name: sanity-check opened PRs

on:
  # needs read/write GH token, do *not* execute arbitrary code from PR
  pull_request_target:
    types: [opened]

jobs:
  check-pr:
    runs-on: ubuntu-latest
    steps:
      - name: Check Commit Message
        uses: actions/github-script@v3
        with:
          github-token: ${{ secrets.GITHUB_TOKEN }}
          script: |
            const { data: commits } = await github.pulls.listCommits({
              owner: context.repo.owner,
              repo: context.repo.repo,
              pull_number: context.issue.number,
            });
            console.log(commits[0].commit.message);
            // check first commit only (and only once) since later commits might be intended to be squashed away
            if (!/^(feat|fix|doc|style|refactor|test|chore|perf): .*[^.]($|\n\n)/.test(commits[0].commit.message)) {
              await github.issues.createComment({
                owner: context.repo.owner,
                repo: context.repo.repo,
                issue_number: context.issue.number,
                body: 'Thanks for your contribution! Please make sure to follow our [Commit Convention](https://leanprover.github.io/lean4/doc/dev/commit_convention.html).',
              });
            }