function normalizeBaseUrl(raw: string): string {
  const trimmed = raw.trim();
  return trimmed.endsWith('/') ? trimmed.slice(0, -1) : trimmed;
}

export function getWebsiteApiBaseUrl(): string {
  const isBrowser = typeof window !== 'undefined';

  const configured = isBrowser
    ? process.env.NEXT_PUBLIC_API_BASE_URL
    : process.env.API_BASE_URL ?? process.env.NEXT_PUBLIC_API_BASE_URL;

  if (configured && configured.trim()) {
    return normalizeBaseUrl(configured);
  }

  // In test-like environments, check if we have any configuration at all
  const isTestLike =
    process.env.NODE_ENV === 'test' ||
    process.env.CI === 'true' ||
    process.env.DOCKER === 'true';

  // If we're in a test-like environment and have NO configuration, that's an error
  // But if we have some configuration (even if empty), we should use the fallback
  if (isTestLike && !process.env.API_BASE_URL && !process.env.NEXT_PUBLIC_API_BASE_URL) {
    throw new Error(
      isBrowser
        ? 'Missing NEXT_PUBLIC_API_BASE_URL. In Docker/CI/test we do not allow falling back to localhost.'
        : 'Missing API_BASE_URL. In Docker/CI/test we do not allow falling back to localhost.',
    );
  }

  const fallback =
    process.env.NODE_ENV === 'development'
      ? 'http://localhost:3001'
      : 'http://api:3000';

  return normalizeBaseUrl(fallback);
}