clang-format.yml

name: clang-format-check

on:
  pull_request:
    types: [opened, synchronize]
    branches:
      - main
  workflow_dispatch:

jobs:
  format-check:
    runs-on: ubuntu-latest

    steps:
      - name: Checkout code
        uses: actions/checkout@v4
        with:
          fetch-depth: 0  # Fetch all commits of the pull request branch


      - name: Install clang-format
        run: sudo apt-get install -y clang-format

      - name: Download clang-format-diff.py
        run: |
          wget https://raw.githubusercontent.com/llvm/llvm-project/main/clang/tools/clang-format/clang-format-diff.py
          chmod +x clang-format-diff.py

      # get names of the base and pr branches
      - name: Get the base and head branches
        id: fetchstep
        run: |
          echo "BASE_BRANCH=${{ github.event.pull_request.base.ref }}" >> $GITHUB_ENV
          echo "HEAD_BRANCH=${{ github.event.pull_request.head.ref }}" >> $GITHUB_ENV
          echo "Base branch: $BASE_BRANCH"
          echo "Head branch: $HEAD_BRANCH"
          git fetch origin ${{ env.BASE_BRANCH }}
          git fetch origin ${{ env.HEAD_BRANCH }}

      #get differences on the PR branch excluding generated folder in the root
      - name: git diff
        id: diffstep
        env:
          ACTIONS_RUNNER_DEBUG: true
        run: |
          # Format only the changed lines using clang-format-diff.py
          set -e
          git diff -U0 --no-color origin/${{ env.BASE_BRANCH }}...origin/${{ env.HEAD_BRANCH }} -- . ':!generated/' > diff_output.patch
          cat diff_output.patch
          
      # run formatter on the differences if any
      - name: format diff
        id: formatstep
        env:
          ACTIONS_RUNNER_DEBUG: true
        run: |
          clang-format --version
          if [ -s diff_output.patch ]; then
            python3 clang-format-diff.py -p1 -style=file:.clang-format < diff_output.patch > formatted_differences.patch 2> error.log || true
            if [ -s error.log ]; then
              echo "Errors from clang-format-diff.py:"
              cat error.log
            else
              echo "No Errors from clang-format-diff.py"
            fi
            rm diff_output.patch
          fi

      # check if differences found after formatting, then exit 
      - name: Check formatting needed
        id: validatestep
        env:
          ACTIONS_RUNNER_DEBUG: true
        run: |
          if [ -s formatted_differences.patch ]; then
            echo "Formatting issues found!. Formatted changes:"
            cat formatted_differences.patch
            rm formatted_differences.patch
            exit 1
          fi