/**
 * Resolve a server-relative attachment URL against the configured API base.
 *
 * Background: when the backend has no CloudFront signer configured (e.g.
 * the self-hosted RustFS / private-S3 case in MUL-2976), `attachment.url`
 * and `attachment.download_url` come back as server-relative paths like
 * `/api/attachments/{id}/download`. Web is happy with that — same-origin
 * `<img src="/api/...">` resolves against the document base — but RN
 * needs an absolute http(s) URL for both `Linking.openURL` (`Cannot open
 * URL` otherwise) and `<Image source={{ uri }}>` (no document origin to
 * resolve against; the request is silently dropped).
 *
 * Mirrors `packages/core/workspace/avatar-url.ts:resolvePublicFileUrl`
 * exactly. We don't import the core helper because its `getBaseUrl()`
 * pulls from a singleton ApiClient that lives in `@multica/core/api` —
 * not on the mobile sharing whitelist (apps/mobile/CLAUDE.md "mirror,
 * don't import"). Mobile reads its own `EXPO_PUBLIC_API_URL` from the
 * Expo env, the same value the rest of `data/api.ts` uses.
 *
 * Contract:
 *   - null / undefined / "" → null (caller should treat as "no URL").
 *   - already-absolute URL  → returned unchanged.
 *   - server-relative path  → API base + path, with a single boundary
 *                             slash (we trim trailing slashes from the
 *                             base before joining).
 */

const API_URL = process.env.EXPO_PUBLIC_API_URL ?? "";

export function resolveAttachmentUrlWithBase(
  rawUrl: string | null | undefined,
  baseUrl: string,
): string | null {
  if (!rawUrl) return null;
  if (!rawUrl.startsWith("/")) return rawUrl;
  const trimmedBaseUrl = baseUrl.replace(/\/+$/, "");
  return `${trimmedBaseUrl}${rawUrl}`;
}

export function resolveAttachmentUrl(
  rawUrl: string | null | undefined,
): string | null {
  return resolveAttachmentUrlWithBase(rawUrl, API_URL);
}