name: Commitlint
on:  # yamllint disable-line rule:truthy
  pull_request:
    types:
      - opened
      - synchronize
      - reopened
      - edited
  merge_group:
    branches:
      - main
    types:
      - checks_requested
jobs:
  commit-checks:
    runs-on: ubuntu-latest
    steps:
      - uses: actions/checkout@v3
        with:
          fetch-depth: 0

      - name: Install conventional-commit linter
        run: npm install @commitlint/config-conventional @commitlint/cli

      # Finding the commit range is not as trivial as it may seem.
      #
      # At this stage, git's HEAD does not refer to the latest commit in the
      # PR, but rather to the merge commit inserted by the PR. So instead we
      # have to get 'HEAD' from the PR event.
      #
      # One cannot use the number of commits
      # (github.event.pull_request.commits) to find the start commit
      # i.e. HEAD~N does not work, this breaks if there are merge commits.
      - name: Run commitlint on commits
        run: >-
          npx commitlint --from '${{ github.event.pull_request.base.sha }}'
          --to '${{ github.event.pull_request.head.sha }}' --verbose

      - name: Run commitlint on PR title
        run: |
          echo '${{ github.event.pull_request.title }}' | npx commitlint --verbose