validate-pull-request-conventions.yml

name: Validate Pull Request Conventions

on:
  pull_request:
    types: [opened, synchronize, reopened, edited, labeled, unlabeled]

permissions:
  contents: read
  pull-requests: write

jobs:
  check-conventions:
    name: Validate Pull Request and Git Conventions
    runs-on: ubuntu-latest

    steps:
      - name: Checkout code
        uses: actions/checkout@v4
        with:
          fetch-depth: 0
          ref: ${{ github.event.pull_request.head.sha }}

      - name: Check pull request title
        if: always()
        env:
          PULL_REQUEST_TITLE: ${{ github.event.pull_request.title }}
        run: |
          EXIT_CODE=0

          if [[ ! "${PULL_REQUEST_TITLE:0:1}" =~ [A-Z] ]]; then
            echo "❌ Pull request title does not start with a capital letter"
            echo "   Title: $PULL_REQUEST_TITLE"
            EXIT_CODE=1
          fi

          if [[ "$PULL_REQUEST_TITLE" =~ \.$ ]] && ! [[ "$PULL_REQUEST_TITLE" =~ (etc\.)$ ]]; then
            echo "❌ Pull request title ends with a period"
            echo "   Title: $PULL_REQUEST_TITLE"
            EXIT_CODE=1
          fi

          if echo "$PULL_REQUEST_TITLE" | grep -P '\. [A-Z]' | grep -vP '(incl\.|e\.g\.|etc\.|i\.e\.) [A-Z]' > /dev/null; then
            echo "❌ Pull request title contains multiple sentences"
            echo "   Title: $PULL_REQUEST_TITLE"
            EXIT_CODE=1
          fi

          if [[ "${PULL_REQUEST_TITLE,,}" =~ ^[[:alnum:]]{1,4}[[:space:]][0-9]+ ]]; then
            echo "❌ Pull request title cannot be a default branch name format like:"
            echo "   'Pp ###', 'Dev ###', 'M42 ###', etc."
            echo "   Please update the title to describe the changes being made"
            EXIT_CODE=1
          fi

          if [[ "$EXIT_CODE" -eq 0 ]]; then
            echo "✅ The pull request title looks valid"
          fi
          exit $EXIT_CODE

      - name: Check pull request description
        if: always()
        env:
          PULL_REQUEST_BODY: ${{ github.event.pull_request.body }}
          GITHUB_TOKEN: ${{ github.token }}
          PULL_REQUEST_NUMBER: ${{ github.event.pull_request.number }}
          PULL_REQUEST_TITLE: ${{ github.event.pull_request.title }}
          GITHUB_REPOSITORY: ${{ github.repository }}
        run: |
          EXIT_CODE=0

          # Check if description contains the phrase "pull request"
          DESCRIPTION=$(gh pr view $PULL_REQUEST_NUMBER --json body -q '.body' --repo $GITHUB_REPOSITORY)
          DESCRIPTION_LOWER="${DESCRIPTION,,}"
          
          if echo "$DESCRIPTION_LOWER" | grep -qiE 'pull(-)?request\b'; then
            echo "❌ Pull request description should not contain the phrase 'pull request' or 'pull-request'"
            EXIT_CODE=1
          fi

          if echo "$PULL_REQUEST_BODY" | grep -q "Please delete this paragraph"; then
            echo "❌ Pull request description contains template text that should be removed"
            EXIT_CODE=1
          fi

          if [[ "$EXIT_CODE" -eq 0 ]]; then
            echo "✅ The pull request description looks valid"
          fi
          exit $EXIT_CODE

      - name: Ensure pull request metadata
        if: always()
        env:
          GITHUB_TOKEN: ${{ github.token }}
          PULL_REQUEST_NUMBER: ${{ github.event.pull_request.number }}
          PULL_REQUEST_AUTHOR: ${{ github.event.pull_request.user.login }}
          GITHUB_REPOSITORY: ${{ github.repository }}
        run: |
          EXIT_CODE=0

          # Check labels
          LABELS=$(gh pr view $PULL_REQUEST_NUMBER --json labels -q '.labels[].name' --repo $GITHUB_REPOSITORY)
          if [[ -z "$LABELS" ]]; then
            echo "❌ Pull request must have at least one label"
            EXIT_CODE=1
          fi

          # Check assignee
          ASSIGNEES=$(gh pr view $PULL_REQUEST_NUMBER --json assignees -q '.assignees[].login' --repo $GITHUB_REPOSITORY)
          if [[ -z "$ASSIGNEES" ]]; then
            echo "❌ Pull request must have at least one assignee"
            EXIT_CODE=1
          fi

          if [[ "$EXIT_CODE" -eq 0 ]]; then
            echo "✅ Pull request metadata is valid"
          fi
          exit $EXIT_CODE

      - name: Check branch naming convention
        if: always()
        run: |
          BRANCH_NAME="${GITHUB_HEAD_REF}"
          if ! [[ "$BRANCH_NAME" =~ ^[a-z0-9-]+$ ]]; then
            echo "❌ Branch name '$BRANCH_NAME' does not follow the convention"
            echo "   Expected format: lowercase letters, numbers, and hyphens only"
            exit 1
          fi
          echo "✅ Branch name is valid"

      - name: Check for merge commits
        if: always()
        run: |
          # Fetch main branch
          git fetch origin main:main

          # Get the commit where the branch diverged from main
          DIVERGENCE_POINT=$(git merge-base main ${{ github.event.pull_request.head.sha }})

          # Look for merge commits between divergence point and pull request head
          MERGE_COMMITS=$(git log --merges --oneline $DIVERGENCE_POINT..${{ github.event.pull_request.head.sha }} || true)
          if [[ -n "$MERGE_COMMITS" ]]; then
            echo "❌ Branch must not contain merge commits. The following were found:"
            echo "$MERGE_COMMITS" | sed 's/^/   /'
            echo "   Please remove these commits by rebasing on the latest main branch and force pushing your changes"
            exit 1
          fi
          echo "✅ No merge commits found"

      - name: Check branch is up to date with main branch
        if: always()
        run: |
          # Get the commit where the branch diverged from main
          DIVERGENCE_POINT=$(git merge-base main ${{ github.event.pull_request.head.sha }})
          MAIN_HEAD_COMMIT=$(git rev-parse main)

          if [[ "$DIVERGENCE_POINT" != "$MAIN_HEAD_COMMIT" ]]; then
            echo "❌ Branch must be up to date with the main branch before merging"
            echo "   Your branch diverged from main at commit: $(git log --oneline -n 1 $DIVERGENCE_POINT)"
            echo "   The current main branch is at: $(git log --oneline -n 1 $MAIN_HEAD_COMMIT)"
            echo "   Please rebase on the latest main branch and force push your changes"
            exit 1
          fi
          echo "✅ Branch is up to date with the main branch"

      - name: Check commit messages
        if: always()
        run: |
          # Check commits between main and pull request head
          COMMITS=$(git rev-list main..${{ github.event.pull_request.head.sha }})
          EXIT_CODE=0

          for COMMIT in $COMMITS; do
            COMMIT_MESSAGE=$(git log --format=%B -n 1 "$COMMIT")
            COMMIT_SHORT="${COMMIT:0:8}"

            # Ensure single-line commit message
            if [[ $(echo "$COMMIT_MESSAGE" | wc -l) -gt 1 ]]; then
              echo "❌ Commit $COMMIT_SHORT has multiple lines"
              echo "   Message: $COMMIT_MESSAGE"
              EXIT_CODE=1
            fi

            # Check first character is uppercase
            if [[ ! "${COMMIT_MESSAGE:0:1}" =~ [A-Z] ]]; then
              echo "❌ Commit $COMMIT_SHORT does not start with a capital letter"
              echo "   Message: $COMMIT_MESSAGE"
              EXIT_CODE=1
            fi

            # Only allow 'etc.' to end a message
            if [[ "$COMMIT_MESSAGE" =~ \.$ ]]; then
              if ! [[ "$COMMIT_MESSAGE" =~ (etc\.)$ ]]; then
                echo "❌ Commit $COMMIT_SHORT ends with a period"
                echo "   Message: $COMMIT_MESSAGE"
                EXIT_CODE=1
              fi
            fi

            # Check for period-space-capital (new sentence)
            if echo "$COMMIT_MESSAGE" | grep -P '\. [A-Z]' | grep -vP '(incl\.|e\.g\.|etc\.|i\.e\.) [A-Z]' > /dev/null; then
              echo "❌ Commit $COMMIT_SHORT contains multiple sentences"
              echo "   Message: $COMMIT_MESSAGE"
              EXIT_CODE=1
            fi
          done

          if [[ "$EXIT_CODE" -eq 0 ]]; then
            echo "✅ All commit messages look good"
          fi

          exit "$EXIT_CODE"