check-copyright-header.yml

name: Verify copyright year in modified files

on:
  pull_request:
  push:
    branches: [ main ]

jobs:
  copyright-check:
    runs-on: ubuntu-latest
    steps:
      - name: Checkout repository
        uses: actions/checkout@v4
        with:
          fetch-depth: 0

      - name: Verify copyright year in modified files
        shell: bash
        run: |
          set -euo pipefail

          CURRENT_YEAR="$(date +%Y)"

          # Determine base ref
          if [[ "${{ github.event_name }}" == "pull_request" ]]; then
            BASE_REF="origin/${{ github.base_ref }}"
          else
            BASE_REF="$(git rev-parse HEAD~1)"
          fi

          MODIFIED_FILES=$(git diff --name-only "$BASE_REF"...HEAD)

          FAIL=0

          for file in $MODIFIED_FILES; do
            # Skip deleted or non-regular files
            [[ -f "$file" ]] || continue

            # Only check Python files
            [[ "$file" == *.py ]] || continue

            # Only inspect the header (first 20 lines)
            if ! head -n 1 "$file" | grep -Eqi "# Copyright.*${CURRENT_YEAR}"; then
              echo "ERROR: $file does not contain a ${CURRENT_YEAR} copyright notice in the header"
              FAIL=1
            fi
          done

          if [[ "$FAIL" -ne 0 ]]; then
            exit 1
          fi