var RECORDS_KEY = 'training_records'
var SETTINGS_KEY = 'user_settings'
var STREAK_KEY = 'current_streak'

function getRecords() {
  return wx.getStorageSync(RECORDS_KEY) || {}
}

function saveRecord(record) {
  record.id = Date.now()
  var records = getRecords()
  var month = record.date.substring(0, 7)
  if (!records[month]) records[month] = []
  records[month].push(record)
  records[month].sort(function (a, b) { return b.date.localeCompare(a.date) })
  wx.setStorageSync(RECORDS_KEY, records)
}

function deleteRecord(recordId) {
  var records = getRecords()
  Object.keys(records).forEach(function (month) {
    records[month] = records[month].filter(function (r) { return r.id !== recordId })
    if (records[month].length === 0) delete records[month]
  })
  wx.setStorageSync(RECORDS_KEY, records)
}

function getRecordsByMonth(month) {
  var records = getRecords()
  return records[month] || []
}

function getTotalStats() {
  var records = getRecords()
  var totalDuration = 0
  var totalSessions = 0
  var maxDuration = 0
  Object.keys(records).forEach(function (key) {
    var list = records[key]
    list.forEach(function (r) {
      totalDuration += r.duration
      totalSessions++
      if (r.duration > maxDuration) maxDuration = r.duration
    })
  })
  return { totalDuration: totalDuration, totalSessions: totalSessions, maxDuration: maxDuration }
}

function getSettings() {
  return wx.getStorageSync(SETTINGS_KEY) || {
    planId: 'beginner',
    dailyReminder: true,
    reminderTime: '08:00',
    voiceGuide: true,
    vibrate: true
  }
}

function saveSettings(settings) {
  wx.setStorageSync(SETTINGS_KEY, settings)
}

function getStreak() {
  return wx.getStorageSync(STREAK_KEY) || { count: 0, lastDate: '' }
}

function updateStreak(date) {
  var streak = getStreak()
  var today = date || getToday()
  var yesterday = getDateOffset(today, -1)

  if (streak.lastDate === today) return streak

  if (streak.lastDate === yesterday) {
    streak.count += 1
  } else {
    streak.count = 1
  }
  streak.lastDate = today
  wx.setStorageSync(STREAK_KEY, streak)
  return streak
}

function getToday() {
  return formatDate(new Date())
}

function formatDate(date) {
  var y = date.getFullYear()
  var m = String(date.getMonth() + 1)
  if (m.length < 2) m = '0' + m
  var d = String(date.getDate())
  if (d.length < 2) d = '0' + d
  return y + '-' + m + '-' + d
}

function getDateOffset(dateStr, offset) {
  var d = new Date(dateStr)
  d.setDate(d.getDate() + offset)
  return formatDate(d)
}

function getTodayRecord() {
  var today = getToday()
  var month = today.substring(0, 7)
  var records = getRecordsByMonth(month)
  var totalDuration = 0
  var hasRecord = false
  for (var i = 0; i < records.length; i++) {
    if (records[i].date === today) {
      totalDuration += records[i].duration
      hasRecord = true
    }
  }
  return hasRecord ? { date: today, duration: totalDuration } : null
}

module.exports = {
  getRecords: getRecords,
  saveRecord: saveRecord,
  deleteRecord: deleteRecord,
  getRecordsByMonth: getRecordsByMonth,
  getTotalStats: getTotalStats,
  getSettings: getSettings,
  saveSettings: saveSettings,
  getStreak: getStreak,
  updateStreak: updateStreak,
  getToday: getToday,
  formatDate: formatDate,
  getDateOffset: getDateOffset,
  getTodayRecord: getTodayRecord
}