finalize-release.yml

name: Finalize Release

# Runs automatically when a release PR is merged into main.
# Creates the git tag, GitHub Release, and opens a back-merge PR to develop.

on:
  pull_request:
    types: [closed]
    branches: [main]

jobs:
  finalize-release:
    name: Tag, Release, and Back-merge
    # Only run when a release PR is actually merged (not just closed)
    if: github.event.pull_request.merged == true && startsWith(github.event.pull_request.head.ref, 'release/')
    runs-on: ubuntu-latest
    permissions:
      contents: write
      pull-requests: write

    steps:
      - name: Checkout main
        uses: actions/checkout@v7
        with:
          ref: main
          fetch-depth: 0
          token: ${{ secrets.RELEASE_PAT }}

      - name: Configure Git
        run: |
          git config user.name "github-actions[bot]"
          git config user.email "github-actions[bot]@users.noreply.github.com"

      - name: Extract release info from branch name
        id: release
        env:
          HEAD_REF: ${{ github.event.pull_request.head.ref }}
        run: |
          BRANCH="$HEAD_REF"
          # Branch name is release/vX.Y.Z or release/vX.Y.Z-beta
          TAG="${BRANCH#release/}"

          if ! [[ "$TAG" =~ ^v[0-9]+\.[0-9]+\.[0-9]+(-[0-9A-Za-z-]+(\.[0-9A-Za-z-]+)*)?$ ]]; then
            echo "::error::Unexpected release branch format: $BRANCH"
            exit 1
          fi

          SEMVER="${TAG#v}"

          # Determine if this is a pre-release
          if echo "$SEMVER" | grep -q '-'; then
            PRERELEASE="true"
          else
            PRERELEASE="false"
          fi

          echo "tag=${TAG}" >> $GITHUB_OUTPUT
          echo "semver=${SEMVER}" >> $GITHUB_OUTPUT
          echo "prerelease=${PRERELEASE}" >> $GITHUB_OUTPUT

      - name: Check if tag already exists
        run: |
          if git rev-parse "${{ steps.release.outputs.tag }}" >/dev/null 2>&1; then
            echo "::error::Tag ${{ steps.release.outputs.tag }} already exists. Skipping."
            exit 1
          fi

      - name: Create annotated tag
        run: |
          TAG="${{ steps.release.outputs.tag }}"
          git tag -a "$TAG" -m "Release $TAG"
          git push origin "$TAG"
          echo "Created and pushed tag: $TAG"

      - name: Create GitHub Release
        env:
          GH_TOKEN: ${{ secrets.RELEASE_PAT }}
          TAG: ${{ steps.release.outputs.tag }}
          SEMVER: ${{ steps.release.outputs.semver }}
          PRERELEASE: ${{ steps.release.outputs.prerelease }}
        run: |
          PRERELEASE_FLAG=""
          if [ "$PRERELEASE" = "true" ]; then
            PRERELEASE_FLAG="--prerelease"
          fi

          gh release create "$TAG" \
            --title "$TAG" \
            --generate-notes \
            $PRERELEASE_FLAG

      - name: Delete release branch
        env:
          HEAD_REF: ${{ github.event.pull_request.head.ref }}
        run: |
          BRANCH="$HEAD_REF"
          git push origin --delete "$BRANCH" || true
          echo "Deleted branch: $BRANCH"

      - name: Create back-merge PR (main → develop)
        env:
          GH_TOKEN: ${{ secrets.RELEASE_PAT }}
          TAG: ${{ steps.release.outputs.tag }}
        run: |
          BACKMERGE_BRANCH="backmerge/${TAG}"
          
          # Create a branch from main for the back-merge
          git checkout -b "$BACKMERGE_BRANCH" main
          git push origin "$BACKMERGE_BRANCH"

          # Create the PR
          gh pr create \
            --base develop \
            --head "$BACKMERGE_BRANCH" \
            --title "Back-merge ${TAG} from main into develop" \
            --body "Automatic back-merge after release ${TAG}. Merge this to keep \`develop\` in sync with \`main\`."

      - name: Summary
        run: |
          echo "## Release Finalized :rocket:" >> $GITHUB_STEP_SUMMARY
          echo "" >> $GITHUB_STEP_SUMMARY
          echo "- **Tag:** ${{ steps.release.outputs.tag }}" >> $GITHUB_STEP_SUMMARY
          echo "- **Version:** ${{ steps.release.outputs.semver }}" >> $GITHUB_STEP_SUMMARY
          echo "- **Pre-release:** ${{ steps.release.outputs.prerelease }}" >> $GITHUB_STEP_SUMMARY
          echo "" >> $GITHUB_STEP_SUMMARY
          echo "### What happened" >> $GITHUB_STEP_SUMMARY
          echo "1. ✅ Tag \`${{ steps.release.outputs.tag }}\` created" >> $GITHUB_STEP_SUMMARY
          echo "2. ✅ GitHub Release created with auto-generated notes" >> $GITHUB_STEP_SUMMARY
          echo "3. ✅ Publish workflow triggered (NuGet)" >> $GITHUB_STEP_SUMMARY
          echo "4. ✅ Back-merge PR opened to develop" >> $GITHUB_STEP_SUMMARY