check-links.yaml

name: check-links
on:
  push:
    branches: [main]
  pull_request:
  merge_group:
    types: [checks_requested]

concurrency:
  group: ${{ github.workflow }}-${{ github.head_ref }}
  cancel-in-progress: true

permissions:
  contents: read

jobs:
  changedfiles:
    name: changed files
    runs-on: ubuntu-latest
    env:
      PR_HEAD: ${{ github.event.pull_request.head.sha }}
    outputs:
      files: ${{ steps.changes.outputs.files }}
    steps:
      - name: Checkout Repo
        uses: actions/checkout@11bd71901bbe5b1630ceea73d27597364c9af683 # v4.2.2
        with:
          fetch-depth: 0
      - name: Get changed files
        id: changes
        run: |
            files=$(git diff --name-only --diff-filter=ACMRTUXB $(git merge-base origin/main $PR_HEAD) $PR_HEAD | grep .md$ | xargs)
            
            if [ -z "$files" ] && git diff --name-only $(git merge-base origin/main $PR_HEAD) $PR_HEAD | grep -q "package.json"; then
              files="**/*.md"
            fi

            echo "files=$files" >> $GITHUB_OUTPUT
  check-links:
    runs-on: ubuntu-latest
    needs: changedfiles
    if: ${{needs.changedfiles.outputs.files}}
    steps:
      - name: Checkout Repo
        uses: actions/checkout@11bd71901bbe5b1630ceea73d27597364c9af683 # v4.2.2
        with:
          fetch-depth: 0

      - name: Install markdown-link-check
        run: npm install

      - name: Run markdown-link-check
        run: |
          npx --no -- markdown-link-check \
            --verbose \
            --config .github/workflows/check_links_config.json \
            ${{needs.changedfiles.outputs.files}} \
            || { echo "Check that anchor links are lowercase"; exit 1; }