const PROGRESS_KEY = 'tang-detective-progress-v1'
const SETTINGS_KEY = 'tang-detective-settings-v1'
const AUDIO_KEY = 'tang-detective-audio-progress-v1'

function defaultProgress() {
  return {
    completedHotspots: {},
    completedChapters: [],
    lastChapter: 1,
  }
}

function isPlainRecord(value) {
  return Boolean(value) && typeof value === 'object' && !Array.isArray(value)
}

function chapterId(number) {
  return `S01-C${String(number).padStart(2, '0')}`
}

function eventId(number) {
  return `S01-H${String(number).padStart(2, '0')}`
}

function normalizeCompletedHotspots(value) {
  const source = isPlainRecord(value) ? value : {}
  const normalized = {}
  for (let chapterNumber = 1; chapterNumber <= 15; chapterNumber += 1) {
    const id = chapterId(chapterNumber)
    const stored = Array.isArray(source[id]) ? source[id] : []
    const firstEvent = (chapterNumber - 1) * 4 + 1
    const allowed = new Set(
      Array.from({ length: 4 }, (_, index) => eventId(firstEvent + index)),
    )
    const clean = [...new Set(stored.filter((item) => allowed.has(item)))]
    if (clean.length > 0 || Object.prototype.hasOwnProperty.call(source, id)) {
      normalized[id] = clean
    }
  }
  return normalized
}

function normalizeCompletedChapters(value) {
  if (!Array.isArray(value)) return []
  const allowed = new Set(
    Array.from({ length: 15 }, (_, index) => chapterId(index + 1)),
  )
  return [...new Set(value.filter((item) => allowed.has(item)))]
}

function normalizeProgress(value) {
  const source = isPlainRecord(value) ? value : {}
  const lastChapter = Number(source.lastChapter)
  return {
    ...source,
    completedHotspots: normalizeCompletedHotspots(source.completedHotspots),
    completedChapters: normalizeCompletedChapters(source.completedChapters),
    lastChapter: Number.isInteger(lastChapter) && lastChapter >= 1 && lastChapter <= 15
      ? lastChapter
      : 1,
  }
}

function normalizeSettings(value) {
  const source = isPlainRecord(value) ? value : {}
  return {
    ...source,
    fontScale: source.fontScale === 'xlarge' ? 'xlarge' : 'large',
    sound: source.sound !== false,
  }
}

function read(key, fallback) {
  try {
    const value = wx.getStorageSync(key)
    return value || fallback
  } catch (error) {
    return fallback
  }
}

function write(key, value) {
  try {
    wx.setStorageSync(key, value)
    return true
  } catch (error) {
    // Storage failure must never block the text game.
    return false
  }
}

function getProgress() {
  return normalizeProgress(read(PROGRESS_KEY, null))
}

function saveProgress(progress) {
  return write(PROGRESS_KEY, normalizeProgress(progress))
}

/**
 * Start the story again without deleting the reader's collected memory cards
 * or accessibility preferences. Only story/level progress is reset.
 */
function resetStoryProgress() {
  const current = getProgress()
  const next = {
    ...current,
    ...defaultProgress(),
  }
  delete next.comicReaderByChapter
  delete next.lastPageId
  if (!saveProgress(next)) return false
  write(AUDIO_KEY, {})
  return true
}

function getSettings() {
  return normalizeSettings(read(SETTINGS_KEY, null))
}

function saveSettings(settings) {
  return write(SETTINGS_KEY, normalizeSettings(settings))
}

function getAudioProgress() {
  const value = read(AUDIO_KEY, {})
  return isPlainRecord(value) ? value : {}
}

function saveAudioProgress(progress) {
  write(AUDIO_KEY, progress)
}

module.exports = {
  getProgress,
  saveProgress,
  resetStoryProgress,
  getSettings,
  saveSettings,
  getAudioProgress,
  saveAudioProgress,
}