presubmit-cpp.yml

---
name: Presubmit (C++)

on: # yamllint disable-line rule:truthy
  pull_request:
    branches: ["main"]

jobs:
  build-cpp:
    runs-on: ubuntu-latest

    steps:
      - uses: actions/checkout@v4
        with:
          fetch-depth: 0 # Fetch full history for git diff

      - name: Detect changed C++ files
        id: detect-changes
        run: |
          # Get list of changed files
          if [ "${{ github.event_name }}" = "pull_request" ]; then
            # For PR, compare with base branch
            CHANGED_FILES=$(git diff --name-only \
              ${{ github.event.pull_request.base.sha }}..HEAD)
          else
            # For push, compare with previous commit
            if [ "${{ github.event.before }}" = \
              "0000000000000000000000000000000000000000" ]; then
              # First commit in repo
              CHANGED_FILES=$(git diff --name-only --diff-filter=A HEAD)
            else
              CHANGED_FILES=$(git diff --name-only \
                ${{ github.event.before }}..HEAD)
            fi
          fi

          echo "All changed files:"
          echo "$CHANGED_FILES"

          # Filter for C++ files only
          CHANGED_CPP_FILES=$(echo "$CHANGED_FILES" | \
            grep -E '\.(cc|cpp|cxx|c\+\+|h|hpp|hxx|h\+\+)$' || true)

          # Filter for C++ files specifically in the problems directory
          CHANGED_CPP_PROBLEMS_FILES=$(echo "$CHANGED_CPP_FILES" | \
            grep -E '^problems/' || true)

          # Extract unique problem directories from changed C++ files
          CHANGED_PROBLEMS=$(echo "$CHANGED_CPP_PROBLEMS_FILES" | \
            grep -E '^problems/[^/]+/' | cut -d'/' -f2 | \
            sort -u | tr '\n' ' ' || true)

          # Check if Makefile or C++-related config files changed
          CPP_CONFIG_CHANGES=$(echo "$CHANGED_FILES" | \
            grep -E '(Makefile|CMakeLists\.txt|\.clang-format|\.clang-tidy) \
            $' || true)

          # Check if common directory changed (affects all problems)
          COMMON_CHANGES=$(echo "$CHANGED_FILES" | \
            grep -E '^common/' || true)

          echo "Changed C++ files:"
          echo "$CHANGED_CPP_FILES"
          echo "Changed C++ files in problems/:"
          echo "$CHANGED_CPP_PROBLEMS_FILES"
          echo "Changed problems: $CHANGED_PROBLEMS"
          echo "C++ config changes: $CPP_CONFIG_CHANGES"
          echo "Common directory changes: $COMMON_CHANGES"

          # Set outputs
          echo "changed_problems=$CHANGED_PROBLEMS" >> $GITHUB_OUTPUT
          echo "has_cpp_changes=$([ -n "$CHANGED_CPP_PROBLEMS_FILES" ] && \
            echo 'true' || echo 'false')" >> $GITHUB_OUTPUT
          echo "has_cpp_config_changes=$([ -n "$CPP_CONFIG_CHANGES" ] && \
            echo 'true' || echo 'false')" >> $GITHUB_OUTPUT
          echo "has_common_changes=$([ -n "$COMMON_CHANGES" ] && \
            echo 'true' || echo 'false')" >> $GITHUB_OUTPUT
          echo "should_run_all_tests=$([ -n "$CPP_CONFIG_CHANGES" ] || \
            [ -n "$COMMON_CHANGES" ] && echo 'true' || echo 'false')" >> \
             $GITHUB_OUTPUT

      - name: Install dependencies
        if: >
          steps.detect-changes.outputs.has_cpp_changes == 'true' ||
          steps.detect-changes.outputs.has_cpp_config_changes == 'true' ||
          steps.detect-changes.outputs.has_common_changes == 'true'
        run: |
          sudo apt-get update
          sudo apt-get install -y cmake build-essential clang-format clang-tidy
          # Install Google Test from source - most reliable approach
          git clone https://github.com/google/googletest.git --depth 1
          cd googletest
          mkdir build && cd build
          cmake .. -DCMAKE_INSTALL_PREFIX=/usr/local -DBUILD_SHARED_LIBS=ON
          make -j$(nproc)
          sudo make install
          sudo ldconfig

      - name: Debug Google Test configuration
        if: >
          steps.detect-changes.outputs.has_cpp_changes == 'true' ||
          steps.detect-changes.outputs.has_cpp_config_changes == 'true' ||
          steps.detect-changes.outputs.has_common_changes == 'true'
        run: make debug-gtest

      - name: Lint C++ code
        if: steps.detect-changes.outputs.has_cpp_changes == 'true'
        run: make lint-cpp

      - name: Run C++ tests for changed problems
        if: >
          steps.detect-changes.outputs.changed_problems != '' &&
          steps.detect-changes.outputs.should_run_all_tests == 'false'
        run: |
          PROBLEMS="${{ steps.detect-changes.outputs.changed_problems }}"
          echo "Running tests for changed problems: $PROBLEMS"

          for problem in $PROBLEMS; do
            echo "Testing problem: $problem"
            # Convert snake_case to kebab-case for make target
            kebab_case=$(echo "$problem" | sed 's/_/-/g')
            make test-cpp:$kebab_case || exit 1
          done

      - name: Run all C++ tests (dependencies changed)
        if: steps.detect-changes.outputs.should_run_all_tests == 'true'
        run: |
          echo "Running all tests due to C++ configuration or common changes"
          make test-cpp:all

      - name: Clean
        if: always()
        run: make clean

      - name: Summary
        if: always()
        run: |
          echo "## Test Summary" >> $GITHUB_STEP_SUMMARY

          if [ "${{ steps.detect-changes.outputs.has_cpp_changes }}" = \
            "false" ] && \
            [ "${{ steps.detect-changes.outputs.has_cpp_config_changes }}" = \
            "false" ] && \
            [ "${{ steps.detect-changes.outputs.has_common_changes }}" = \
            "false" ]; then
            echo "- No C++ files in problems/ changed - skipped all tasks" >> \
            $GITHUB_STEP_SUMMARY
          elif [ "${{ steps.detect-changes.outputs.should_run_all_tests }}" = \
            "true" ]; then
            if [ "${{ steps.detect-changes.outputs.has_cpp_config_changes }}" \
            = "true" ]; then
              echo "- Ran all tests due to config changes" >> \
              $GITHUB_STEP_SUMMARY
            fi
            if [ "${{ steps.detect-changes.outputs.has_common_changes }}" = \
              "true" ]; then
              echo "- Ran all tests due to common directory changes" >> \
              $GITHUB_STEP_SUMMARY
            fi
          elif [ "${{ steps.detect-changes.outputs.changed_problems }}" != \
            "" ]; then
            problems="${{ steps.detect-changes.outputs.changed_problems }}"
            echo "- Ran targeted tests for: $problems" >> \
            $GITHUB_STEP_SUMMARY
          else
            echo "- No tests needed (no problem files changed)" >> \
            $GITHUB_STEP_SUMMARY
          fi