name: Build 'cts.json'
on:
  push:
    branches:
      - main
  pull_request:

jobs:
  build-cts:
    runs-on: ubuntu-latest

    permissions:
      # Allow the job to push the changed file to the repository
      # For pull requests from forks this seems to be implicitly changed to 'read', as desired, see
      # https://docs.github.com/en/actions/security-guides/automatic-token-authentication#how-the-permissions-are-calculated-for-a-workflow-job
      contents: write

    steps:
    - uses: actions/checkout@v4

    - name: Setup Node.js
      id: setup-node
      uses: actions/setup-node@v4
      with:
        node-version: 'lts/*'

    - name: Run build
      run: ./build.sh

    # To be safe, verify that either there are no changes or only `cts.json` has changed
    - name: Verify no unexpected changes
      run: |
        # Check for changes to any file other than `cts.json`,
        # see https://stackoverflow.com/a/29374503
        # Note that this does not detect new untracked files
        if ! git diff --exit-code --quiet -- . ':!cts.json'; then
          echo "Unexpected changes:"
          git diff -- . ':!cts.json'
          exit 1
        fi

    # Commit and push changes; has no effect if the file did not change
    # Important: The push event will not trigger any other workflows, see
    # https://github.com/stefanzweifel/git-auto-commit-action?tab=readme-ov-file#commits-made-by-this-action-do-not-trigger-new-workflow-runs
    - name: Commit & push changes
      # Only run for push events on `main` branch
      if: github.event_name == 'push' && github.ref == 'refs/heads/main'
      uses: stefanzweifel/git-auto-commit-action@v5
      with:
        commit_message: 'Update `cts.json`'
        file_pattern: 'cts.json'