export let cache = new Cache()

/**
 * 需要緩存的數據會在mutations-type后面添加-CACHED
 */
export const SET_HOME_INDEX = 'SET_HOME_INDEX-CACHED'
/modules/home/index.js


const actions = {
 /**
  * @description 如果有緩存，就返回把緩存的數據，傳入mutations，
  * 沒有緩存就從接口拿數據，存入緩存，把數據傳入mutations
  */
 async fetchAction ({commit}, {mutationType, fetchData, oPayload}) {
  // vuex開啟了命名空間，所這里從cachekey要把命名空間前綴 + 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('已經進入緩存取數據！！！')
   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標志的數據存入緩存，
 * 現在key值是mutations-type
 * 問題：
 * 沒辦法區分不同參數query的請求，
 *
 * 方法1: 用每個mutations-type + payload的json格式為key來緩存數據
 */
function cachePlugin () {
 return store => {
  store.subscribe(({ type, payload }, state) => {
   // 需要緩存的數據會在mutations-type后面添加CACHED
   const needCache = type.split('-').pop() === 'CACHED'
   if (needCache) {
    // 這里的type會自動加入命名空間所以 cacheKey = type + 把payload格式化成JSON
    const cacheKey = type + JSON.stringify(payload && payload.oPayload)
    const cacheResponse = cache.get(cacheKey)
    // 如果沒有緩存就存入緩存
    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]
 }
}

/**
 * 用這個函數就說明是需要進入緩存
 * @param {*} api 請求的接口
 * @param {*} queryArr 請求的參數
 * @param {*} mutationType 傳入mutationType作為cache的key值
 */
export async function fetchOrCache ({api, queryArr, mutationType, diff}) {
 // 這里是請求接口
 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 {
   // 超時就刪除
   cache.delete(cachekey)
  }
 }
 // 不取緩存的處理
 let response = await fetch()
 // 時間戳綁定在數組的屬性上
 response.cacheTimestemp = Date.now()
 cache.set(cachekey, response)
 // 返回cloneDeep的對象
 return cloneDeep(response)
}
/**
 * 判斷緩存是否失效
 * @param {*} diff 失效時間差，默認15分鐘=900s
 */
const cacheFresh = (cacheTimestemp, diff = 900) => {
 if (cacheTimestemp) {
  return ((Date.now() - cacheTimestemp) / 1000) <= diff
 } else {
  return true
 }
}