name: Link Check (lychee)
on: pull_request
jobs:
  link_check:
    name: Link Check
    runs-on: ubuntu-latest
    steps:
      - name: Code checkout
        uses: actions/checkout@v6
        with:
          # Fetch the entire history so git diff can compare against the base branch
          fetch-depth: 0
      - name: Get changed files in PR
        id: changed-files
        uses: tj-actions/changed-files@v47 # Using a dedicated action for robustness
        with:
          # Compare the HEAD of the PR with the merge-base (where the PR branches off)
          base_sha: ${{ github.event.pull_request.base.sha }}

      # NEW STEP: Print all changed-files outputs for verification
      - name: Verify Changed Files
        run: |
          echo "--- tj-actions/changed-files Outputs ---"
          echo "any_changed: ${{ steps.changed-files.outputs.any_changed }}"
          echo "all_changed_files: ${{ steps.changed-files.outputs.all_changed_files }}"
          echo "added_files: ${{ steps.changed-files.outputs.added_files }}"
          echo "modified_files: ${{ steps.changed-files.outputs.modified_files }}"
          echo "deleted_files: ${{ steps.changed-files.outputs.deleted_files }}"
          echo "renamed_files: ${{ steps.changed-files.outputs.renamed_files }}"
          echo "----------------------------------------"
          # This will also show if the all_changed_files string is empty or not
          if [ -n "${{ steps.changed-files.outputs.all_changed_files }}" ]; then
            echo "Detected changes: all_changed_files output is NOT empty."
          else
            echo "No changes detected: all_changed_files output IS empty."
          fi
      - name: Link Availability Check (Diff Only)
        # MODIFIED: Only run lychee if the 'all_changed_files' output is not an empty string
        if: ${{ steps.changed-files.outputs.all_changed_files != '' }}
        uses: lycheeverse/lychee-action@master
        with:
          # Pass the space-separated list of changed files to lychee
          args: --verbose --config .lychee.toml ${{ steps.changed-files.outputs.all_changed_files }}
          failIfEmpty: false
          fail: true