<template>
  <div id="app">
    <div class="upload-wrap">
      <UploadSlice
        :action="uploadInfoSlice.actionChunk"
        :headers="uploadInfoSlice.headers"
        :limit="uploadInfoSlice.limit"
        :accept="uploadInfoSlice.accept"
        :show-file-list="false"
        cancelable
        :on-success="handleSuccess"
        :on-remove="handleRemove"
        :on-cancel="handleCancel"
        :on-upload-pre="handleUploadPre"
        :on-upload-merge="handleUploadMerge"
        :on-form-data="genFormData"
      />
    </div>
  </div>
</template>

<script>
import UploadSlice from './components/UploadSlice.vue'
import { uploadPre, uploadMerge } from '@/api/upload-slice'

export default {
  name: 'App',
  components: {
    UploadSlice
  },
  data() {
    return {
      // 上傳部分
      uploadInfoSlice: {
        actionChunk: process.env.VUE_APP_BASE_API + '/storage/file/v3/chunk', // 切片請(qǐng)求上傳路徑
        headers: { 'Authorization': 'Bearer XXX' }
      }
    }
  },
  methods: {
    // 分片預(yù)請(qǐng)求
    async handleUploadPre(file) {
      const form = new FormData()
      form.append('fileSource', 'APPLICATION')
      form.append('originFileName', file.name)
      let res = ''
      try {
        res = await uploadPre(form)
      } catch (error) {
        throw new Error(error)
      }
    },
    // 構(gòu)造分片參數(shù)
    genFormData(chunks, uid) {
      const prepareId = this.getCurrentPrepareId(uid)
      return chunks.map(chunk => {
        const form = new FormData()
        form.append('chunk', chunk.file)
        form.append('uploadId', prepareId)
        form.append('partNumber', chunk.index)
        return form
      })
    },
    // 合并請(qǐng)求
    async handleUploadMerge(file, uid) {
      const prepareId = this.getCurrentPrepareId(uid)
      const form = new FormData()
      form.append('fileSource', 'APPLICATION')
      form.append('hash', prepareId)
      form.append('filename', file.name)
      // return 建議使用, 用于handleSuccess獲取數(shù)據(jù)
      try {
        const res = await uploadMerge(form)
        return res
      } catch (error) {
        return error
      }
    },
    // 判斷當(dāng)前處理prepareId
    getCurrentPrepareId(uid) {
      for (const item of this.progressFileList) {
        if (item.uid === uid) {
          return item.prepareId
        }
      }
    }
  }
}
</script>

genFileChunks(file) {
  const chunks = []
  let cur = 0
  // 小于10M 固定一片
  if (file.size < (10 * 1024 * 1024)) {
    chunks.push({
      index: cur,
      file: file.raw.slice(cur, file.size),
      originFilename: file.name
    })
    return chunks
  }
  // 小于50M 文件10%為一片
  if (file.size < (50 * 1024 * 1024)) {
    const chunkSize = parseInt(file.size * 0.1)
    while (cur < file.size) {
      chunks.push({
        index: cur,
        file: file.raw.slice(cur, cur + chunkSize),
        originFilename: file.name
      })
      cur += chunkSize
    }
    return chunks
  }
  // 大于50M 固定5M 一片
  const chunkSize = parseInt(5 * 1024 * 1024)
  while (cur < file.size) {
    chunks.push({
      index: cur,
      file: file.raw.slice(cur, cur + chunkSize),
      originFilename: file.name
    })
    cur += chunkSize
  }
  return chunks
},

<template>
  <UploadSlice
    :action="uploadInfoSlice.actionChunk"
    :headers="uploadInfoSlice.headers"
    :on-form-data="genFormData"
  />
</template>

<script>
  methods: {
    // 構(gòu)造分片參數(shù)
    genFormData(chunks, uid) {
      const prepareId = this.getCurrentPrepareId(uid)
      return chunks.map(chunk => {
        const form = new FormData()
        form.append('chunk', chunk.file)
        form.append('uploadId', prepareId)
        form.append('partNumber', chunk.index)
        return form
      })
    },
  },
</script>

<template>
  <el-upload
      action=""
      :accept="accept"
  >
</template>

<script>
  props: {
    onFormData: {
      type: Function,
      default: () => {}
    },
  },
  methods: {
    async uploadChunks(uid) {
      // 預(yù)請(qǐng)求
      // ---------------

      // 上傳切片
      const requests = this._genRequest(this._genUploadData(uid), uid)
      // 控制并發(fā)
      await this.sendRequest(requests)
      
      // 合并請(qǐng)求
      // ---------------
    },
    
    // 構(gòu)造分片參數(shù)
    _genUploadData(uid) {
      const chunks = this.getCurrentChunks(uid)
      return this.onFormData(chunks, uid)
    },
    
    // 生成調(diào)用請(qǐng)求：[Promise, Promise]
    _genRequest(uploadData, uid) {
      console.log('uploadData', uploadData)
      const file = this.getCurrentFile(uid)
      const chunks = this.getCurrentChunks(uid)
      return uploadData.map((form, index) => {
        const options = {
          headers: this.$attrs.headers,
          file: file,
          data: form,
          action: this.action,
          onProgress: progress => {
            chunks[index].progress = Number(
              ((progress.loaded / progress.total) * 100).toFixed(2)
            )
            this.handleProgress(progress, file, uid)
          }
        }
        return options
      })
    },
  },
</script>

    sendRequest(requests, limit = 3) {
      return new Promise((resolve, reject) => {
        const len = requests.length
        let counter = 0
        let isTips = false // 只提示一次失敗
        let isStop = false // 如果一個(gè)片段失敗超過(guò)三次 認(rèn)為當(dāng)前網(wǎng)洛有問(wèn)題 停止全部上傳
        const startRequest = async() => {
          if (isStop) return
          const task = requests.shift()
          if (task && task.file.status !== 'cancel') {
            // 利用try...catch捕獲錯(cuò)誤
            try {
              // 具體的接口  抽離出去了
              await ajax(task)
              if (counter === len - 1) { // 最后一個(gè)任務(wù)
                resolve()
              } else { // 否則接著執(zhí)行
                counter++
                startRequest() // 啟動(dòng)下一個(gè)任務(wù)
              }
            } catch (error) {
              // 網(wǎng)絡(luò)異常
              if (error === 'NETWORK_ERROR' && !isTips) {
                Message.error('網(wǎng)絡(luò)異常，文件上傳失敗')
                this.upLoading = false
                this.preLoading = false
                isTips = true
                this.handleRemove('', [])
              }

              // 接口報(bào)錯(cuò)重試，限制為3次
              if (task.error < 3) {
                task.error++
                requests.unshift(task)
                startRequest()
              } else {
                isStop = true
                reject(error)
              }
            }
          }
        }
        // 啟動(dòng)任務(wù)
        while (limit > 0) {
          // 模擬不同大小啟動(dòng)
          setTimeout(() => {
            startRequest()
          }, Math.random() * 2000)
          limit--
        }
      })
    }
  }