/** Absolute VITE_API_URL values must end with this segment (API_PATHS omit /api). */
export const ABSOLUTE_API_URL_SUFFIX = /\/api\/?$/;

/**
 * Fails fast when an absolute VITE_API_URL omits the /api segment.
 * Relative values (e.g. /api) are valid and skipped.
 */
export function assertAbsoluteApiUrlHasApiSegment(apiUrl: string | undefined): void {
  const trimmed = apiUrl?.trim();
  if (!trimmed?.startsWith("http")) {
    return;
  }

  if (!ABSOLUTE_API_URL_SUFFIX.test(trimmed)) {
    throw new Error(
      `VITE_API_URL absolute URLs must end with /api (got: ${trimmed}). ` +
        "API route paths do not include /api — set VITE_API_URL to the full API base, e.g. https://api.example.com/api. " +
        "See README.md and .env.example.",
    );
  }
}