ruff-check.yml

name: Ruff check on changed files only

on:
  push:
    branches: [main]
  pull_request:
    branches: [main]
  workflow_dispatch:

permissions:
  contents: read

jobs:
  ruff-changed-files:
    runs-on: ubuntu-latest
    
    steps:
      # 1. Checkout entire history for accurate diffs
      - name: Checkout code
        uses: actions/checkout@v4
        with:
          fetch-depth: 0
      
      # 2. Set up Python for Ruff
      - name: Set up Python
        uses: actions/setup-python@v5
        with:
          python-version: '3.12'
      
      # 3. Determine changed Python files
      - name: Get changed Python files
        id: changed-files
        run: |
          if [[ "${{ github.event_name }}" == "pull_request" ]]; then
            BASE_SHA=${{ github.event.pull_request.base.sha }}
            HEAD_SHA=${{ github.event.pull_request.head.sha }}
          else
            BASE_SHA=${{ github.event.before }}
            HEAD_SHA=${{ github.sha }}
          fi
          
          echo "BASE_SHA: $BASE_SHA"
          echo "HEAD_SHA: $HEAD_SHA"
          
          # List all changed .py files
          FILES=$(git diff --name-only --diff-filter=ACMRT $BASE_SHA $HEAD_SHA \
                  | grep -E '\.py$' || true)
          
          # Handle multi-line output properly for GitHub Actions
          if [ -n "$FILES" ]; then
            {
              echo 'files<<EOF'
              echo "$FILES"
              echo 'EOF'
            } >> "$GITHUB_OUTPUT"
            echo "has_files=true" >> "$GITHUB_OUTPUT"
          else
            echo "files=" >> "$GITHUB_OUTPUT"
            echo "has_files=false" >> "$GITHUB_OUTPUT"
          fi
      
      # 4. Install and Run Ruff on changed files, if any
      - name: Run Ruff on changed files
        if: steps.changed-files.outputs.has_files == 'true'
        run: |
          pip install ruff
          echo "Linting the following Python files:"
          echo "${{ steps.changed-files.outputs.files }}"
          
          # Convert multiline string to space-separated for ruff
          FILES_ARGS=$(echo "${{ steps.changed-files.outputs.files }}" | tr '\n' ' ')
          ruff check $FILES_ARGS
      
      # 5. Skip Ruff when no relevant files changed
      - name: Skip Ruff if no files changed
        if: steps.changed-files.outputs.has_files == 'false'
        run: |
          echo "No Python files changed. Skipping Ruff."