balanceofsatoshis/telegram/get_socks_proxy.js

const asyncAuto = require('async/auto');
const {returnResult} = require('asyncjs-util');

const {parse} = JSON;

/** Get a SOCKS proxy given a JSON configuration file path
  {
    fs: {
      getFile: <Get File From Filesystem Function>
    }
    path: <Path To Proxy Configuration JSON File String>
  }

  @returns via cbk or Promise
  {
    agent: <Socks Proxy Agent Object>
  }
*/
module.exports = ({fs, path}, cbk) => {
  return new Promise((resolve, reject) => {
    return asyncAuto({
      // Check arguments
      validate: cbk => {
        if (!fs) {
          return cbk([400, 'ExpectedFileSystemMethodsToGetSocksProxyAgent']);
        }

        if (!path) {
          return cbk([400, 'ExpectedPathToSocksJsonFileToGetSocksProxyAgent']);
        }

        return cbk();
      },

      // Import socks-proxy-agent as ESM
      getSocksAgent: ['validate', async ({}) => {
        try {
          const {SocksProxyAgent} = await import('socks-proxy-agent');

          return SocksProxyAgent;
        } catch (err) {
          throw([503, 'FailedToImportSocksProxyAgent', {err}]);
        }
      }],

      // Get the configuration file
      getFile: ['validate', ({}, cbk) => {
        return fs.getFile(path, (err, res) => {
          if (!!err) {
            return cbk([400, 'FailedToFindFileAtProxySpecifiedPath', {err}]);
          }

          if (!res) {
            return cbk([400, 'ExpectedFileDataAtProxySpecifiedPath']);
          }

          return cbk(null, res.toString());
        });
      }],

      // Construct the SOCKS proxy agent
      agent: ['getFile', 'getSocksAgent', ({getFile, getSocksAgent}, cbk) => {
        try {
          parse(getFile);
        } catch (err) {
          return cbk([400, 'ExpectedValidJsonConfigFileForProxy', {err}]);
        }

        const {host, password, port, userId} = parse(getFile);

        try {
          if (!host) {
            throw new Error('ExpectedProxyHostAddressToCreateSocksProxy');
          }

          const url = new URL(`socks://${host}`);

          if (!!password) {
            url.password = password;
          }

          if (!!port) {
            url.port = port;
          }

          if (!!userId) {
            url.username = userId;
          }

          const agent = new getSocksAgent(url.toString());

          return cbk(null, {agent});
        } catch (err) {
          return cbk([503, 'FailedToCreateSocksProxyAgent', {err}]);
        }
      }],
    },
    returnResult({reject, resolve, of: 'agent'}, cbk));
  });
};