONNECTIONS,
    queueLimit: 0,
    enableKeepAlive: true,
    keepAliveInitialDelay: 10000,
  });

  return pool;
}

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

export async function closePool(): Promise<void> {
  if (pool) {
    await pool.end();
    pool = null;
  }
}

export async function query<T extends RowDataPacket[]>(
  sql: string,
  params?: unknown[]
): Promise<T> {
  const [rows] = await getPool().execute<T>(sql, params);
  return rows;
}

export async function queryOne<T extends RowDataPacket>(
  sql: string,
  params?: unknown[]
): Promise<T | null> {
  const rows = await query<T[]>(sql, params);
  return rows[0] ?? null;
}

export async function execute(
  sql: string,
  params?: unknown[]
): Promise<ResultSetHeader> {
  const [result] = await getPool().execute<ResultSetHeader>(sql, params);
  return result;
}

export async function getConnection(): Promise<PoolConnection> {
  return getPool().getConnection();
}