import 'dotenv/config';

export class MissingEnvironmentError extends Error {
  readonly code = 'MISSING_ENVIRONMENT_VARIABLE';

  constructor(readonly variableName: string) {
    super(`Missing required environment variable: ${variableName}`);
    this.name = 'MissingEnvironmentError';
  }
}

export function requireEnv(
  name: string,
  env: NodeJS.ProcessEnv = process.env,
): string {
  const value = env[name]?.trim();
  if (!value) throw new MissingEnvironmentError(name);
  return value;
}

export function envPort(
  name: string,
  fallback: number,
  env: NodeJS.ProcessEnv = process.env,
): number {
  const raw = env[name]?.trim();
  if (!raw) return fallback;
  const value = Number(raw);
  if (!Number.isInteger(value) || value < 1 || value > 65535) {
    throw new Error(`Invalid port in environment variable: ${name}`);
  }
  return value;
}