name: Documentation preview cleanup

# Removes the per-PR documentation preview published by docs.yml under
# gh-pages:preview/pr-<number>/ once the pull request is closed (merged or not).
#
# Deliberately has no `paths` filter: docs.yml only publishes a preview when
# documentation-related files changed, but this must fire for every close so a
# preview can never be orphaned on the branch.
on:
  pull_request:
    types: [closed]

permissions:
  contents: read

jobs:
  cleanup:
    name: Remove PR preview
    # Forks never get a preview (their token is read-only), so nothing to clean.
    if: github.event.pull_request.head.repo.full_name == github.repository
    runs-on: ubuntu-24.04

    # Same group as docs.yml's publish job: both push to gh-pages, and two
    # concurrent pushes would collide.
    concurrency:
      group: gh-pages-publish
      cancel-in-progress: false

    permissions:
      contents: write

    steps:
      - name: Checkout gh-pages
        uses: actions/checkout@v4
        with:
          ref: gh-pages
          fetch-depth: 1

      - name: Remove preview directory
        env:
          PREVIEW_DIR: preview/pr-${{ github.event.number }}
        run: |
          set -eux
          if [[ ! -d "${PREVIEW_DIR}" ]]; then
            echo "No preview at ${PREVIEW_DIR}, nothing to do."
            exit 0
          fi
          git config user.name 'github-actions[bot]'
          git config user.email 'github-actions[bot]@users.noreply.github.com'
          git rm -r --quiet "${PREVIEW_DIR}"
          # Drop the parent too once the last preview is gone.
          rmdir preview 2>/dev/null || true
          git commit -m "Remove preview for PR #${{ github.event.number }}"
          git push