// Keep the native Page lifecycle, but hydrate the correct account before any
// story page reads/writes storage. This also covers cold starts from shares.
const bridge = require('./platformBridge')
const LIFECYCLE_METHODS = new Set(['onLoad', 'onShow', 'onReady', 'onHide', 'onUnload'])
const CLEANUP_METHOD = /^(?:destroy|clear|unbind|pause|invalidate|beginPauseLock)/
module.exports = function registerTangPage(options) {
  function isCurrent(page) {
    return !page.__tangDead && !page.__tangOriginalUnloaded
      && page.__tangVisible && page.__tangScope === bridge.getScope()
  }
  function returnHome(page) {
    if (page.__tangRedirected || page.__tangDead) return
    page.__tangRedirected = true
    wx.reLaunch({ url: '/tang-detective/pages/home/home' })
  }
  function cleanUp(page, name) {
    if (!page.__tangLoaded || typeof options[name] !== 'function') return
    if (name !== 'onUnload' && page.__tangOriginalUnloaded) return
    if (name === 'onUnload') {
      if (page.__tangOriginalUnloaded) return
      page.__tangOriginalUnloaded = true
    }
    page.__tangCleaning = true
    try {
      options[name].call(page)
    } finally {
      // This exception is synchronous only; pending timers and audio callbacks
      // regain the normal visible/account/dead guards as soon as cleanup ends.
      page.__tangCleaning = false
    }
  }
  function deliverReady(page) {
    if (!isCurrent(page) || !page.__tangLoaded || !page.__tangHasShown
      || !page.__tangReadyRequested || page.__tangReadyDelivered) return
    page.__tangReadyDelivered = true
    if (typeof options.onReady === 'function') options.onReady.call(page)
  }
  const guarded = { ...options }
  Object.keys(options).forEach(key => {
    // Event handlers such as onAudioTimeUpdate are ordinary guarded methods,
    // even though their names begin with "on".
    if (typeof options[key] !== 'function' || LIFECYCLE_METHODS.has(key)) return
    guarded[key] = function (...args) {
      if (this.__tangCleaning) {
        // Release resources across an account change, but do not run helpers
        // such as saveCurrentAudioTime against the newly selected account.
        if (this.__tangScope === bridge.getScope() || CLEANUP_METHOD.test(key)) {
          return options[key].apply(this, args)
        }
        return
      }
      if (this.__tangDead || this.__tangOriginalUnloaded || !this.__tangLoaded || !this.__tangVisible) return
      if (this.__tangScope && this.__tangScope !== bridge.getScope()) {
        returnHome(this)
        return
      }
      return options[key].apply(this, args)
    }
  })
  Page({
    ...guarded,
    data: { ...(options.data || {}), tangBootPending: true },
    tangIgnoreBootTap() {},
    onLoad(query) {
      this.__tangQuery = query
      this.__tangScope = bridge.getScope()
      this.__tangDead = false
      this.__tangVisible = false
      this.__tangLoaded = false
      this.__tangCleaning = false
      this.__tangOriginalUnloaded = false
      this.__tangRedirected = false
      this.__tangShowGeneration = 0
      this.__tangReadyRequested = false
      this.__tangReadyDelivered = false
      this.__tangHasShown = false
      const nativeSetData = this.setData
      this.setData = function (...args) {
        if (this.__tangScope !== bridge.getScope()) return
        if (!this.__tangCleaning && !isCurrent(this)) return
        return nativeSetData.apply(this, args)
      }
      this.__tangBoot = bridge.open()
    },
    onShow() {
      if (this.__tangDead) return
      this.__tangVisible = true
      const generation = ++this.__tangShowGeneration
      const scope = bridge.getScope()
      if (this.__tangOriginalUnloaded || scope !== this.__tangScope) {
        returnHome(this)
        return
      }
      Promise.resolve(this.__tangBoot).then(() => {
        if (this.__tangDead || !this.__tangVisible || generation !== this.__tangShowGeneration) return
        if (bridge.getScope() !== scope) {
          returnHome(this)
          return
        }
        if (!this.__tangLoaded) {
          this.__tangLoaded = true
          if (options.onLoad) options.onLoad.call(this, this.__tangQuery)
          if (!isCurrent(this)) return
          this.setData({ tangBootPending: false })
        }
        if (options.onShow) options.onShow.call(this)
        this.__tangHasShown = true
        deliverReady(this)
      }).catch(() => {
        if (isCurrent(this) && generation === this.__tangShowGeneration) {
          wx.showToast({ title: '故事暂时未能打开，请返回重试', icon: 'none' })
        }
      })
    },
    onReady() {
      this.__tangReadyRequested = true
      deliverReady(this)
    },
    onHide() {
      this.__tangVisible = false
      ++this.__tangShowGeneration
      try {
        cleanUp(this, 'onHide')
      } finally {
        // A hidden page from an obsolete account must not retain contexts with
        // callbacks that directly reference storage instead of guarded methods.
        try {
          if (this.__tangScope !== bridge.getScope()) cleanUp(this, 'onUnload')
        } finally {
          bridge.flush()
        }
      }
    },
    onUnload() {
      this.__tangDead = true
      this.__tangVisible = false
      ++this.__tangShowGeneration
      try {
        cleanUp(this, 'onUnload')
      } finally {
        bridge.flush()
      }
    },
  })
}