knightcrawler/lib/torrent.js

const torrentStream = require('torrent-stream');
const needle = require('needle');
const parseTorrent = require('parse-torrent');
const { retrieveTorrentFiles } = require('./cache');

const MAX_PEER_CONNECTIONS = process.env.MAX_PEER_CONNECTIONS || 20;
const EXTENSIONS = ["3g2", "3gp", "avi", "flv", "mkv", "mov", "mp2", "mp4", "mpe", "mpeg", "mpg", "mpv", "webm", "wmv"];

module.exports.updateCurrentSeeders = function (torrent) {
  return Promise.resolve({ ...torrent, seeders: torrent.seeders || 0 });
};

module.exports.torrentFiles = function (torrent) {
  return filesFromTorrentFile(torrent)
      .catch(() => filesFromTorrentStream(torrent))
      .catch(() => filesFromCache(torrent.infoHash))
      .then((files) => files.filter((file) => isVideo(file)));
};

function filesFromCache(infoHash) {
  return retrieveTorrentFiles(infoHash)
      .then((files) => files.map((file) => ({
        fileIndex: parseInt(file.match(/^(\d+)@@/)[1]),
        name: file.replace(/.+\/|^\d+@@/, ''),
        path: file.replace(/^\d+@@/, ''),
        size: 300000000
      })));
}

async function filesFromTorrentFile(torrent) {
  if (!torrent.torrentLink) {
    return Promise.reject(new Error("no torrentLink"));
  }

  return needle('get', torrent.torrentLink, { open_timeout: 10000 })
      .then((response) => {
        if (!response.body || response.statusCode !== 200) {
          throw new Error('torrent not found')
        }
        return response.body
      })
      .then((body) => parseTorrent(body))
      .then((info) => info.files.map((file, fileId) => ({
        fileIndex: fileId,
        name: file.name,
        path: file.path.replace(/^[^\/]+\//, ''),
        size: file.length
      })));
}

async function filesFromTorrentStream(torrent) {
  if (!torrent.infoHash && !torrent.magnetLink) {
    return Promise.reject(new Error("no infoHash or magnetLink"));
  }
  return new Promise((resolve, rejected) => {
    const engine = new torrentStream(torrent.magnetLink || torrent.infoHash, { connections: MAX_PEER_CONNECTIONS });

    engine.ready(() => {
      const files = engine.files
          .map((file, fileId) => ({
            fileIndex: fileId,
            name: file.name,
            path: file.path.replace(/^[^\/]+\//, ''),
            size: file.length
          }));

      engine.destroy();
      resolve(files);
    });
    setTimeout(() => {
      engine.destroy();
      rejected(new Error('No available connections for torrent!'));
    }, 30000);
  });
}

function isVideo(title) {
  return EXTENSIONS.includes(title.path.match(/\.(\w{2,4})$/)[1]);
}

function dynamicTimeout(torrent) {
  if (torrent.seeders < 5) {
    return 5000;
  } else if (torrent.seeders < 10) {
    return 7000;
  } else if (torrent.seeders < 20) {
    return 10000;
  } else if (torrent.seeders < 30) {
    return 15000;
  } else if (torrent.seeders < 50) {
    return 20000;
  } else {
    return 30000;
  }
}