release.yml

name: Draft release

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

jobs:
  set-body:
    runs-on: ubuntu-latest

    steps:
    - run: sudo apt install pcregrep

    - uses: actions/checkout@v4

    - name: Parse changelog
      id: parse-changelog
      run: |
        tag='${{ github.ref_name }}'
        re_current_tag="## \[$tag\].*\n\n" # Match, but do not capture, current version tag, then...
        re_changes_body='((.|\n)+?)' # capture everything including newlines...
        re_previous_tag='## \[[0-9]+.[0-9]+.[0-9]+\]' # until previous version tag.
        re_full="${re_current_tag}${re_changes_body}${re_previous_tag}"
        echo 'match<<EOF' >> $GITHUB_OUTPUT
        # Match multiple lines, output capture group 1.
        pcregrep -M -o1 "$re_full" ./CHANGELOG.md >> $GITHUB_OUTPUT
        echo 'EOF' >> $GITHUB_OUTPUT

    - name: Set release body
      uses: softprops/action-gh-release@v2
      with:
        draft: true
        body: ${{ steps.parse-changelog.outputs.match }}