const themeMod = require('../../utils/theme')
const iconsMod = require('../../utils/icons')
const util = require('../../utils/util')
const storage = require('../../utils/storage')
const config = require('../../config')

Page({
  data: {
    theme: { primary: '#FF6B35', primaryLight: '#FF8C5A', primaryBg: '#FFF3ED', primaryRgb: '255,107,53' },
    themeStyle: themeMod.BASE_VARS,
    periods: [
      { key: 'day', label: '日榜' },
      { key: 'month', label: '月榜' },
      { key: 'year', label: '年榜' }
    ],
    activePeriod: 'day',
    rankedList: [],
    myEntry: null,
    loading: false,
    refreshing: false,
    empty: false,
    icons: iconsMod.build()
  },

  onLoad() {
    themeMod.applyThemeToPage(this)
    this._firstShow = true
  },

  onShow() {
    themeMod.applyThemeToPage(this)
    const theme = themeMod.getCurrentTheme()
    this.setData({ theme, icons: iconsMod.build(theme) })
    try {
      const tb = this.getTabBar()
      if (tb) tb.setData({ selected: 2 })
    } catch (e) {}
    if (this._firstShow) {
      this._firstShow = false
      this.fetchRank()
      return
    }
    this.fetchRank()
  },

  onPullDownRefresh() {
    this.fetchRank(() => wx.stopPullDownRefresh())
  },

  switchPeriod(e) {
    const period = e.currentTarget.dataset.period
    if (period === this.data.activePeriod) return
    this.setData({ activePeriod: period, rankedList: [], myEntry: null })
    this.fetchRank()
  },

  fetchRank(cb) {
    // 序列号:快速切换周期时丢弃旧响应,避免旧 period 的数据覆盖新 period
    this._fetchSeq = (this._fetchSeq || 0) + 1
    const seq = this._fetchSeq
    const period = this.data.activePeriod

    // 乐观缓存:命中该 period 的近期缓存就先秒显旧数据,后台再静默拉新。
    // 命中时不进 loading 骨架屏(避免旧数据被空白覆盖),用 refreshing 标记
    // 后台刷新状态;未命中才显示骨架屏。云函数全表扫描冷启动可达 2-3s,
    // 这层客户端缓存把"重复进入 / 切 period"的等待几乎降到无感。
    const cached = storage.getLeaderboardCache(period)
    if (cached && cached.rankedList) {
      this.setData({
        rankedList: cached.rankedList,
        myEntry: cached.myEntry,
        loading: false,
        empty: cached.empty,
        refreshing: true
      })
    } else {
      this.setData({ loading: true, empty: false, refreshing: false })
    }

    wx.cloud.callFunction({
      name: 'leaderboard',
      data: {
        period,
        maxRank: config.leaderboardMaxRank
      }
    }).then(res => {
      if (seq !== this._fetchSeq) { if (cb) cb(); return }  // 过期响应,丢弃
      this._applyResult(res.result || {})
      if (cb) cb()
    }).catch((err) => {
      // Cloud function not deployed or network error — fall back to
      // local data silently. No toast here: empty day-leaderboard is
      // normal (user didn't train today), and a toast would mislead
      // them into thinking the cloud is broken.
      console.warn('[leaderboard] cloud function failed, using local fallback:', err)
      if (seq !== this._fetchSeq) { if (cb) cb(); return }
      // 已有缓存秒显时后台刷新失败:保持旧数据,不打断用户;仅无缓存才走本地兜底。
      if (cached && cached.rankedList) {
        this.setData({ refreshing: false })
      } else {
        this._applyLocal()
      }
      if (cb) cb()
    })
  },

  _applyResult(result) {
    const list = (result.ranked || []).map(item => ({
      ...item,
      durationText: util.formatDuration(item.duration)
    }))
    const myEntry = result.myEntry ? {
      ...result.myEntry,
      durationText: util.formatDuration(result.myEntry.duration),
      isMe: true
    } : null
    const empty = list.length === 0 && !myEntry
    this.setData({
      rankedList: list,
      myEntry,
      loading: false,
      refreshing: false,
      empty
    })
    // 写入乐观缓存:下次进页面 / 切 period 秒显
    storage.setLeaderboardCache(this.data.activePeriod, { rankedList: list, myEntry, empty })
  },

  /** Local fallback: use local storage when cloud function isn't deployed */
  _applyLocal() {
    const period = this.data.activePeriod
    const allRecords = Object.values(storage.getRecords()).flat()
    const today = storage.getToday()
    const thisMonth = today.substring(0, 7)
    const thisYear = String(new Date().getFullYear())
    const profile = storage.getProfile()
    const localName = profile.nickname || '我'

    let duration = 0
    let sessions = 0
    allRecords.forEach(r => {
      if (period === 'day' && util.dateOnly(r.date) === util.dateOnly(today)) { duration += r.duration; sessions++ }
      if (period === 'month' && r.date.startsWith(thisMonth)) { duration += r.duration; sessions++ }
      if (period === 'year' && r.date.startsWith(thisYear)) { duration += r.duration; sessions++ }
    })

    if (duration > 0) {
      const entry = {
        rank: 1, openid: 'local', name: localName, nickname: profile.nickname || '',
        duration, durationText: util.formatDuration(duration), sessions
      }
      this.setData({ rankedList: [entry], myEntry: { ...entry, isMe: true }, loading: false, refreshing: false, empty: false })
    } else {
      this.setData({ loading: false, refreshing: false, empty: true })
    }
  },

  /**
   * 分享给朋友 — 排行榜页。把用户当前名次写进标题,有"攀比"属性,
   * 分享欲望会强一些。
   */
  onShareAppMessage() {
    const me = this.data.myEntry
    const s = config.share.leaderboard
    // myEntry.rank 依赖云函数返回,缺失时回退静态 title,避免出现"排第 undefined"
    if (me && me.rank) {
      const periodLabel = { day: '日', month: '月', year: '年' }[this.data.activePeriod] || ''
      return {
        title: s.titleTemplate.replace('{period}', periodLabel).replace('{rank}', me.rank),
        path: s.path
      }
    }
    return { title: s.title, path: s.path }
  },

  /**
   * 分享到朋友圈。
   */
  onShareTimeline() {
    return {
      title: config.share.timelineTitle
    }
  }
})