import { UploadOptions } from './Props'

export const UPLOADING = 1
export const SUCCESS = 2
export const ERROR = 3

declare class XDomainRequest extends XMLHttpRequest {}

function createCORSRequest(method: string, url: string) {
  let xhr: XMLHttpRequest | null = new XMLHttpRequest()
  if ('withCredentials' in xhr) {
    // XHR for Chrome/Firefox/Opera/Safari.
    xhr.open(method, url, true)
  } else if (typeof XDomainRequest !== 'undefined') {
    // XDomainRequest for IE.
    xhr = new XDomainRequest()
    xhr.open(method, url)
  } else {
    // CORS not supported.
    xhr = null
  }
  return xhr
}

export default function(args: UploadOptions<any>) {
  const {
    url,
    name,
    cors,
    file,
    onProgress,
    onLoad,
    onError,
    withCredentials,
    params = {},
    headers = {},
    onStart,
    responseType,
  } = args

  if (!url) {
    console.error(new Error(`action is required, but its value is ${url}`))
    return undefined
  }

  const data = new FormData()
  Object.keys(params).forEach(k => {
    data.append(k, params[k])
  })

  data.append(name, file)

  // @ts-ignore 多传了一个参数
  const xhr = createCORSRequest('post', url, cors)
  if (!xhr) return undefined
  xhr.withCredentials = !!withCredentials
  if (responseType) {
    xhr.responseType = responseType
  }
  if (onProgress) xhr.upload.addEventListener('progress', onProgress, false)
  xhr.onload = e => onLoad(e.currentTarget as any)
  xhr.onerror = onError

  Object.keys(headers).forEach(k => {
    xhr.setRequestHeader(k, headers[k])
  })

  if (onStart) onStart(file)

  xhr.send(data)

  return xhr
}