import { openWindow } from '.';

export function dataURLtoBlob(base64Buf: string): Blob {
  const arr = base64Buf.split(',');
  const typeItem = arr[0];
  const mime = typeItem.match(/:(.*?);/)![1];
  const bstr = window.atob(arr[1]);
  let n = bstr.length;
  const u8arr = new Uint8Array(n);
  while (n--) {
    u8arr[n] = bstr.charCodeAt(n);
  }
  return new Blob([u8arr], { type: mime });
}

/**
 * @description:将base64转换为文件
 */
export function dataURLtoFile(dataurl: string, filename: string): File {
  const arr = dataurl.split(',');
  const mime = arr[0].match(/:(.*?);/)![1];
  const bstr = atob(arr[1]);
  let n = bstr.length;
  const u8arr = new Uint8Array(n);
  while (n--) {
    u8arr[n] = bstr.charCodeAt(n);
  }
  return new File([u8arr], filename, { type: mime });
}

/**
 * img url to base64
 * @param url
 */
export function urlToBase64(url: string, mineType?: string): Promise<string> {
  return new Promise((resolve, reject) => {
    let canvas = document.createElement('CANVAS') as Nullable<HTMLCanvasElement>;
    const ctx = canvas!.getContext('2d');

    const img = new Image();
    img.crossOrigin = '';
    img.onload = function () {
      if (!canvas || !ctx) {
        return reject();
      }
      canvas.height = img.height;
      canvas.width = img.width;
      ctx.drawImage(img, 0, 0);
      const dataURL = canvas.toDataURL(mineType || 'image/png');
      canvas = null;
      resolve(dataURL);
    };
    img.src = url;
  });
}

/**
 * Download online pictures
 * @param url
 * @param filename
 * @param mime
 * @param bom
 */
export function downloadByOnlineUrl(url: string, filename: string, mime?: string, bom?: BlobPart) {
  urlToBase64(url).then((base64) => {
    downloadByBase64(base64, filename, mime, bom);
  });
}

/**
 * Download pictures based on base64
 * @param buf
 * @param filename
 * @param mime
 * @param bom
 */
export function downloadByBase64(buf: string, filename: string, mime?: string, bom?: BlobPart) {
  const base64Buf = dataURLtoBlob(buf);
  downloadByData(base64Buf, filename, mime, bom);
}

/**
 * Download according to the background interface file stream
 * @param {*} data
 * @param {*} filename
 * @param {*} mime
 * @param {*} bom
 */
export function downloadByData(data: BlobPart, filename: string, mime?: string, bom?: BlobPart) {
  const blobData = typeof bom !== 'undefined' ? [bom, data] : [data];
  const blob = new Blob(blobData, { type: mime || 'application/octet-stream' });

  const blobURL = window.URL.createObjectURL(blob);
  const tempLink = document.createElement('a');
  tempLink.style.display = 'none';
  tempLink.href = blobURL;
  tempLink.setAttribute('download', filename);
  if (typeof tempLink.download === 'undefined') {
    tempLink.setAttribute('target', '_blank');
  }
  document.body.appendChild(tempLink);
  tempLink.click();
  document.body.removeChild(tempLink);
  window.URL.revokeObjectURL(blobURL);
}

/**
 * Download file according to file address
 * @param {*} sUrl
 */
export async function downloadByUrl({
  url,
  target = '_blank',
  fileName,
  sameSite = true,
}: {
  url: string;
  target?: TargetContext;
  fileName?: string;
  sameSite?: boolean;
}): Promise<boolean> {
  const isChrome = window.navigator.userAgent.toLowerCase().indexOf('chrome') > -1;
  const isSafari = window.navigator.userAgent.toLowerCase().indexOf('safari') > -1;

  if (/(iP)/g.test(window.navigator.userAgent)) {
    console.error('Your browser does not support download!');
    return false;
  }
  if (isChrome || isSafari) {
    const link = document.createElement('a');
    if (sameSite) {
      link.href = url;
    } else {
      link.href = await xhrDownload(url);
    }

    link.target = target;

    if (link.download !== undefined) {
      link.download = fileName || url.substring(url.lastIndexOf('/') + 1, url.length);
    }

    if (document.createEvent) {
      const e = document.createEvent('MouseEvents');
      e.initEvent('click', true, true);
      link.dispatchEvent(e);
      if (!sameSite) {
        window.URL.revokeObjectURL(link.href);
      }

      return true;
    }
  }
  if (url.indexOf('?') === -1) {
    url += '?download';
  }

  openWindow(url, { target });
  return true;
}

async function xhrDownload(url: string): Promise<string> {
  return new Promise((resolve, reject) => {
    const xhr = new XMLHttpRequest();
    xhr.open('GET', url, true);
    xhr.responseType = 'blob';
    xhr.onload = function () {
      if (xhr.status === 200) {
        resolve(window.URL.createObjectURL(xhr.response));
      } else {
        reject();
      }
    };
    xhr.onerror = function () {
      reject();
    };
    xhr.send();
  });
}

export function openFilePicker(): Promise<File> {
  return new Promise((resolve, reject) => {
    let selected = false;
    const input = document.createElement('input');
    input.type = 'file';
    input.accept = 'image/*';
    input.multiple = false;
    input.style.display = 'none';
    document.body.appendChild(input);
    function onChange(this: HTMLInputElement) {
      const file = this.files![0];
      resolve(file);
      selected = true;
      document.body.removeChild(input);
    }
    input.addEventListener('change', onChange, { once: true });
    input.click();
    window.addEventListener(
      'focus',
      () => {
        setTimeout(() => {
          if (!selected) {
            reject(false);
          }
        }, 200);
      },
      {
        once: true,
      },
    );
  });
}