/**
 * Optional `/bin` manifest on the personal drive for large images (`BARE_OS_VFS_BIN_INDEX_BUILD=1`).
 */

/**
 * Deterministic SHA-256 over UTF-8 names with `\0` terminators (Web Crypto — Node 20 + Bare).
 * @param {string[]} sortedNames
 */
async function bareOsBinIndexNamesDigestAsync(sortedNames) {
  const enc = new TextEncoder()
  let totalLen = 0
  for (const n of sortedNames) {
    totalLen += enc.encode(String(n)).byteLength + 1
  }
  const u8 = new Uint8Array(totalLen)
  let o = 0
  for (const n of sortedNames) {
    const s = enc.encode(String(n))
    u8.set(s, o)
    o += s.byteLength
    u8[o++] = 0
  }
  const subtle = globalThis.crypto && globalThis.crypto.subtle
  if (!subtle || typeof subtle.digest !== 'function') {
    throw new Error('bare-os bin index: Web Crypto subtle.digest unavailable')
  }
  const digest = await subtle.digest('SHA-256', u8)
  return Array.from(new Uint8Array(digest), (b) =>
    b.toString(16).padStart(2, '0')
  ).join('')
}

/**
 * When **`BARE_OS_BIN_HYPERBEE_INDEX=1`**, writes **`/.bare-os/index/bin-hyperbee-hint.json`**
 * (module resolution probe + name list) for operators integrating Hyperbee/Corestore offline.
 */
export async function maybeBareOsBuildBinHyperbeeHint(ctx) {
  const e = ctx.env
  if (
    e.BARE_OS_BIN_HYPERBEE_INDEX !== '1' &&
    e.BARE_OS_BIN_HYPERBEE_INDEX !== 'true'
  ) {
    return
  }
  const vfs = ctx.vfs
  const drive = ctx.drive
  const b4 = ctx.b4a
  if (!vfs || !drive || typeof drive.readdir !== 'function' || !b4) return
  let moduleResolves = false
  try {
    await import('hyperbee')
    moduleResolves = true
  } catch {
    moduleResolves = false
  }
  const names = []
  try {
    const stream = drive.readdir('/bin')
    for await (const n of stream) names.push(String(n))
  } catch {
    return
  }
  names.sort()
  const digest = await bareOsBinIndexNamesDigestAsync(names)
  const body =
    JSON.stringify({
      schema: 2,
      atMs: Date.now(),
      namesDigest: digest,
      namesDigestAlgo: 'sha256-null-suffixed-utf8',
      moduleResolves,
      count: names.length,
      names: names.slice(0, 8000),
      invalidation: {
        schema: 1,
        triggers: ['bareOsVfsBatchWrite bin/*', 'BARE_OS_VFS_BIN_INDEX_BUILD'],
        note: 'Rebuild when batch writes touch /bin or on boot when index env flags are set.'
      },
      note:
        'Hyperbee-backed KV index is host-wired; this file lists /bin names and whether hyperbee imports on the booter runtime.'
    }) + '\n'
  try {
    await vfs.writeFile('/.bare-os/index/bin-hyperbee-hint.json', b4.from(body))
  } catch (err) {
    ctx.console?.error?.(
      '[bare-os] bin hyperbee hint: ' + ((err && err.message) || String(err))
    )
  }
  try {
    const idx =
      JSON.stringify({
        schema: 2,
        atMs: Date.now(),
        namesDigest: digest,
        primaryHint: '/.bare-os/index/bin-hyperbee-hint.json',
        note: 'Secondary metadata path for `/.bare-os/indexes/` namespace (Hyperbee operator integration).'
      }) + '\n'
    await vfs.writeFile('/.bare-os/indexes/hyperbee_status.json', b4.from(idx))
  } catch {
    /* personal tree may deny path on some images */
  }
}

export async function maybeBareOsBuildBinManifest(ctx) {
  const e = ctx.env
  if (
    e.BARE_OS_VFS_BIN_INDEX_BUILD !== '1' &&
    e.BARE_OS_VFS_BIN_INDEX_BUILD !== 'true'
  ) {
    return
  }
  const vfs = ctx.vfs
  const drive = ctx.drive
  const b4 = ctx.b4a
  if (!vfs || !drive || typeof drive.readdir !== 'function' || !b4) return
  /** @type {string[]} */
  const names = []
  try {
    const stream = drive.readdir('/bin')
    for await (const n of stream) names.push(String(n))
  } catch {
    return
  }
  names.sort()
  const digest = await bareOsBinIndexNamesDigestAsync(names)
  const body =
    JSON.stringify({
      schema: 2,
      atMs: Date.now(),
      path: '/bin',
      namesDigest: digest,
      namesDigestAlgo: 'sha256-null-suffixed-utf8',
      count: names.length,
      names: names.slice(0, 8000),
      note: 'Sorted lexicographic /bin listing; digest covers full sorted set before truncation.'
    }) + '\n'
  try {
    await vfs.writeFile('/.bare-os/index/bin-manifest.json', b4.from(body))
  } catch (err) {
    ctx.console?.error?.(
      '[bare-os] bin index: ' + ((err && err.message) || String(err))
    )
  }
}