import dotenv from 'dotenv';

dotenv.config();

const requiredKeys = ['DB_HOST', 'DB_PORT', 'DB_NAME', 'DB_USER', 'DB_PASSWORD'];

/*
 * Environment validation happens at module load time so configuration mistakes
 * are discovered immediately. That is intentional because this service is small
 * enough that there is no benefit in deferring a misconfiguration error until a
 * later database call or request handler.
 */
for (const key of requiredKeys) {
  if (!process.env[key]) {
    throw new Error(`Missing required environment variable: ${key}`);
  }
}

/*
 * The exported env object becomes the single place where raw process variables
 * are normalized into application-friendly types such as numbers. That keeps the
 * rest of the codebase from repeating string-to-number conversion logic.
 */
export const env = {
  port: Number(process.env.PORT || 3000),
  db: {
    host: process.env.DB_HOST,
    port: Number(process.env.DB_PORT),
    database: process.env.DB_NAME,
    user: process.env.DB_USER,
    password: process.env.DB_PASSWORD,
    connectionLimit: Number(process.env.DB_CONNECTION_LIMIT || 5)
  }
};