const { formatDate, dateOnly } = require('./util')
const cloud = require('./cloud')

const RECORDS_KEY = 'training_records'
const SETTINGS_KEY = 'user_settings'
const STREAK_KEY = 'current_streak'
const CUSTOM_PLANS_KEY = 'custom_plans'
const PROFILE_KEY = 'user_profile'

let _idSeq = 0

/**
 * Record the timestamp of the last local mutation to single-value fields
 * (settings / profile / customPlans / theme). _restoreFromCloud compares
 * this against the cloud doc's updatedAt: if local changed after the cloud
 * snapshot, we keep local to avoid clobbering unsynced edits. Records are
 * exempt - they go through mergeRecords() which never loses data.
 */
const _markLocalChanged = () => {
  try { wx.setStorageSync('_local_changed_at', Date.now()) } catch (e) {}
}

/**
 * Backfill an `id` for any record that doesn't have one.
 * Older records (e.g. data restored from cloud or migrated from a build
 * that didn't yet write the id field) come in without an id, which makes
 * delete-by-id fail with "记录数据异常". Assign a stable, deterministic id
 * derived from the record's position + payload so the user can still
 * delete them.
 *
 * Returns true if any record was patched.
 */
const _ensureRecordIds = (records) => {
  if (!records || typeof records !== 'object') return false
  let changed = false
  Object.keys(records).forEach((month) => {
    const list = records[month]
    if (!Array.isArray(list)) return
    list.forEach((r, i) => {
      if (r && (r.id == null || r.id === '')) {
        // month is YYYY-MM; strip the dash so the id stays a safe token
        const m = String(month).replace(/[^0-9]/g, '')
        r.id = `legacy-${m}-${i}-${r.duration || 0}`
        changed = true
      }
    })
  })
  return changed
}

const getRecords = () => {
  const records = wx.getStorageSync(RECORDS_KEY) || {}
  if (_ensureRecordIds(records)) {
    // Persist the backfill so subsequent calls don't re-mutate; the cloud
    // will resync on the next saveRecord/deleteRecord.
    try { wx.setStorageSync(RECORDS_KEY, records) } catch (e) {}
  }
  return records
}

const saveRecord = (record) => {
  record.id = String(Date.now()) + '_' + (++_idSeq)

  // Defensive: reject records with a future date. Indicates the user has
  // changed their phone clock, which would otherwise poison the cloud
  // leaderboard (and their own stats) with impossible timestamps. Allow
  // a 1-minute tolerance for normal clock skew.
  const recordTime = new Date(record.date.replace(/-/g, '/')).getTime()
  if (recordTime > Date.now() + 60 * 1000) {
    console.warn('[storage] saveRecord rejected: future date', record.date)
    wx.showToast({ title: '系统时间异常,请检查', icon: 'none' })
    return
  }

  const records = getRecords()
  const month = record.date.substring(0, 7)
  if (!records[month]) records[month] = []
  records[month].push(record)
  records[month].sort((a, b) => b.date.localeCompare(a.date))
  wx.setStorageSync(RECORDS_KEY, records)
  console.log('[storage] saveRecord date=' + record.date + ' duration=' + record.duration)
  cloud.pushAll()
}

const deleteRecord = (recordId) => {
  if (!recordId && recordId !== 0) return  // guard against undefined/null
  const id = String(recordId)
  if (!id || id === 'undefined' || id === 'null') return
  const records = getRecords()
  let found = false
  Object.keys(records).forEach((month) => {
    const before = records[month].length
    records[month] = records[month].filter((r) => String(r.id) !== id)
    if (records[month].length < before) found = true
    if (records[month].length === 0) delete records[month]
  })
  if (!found) return  // id not found, don't overwrite storage
  wx.setStorageSync(RECORDS_KEY, records)
  // 重新计算连续打卡:删连续链中间某天会断链,validateStreak 只在 lastDate 被删时重算,不够
  recomputeStreak()
  cloud.pushAll()
}

/**
 * Merge cloud records into local records WITHOUT losing either side.
 *
 * Why this exists: _restoreFromCloud used to overwrite training_records
 * with the cloud doc verbatim. If the user finished a training during the
 * async pullAll on launch, saveRecord had already written locally, and the
 * subsequent restore wiped that fresh record with the cloud's older
 * snapshot. Same hazard for multi-device edits.
 *
 * Dedup: records with a real (non-legacy) id dedup by id; legacy/idless
 * records dedup by `date|duration` so old migrated data doesn't double up.
 * Result is re-bucketed by month and sorted newest-first.
 */
const mergeRecords = (cloudRecords) => {
  const local = wx.getStorageSync(RECORDS_KEY) || {}
  const cloud = (cloudRecords && typeof cloudRecords === 'object') ? cloudRecords : {}
  const seen = new Set()
  const out = []
  const push = (r) => {
    if (!r) return
    const id = r.id
    const isRealId = id != null && id !== '' && !String(id).startsWith('legacy-')
    const key = isRealId ? `id:${id}` : `c:${r.date}|${r.duration}`
    if (seen.has(key)) return
    seen.add(key)
    out.push(r)
  }
  Object.keys(local).forEach((m) => (local[m] || []).forEach(push))
  Object.keys(cloud).forEach((m) => (cloud[m] || []).forEach(push))

  const merged = {}
  out.forEach((r) => {
    const mo = (r.date && r.date.substring) ? r.date.substring(0, 7) : 'unknown'
    if (!merged[mo]) merged[mo] = []
    merged[mo].push(r)
  })
  Object.keys(merged).forEach((mo) => {
    merged[mo].sort((a, b) => (b.date || '').localeCompare(a.date || ''))
  })
  _ensureRecordIds(merged)
  return merged
}

const getRecordsByMonth = (month) => {
  const records = getRecords()
  return records[month] || []
}

const getTotalStats = () => {
  const records = getRecords()
  let totalDuration = 0
  let totalSessions = 0
  let maxDuration = 0
  Object.keys(records).forEach((key) => {
    records[key].forEach((r) => {
      const d = Number(r && r.duration) || 0
      totalDuration += d
      totalSessions++
      if (d > maxDuration) maxDuration = d
    })
  })
  return { totalDuration, totalSessions, maxDuration }
}

const getSettings = () => {
  const s = wx.getStorageSync(SETTINGS_KEY)
  if (s) {
    // Backfill voiceGender for existing users (added with the male/female
    // voice option). Defaults to female, the prior behavior.
    if (!s.voiceGender) s.voiceGender = 'female'
    // Backfill vibrate/voiceGuide for users whose settings predate these
    // toggles. Without this, s.vibrate is undefined and `!s.vibrate` in
    // the timer reads it as "off" - vibration silently no-ops until the
    // user manually toggles the switch (which writes a real boolean).
    if (s.vibrate == null) s.vibrate = true
    if (s.voiceGuide == null) s.voiceGuide = true
    if (!s.vibrateIntensity) s.vibrateIntensity = 'heavy'
    return s
  }
  return {
    planId: 'beginner',
    voiceGuide: true,
    vibrate: true,
    voiceGender: 'female',
    vibrateIntensity: 'heavy'
  }
}

const saveSettings = (settings) => {
  wx.setStorageSync(SETTINGS_KEY, settings)
  _markLocalChanged()
  cloud.pushAll()
}

/**
 * User profile (nickname + avatar). Stored locally and pushed to the
 * cloud alongside records/settings so the leaderboard can show real
 * names instead of masked openids.
 *
 * Shape: { nickname: string, avatarUrl: string (wxfile://...) }
 * Both fields are optional; absent profile returns `{}`.
 */
const getProfile = () => {
  const raw = wx.getStorageSync(PROFILE_KEY)
  if (raw && typeof raw === 'object' && !Array.isArray(raw)) return raw
  return {}
}

const saveProfile = (profile) => {
  // Strip empties so we don't push {nickname: '', avatarUrl: ''}
  const clean = {}
  if (profile && typeof profile.nickname === 'string' && profile.nickname.trim()) {
    clean.nickname = profile.nickname.trim().slice(0, 16)
  }
  if (profile && typeof profile.avatarUrl === 'string' && profile.avatarUrl) {
    clean.avatarUrl = profile.avatarUrl
  }
  wx.setStorageSync(PROFILE_KEY, clean)
  _markLocalChanged()
  cloud.pushAll()
  return clean
}

const getStreak = () => wx.getStorageSync(STREAK_KEY) || { count: 0, lastDate: '' }

/**
 * User-customized training plans, keyed by planId (e.g. 'beginner').
 * Each value is a full plan object built by `utils/plan.generatePlanDays`
 * plus the editor's formula fields (startTarget / increment / cycleDays).
 *
 * Storage shape mirrors `getRecords()`: an object map so partial writes
 * don't have to read+modify+write the whole collection.
 */
const getCustomPlans = () => {
  const raw = wx.getStorageSync(CUSTOM_PLANS_KEY)
  if (raw && typeof raw === 'object' && !Array.isArray(raw)) return raw
  return {}
}

const saveCustomPlan = (planId, planData) => {
  if (!planId) return
  const plans = getCustomPlans()
  plans[planId] = planData
  wx.setStorageSync(CUSTOM_PLANS_KEY, plans)
  _markLocalChanged()
  cloud.pushAll()
}

const resetCustomPlan = (planId) => {
  if (!planId) return
  const plans = getCustomPlans()
  if (!(planId in plans)) return
  delete plans[planId]
  wx.setStorageSync(CUSTOM_PLANS_KEY, plans)
  _markLocalChanged()
  cloud.pushAll()
}

/**
 * Validate streak against actual training records.
 * Call on app launch to correct any inconsistencies
 * (e.g. after deleting the only record for a day).
 *
 * Streak compares date-ONLY portions of `lastDate` so that training
 * twice on the same day (with different seconds in `record.date`)
 * doesn't accidentally reset the streak.
 */
const validateStreak = () => {
  const streak = getStreak()
  if (!streak.lastDate) return streak

  const today = getToday()
  const todayOnly = dateOnly(today)
  const yesterdayOnly = dateOnly(getDateOffset(today, -1))
  const records = getRecords()
  const allDates = new Set()
  Object.values(records).forEach(monthRecs => {
    monthRecs.forEach(r => allDates.add(dateOnly(r.date)))
  })

  const lastOnly = dateOnly(streak.lastDate)

  // If lastDate is today, check today still has records
  if (lastOnly === todayOnly) {
    if (!allDates.has(todayOnly)) {
      // Today's records were deleted
      if (allDates.has(yesterdayOnly)) {
        streak.lastDate = yesterdayOnly
        streak.count = Math.max(1, streak.count - 1)
      } else {
        streak.count = 0
        streak.lastDate = ''
      }
      wx.setStorageSync(STREAK_KEY, streak)
    }
    return streak
  }

  // If lastDate points to a date that no longer has ANY records,
  // recompute the streak from actual recorded dates.
  if (!allDates.has(lastOnly)) {
    const sorted = Array.from(allDates).sort().reverse()
    if (sorted.length === 0) {
      streak.count = 0
      streak.lastDate = ''
    } else {
      let count = 1
      let prev = sorted[0]
      for (let i = 1; i < sorted.length; i++) {
        const prevDate = new Date(prev.replace(/-/g, '/'))
        const curDate = new Date(sorted[i].replace(/-/g, '/'))
        const diff = Math.round((prevDate - curDate) / (1000 * 60 * 60 * 24))
        if (diff === 1) {
          count++
          prev = sorted[i]
        } else {
          break
        }
      }
      streak.count = count
      streak.lastDate = sorted[0]
    }
    wx.setStorageSync(STREAK_KEY, streak)
  }

  return streak
}

/**
 * Fully recompute the streak from actual training records. Used after a
 * cloud restore/merge: the cloud doc's streak may be stale or belong to
 * another device, so we trust the merged records over the cloud value.
 */
const recomputeStreak = () => {
  const records = getRecords()
  const allDates = new Set()
  Object.values(records).forEach((monthRecs) => {
    monthRecs.forEach((r) => allDates.add(dateOnly(r.date)))
  })
  const sorted = Array.from(allDates).sort().reverse()
  if (sorted.length === 0) {
    const empty = { count: 0, lastDate: '' }
    wx.setStorageSync(STREAK_KEY, empty)
    return empty
  }
  let count = 1
  let prev = sorted[0]
  for (let i = 1; i < sorted.length; i++) {
    const prevDate = new Date(prev.replace(/-/g, '/'))
    const curDate = new Date(sorted[i].replace(/-/g, '/'))
    const diff = Math.round((prevDate - curDate) / (1000 * 60 * 60 * 24))
    if (diff === 1) {
      count++
      prev = sorted[i]
    } else {
      break
    }
  }
  const streak = { count, lastDate: sorted[0] }
  wx.setStorageSync(STREAK_KEY, streak)
  return streak
}

const updateStreak = (date) => {
  const streak = getStreak()
  const todayFull = date || getToday()
  const todayOnly = dateOnly(todayFull)
  const yesterdayOnly = dateOnly(getDateOffset(todayFull, -1))

  if (dateOnly(streak.lastDate) === todayOnly) return streak

  if (dateOnly(streak.lastDate) === yesterdayOnly) {
    streak.count += 1
  } else {
    streak.count = 1
  }
  // Store the date-ONLY portion so subsequent comparisons are stable
  // across multiple same-day trainings with different seconds.
  streak.lastDate = todayOnly
  wx.setStorageSync(STREAK_KEY, streak)
  cloud.pushAll()
  return streak
}

const getToday = () => formatDate(new Date())

const getDateOffset = (dateStr, offset) => {
  // Strip the time portion (formatDate now includes HH:MM:SS) and convert
  // dashes to slashes — `new Date("YYYY/MM/DD")` is the only reliably-
  // parsed form across both V8 (WeChat dev tools) and JSCore (iOS).
  const d = new Date(dateOnly(dateStr).replace(/-/g, '/'))
  d.setDate(d.getDate() + offset)
  return formatDate(d)
}

const getTodayRecord = () => {
  const today = getToday()
  // Record `date` is "YYYY-MM-DD HH:MM:SS" (formatted at saveRecord time),
  // so a strict === check against the freshly-formatted `today` only matches
  // a record saved in the exact same second. Compare date-only portions
  // instead, otherwise the second training of the day reads as zero and
  // the home page flips "今日已完成" back off.
  const todayOnly = dateOnly(today)
  const records = getRecords()
  let totalDuration = 0
  let hasRecord = false
  Object.keys(records).forEach((month) => {
    records[month].forEach((r) => {
      if (dateOnly(r.date) === todayOnly) {
        totalDuration += r.duration
        hasRecord = true
      }
    })
  })
  return hasRecord ? { date: today, duration: totalDuration } : null
}

module.exports = {
  getRecords,
  saveRecord,
  deleteRecord,
  mergeRecords,
  getRecordsByMonth,
  getTotalStats,
  getSettings,
  saveSettings,
  getCustomPlans,
  saveCustomPlan,
  resetCustomPlan,
  getProfile,
  saveProfile,
  getStreak,
  validateStreak,
  recomputeStreak,
  updateStreak,
  _markLocalChanged,
  getToday,
  getDateOffset,
  getTodayRecord
}