polkadot-js/api

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packages/rpc-provider/src/coder/index.ts

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// Copyright 2017-2022 @polkadot/rpc-provider authors & contributors
// SPDX-License-Identifier: Apache-2.0

import type { JsonRpcRequest, JsonRpcResponse, JsonRpcResponseBaseError } from '../types';

import { isNumber, isString, isUndefined, stringify } from '@polkadot/util';

import RpcError from './error';

function formatErrorData (data?: string | number): string {
  if (isUndefined(data)) {
    return '';
  }

  const formatted = `: ${isString(data)
    ? data.replace(/Error\("/g, '').replace(/\("/g, '(').replace(/"\)/g, ')').replace(/\(/g, ', ').replace(/\)/g, '')
    : stringify(data)}`;

  // We need some sort of cut-off here since these can be very large and
  // very nested, pick a number and trim the result display to it
  return formatted.length <= 256
    ? formatted
    : `${formatted.substring(0, 255)}…`;
}

function checkError (error?: JsonRpcResponseBaseError): void {
  if (error) {
    const { code, data, message } = error;

    throw new RpcError(`${code}: ${message}${formatErrorData(data)}`, code, data);
  }
}

/** @internal */
export class RpcCoder {
  #id = 0;

  public decodeResponse (response?: JsonRpcResponse): unknown {
    if (!response || response.jsonrpc !== '2.0') {
      throw new Error('Invalid jsonrpc field in decoded object');
    }

    const isSubscription = !isUndefined(response.params) && !isUndefined(response.method);

    if (
      !isNumber(response.id) &&
      (
        !isSubscription || (
          !isNumber(response.params.subscription) &&
          !isString(response.params.subscription)
        )
      )
    ) {
      throw new Error('Invalid id field in decoded object');
    }

    checkError(response.error);

    if (response.result === undefined && !isSubscription) {
      throw new Error('No result found in jsonrpc response');
    }

    if (isSubscription) {
      checkError(response.params.error);

      return response.params.result;
    }

    return response.result;
  }

  public encodeJson (method: string, params: unknown[]): [number, string] {
    const [id, data] = this.encodeObject(method, params);

    return [id, stringify(data)];
  }

  public encodeObject (method: string, params: unknown[]): [number, JsonRpcRequest] {
    const id = ++this.#id;

    return [id, {
      id,
      jsonrpc: '2.0',
      method,
      params
    }];
  }
}