# Derived from https://github.com/NixOS/nixpkgs/blob/2ab6f6d61630889491f86396b27a76ffb6fbc7bb/.github/workflows/backport.yml

name: Backport

on:
  pull_request_target:
    types: [closed, labeled]

permissions: {}

jobs:
  backport:
    name: Backport
    runs-on: ubuntu-latest

    if: >
      (
        github.repository_owner == 'danth' &&
        github.event.pull_request.merged == true &&
        (github.event_name != 'labeled' || startsWith('backport', github.event.label.name))
      )

    steps:
      # Use a GitHub App rather than the default token so that GitHub Actions
      # workflows may run on the created pull request.
      - name: Create GitHub access token
        uses: actions/create-github-app-token@v1
        id: app-token
        with:
          app-id: ${{ vars.BACKPORT_APP_ID }}
          private-key: ${{ secrets.BACKPORT_PRIVATE_KEY }}

      - name: Checkout original pull request
        uses: actions/checkout@v4
        with:
          ref: ${{ github.event.pull_request.head.sha }}
          token: ${{ steps.app-token.outputs.token }}

      - name: Create backport pull request
        uses: korthout/backport-action@v3
        with:
          github_token: ${{ steps.app-token.outputs.token }}
          pull_title: "[${target_branch}] ${pull_title}"
          pull_description: |-
            This is an automated backport of #${pull_number}.