import JsSHA from 'jssha';
import { getServiceDomain } from './domains';

// Helper for URL generator
function hex2a(hexx: string) {
  const hex = hexx.toString(); // force conversion
  let str = '';
  for (let i = 0; i < hex.length; i += 2)
    str += String.fromCharCode(parseInt(hex.substr(i, 2), 16));
  return str;
}

export interface GeneratorOpts {
  enlarge?: 0 | 1;
  extension?: 'jpg' | 'png' | 'webp';
  gravity?: 'no' | 'so' | 'ea' | 'we' | 'ce' | 'sm';
  height?: string;
  key?: string;
  proxyUrl?: string;
  resize?: string;
  salt?: string;
  url: string;
  width?: string;
}

// URL generator logic
export function generateProxyUrl({
  resize = 'fit',
  width,
  height,
  gravity = 'no',
  enlarge = 0,
  extension = 'webp',
  key = '',
  salt = '',
  url,
  proxyUrl,
}: GeneratorOpts) {
  // btoa 废弃，且无法处理特殊字符，例如 ❤️
  // https://www.notion.so/dodotopia/tokenlist-5aaaf3210d304a0385deb616ffa89f9b?pvs=4
  // const encodedUrl = btoa(url)
  const encodedUrl = Buffer.from(url)
    .toString('base64')
    .replace(/=/g, '')
    .replace(/\//g, '_')
    .replace(/\+/g, '-');
  const path = `/rs:${resize}${width ? `:${width}` : ''}${
    height ? `:${height}` : ''
  }:${enlarge}/g:${gravity}/${encodedUrl}.${extension}`;
  const shaObj = new JsSHA('SHA-256', 'BYTES');
  shaObj.setHMACKey(key, 'HEX');
  shaObj.update(hex2a(salt));
  shaObj.update(path);
  const hmac = shaObj
    .getHMAC('B64')
    .replace(/=/g, '')
    .replace(/\//g, '_')
    .replace(/\+/g, '-');
  if (!proxyUrl) {
    proxyUrl = `https://images.${getServiceDomain()}`;
  }
  return `${proxyUrl}/${hmac}${path}`;
}