name: Block Forbidden Workflow Contribution Files

on:
  pull_request:
    branches: [staged]
    types: [opened, synchronize, reopened]
    paths:
      - "workflows/**"

permissions:
  contents: read
  pull-requests: write

jobs:
  check-forbidden-files:
    runs-on: ubuntu-latest
    steps:
      - name: Checkout code
        uses: actions/checkout@v4
        with:
          fetch-depth: 0

      - name: Check for forbidden files in workflows/
        id: check
        run: |
          # Check for YAML/lock files in workflows/ and any .github/ modifications
          forbidden=$(git diff --name-only --diff-filter=ACM origin/${{ github.base_ref }}...HEAD -- \
            'workflows/**/*.yml' \
            'workflows/**/*.yaml' \
            'workflows/**/*.lock.yml' \
            '.github/*' \
            '.github/**')

          if [ -n "$forbidden" ]; then
            echo "❌ Forbidden files detected:"
            echo "$forbidden"
            echo "files<<EOF" >> "$GITHUB_OUTPUT"
            echo "$forbidden" >> "$GITHUB_OUTPUT"
            echo "EOF" >> "$GITHUB_OUTPUT"
            exit 1
          else
            echo "✅ No forbidden files found in workflows/"
          fi

      - name: Comment on PR
        if: failure()
        uses: marocchino/sticky-pull-request-comment@v2
        with:
          header: workflow-forbidden-files
          message: |
            ## 🚫 Forbidden files in `workflows/`

            Only `.md` markdown files are accepted in the `workflows/` directory. The following are **not allowed**:
            - Compiled workflow files (`.yml`, `.yaml`, `.lock.yml`) — could contain untrusted Actions code
            - `.github/` modifications — workflow contributions must not modify repository configuration

            **Files that must be removed:**
            ```
            ${{ steps.check.outputs.files }}
            ```

            Contributors provide the workflow **source** (`.md`) only. Compilation happens downstream via `gh aw compile`.

            Please remove these files and push again.