/**
 * Asset URL helpers for the host app's CORS-safe asset proxy (`/asset`).
 * Shared by the web viewers and `@tts/tabletop`, which both route external
 * assets (textures, models) through the proxy so three.js can load them.
 */

/**
 * Resolve a part's asset URL. Absolute URLs (http/https, data:, blob:) pass
 * through unchanged; relative paths are resolved against `baseUrl` — the
 * directory of the part's source file (the json/yaml/markdown that defined
 * it). Without a `baseUrl`, a relative path is returned as-is.
 */
export function resolveAssetUrl(url: string, baseUrl?: string): string {
  if (/^(https?:|data:|blob:)/i.test(url)) return url;
  if (!baseUrl) return url;
  // `baseUrl` is a path relative to the games root (no scheme), so join rather
  // than resolve as a URL. A fake origin lets `new URL` normalize `./` and
  // `../`; the origin is stripped from the result.
  const resolved = new URL(url, `http://localhost/${baseUrl}`).pathname;
  return resolved.replace(/^\/+/, '');
}

/** Route an external asset URL through the proxy so three.js can load it. */
export function assetUrl(url: string): string {
  return `/asset?url=${encodeURIComponent(url)}`;
}