export let cache = new Cache()

/**
 * 需要缓存的数据会在mutations-type后面添加-CACHED
 */
export const SET_HOME_INDEX = 'SET_HOME_INDEX-CACHED'
/modules/home/index.js


const actions = {
 /**
  * @description 如果有缓存，就返回把缓存的数据，传入mutations，
  * 没有缓存就从接口拿数据，存入缓存，把数据传入mutations
  */
 async fetchAction ({commit}, {mutationType, fetchData, oPayload}) {
  // vuex开启了命名空间，所这里从cachekey要把命名空间前缀 + type + 把payload格式化成JSON
  const cacheKey = NAMESPACE + mutationType + JSON.stringify(oPayload)
  const cacheResponse = cache.get(cacheKey || '')
  if (!cacheResponse) {
   const [err, response] = await fetchData()
   if (err) {
    console.error(err, 'error in fetchAction')
    return false
   }
   commit(mutationType, {response: response, oPayload})
  } else {
   console.log('已经进入缓存取数据！！！')
   commit(mutationType, {response: cacheResponse, oPayload})
  }
 },
 loadHomeData ({ dispatch, commit }) {
  dispatch(
   'fetchAction',
   {
    mutationType: SET_HOME_INDEX,
    fetchData: api.index,
   }
  )
 }
}

const mutations = {
 [SET_HOME_INDEX] (state, {response, oPayload}) {},
}

const state = {
 indexData: {}
}

export default {
 namespaced: NAMESPACED,
 actions,
 state,
 getters,
 mutations
}

import cache from 'src/store/util/CacheOfStore'
// import {strOfPayloadQuery} from 'src/store/util/index'
/**
 * 在每次mutations提交之后，把mutations-type后面有CACHED标志的数据存入缓存，
 * 现在key值是mutations-type
 * 问题：
 * 没办法区分不同参数query的请求，
 *
 * 方法1: 用每个mutations-type + payload的json格式为key来缓存数据
 */
function cachePlugin () {
 return store => {
  store.subscribe(({ type, payload }, state) => {
   // 需要缓存的数据会在mutations-type后面添加CACHED
   const needCache = type.split('-').pop() === 'CACHED'
   if (needCache) {
    // 这里的type会自动加入命名空间所以 cacheKey = type + 把payload格式化成JSON
    const cacheKey = type + JSON.stringify(payload && payload.oPayload)
    const cacheResponse = cache.get(cacheKey)
    // 如果没有缓存就存入缓存
    if (!cacheResponse) {
     cache.set(cacheKey, payload.response)
    }
   }
   console.log(cache)
  })
 }
}
const plugin = cachePlugin()
export default plugin

import Vue from 'vue'
import Vuex from 'vuex'
import home from './modules/home'
import cachePlugin from './plugins/cache'

Vue.use(Vuex)
const store = new Vuex.Store({
 modules: {
  home,
  editActivity,
  editGuide
 }
 plugins: [cachePlugin]
})

export default store

const actions = {
 async loadHomeData ({ dispatch, commit }, oPayload) {
  commit(SET_HOME_LOADSTATUS)
  const [err, response] = await fetchOrCache({
   api: api.index,
   queryArr: oPayload.queryArr,
   mutationType: SET_HOME_INDEX
  })
  if (err) {
   console.log(err, 'loadHomeData error')
   return [err, response]
  }
  commit(SET_HOME_INDEX, { response })
  return [err, response]
 }
}

/**
 * 用这个函数就说明是需要进入缓存
 * @param {*} api 请求的接口
 * @param {*} queryArr 请求的参数
 * @param {*} mutationType 传入mutationType作为cache的key值
 */
export async function fetchOrCache ({api, queryArr, mutationType, diff}) {
 // 这里是请求接口
 const fetch = httpGet(api, queryArr)
 const cachekey = `${mutationType}:${JSON.stringify(queryArr)}`
 if (cache.has(cachekey)) {
  const obj = cache.get(cachekey)
  if (cacheFresh(obj.cacheTimestemp, diff)) {
   return cloneDeep(obj)
  } else {
   // 超时就删除
   cache.delete(cachekey)
  }
 }
 // 不取缓存的处理
 let response = await fetch()
 // 时间戳绑定在数组的属性上
 response.cacheTimestemp = Date.now()
 cache.set(cachekey, response)
 // 返回cloneDeep的对象
 return cloneDeep(response)
}
/**
 * 判断缓存是否失效
 * @param {*} diff 失效时间差，默认15分钟=900s
 */
const cacheFresh = (cacheTimestemp, diff = 900) => {
 if (cacheTimestemp) {
  return ((Date.now() - cacheTimestemp) / 1000) <= diff
 } else {
  return true
 }
}