gh_pr_auto_updater.yml

name: '[gh] pull request auto updater'

on:
  pull_request_target:
    types:
      - auto_merge_enabled
  push:

jobs:
  up_to_date:
    if: github.repository == 'Tencent/Hippy'
    runs-on: ubuntu-latest
    steps:
    - name: Updater
      uses: actions/github-script@v6.3.3
      with:
        # Because the Github App Token, Github Token, and Fine-grained PAT
        # cannot obtain the permission to update the workflow files in the head branch,
        # so use classic PAT to avoid failures caused by modification of workflow files.
        # TODO: use Github App Token or Github Token if permission is granted in the future.
        github-token: ${{ secrets.BOT_PAT }}
        script: |
          const { pulls, repos } = github.rest;

          let pull_requests;
          switch (context.eventName) {
            case 'push': {
              pull_requests = (await github.paginate(pulls.list, {
                per_page: 100,
                state: 'open',
                base: '${{ github.ref_name }}',
                ...context.repo
              })).filter(pull => pull.draft === false && pull.auto_merge);
              break;
            }
            case 'pull_request_target': {
              const { pull_request } = context.payload;
              if (pull_request.draft === true) {
                return;
              }
              pull_requests = [pull_request];
              break;
            }
            default: {
              throw new Error(`Unsupported event name: ${context.eventName}`);
              break;
            }
          }

          await Promise.all(
            pull_requests.map(pull =>
              repos.compareCommitsWithBasehead({
                ...context.repo,
                basehead: `${pull.base.label}...${pull.head.label}`,
              }).then(({ data: comparison }) => {
                if (comparison.behind_by > 0) {
                  return pulls.updateBranch({
                    ...context.repo,
                    pull_number: pull.number
                  }).catch(error => console.error(error));
                }
              })
            )
          );