// 准备
let options = {
  'Content-Length': <file.size>, // 添加http header
  'Content-Type': 'application/json', // 添加http header
  'Cache-Control': 'public, max-age=31536000', // 指定缓存指令
  'Content-Disposition': 'attachment; filename="example.jpg"', // 指示回复的内容该以何种形式展示

  'x-bce-meta-foo1': 'bar1', // 添加自定义meta信息
  'x-bce-meta-foo2': 'bar2', // 添加自定义meta信息
  'x-bce-meta-foo3': 'bar3' // 添加自定义meta信息
}; 
let PART_SIZE = 5 * 1024 * 1024; // 指定分块大小

/** 第一步 init **/
// SrcBucketName, SrcKey为原Bucket/Object
// DestBucketName, DestKey为拷贝到的目的Bucket/Object
client.initiateMultipartUpload(srcBucketName, SrcKey)
    .then(function(response) {
        uploadId = response.body.uploadId; // 获取服务器生成的uploadId标识任务
    })
   

/** 第二步 分块拷贝 **/
// 获取文件大小
let leftSize = 0;
client.getObjectMetadata(<SrcBucketName>, <SrcKey>).then(response => {
    leftSize = response.http_headers?.['content-length']
});

let tasks = [];
let offset = 0;
let partNumber = 1;

while (leftSize > 0) {
    let partSize = Math.min(leftSize, PART_SIZE);
    tasks.push({
        file: <SrcKey>,
        bucketName: <SrcBucketName>,
        uploadId: uploadId,
        partNumber: partNumber,
        partSize: partSize,
        start: offset,
        stop: offset + partSize - 1
    })
    leftSize -= partSize;
    offset += partSize;
    partNumber+=1;
}
    let partList = [];
    Promise.all(tasks.map(async (task, index) => {
         return client.uploadPartCopy(<SrcBucketName>, <SrcKey>, <DestBucketName>, <DestKey>,uploadId, partNumber, range, <options>).then(response => {
            // do something
        })
    })).then(response => {
        partList = response
            .map(res => ({partNumber: res.partNumber, eTag: res.http_headers.eTag}));
    });


/** 第三步 complete **/
client.completeMultipartUpload(<DestBucketName>, <DestKey>, uploadId, partList)