<template>
 <transition name="fade" @after-leave="afterLeave" @after-enter="setHeight">
  <div
   v-show="visible"
   :class="['notification']"
   :style="style"
   @mouseenter="clearTimer"
   @mouseleave="createTimer"
  >
   <span class="content">{{content}}</span>
   <a class="btn" @click="handleClose">{{btn || '關(guān)閉'}}</a>
  </div>
 </transition>
</template>

<script>
export default {
 name: 'Notification',
 props: {
  content: {
   type: String,
   default: ''
  },
  btn: {
   type: String,
   default: ''
  }
 },
 data () {
  return {
   visible: true
  }
 },
 computed: {
  style () {
   return {}
  }
 },
 methods: {
  handleClose (e) {
   e.preventDefault()
   this.doClose()
  },
  doClose () {
   this.visible = false
   this.$emit('close')
  },
  afterLeave () {
   this.$emit('closed')
  },
  clearTimer () {},
  createTimer () {},
  setHeight () {}
 }
}
</script>

<style lang="stylus" scoped>
.notification
 display: flex
 background-color #303030
 color rgba(255, 255, 255, 1)
 align-items center
 padding 20px
 position fixed
 min-width 280px
 box-shadow 0px 3px 5px -1px rgba(0, 0, 0, 0.2), 0px 6px 10px 0px rgba(0, 0, 0, 0.14), 0px 1px 18px 0px rgba(0, 0, 0, 0.12)
 flex-wrap wrap
 transition all .3s
.content
 padding 0
.btn
 color #ff4081
 padding-left 24px
 margin-left auto
 cursor pointer
</style>

import Notification from './notification.vue'

export default {
 extends: Notification,
 computed: {
  style () {
   return {
    position: 'fixed',
    right: '20px',
    bottom: `${this.verticalOffset + 20}px`
   }
  }
 },
 data () {
  return {
   verticalOffset: 0,
   visible: false,
   height: 0,
   autoClose: 3000
  }
 },
 mounted () {
  this.createTimer()
 },
 methods: {
  createTimer () {
   if (this.autoClose) {
    this.timer = setTimeout(() => {
     this.doClose()
    }, this.autoClose)
   }
  },
  clearTimer () {
   if (this.timer) {
    clearTimeout(this.timer)
   }
  },
  setHeight () {
   this.height = this.$el.offsetHeight
  }
 }
}

// function-component.js
import Vue from 'vue'
import Component from './fun-component'
const NotificationConstructor = Vue.extend(Component)

const instances = []
let seed = 1

const removeInstance = (instance) => {
 const len = instances.length
 if (!instance) return
 const index = instances.findIndex(inst => instance.id === inst.id)

 instances.splice(index, 1)

 if (len <= 1) return
 const removedHeight = instance.vm.height
 for (let i = index; i < len - 1; i++) {
  instances[i].verticalOffset =
   parseInt(instances[i].verticalOffset) - removedHeight - 16
 }
}

const notify = function (options) {
 const {
  onClose,
  ...rest
 } = options
 if (Vue.prototype.$isServer) return
 options = options || {}
 const id = `notification_${seed++}`

 const instance = new NotificationConstructor({
  propsData: {
   ...rest
  }
 })

 instance.id = id
 instance.vm = instance.$mount()
 document.body.appendChild(instance.vm.$el)
 instance.vm.visible = true

 let verticalOffset = 0
 instances.forEach(item => {
  verticalOffset += item.$el.offsetHeight + 16
 })
 verticalOffset += 16
 instance.verticalOffset = verticalOffset
 instances.push(instance)
 instance.vm.$on('closed', () => {
  if (typeof onClose === 'function') {
   onClose(instance)
  }
  removeInstance(instance)
  instance.vm.$destroy()
 })
 return instance.vm
}

export default notify

import notify from './function-component.js'

notify({
 content: 'xxx',
 btn: 'xxx'
})

import Notification from './notification.vue'
import notify from './function'

export default (Vue) => {
 Vue.component(Notification.name, Notification)
 Vue.prototype.$notify = notify
 Vue.notify = notify
}

import notify from '/path/to/notification/module'

Vue.use(notify)