import { lstat, mkdir, readFile, readdir } from 'node:fs/promises';
import { dirname, resolve } from 'node:path';
import { fileURLToPath } from 'node:url';

const repositoryRoot = resolve(dirname(fileURLToPath(import.meta.url)), '..');
const manifestPath = resolve(repositoryRoot, 'content/public/asset-manifest.json');
const preparedAssetsPath = resolve(repositoryRoot, 'inputs/prepared-assets');

const readEmptyManifest = async () => {
  const manifest = JSON.parse(await readFile(manifestPath, 'utf8'));
  if (Object.keys(manifest).length !== 1 || !Array.isArray(manifest.assets) || manifest.assets.length !== 0) {
    throw new Error('Phase 1 asset manifest must contain exactly zero assets.');
  }
};

const ensureEmptyPreparedAssetDirectory = async () => {
  try {
    const stats = await lstat(preparedAssetsPath);
    if (stats.isSymbolicLink() || !stats.isDirectory()) {
      throw new Error('Prepared asset path must be a non-symlink directory.');
    }
  } catch (error) {
    if ((error).code !== 'ENOENT') throw error;
    await mkdir(preparedAssetsPath, { recursive: true });
  }

  if ((await readdir(preparedAssetsPath)).length !== 0) {
    throw new Error('Prepared asset directory must be empty during Phase 1.');
  }
};

await readEmptyManifest();
await ensureEmptyPreparedAssetDirectory();