/**
 * 获取 query string
 * @param {*} params 
 * @returns string
 */
function getQueryString(params) {
  if (!params) return ;

  const keys = Object.keys(params)
  const arr = keys.map((key) => {
    const val = params[key]
    if (val === null || val === undefined) return false;

    return `${key}=${encodeURIComponent(val)}`
  })

  // eslint-disable-next-line consistent-return
  return arr.filter(Boolean).join('&')
}

export function fetchBlob(url, opt) {
  const { params, ...initArgs } = opt || {}
  const resource = params ? `${url}?${getQueryString(params)}` : url

  return window.fetch(resource, initArgs).then(response => response.blob())
}

export function downloadBlob(fileName, blob) {
  const url = window.URL.createObjectURL(blob);
  const link = document.createElement('a');
  link.href = url;
  link.setAttribute('download', fileName);
  link.click();
  window.URL.revokeObjectURL(url);
}

export function downloadUrl(fileName, url, opt) {
  return fetchBlob(url, opt).then(blob => downloadBlob(fileName, blob))
};