name: "Draft new release"

on:
  milestone:
    types: [closed]

jobs:
  draft-new-release:
    name: "Draft a new release"
    runs-on: ubuntu-latest
    steps:
      - uses: actions/checkout@v2
        with:
          ref: 'release'
      - name: Extract version from milestone
        run: |
          VERSION="${{ github.event.milestone.title }}"
          echo "::set-env name=RELEASE_VERSION::$VERSION"

      - name: Create release branch
        run: git checkout -b release-${{ env.RELEASE_VERSION }}

      - name: Update changelog
        uses: thomaseizinger/keep-a-changelog-new-release@1.1.0
        with:
          version: v${{ env.RELEASE_VERSION }}

      - name: Initialize git config
        run: |
          git config user.name "GitHub Actions"
          git config user.email noreply@github.com

      - name: Create Pull Request
        uses: peter-evans/create-pull-request@v3
        with:
          commit-message: "Prepare release ${{ env.RELEASE_VERSION }}"
          branch: release-${{ env.RELEASE_VERSION }}
          base: release
          title: Release ${{ env.RELEASE_VERSION }}