//
// Copyright (C) Stanislaw Adaszewski, 2020
// Contact: s.adaszewski@gmail.com
// Website: https://adared.ch/wba
// License: GNU Affero General Public License, Version 3
//

import makeArvadosRequest from 'make-arvados-request';

function rdvHash(serviceId, locator) {
  let blockHash = /^[0-9a-f]{32}/.exec(locator);
  if (!blockHash)
    throw Error('Invalid locator');
  if (typeof(serviceId) !== 'string')
    throw Error('Invalid service ID');
  let res = CryptoJS.MD5(serviceId + blockHash).toString();
  return res;
}

function wbDownloadFile(arvHost, arvToken,
  manifestReader, path) {

  const file = manifestReader.getFile(path);
  const name = path.split('/').reverse()[0];
  const blockRefs = file[0];
  let services;

  let prom = makeArvadosRequest(arvHost, arvToken,
    '/arvados/v1/keep_services/accessible');
  prom = prom.then(xhr => (services = xhr.response['items']));

  const blocks = [];
  for (let i = 0; i < blockRefs.length; i++) {
    prom = prom.then(() => {
      const [ locator, position, size ] = blockRefs[i];
      const weights = services.map(s => rdvHash(s['uuid'], locator));
      const order = Object.keys(services).sort((a, b) => weights[b].localeCompare(weights[a]));
      const orderedServices = order.map(i => services[i]);

      let k = 0;
      const cb = () => {
        if (k >= orderedServices.length)
          throw Error('Block not found');

        const svc = orderedServices[k];
        k++;

        let prom_1 = makeArvadosRequest(svc.service_host +
          ':' + svc.service_port, arvToken,
          '/' + locator, { 'useSsl': svc.service_ssl_flag,
          'responseType': 'arraybuffer' });
        //prom_1 = prom_1.then(xhr => xhr.response);
        prom_1 = prom_1.catch(cb);

        return prom_1;
      };

      return cb().then(xhr => (blocks.append(xhr.response.slice(position, size))));
    });
  }

  prom = prom.then(() => {
    const blob = new Blob(blocks);
    const url = window.URL.createObjectURL(blob);
    const a = document.createElement('a');
    a.href = url;
    a.download = name;

  });
}

export default wbDownloadFile;