trufflesuite/truffle

const TruffleError = require("@truffle/error");

// HACK: string comparison seems to be only way to identify being unable to
// connect to RPC node.
const NOT_CONNECTED_MESSAGE = 'Invalid JSON RPC response: ""';

class ProviderError extends TruffleError {
  constructor(message, options) {
    if (message === NOT_CONNECTED_MESSAGE) {
      message = buildMessage(options);
    }
    super(message);

    // important fields from RPC error responses, should be retained
    // see: https://www.jsonrpc.org/specification#error_object
    if (options && options.underlyingError && options.underlyingError.code !== undefined) {
      this.code = options.underlyingError.code;
    }

    if (options && options.underlyingError && options.underlyingError.data) {
      this.data = options.underlyingError.data;
    }
  }
}

const buildMessage = options => {
  const { host, port, network_id } = options;
  let message;
  if (host) {
    message =
      "\nCould not connect to your Ethereum client with the following parameters:\n" +
      `    - host       > ${host}\n` +
      `    - port       > ${port}\n` +
      `    - network_id > ${network_id}\n`;
  } else {
    message = "\nCould not connect to your Ethereum client.\n";
  }

  message +=
    "Please check that your Ethereum client:\n" +
    "    - is running\n" +
    '    - is accepting RPC connections (i.e., "--rpc" or "--http" option is used in geth)\n' +
    "    - is accessible over the network\n" +
    "    - is properly configured in your Truffle configuration file (truffle-config.js)\n";
  return message;
};

module.exports = ProviderError;