name: "Lint Commit Message Size"

on:
  pull_request:
    types: [opened, synchronize, reopened]

jobs:
  check-commit-bounds:
    runs-on: ubuntu-latest
    steps:
      - name: Check out code
        uses: actions/checkout@v4
        with:
          fetch-depth: 0

      - name: Validate Line Count, Width, and Spacing
        run: |
          # Fetch commit hashes unique to this PR branch
          COMMITS=$(git log --no-merges --pretty=format:"%H" origin/${{ github.base_ref }}..HEAD)

          MAX_LINES=3
          MAX_CHARS=90
          FAILED=0

          for commit in $COMMITS; do
            SUBJECT=$(git log --format="%s" -n 1 $commit)

            # Extract clean commit message, trimming trailing blank lines
            RAW_MSG=$(git log --format="%B" -n 1 $commit)
            CLEAN_MSG=$(echo "$RAW_MSG" | awk '{msg[NR]=$0} END {while(NR>0 && msg[NR]=="") NR--; for(i=1;i<=NR;i++) print msg[i]}')

            # 1. Check total line count
            LINE_COUNT=$(echo "$CLEAN_MSG" | wc -l)
            if [ "$LINE_COUNT" -gt "$MAX_LINES" ]; then
              echo "❌ Error: Commit message has too many lines ($LINE_COUNT/$MAX_LINES)."
              echo "   Commit: '$SUBJECT'"
              FAILED=1
            fi

            # 2. Check for multiple consecutive blank lines
            # This regex looks for 2 or more empty lines anywhere in the message
            if echo "$CLEAN_MSG" | grep -pz '(\r?\n){3,}'; then
              echo "❌ Error: Commit message contains multiple consecutive line breaks."
              echo "   Commit: '$SUBJECT'"
              FAILED=1
            fi

            # 3. Check maximum width of any individual line
            while IFS= read -r line; do
              LINE_LENGTH=${#line}
              if [ "$LINE_LENGTH" -gt "$MAX_CHARS" ]; then
                echo "❌ Error: Line length exceeds limit ($LINE_LENGTH / $MAX_CHARS chars)."
                echo "   Offending line: '$line'"
                FAILED=1
              fi
            done <<< "$CLEAN_MSG"

          done

          # Fail the job if any check failed
          if [ "$FAILED" -ne 0 ]; then
            exit 1
          fi

          echo "✅ All commit messages passed style rules!"