release-preview.yml

name: Release Preview

on:
  pull_request:
    branches:
      - main
      - 'mc/*'

permissions:
  contents: write
  pull-requests: write

jobs:
  preview:
    name: Preview Release Notes
    runs-on: ubuntu-latest
    steps:
      - name: Checkout
        uses: actions/checkout@v4
        with:
          fetch-depth: 0

      - name: Setup Node.js
        uses: actions/setup-node@v4
        with:
          node-version: "lts/*"

      - run: npm ci

      - name: Checkout PR branch (required for semantic-release)
        run: git checkout "origin/${{ github.head_ref }}"

      - name: Generate release notes (Dry Run)
        id: dryrun
        env:
          GITHUB_TOKEN: ${{ secrets.GITHUB_TOKEN }}
        run: |
          # Run semantic-release in dry-run mode and capture all output
          # Unset GITHUB_ACTIONS to avoid issues with semantic-release refusing to run in CI
          output=$(unset GITHUB_ACTIONS && npx semantic-release --dry-run --no-ci --branches "${{ github.head_ref }}")

          # Output the raw result for debugging
          echo "Raw output from semantic-release:"
          echo "$output"

          if [[ $? -ne 0 ]]; then
            echo "❌ Error generating release notes."
            echo "$output"
            exit 1
          fi
          
          # Check if a release would be created
          if echo "$output" | grep -q "There are no relevant changes"; then
            notes="NO_RELEASE"
          else
            # Extract just the release notes section for a cleaner comment
            notes=$(echo "$output" | awk '/Release note for version/{flag=1; next} flag')
          fi
          
          # Use multiline output for the notes
          echo "notes<<EOF" >> $GITHUB_OUTPUT
          echo "$notes" >> $GITHUB_OUTPUT
          echo "EOF" >> $GITHUB_OUTPUT
      
      - name: Generate PR body
        id: pr_body
        run: |
          echo "body<<EOF" >> $GITHUB_OUTPUT

          if [[ "${{ steps.dryrun.outputs.notes }}" == "NO_RELEASE" ]]; then
            echo "No release will be created when this pull request is merged." >> $GITHUB_OUTPUT
          else
            echo "This pull request will trigger a new release when merged." >> $GITHUB_OUTPUT
            echo -e "<details>\n" >> $GITHUB_OUTPUT
            echo -e "<summary>Release notes</summary>\n\n" >> $GITHUB_OUTPUT
            echo -e "${{ steps.dryrun.outputs.notes }}\n" >> $GITHUB_OUTPUT
            echo -e "</details>\n" >> $GITHUB_OUTPUT
          fi

          echo "EOF" >> $GITHUB_OUTPUT

      - name: Post or Update PR Comment
        uses: marocchino/sticky-pull-request-comment@v2
        with:
          header: release-preview
          message: |
            ### 🚀 Release Preview
            ${{ steps.pr_body.outputs.body }}