name: Backport merged pull request

on:
  pull_request_target:
    types: [closed, labeled]
    branches: [main, releases/*]

permissions:
  contents: write
  pull-requests: write

jobs:
  backport:
    name: Create backport pull request
    runs-on: ubuntu-latest

    # Run the action if a PR is merged with backport labels
    # OR
    # when already merged PR is labeled with backport labels
    if: >
      github.event.pull_request.merged
      && (
        github.event.action == 'closed'
        || (
          github.event.action == 'labeled'
          && startsWith(github.event.label.name, 'backport ')
        )
      )
    steps:
      - name: Checkout
        uses: actions/checkout@de0fac2e4500dabe0009e67214ff5f5447ce83dd # v6.0.2
        with:
          token: ${{ secrets.GH_TOKEN_FOR_CI_RUNNERS }}

      - name: Create backport pull requests
        uses: korthout/backport-action@d07416681cab29bf2661702f925f020aaa962997 # v3.4.1
        with:
          # Inputs documented here: https://github.com/korthout/backport-action?tab=readme-ov-file#inputs
          github_token: ${{ secrets.GH_TOKEN_FOR_CI_RUNNERS }}
          github_workspace: ${{ github.workspace }}

          # permit PRs with merge commits to be backported
          merge_commits: 'skip'

          # copy labels to backport to identify affected systems and priorities
          copy_labels_pattern: '.*'

          # Regex pattern to match github labels
          # The capture group catches the target branch
          # i.e. label "backport releases/FreeCAD-1-0" will create backport
          # PR for branch releases/FreeCAD-1-0
          label_pattern: ^backport ([^ ]+)$