index.js

import fetch from 'node-fetch';
import { getInput, setFailed } from '@actions/core';
import { context } from '@actions/github';
import { Octokit } from '@octokit/core';
import * as core from '@actions/core';

async function run() {
  try {
    const githubToken = getInput('github-token');
    const octokit = new Octokit({ auth: githubToken });

    const comment = context.payload.comment || context.payload.review;
    if (!comment) {
      core.debug('No comment or review body found.');
      return;
    }

    if (!(comment.body || '').toLowerCase().match(/lgtm/)) {
      core.debug('nothing to do.');
      return;
    }

    switch (context.eventName) {
      case 'issue_comment':
        break;
      case 'pull_request_review':
        if (context.payload.review.state !== 'approved') {
          core.debug('nothing to do.');
          return;
        }
        break;
      case 'pull_request_review_comment':
        break;
      default:
        core.debug('nothing to do.');
        return;
    }

    fetch('https://lgtmoon.herokuapp.com/api/images/random')
      .then(response => {
        return response.json();
      })
      .then(data => {
        const imageUrl = data.images[0].url;

        if (
          context.eventName === 'issue_comment' ||
          context.eventName === 'pull_request_review'
        ) {
          octokit.request(
            'POST /repos/{owner}/{repo}/issues/{issue_number}/comments',
            {
              issue_number: context.issue.number,
              owner: context.repo.owner,
              repo: context.repo.repo,
              body: `![](${imageUrl})`,
            },
          );
        } else if (context.eventName === 'pull_request_review_comment') {
          octokit.request(
            'POST /repos/{owner}/{repo}/pulls/{pull_number}/comments/{comment_id}/replies',
            {
              owner: context.repo.owner,
              repo: context.repo.repo,
              body: `![](${imageUrl})`,
              pull_number: context.payload.pull_request.number,
              comment_id: context.payload.comment.id,
            },
          );
        }
      });
  } catch (error) {
    setFailed(error.message);
  }
}

run();