name: cleanup-branch-caches
on:
  pull_request_target:
    types:
      - closed
  workflow_dispatch:

jobs:
  cleanup:
    runs-on: ubuntu-latest
    permissions:
      # `actions:write` permission is required to delete caches
      #   See also: https://docs.github.com/en/rest/actions/cache?apiVersion=2022-11-28#delete-a-github-actions-cache-for-a-repository-using-a-cache-id
      actions: write
      contents: read
    steps:
      - name: Check out code
        uses: actions/checkout@9c091bb21b7c1c1d1991bb908d89e4e9dddfe3e0 # v7.0.0
        with:
          persist-credentials: false

      - name: Cleanup
        run: |
          gh extension install actions/gh-actions-cache

          REPO="${{ github.repository }}"
          BRANCH="refs/pull/${{ github.event.pull_request.number }}/merge"

          echo "Fetching list of cache key"
          cacheKeysForPR=$(gh actions-cache list -R "$REPO" -B "$BRANCH" | cut -f 1 )

          # set this to not fail the workflow while deleting cache keys
          set +e
          echo "Deleting caches..."
          for cacheKey in $cacheKeysForPR
          do
            gh actions-cache delete "$cacheKey" -R "$REPO" -B "$BRANCH" --confirm
          done
          echo "Done"
        env:
          GH_TOKEN: ${{ secrets.GITHUB_TOKEN }}