name: Changelog
on:
  pull_request:
    types:
      - opened
      - reopened
      - synchronize
      - labeled
      - unlabeled
    branches:
      - main

jobs:
  towncrier:
    name: Towncrier
    runs-on: ubuntu-latest
    # skip if this is a bot or the PR has the skip-changelog label
    # note that the towncrier check command can recognize a release PR, by looking
    # for changes to the CHANGELOG.md file.
    if: |
      !(
           github.event.pull_request.user.login == 'dependabot[bot]'
        || contains(github.event.pull_request.labels.*.name, 'skip-changelog')
      )
    steps:
    - uses: actions/checkout@v4
    - name: Install Poetry
      run: pipx install poetry
    - name: Setup Python
      id: setup-python
      uses: actions/setup-python@v5
      with:
        python-version: '3.x'
        cache: poetry
    - name: Install development tools
      run: poetry install --no-root --only=dev
    - name: Check for a towncrier fragment
      run: |
        # fetch enough commits from this merge commit to the base sha to ensure
        # towncrier can inspect what changed
        while [[ -z $(git merge-base $PR_BASE_SHA HEAD 2> /dev/null) ]]; do
          git fetch --quiet --deepen=50 --no-tags --no-recurse-submodules origin $PR_BASE_SHA HEAD
        done
        if poetry run towncrier check --compare-with $PR_BASE_SHA; then
          gh pr edit "$PR_URL" --add-label "changelog-provided"
        else
          gh pr edit "$PR_URL" --remove-label "changelog-provided"
          exit 1
        fi

      env:
        PR_BASE_SHA: ${{github.event.pull_request.base.sha}}
        PR_URL: ${{github.event.pull_request.html_url}}
        GITHUB_TOKEN: ${{secrets.GITHUB_TOKEN}}