name: Validate pull request

on:
  pull_request_target:
    types: [opened, synchronize, edited]

permissions:
  contents: read
  pull-requests: write

jobs:
  check-pr:
    name: Commit subject lines
    runs-on: ubuntu-latest
    steps:
      - name: Run validation script
        uses: actions/github-script@v8
        with:
          github-token: ${{ secrets.GITHUB_TOKEN }}
          script: |
            const pullRequest = {
              pull_number: context.issue.number,
              owner: context.repo.owner,
              repo: context.repo.repo,
            };

            const { data: commits } = await github.rest.pulls.listCommits(pullRequest);
            const { data: reviews } = await github.rest.pulls.listReviews(pullRequest);

            // Get latest review by `github-actions[bot]`
            const githubActionsBot = 41898282;
            const latestReview = reviews
              .filter(r => r.user.id === githubActionsBot)
              .at(-1);

            // Ensure commit subject lines are in the form `area or areas: Description`
            const subjectLineFormat = /^.+:\s.+$/;
            const badCommits = commits
              .map(c => [c.sha.slice(0, 8), c.commit.message.split('\n')[0]])
              .filter(([_, s]) => !subjectLineFormat.test(s))
              .map(([sha, title]) => `- ${sha}: ${title}`);

            if (badCommits.length > 0) {
              // One or commits are bad, make sure changes are requested.
              const body = 'The following commits do not follow our format for subject lines:\n\n'
                + `${badCommits.join('\n')}\n\nCommits should have a subject line following the `
                + 'format `<topic>: <description>`. Please review the [commit guidelines]'
                + '(https://jj-vcs.github.io/jj/prerelease/contributing/#commit-guidelines) for '
                + 'more information.';

              if (latestReview?.state !== 'CHANGES_REQUESTED') {
                await github.rest.pulls.createReview({
                  event: 'REQUEST_CHANGES',
                  ...pullRequest,
                  body,
                });
              }
              else {
                await github.rest.pulls.updateReview({
                  review_id: latestReview.id,
                  ...pullRequest,
                  body,
                });
              }

              await core.setFailed('One or more commits were not formatted correctly.');
            }
            else {
              // All commits are formatted correctly, dismiss any change requests.
              if (latestReview && latestReview.state === 'CHANGES_REQUESTED') {
                await github.rest.pulls.dismissReview({
                  message: 'All commits are now correctly formatted. Thank you for your contribution!',
                  review_id: latestReview.id,
                  ...pullRequest,
                });
              }

              console.log('All commits were correctly formatted.');
            }