import type { PublicAssetManifest } from './types.ts';

const syntheticOrigin = 'https://portfolio-assets.invalid';

const normalizeAssetBase = (base: string): string => {
  if (
    !base.startsWith('/') ||
    base.startsWith('//') ||
    /[\u0000-\u001f\u007f\\%?#]/u.test(base) ||
    base.split('/').some((segment) => segment === '.' || segment === '..')
  ) {
    throw new Error('Asset URL base must be a safe absolute path.');
  }
  const resolved = new URL(base, syntheticOrigin);
  if (resolved.origin !== syntheticOrigin) {
    throw new Error('Asset URL base must remain under the synthetic origin.');
  }
  const normalizedPath = resolved.pathname.replace(/\/+/gu, '/');
  return normalizedPath.endsWith('/') ? normalizedPath : `${normalizedPath}/`;
};

export const assetUrl = (manifest: PublicAssetManifest, assetId: string, base = '/assets/'): string => {
  const asset = manifest.assets.find((candidate) => candidate.id === assetId);
  if (asset === undefined) {
    throw new Error(`Unknown asset ID: ${assetId}`);
  }
  return `${normalizeAssetBase(base)}${encodeURIComponent(asset.fileName)}`;
};