name: Check formatting

on:
  pull_request:
    paths:
      - '**'
      - '!.gitignore'
      - '!*.md'
      - '!.github/**'
      - '.github/workflows/clang-format.yml'

permissions:
  contents: read
  pull-requests: write

jobs:
  format-check:
    runs-on: ubuntu-latest
    steps:
      - uses: actions/checkout@v6
        with:
          ref: ${{ github.event.pull_request.head.sha }}
          fetch-depth: 0
 
      - name: Fetch base commit
        run: git fetch origin ${{ github.event.pull_request.base.sha }}
 
      - name: Install clang-format-20
        run: |
          wget -qO- https://apt.llvm.org/llvm-snapshot.gpg.key | sudo tee /etc/apt/trusted.gpg.d/apt.llvm.org.asc
          sudo add-apt-repository -y "deb http://apt.llvm.org/noble/ llvm-toolchain-noble-20 main"
          sudo apt-get install -y -qq clang-format-20
 
      - uses: reviewdog/action-setup@v1
 
      - name: Check formatting on changed lines
        env:
          REVIEWDOG_GITHUB_API_TOKEN: ${{ secrets.GITHUB_TOKEN }}
        run: |
          git clang-format-20 --binary clang-format-20 \
            --diff ${{ github.event.pull_request.base.sha }} -- \
            '*.c' '*.cpp' '*.cc' '*.h' '*.hpp' \
            | reviewdog \
                -name="clang-format" \
                -f=diff \
                -reporter=github-pr-check \
                -fail-level=error \
                -filter-mode=added