export type ListDir = (dir: string) => Promise<string[]>
export type ReadFile = (path: string) => Promise<Uint8Array>

function toBase64(u8: Uint8Array): string {
  if (typeof Buffer !== 'undefined') return Buffer.from(u8).toString('base64')
  throw new Error('Buffer not available')
}

// Generate inputs for verify CLI from a folder tree.
// - root: export folder (contains assets.integrity.index.json and assets/*)
// - listDir: returns list of file paths under root (can be recursive listing)
// - readFile: reads a file into bytes
export async function generateVerifyInputs(
  root: string,
  listDir: ListDir,
  readFile: ReadFile
): Promise<{ extras: Record<string, string>; assets: Record<string, string> }> {
  const all = await listDir(root)
  const norm = (p: string) => p.replace(/\\/g, '/')
  const rootNorm = norm(root).replace(/\/$/, '')
  const rel = (p: string) => {
    const pn = norm(p)
    return pn.startsWith(rootNorm + '/') ? pn.slice(rootNorm.length + 1) : pn
  }

  const extras: Record<string, string> = {}
  const assets: Record<string, string> = {}

  // assets.integrity.index.json at root
  const integrityPath = all.find((p) => rel(p) === 'assets.integrity.index.json')
  if (integrityPath) {
    const bytes = await readFile(integrityPath)
    extras['assets.integrity.index.json'] = toBase64(bytes)
  }

  // collect assets/**/*
  for (const abs of all) {
    const r = rel(abs)
    if (!r.startsWith('assets/')) continue
    // skip directories: best-effort by checking trailing slash
    if (r.endsWith('/')) continue
    const bytes = await readFile(abs)
    assets[r] = toBase64(bytes)
  }

  return { extras, assets }
}