pr-label.yml

name: PR Type Label

# Runs on every PR event that could change the title, commits, or labels.
# 1. If a recognised type label is already present → pass (nothing to do).
# 2. Otherwise scan the PR title and all commit messages for a conventional
#    commit prefix and auto-apply the matching label.
# 3. If neither is found → fail with a helpful message so the contributor knows
#    what to do.

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

permissions:
  contents: read
  # issues: write         # needed to create/update repo labels
  pull-requests: write  # needed to add labels to PRs

jobs:
  check-and-label:
    name: Check PR type label
    runs-on: ubuntu-latest

    steps:
      # - name: Ensure type labels exist in the repo
      #   env:
      #     GH_TOKEN: ${{ secrets.GITHUB_TOKEN }}
      #     REPO: ${{ github.repository }}
      #   run: |
      #     # Create labels if they don't already exist.
      #     # `gh label create` exits non-zero when the label already exists,
      #     # so we suppress that with --force (update colour/description if changed).
      #     gh label create "feat"     --color "0075ca" --description "New feature (minor version bump)"              --force --repo "$REPO"
      #     gh label create "fix"      --color "e4e669" --description "Bug fix (patch version bump)"                  --force --repo "$REPO"
      #     gh label create "refactor" --color "cfd3d7" --description "Code refactoring, no functional change"        --force --repo "$REPO"
      #     gh label create "docs"     --color "0052cc" --description "Documentation only"                            --force --repo "$REPO"
      #     gh label create "test"     --color "bfd4f2" --description "Adding or updating tests"                      --force --repo "$REPO"
      #     gh label create "chore"    --color "d4c5f9" --description "Build, CI, dependency updates"                 --force --repo "$REPO"
      #     gh label create "major"    --color "d93f0b" --description "Breaking change (major version bump)"          --force --repo "$REPO"

      - name: Check labels and apply from title / commits if missing
        id: label-check
        env:
          GH_TOKEN: ${{ secrets.GITHUB_TOKEN }}
          REPO: ${{ github.repository }}
          PR_NUMBER: ${{ github.event.pull_request.number }}
          PR_TITLE: ${{ github.event.pull_request.title }}
        run: |
          set -euo pipefail

          # ── 1. Collect existing labels on this PR ──────────────────────────
          CURRENT_LABELS=$(gh pr view "$PR_NUMBER" --repo "$REPO" --json labels \
            --jq '[.labels[].name] | join(" ")')
          echo "Current labels: $CURRENT_LABELS"

          # ── 2. Check whether any type label is already set ─────────────────
          TYPE_LABELS="feat fix refactor docs test chore major"
          FOUND_LABEL=""
          for lbl in $TYPE_LABELS; do
            if echo " $CURRENT_LABELS " | grep -qw "$lbl"; then
              FOUND_LABEL="$lbl"
              break
            fi
          done

          if [ -n "$FOUND_LABEL" ]; then
            echo "✅ Type label already set: $FOUND_LABEL"
            echo "label=$FOUND_LABEL" >> "$GITHUB_OUTPUT"
            exit 0
          fi

          # ── 3. No label yet – scan PR title first ──────────────────────────
          # Matches:  feat:  feat!:  feat(scope):  feat(scope)!:
          # Also matches standalone prefixes: major / BREAKING CHANGE
          detect_type() {
            local text="$1"
            local lower
            lower=$(echo "$text" | tr '[:upper:]' '[:lower:]')

            if echo "$lower" | grep -qE '^major[^a-z]|breaking.?change'; then
              echo "major"; return
            elif echo "$lower" | grep -qE '^feat(\([^)]*\))?!?:'; then
              echo "feat"; return
            elif echo "$lower" | grep -qE '^fix(\([^)]*\))?!?:'; then
              echo "fix"; return
            elif echo "$lower" | grep -qE '^refactor(\([^)]*\))?!?:'; then
              echo "refactor"; return
            elif echo "$lower" | grep -qE '^docs?(\([^)]*\))?!?:'; then
              echo "docs"; return
            elif echo "$lower" | grep -qE '^tests?(\([^)]*\))?!?:'; then
              echo "test"; return
            elif echo "$lower" | grep -qE '^(chore|build|ci)(\([^)]*\))?!?:'; then
              echo "chore"; return
            fi
            echo ""
          }

          DETECTED=$(detect_type "$PR_TITLE")

          # ── 4. If not in title, scan commit messages ───────────────────────
          if [ -z "$DETECTED" ]; then
            echo "No prefix in PR title – scanning commit messages..."
            COMMITS=$(gh pr view "$PR_NUMBER" --repo "$REPO" --json commits \
              --jq '[.commits[].messageHeadline] | join("\n")')

            while IFS= read -r msg; do
              TYPE=$(detect_type "$msg")
              if [ -n "$TYPE" ]; then
                DETECTED="$TYPE"
                echo "  Found prefix '$DETECTED' in commit: $msg"
                break
              fi
            done <<< "$COMMITS"
          fi

          # ── 5. Apply label if detected; otherwise fail ─────────────────────
          if [ -n "$DETECTED" ]; then
            echo "Applying label: $DETECTED"
            gh pr edit "$PR_NUMBER" --repo "$REPO" --add-label "$DETECTED"
            echo "label=$DETECTED" >> "$GITHUB_OUTPUT"
            echo "✅ Label '$DETECTED' applied automatically."
          else
            echo ""
            echo "❌ No type label found and no conventional commit prefix detected."
            echo ""
            echo "Please either:"
            echo "  • Add one of these labels to the PR:  $TYPE_LABELS"
            echo "  • OR prefix your PR title or a commit message with one of:"
            echo "      feat:  fix:  refactor:  docs:  test:  chore:  major:"
            echo ""
            echo "Examples:"
            echo "  feat: add OAuth2 provider support"
            echo "  fix(sessions): correct token expiry calculation"
            echo "  major: BREAKING CHANGE: redesign workflow DSL"
            exit 1
          fi