name: Release

on:
  push:
    tags:
      - 'v[0-9]+.[0-9]+.[0-9]+*'

jobs:
  release:
    runs-on: ubuntu-latest
    steps:
      - name: Checkout
        uses: actions/checkout@v2
      - name: Prepare notes
        run: |
          # Extract changelog entries between this and previous version headers
          escaped_version=$(echo ${GITHUB_REF_NAME#v} | sed -e 's/[]\/$*.^[]/\\&/g')
          awk "BEGIN{inrelease=0} /## \[${escaped_version}\]/{inrelease=1;next} /## \[[0-9]+\.[0-9]+\.[0-9]+.*\]/{inrelease=0;exit} {if (inrelease) print}" CHANGELOG.md \
            > RELEASE_NOTES.txt

          # Write PRERELEASE="true" env if tag name has any suffix after vMAJOR.MINOR.PATCH
          if [[ ${GITHUB_REF_NAME} =~ ^v[0-9]+\.[0-9]+\.[0-9]+.+ ]]; then
            echo 'PRERELEASE="true"' >> $GITHUB_ENV
          else
            echo 'PRERELEASE="false"' >> $GITHUB_ENV
          fi
      - name: Release
        uses: softprops/action-gh-release@v1
        with:
          body_path: RELEASE_NOTES.txt
          prerelease: ${{ fromJSON(env.PRERELEASE) }}