import 'dotenv/config';

const REQUIRED_VARS = ['STORAGE_DIR', 'DB_HOST', 'DB_USER', 'DB_PASSWORD', 'DB_NAME'];

export function loadConfig() {
  const missing = REQUIRED_VARS.filter((key) => !process.env[key]);
  if (missing.length > 0) {
    throw new Error(`Missing required environment variables: ${missing.join(', ')}`);
  }

  return {
    port: Number(process.env.PORT ?? 3000),
    storageDir: process.env.STORAGE_DIR,
    db: {
      host: process.env.DB_HOST,
      user: process.env.DB_USER,
      password: process.env.DB_PASSWORD,
      database: process.env.DB_NAME,
    },
    maxFileSizeMb: Number(process.env.MAX_FILE_SIZE_MB ?? 100),
    retentionHours: Number(process.env.RETENTION_HOURS ?? 1),
    workerPollIntervalMs: Number(process.env.WORKER_POLL_INTERVAL_MS ?? 1500),
    workerConcurrency: Number(process.env.WORKER_CONCURRENCY ?? 3),
    ebookJobTimeoutMs: Number(process.env.EBOOK_JOB_TIMEOUT_MS ?? 180000),
    rateLimitMaxJobs: Number(process.env.RATE_LIMIT_MAX_JOBS ?? 20),
    rateLimitWindowMinutes: Number(process.env.RATE_LIMIT_WINDOW_MINUTES ?? 10),
  };
}