import mysql from "mysql2/promise";

const globalForMysql = globalThis as unknown as {
  mysqlPool?: mysql.Pool;
};

function required(name: string): string {
  const value = process.env[name];
  if (!value) throw new Error(`Missing environment variable: ${name}`);
  return value;
}

export const db = globalForMysql.mysqlPool ?? mysql.createPool({
  host: required("DB_HOST"),
  port: Number(process.env.DB_PORT || 3306),
  database: required("DB_NAME"),
  user: required("DB_USER"),
  password: required("DB_PASSWORD"),
  waitForConnections: true,
  connectionLimit: 10,
  queueLimit: 0,
  charset: "utf8mb4"
});

if (process.env.NODE_ENV !== "production") globalForMysql.mysqlPool = db;