// https://github.com/ElemeFE/element/blob/dev/packages/upload/src/ajax.js

function getError(uploadUrl: string, option, xhr: XMLHttpRequest) {
  const msg = `fail to post ${uploadUrl} ${xhr.status}`;

  const error: any = new Error(msg);
  error.status = xhr.status;
  error.methods = 'post';
  error.url = uploadUrl;
  return error;
}

function getBody(xhr) {
  const text = xhr.responseText || xhr.response;

  if (!text) {
    return text;
  }

  try {
    return JSON.parse(text);
  } catch (e) {
    return text;
  }
}

export default function upload(option) {
  if (typeof XMLHttpRequest === 'undefined') {
    return;
  }

  const xhr = new XMLHttpRequest();
  const uploadUrl = option.uploadUrl;

  if (xhr.upload) {
    // 数据传输进行中
    xhr.upload.onprogress = function progress(e: any) {
      if (e.total > 0) {
        // 操作处理的当前字节数 / 操作将处理的总字节数 * 100
        e.percent = (e.loaded / e.total) * 100;
      }
      option.onProgress(e);
    };
  }

  const formData = new FormData();

  // 是否有上传时附带的额外参数
  if (option.data) {
    Object.keys(option.data).map((key) => {
      formData.append(key, option.data[key]);
    });
  }

  formData.append(option.filename, option.file);

  // 处理操作时发生错误时调用的回调处理程序
  xhr.onerror = function error(e) {
    option.onError(e);
  };

  // 上传成功完成
  xhr.onload = function onload() {
    if (xhr.status < 200 || xhr.status >= 300) {
      return option.onError(getError(uploadUrl, option, xhr), getBody(xhr));
    }
    option.onSuccess(getBody(xhr));
  };

  xhr.open('post', uploadUrl, true);

  // 是否支持cookie
  if (option.withCredentials && 'withCredentials' in xhr) {
    xhr.withCredentials = true;
  }

  // 设置请求头
  const headers = option.headers || {};
  for (const item in headers) {
    // eslint-disable-next-line no-prototype-builtins
    if (headers.hasOwnProperty(item) && headers[item] !== null) {
      xhr.setRequestHeader(item, headers[item]);
    }
  }

  xhr.send(formData);
}