import crypto from 'crypto-js';

import { flags } from '@/main/targets';
import { makeEmbed } from '@/providers/base';

const { AES, enc } = crypto;

interface StreamRes {
  server: number;
  sources: string;
  tracks: {
    file: string;
    kind: 'captions' | 'thumbnails';
    label: string;
  }[];
}

function isJSON(json: string) {
  try {
    JSON.parse(json);
    return true;
  } catch {
    return false;
  }
}

/*
example script segment:
switch(I9){case 0x0:II=X,IM=t;break;case 0x1:II=b,IM=D;break;case 0x2:II=x,IM=f;break;case 0x3:II=S,IM=j;break;case 0x4:II=U,IM=G;break;case 0x5:II=partKeyStartPosition_5,IM=partKeyLength_5;}
*/
function extractKey(script: string): [number, number][] | null {
  const startOfSwitch = script.lastIndexOf('switch');
  const endOfCases = script.indexOf('partKeyStartPosition');
  const switchBody = script.slice(startOfSwitch, endOfCases);

  const nums: [number, number][] = [];
  const matches = switchBody.matchAll(/:[a-zA-Z0-9]+=([a-zA-Z0-9]+),[a-zA-Z0-9]+=([a-zA-Z0-9]+);/g);
  for (const match of matches) {
    const innerNumbers: number[] = [];
    for (const varMatch of [match[1], match[2]]) {
      const regex = new RegExp(`${varMatch}=0x([a-zA-Z0-9]+)`, 'g');
      const varMatches = [...script.matchAll(regex)];
      const lastMatch = varMatches[varMatches.length - 1];
      if (!lastMatch) return null;
      const number = parseInt(lastMatch[1], 16);
      innerNumbers.push(number);
    }

    nums.push([innerNumbers[0], innerNumbers[1]]);
  }

  return nums;
}

export const upcloudScraper = makeEmbed({
  id: 'upcloud',
  name: 'UpCloud',
  rank: 200,
  async scrape(ctx) {
    // Example url: https://dokicloud.one/embed-4/{id}?z=
    const parsedUrl = new URL(ctx.url.replace('embed-5', 'embed-4'));

    const dataPath = parsedUrl.pathname.split('/');
    const dataId = dataPath[dataPath.length - 1];

    const streamRes = await ctx.proxiedFetcher<StreamRes>(`${parsedUrl.origin}/ajax/embed-4/getSources?id=${dataId}`, {
      headers: {
        Referer: parsedUrl.origin,
        'X-Requested-With': 'XMLHttpRequest',
      },
    });

    let sources: { file: string; type: string } | null = null;

    if (!isJSON(streamRes.sources)) {
      const scriptJs = await ctx.proxiedFetcher<string>(`https://rabbitstream.net/js/player/prod/e4-player.min.js`);
      const decryptionKey = extractKey(scriptJs);
      if (!decryptionKey) throw new Error('Key extraction failed');

      let extractedKey = '';
      let strippedSources = streamRes.sources;
      let totalledOffset = 0;
      decryptionKey.forEach(([a, b]) => {
        const start = a + totalledOffset;
        const end = start + b;
        extractedKey += streamRes.sources.slice(start, end);
        strippedSources = strippedSources.replace(streamRes.sources.substring(start, end), '');
        totalledOffset += b;
      });

      const decryptedStream = AES.decrypt(strippedSources, extractedKey).toString(enc.Utf8);
      const parsedStream = JSON.parse(decryptedStream)[0];
      if (!parsedStream) throw new Error('No stream found');
      sources = parsedStream;
    }

    if (!sources) throw new Error('upcloud source not found');

    return {
      stream: {
        type: 'hls',
        playlist: sources.file,
        flags: [flags.NO_CORS],
        captions: [],
      },
    };
  },
});