type StoredFileCapture = {
  url?: string;
  path?: string;
};

/**
 * Reduce any stored file reference to the canonical relative storage path
 * (e.g. `files/claim-captures/x.jpg`).
 *
 * Handles values that were persisted as absolute URLs on a different portal
 * (e.g. `https://host/car-damage/user/api/files/...`) so we never leak a
 * baked-in host/prefix into responses served from another origin.
 */
function toRelativeFilePath(value: string | null | undefined): string {
  const s = String(value ?? "").trim();
  if (!s) return "";

  // Prefer the `files/...` segment wherever it appears in the string.
  const match = s.match(/(?:^|\/)(files\/.+)$/i);
  if (match) return match[1];

  // No recognizable file root: keep external URLs intact, otherwise strip
  // any leading slashes so we can safely prefix the base URL.
  if (/^https?:\/\//i.test(s)) return s;
  return s.replace(/^\/+/, "");
}

/**
 * Build a public file URL from a stored path (relative or absolute).
 *
 * The link is always rebuilt from the current `URL` env, so deployments with
 * custom routing (different sub-paths per portal) stay correct even when the
 * persisted value was created elsewhere.
 */
export function buildFileLink(path: string): string {
  const relative = toRelativeFilePath(path);
  if (!relative) return "";

  // Already an absolute external URL with no recognizable file root.
  if (/^https?:\/\//i.test(relative)) return relative;

  const baseUrl = (process.env.URL ?? "").replace(/\/+$/, "");
  if (process.env.NODE_ENV === "local") {
    return `${baseUrl}/${relative}`;
  }
  return `${baseUrl}/api/${relative}`;
}

/**
 * Resolve a file URL from persisted capture metadata.
 *
 * Prefer `path`, fall back to `url`, and always rebuild through
 * {@link buildFileLink} so stale portal-prefixed values (e.g. `.../user/api/...`)
 * are normalized to the current server origin.
 */
export function resolveStoredFileUrl(
  stored?: StoredFileCapture | null,
): string | undefined {
  const source = stored?.path?.trim() || stored?.url?.trim();
  if (!source) return undefined;
  return buildFileLink(source);
}