/**
 * Caddy 등 리버스 프록시 뒤에서 request.url 이
 * http://0.0.0.0:13000 처럼 잡히는 경우가 있어, 공개 Origin 을 따로 계산한다.
 */
export function getPublicOrigin(request: Request): string {
  const fromEnv =
    process.env.APP_ORIGIN?.trim() ||
    process.env.NEXT_PUBLIC_APP_ORIGIN?.trim();
  if (fromEnv) {
    try {
      return new URL(fromEnv).origin;
    } catch {
      // fall through
    }
  }

  const redirectUri = process.env.CHZZK_REDIRECT_URI?.trim();
  if (redirectUri) {
    try {
      return new URL(redirectUri).origin;
    } catch {
      // fall through
    }
  }

  const xfHost = request.headers.get('x-forwarded-host')?.split(',')[0]?.trim();
  const xfProto =
    request.headers.get('x-forwarded-proto')?.split(',')[0]?.trim() || 'https';
  if (xfHost && !isBadHost(xfHost)) {
    return `${xfProto}://${xfHost}`;
  }

  const host = request.headers.get('host')?.trim();
  if (host && !isBadHost(host)) {
    const proto =
      request.headers.get('x-forwarded-proto')?.split(',')[0]?.trim() ||
      (host.includes('localhost') || host.startsWith('127.') ? 'http' : 'https');
    return `${proto}://${host}`;
  }

  try {
    const origin = new URL(request.url).origin;
    if (!isBadHost(new URL(origin).host)) return origin;
  } catch {
    // fall through
  }

  return 'https://drink.kimyu.xyz';
}

function isBadHost(host: string) {
  const h = host.toLowerCase().split(':')[0];
  return (
    h === '0.0.0.0' ||
    h === '::' ||
    h === '[::]' ||
    h === 'host.docker.internal'
  );
}