const ls = window.localStorage
// https://github.com/tsironis/lockr
export default {
 getItem(key) {
  try {
   return JSON.parse(ls.getItem(key))
  } catch (err) {
   return null
  }
 },
 setItem(key, val) {
  ls.setItem(key, JSON.stringify(val))
 },
 clear() {
  ls.clear()
 },
 keys() {
  return ls.keys()
 },
 removeItem(key) {
  ls.removeItem(key)
 }
}

import LStorage from './LStorage'

/**
 * 代理二級屬性
 * @param {*} lsKey 存在localStorage的key
 * @param {*} pk  一級屬性的key
 */
function createHanlder(lsKey, pk) {
 return {
  set: function (target, key, value, receiver) {
   let item = LStorage.getItem(lsKey)
   if (item && item[pk]) {
    item[pk][key] = value
    LStorage.setItem(lsKey, item)
   }
   return Reflect.set(target, key, value, receiver)
  }
 }
}

/**
 * 僅僅存需要存放的數據
 * @param {*} source 
 * @param {*} keys 
 */
function copy(source, keys = []) {
 if (!source) {
  return source
 }
 let d = Object.create(null)
 keys.forEach(k => { d[k] = source[k] })
 return d
}

/**
 * 代理state
 * @param {*} initState 初始化的值
 * @param {*} lsKey localStorage的key
 * @param {*} keys  需要存儲的鍵
 */
const proxy = function (initState, lsKey, keys = []) {
 let ks = keys, obj = Object.assign({}, initState, LStorage.getItem(lsKey))

 // 代理二級屬性
 keys.forEach(k => {
  obj[k] = new Proxy(obj[k], createHanlder(lsKey, k))
 })
 // 存入合并的值
 LStorage.setItem(lsKey, copy(obj, keys))
 return new Proxy(obj, {
  set: function (target, key, value, receiver) {
   ks.indexOf(key) >= 0 && LStorage.setItem(lsKey, copy(target, keys))
   return Reflect.set(target, key, value, receiver)
  }
 })
}

export { proxy }

import { proxy } from '../utils/LSProxy'
let state = {
 list: [],
 current: null
}
state = proxy(state, 'playing', ['list'])

const mutations = {

 /**
  * 添加歌曲
  * @param {*} state 
  * @param {*} song 歌曲信息 
  */
 addSong(state, song) {
  let index = state.list.findIndex(s => s.songmid === song.songmid)
  if (index < 0) {
   state.list.push(song)
  }
 },

 /**
  * 添加歌曲
  * @param {*} state 內置
  * @param {*} songs 歌曲列表
  */
 addSongs(state, songs) {
  let index = -1
  songs.forEach(song => {
   index = state.list.findIndex(s => s.songmid === song.songmid)
   if (index < 0) {
    state.list.push(song)
   }
  })
 },

 /**
  * 刪除歌曲
  * @param {*} state 
  * @param {*} songmid 歌曲媒體id 
  */
 removeSong(state, songmid) {
  let index = state.list.findIndex(s => s.songmid === songmid)
  index >= 0 && state.list.splice(index, 1)
 },

 /**
  * 批量刪除歌曲
  * @param {*} state 
  * @param {*} songmids 歌曲媒體列表 
  */
 removeSongs(state, songmids = []) {
  let index = -1
  songmids.forEach(songmid => {
   index = state.list.findIndex(s => s.songmid === songmid)
   index >= 0 && state.list.splice(index, 1)
  })
 },

 /**
  * 播放下一首，
  * @param {*} state 
  * @param {*} song 為空
  */
 next(state, song) {
  // 如果song不為空，表示是插放，（前提是已經添加到playing）
  if (song) {
   let index = state.list.findIndex(s => s.songmid === song.songmid)
   if (index >= 0) {
    state.current = state.list[index]
    return
   }
   return
  }
  // 如果current為空，表示沒有播放的歌曲
  if (!state.current && state.list && state.list.length > 0) {
   state.current = state.list[0]
   return
  }
  // 如果不是插放，并且current不為空
  if (!song && state.current) {
   // 播放的歌曲是不是在當前的列表
   let index = state.list.findIndex(s => s.songmid === state.current.songmid)
   // 如果在歌曲列表里面，接著播放下首
   if (index >= 0) {
    state.current = (index === state.list.length - 1 ? state.list[0] : state.list[index + 1])
   } else {
    state.current = state.list[0]
   }
  }
 }
}

export default {
 namespaced: true,
 state,
 mutations
}