/**
 * Configuration helpers for the db package.
 *
 * Reads from environment variables. Throws clearly if a required var
 * is missing.
 */

export interface DbConfig {
  /** Postgres connection URL, e.g. postgres://user:pass@host:5432/db */
  databaseUrl: string;
  /** Redis connection URL, e.g. redis://host:6379 */
  redisUrl: string;
  /** When true, callers should use the in-memory fallback instead. */
  useInMemory: boolean;
}

const REQUIRED_FOR_DB = ['DATABASE_URL', 'REDIS_URL'] as const;

export function loadConfig(env: NodeJS.ProcessEnv = process.env): DbConfig {
  const databaseUrl = env.DATABASE_URL;
  const redisUrl = env.REDIS_URL;
  // Allow opt-out for dev (e.g. when Docker isn't available)
  const forceInMemory = env.USE_IN_MEMORY === '1' || env.USE_IN_MEMORY === 'true';

  if (forceInMemory) {
    return { databaseUrl: '', redisUrl: '', useInMemory: true };
  }

  const missing = REQUIRED_FOR_DB.filter((k) => !env[k]);
  if (missing.length > 0) {
    // Don't crash on import — let the caller decide. The API's
    // bootstrap() logs a warning and falls back to in-memory mode.
    return {
      databaseUrl: databaseUrl ?? '',
      redisUrl: redisUrl ?? '',
      useInMemory: true,
    };
  }

  return {
    databaseUrl: databaseUrl!,
    redisUrl: redisUrl!,
    useInMemory: false,
  };
}