watcher-ts/packages/solidity-mapper/src/logs.ts

import { JsonFragment } from '@ethersproject/abi';
import { utils } from 'ethers';

interface EventNameTopics {
  [eventName: string]: string
}

/**
 * Function to get event name topics from abi.
 * @param abi
 */
export const getEventNameTopics = (abi: JsonFragment[]): EventNameTopics => {
  const eventFragments = abi.filter(({ type }) => type === 'event');

  return eventFragments.reduce((acc: EventNameTopics, { name, inputs }) => {
    if (inputs && name) {
      const inputParamsString = inputs.map(({ type }) => type)
        .join(',');

      const signature = utils.keccak256(utils.toUtf8Bytes(`${name}(${inputParamsString})`));
      acc[name] = signature;
    }

    return acc;
  }, {});
};