<template>
  <div id="app">
    <!-- 上傳組件 -->
    <el-upload action drag :auto-upload="false" :show-file-list="false" :on-change="handleChange">
      <i class="el-icon-upload"></i>
      <div class="el-upload__text">將文件拖到此處，或<em>點擊上傳</em></div>
      <div class="el-upload__tip" slot="tip">大小不超過 200M 的視頻</div>
    </el-upload>

    <!-- 進度顯示 -->
    <div class="progress-box">
      <span>上傳進度：{{ percent.toFixed() }}%</span>
      <el-button type="primary" size="mini" @click="handleClickBtn">{{ upload | btnTextFilter}}</el-button>
    </div>

    <!-- 展示上傳成功的視頻 -->
    <div v-if="videoUrl">
      <video :src="videoUrl" controls />
    </div>
  </div>
</template>

async handleChange(file) {
  const fileObj = file.raw
  try{
    const buffer = await this.fileToBuffer(fileObj)
    console.log(buffer)
  }catch(e){
    console.log(e)
  }
}

// 將 File 對象轉(zhuǎn)為 ArrayBuffer 
fileToBuffer(file) {
  return new Promise((resolve, reject) => {
    const fr = new FileReader()
    fr.onload = e => {
      resolve(e.target.result)
    }
    fr.readAsArrayBuffer(file)
    fr.onerror = () => {
      reject(new Error('轉(zhuǎn)換文件格式發(fā)生錯誤'))
    }
  })
}

// 將文件按固定大?。?M）進行切片，注意此處同時聲明了多個常量
const chunkSize = 2097152,
  chunkList = [], // 保存所有切片的數(shù)組
  chunkListLength = Math.ceil(fileObj.size / chunkSize), // 計算總共多個切片
  suffix = /\.([0-9A-z]+)$/.exec(fileObj.name)[1] // 文件后綴名
  
// 根據(jù)文件內(nèi)容生成 hash 值
const spark = new SparkMD5.ArrayBuffer()
spark.append(buffer)
const hash = spark.end()

// 生成切片，這里后端要求傳遞的參數(shù)為字節(jié)數(shù)據(jù)塊（chunk）和每個數(shù)據(jù)塊的文件名（fileName）
let curChunk = 0 // 切片時的初始位置
for (let i = 0; i < chunkListLength; i++) {
  const item = {
    chunk: fileObj.slice(curChunk, curChunk + chunkSize),
    fileName: `${hash}_${i}.${suffix}` // 文件名規(guī)則按照 hash_1.jpg 命名
  }
  curChunk += chunkSize
  chunkList.push(item)
}
console.log(chunkList)

sendRequest() {
  const requestList = [] // 請求集合
  this.chunkList.forEach(item => {
    const fn = () => {
      const formData = new FormData()
      formData.append('chunk', item.chunk)
      formData.append('filename', item.fileName)
      return axios({
        url: '/single3',
        method: 'post',
        headers: { 'Content-Type': 'multipart/form-data' },
        data: formData
      }).then(res => {
        if (res.data.code === 0) { // 成功
          if (this.percentCount === 0) {
            this.percentCount = 100 / this.chunkList.length
          }
          this.percent += this.percentCount // 改變進度
        }
      })
    }
    requestList.push(fn)
  })
  
  let i = 0 // 記錄發(fā)送的請求個數(shù)
  const send = async () => {
    // if ('暫停') return
    if (i >= requestList.length) {
      // 發(fā)送完畢
      return
    } 
    await requestList[i]()
    i++
    send()
  }
  send() // 發(fā)送請求
},

axios.post('/single3', formData, {
  headers: { 'Content-Type': 'multipart/form-data' }
})

const complete = () => {
  axios({
    url: '/merge',
    method: 'get',
    params: { hash: this.hash }
  }).then(res => {
    if (res.data.code === 0) { // 請求發(fā)送成功
      this.videoUrl = res.data.path
    }
  })
}

filters: {
  btnTextFilter(val) {
    return val ? '暫停' : '繼續(xù)'
  }
}

handleClickBtn() {
  this.upload = !this.upload
  // 如果不暫停則繼續(xù)上傳
  if (this.upload) this.sendRequest()
}

<template>
  <div id="app">
    <!-- 上傳組件 -->
    <el-upload action drag :auto-upload="false" :show-file-list="false" :on-change="handleChange">
      <i class="el-icon-upload"></i>
      <div class="el-upload__text">將文件拖到此處，或<em>點擊上傳</em></div>
      <div class="el-upload__tip" slot="tip">大小不超過 200M 的視頻</div>
    </el-upload>

    <!-- 進度顯示 -->
    <div class="progress-box">
      <span>上傳進度：{{ percent.toFixed() }}%</span>
      <el-button type="primary" size="mini" @click="handleClickBtn">{{ upload | btnTextFilter}}</el-button>
    </div>

    <!-- 展示上傳成功的視頻 -->
    <div v-if="videoUrl">
      <video :src="videoUrl" controls />
    </div>
  </div>
</template>

<script>
  import SparkMD5 from "spark-md5"
  import axios from "axios"
  
  export default {
    name: 'App3',
    filters: {
      btnTextFilter(val) {
        return val ? '暫停' : '繼續(xù)'
      }
    },
    data() {
      return {
        percent: 0,
        videoUrl: '',
        upload: true,
        percentCount: 0
      }
    },
    methods: {
      async handleChange(file) {
        if (!file) return
        this.percent = 0
        this.videoUrl = ''
        // 獲取文件并轉(zhuǎn)成 ArrayBuffer 對象
        const fileObj = file.raw
        let buffer
        try {
          buffer = await this.fileToBuffer(fileObj)
        } catch (e) {
          console.log(e)
        }
        
        // 將文件按固定大小（2M）進行切片，注意此處同時聲明了多個常量
        const chunkSize = 2097152,
          chunkList = [], // 保存所有切片的數(shù)組
          chunkListLength = Math.ceil(fileObj.size / chunkSize), // 計算總共多個切片
          suffix = /\.([0-9A-z]+)$/.exec(fileObj.name)[1] // 文件后綴名
          
        // 根據(jù)文件內(nèi)容生成 hash 值
        const spark = new SparkMD5.ArrayBuffer()
        spark.append(buffer)
        const hash = spark.end()

        // 生成切片，這里后端要求傳遞的參數(shù)為字節(jié)數(shù)據(jù)塊（chunk）和每個數(shù)據(jù)塊的文件名（fileName）
        let curChunk = 0 // 切片時的初始位置
        for (let i = 0; i < chunkListLength; i++) {
          const item = {
            chunk: fileObj.slice(curChunk, curChunk + chunkSize),
            fileName: `${hash}_${i}.${suffix}` // 文件名規(guī)則按照 hash_1.jpg 命名
          }
          curChunk += chunkSize
          chunkList.push(item)
        }
        this.chunkList = chunkList // sendRequest 要用到
        this.hash = hash // sendRequest 要用到
        this.sendRequest()
      },
      
      // 發(fā)送請求
      sendRequest() {
        const requestList = [] // 請求集合
        this.chunkList.forEach((item, index) => {
          const fn = () => {
            const formData = new FormData()
            formData.append('chunk', item.chunk)
            formData.append('filename', item.fileName)
            return axios({
              url: '/single3',
              method: 'post',
              headers: { 'Content-Type': 'multipart/form-data' },
              data: formData
            }).then(res => {
              if (res.data.code === 0) { // 成功
                if (this.percentCount === 0) { // 避免上傳成功后會刪除切片改變 chunkList 的長度影響到 percentCount 的值
                  this.percentCount = 100 / this.chunkList.length
                }
                this.percent += this.percentCount // 改變進度
                this.chunkList.splice(index, 1) // 一旦上傳成功就刪除這一個 chunk，方便斷點續(xù)傳
              }
            })
          }
          requestList.push(fn)
        })
        
        let i = 0 // 記錄發(fā)送的請求個數(shù)
        // 文件切片全部發(fā)送完畢后，需要請求 '/merge' 接口，把文件的 hash 傳遞給服務(wù)器
        const complete = () => {
          axios({
            url: '/merge',
            method: 'get',
            params: { hash: this.hash }
          }).then(res => {
            if (res.data.code === 0) { // 請求發(fā)送成功
              this.videoUrl = res.data.path
            }
          })
        }
        const send = async () => {
          if (!this.upload) return
          if (i >= requestList.length) {
            // 發(fā)送完畢
            complete()
            return
          } 
          await requestList[i]()
          i++
          send()
        }
        send() // 發(fā)送請求
      },
      
      // 按下暫停按鈕
      handleClickBtn() {
        this.upload = !this.upload
        // 如果不暫停則繼續(xù)上傳
        if (this.upload) this.sendRequest()
      },
      
      // 將 File 對象轉(zhuǎn)為 ArrayBuffer 
      fileToBuffer(file) {
        return new Promise((resolve, reject) => {
          const fr = new FileReader()
          fr.onload = e => {
            resolve(e.target.result)
          }
          fr.readAsArrayBuffer(file)
          fr.onerror = () => {
            reject(new Error('轉(zhuǎn)換文件格式發(fā)生錯誤'))
          }
        })
      }
    }
  }
</script>

<style scoped>
  .progress-box {
    box-sizing: border-box;
    width: 360px;
    display: flex;
    justify-content: space-between;
    align-items: center;
    margin-top: 10px;
    padding: 8px 10px;
    background-color: #ecf5ff;
    font-size: 14px;
    border-radius: 4px;
  }
</style>