/**
 * C02-C15 remote full-page audio manifest v1.
 *
 * Import contract for a future reviewed batch:
 *
 * 'S01-C09-P05': Object.freeze({
 *   pageId: 'S01-C09-P05',
 *   chapterNumber: 9,
 *   pageNumber: 5,
 *   assetId: 'audio.page.s01.c09.p05',
 *   durationSeconds: 42.1,
 *   reviewStatus: 'approved',
 * })
 *
 * The matching releaseAssetManifest entry must independently be an approved,
 * remote-only, immutable hash-named audio asset. Automated QA, pending human
 * listening, and missing CDN records must never be relabelled as approved.
 */

const REMOTE_PAGE_AUDIO_MANIFEST_VERSION = 1
const REMOTE_PAGE_AUDIO_ID_PATTERN = /^S01-C(0[2-9]|1[0-5])-P(0[1-8])$/
const SHA256_PATTERN = /^[a-f0-9]{64}$/

// Deliberately empty until full-page tracks pass the required human reviews
// and their immutable CDN objects are available. This is a release gate, not
// a placeholder that the UI may treat as playable.
const remotePageAudioPages = Object.freeze({})

function clean(value) {
  return typeof value === 'string' ? value.trim() : ''
}

function remotePageAudioAssetId(pageId) {
  const stablePageId = clean(pageId)
  const match = REMOTE_PAGE_AUDIO_ID_PATTERN.exec(stablePageId)
  if (!match) return ''
  return `audio.page.s01.c${match[1]}.p${match[2]}`
}

function getApprovedRemotePageAudio(
  pageId,
  releaseAssets = {},
  pageManifest = remotePageAudioPages,
) {
  const stablePageId = clean(pageId)
  const match = REMOTE_PAGE_AUDIO_ID_PATTERN.exec(stablePageId)
  if (!match) return null

  const entry = pageManifest && pageManifest[stablePageId]
  if (!entry || typeof entry !== 'object') return null
  const chapterNumber = Number(match[1])
  const pageNumber = Number(match[2])
  const assetId = remotePageAudioAssetId(stablePageId)
  const durationSeconds = Number(entry.durationSeconds)
  if (
    clean(entry.reviewStatus).toLowerCase() !== 'approved'
    || entry.pageId !== stablePageId
    || Number(entry.chapterNumber) !== chapterNumber
    || Number(entry.pageNumber) !== pageNumber
    || entry.assetId !== assetId
    || !Number.isFinite(durationSeconds)
    || durationSeconds <= 0
  ) {
    return null
  }

  const asset = releaseAssets && releaseAssets[assetId]
  const sha256 = asset && typeof asset.sha256 === 'string'
    ? asset.sha256
    : ''
  const remotePath = asset && asset.remotePath
  const expectedRemotePath = (
    `audio/${stablePageId.slice(0, 7).toLowerCase()}`
    + `/${stablePageId}.${sha256.slice(0, 12)}.mp3`
  )
  if (
    !asset
    || asset.kind !== 'audio'
    || clean(asset.reviewStatus).toLowerCase() !== 'approved'
    || asset.localSeed !== ''
    || !SHA256_PATTERN.test(sha256)
    || typeof remotePath !== 'string'
    || remotePath !== expectedRemotePath
  ) {
    return null
  }

  return { ...entry, assetId }
}

module.exports = {
  REMOTE_PAGE_AUDIO_ID_PATTERN,
  REMOTE_PAGE_AUDIO_MANIFEST_VERSION,
  getApprovedRemotePageAudio,
  remotePageAudioAssetId,
  remotePageAudioPages,
}