name: backport

on:
  pull_request_target:
    types: [closed, labeled]

jobs:
  pull-request:
    runs-on: ubuntu-latest
    permissions:
      contents: write
      pull-requests: write
    if: github.event.pull_request.state == 'closed' && github.event.pull_request.merged && (github.event_name != 'labeled' || startsWith('backport:', github.event.label.name))
    steps:
      - name: Checkout
        uses: actions/checkout@f43a0e5ff2bd294095638e18286ca9a3d1956744 # v3.6.0
        with:
          ref: ${{ github.event.pull_request.head.sha }}
      - name: Create backport PRs
        uses: korthout/backport-action@bd68141f079bd036e45ea8149bc9d174d5a04703 # v1.4.0
        # xref: https://github.com/korthout/backport-action#inputs
        with:
          # Use token to allow workflows to be triggered for the created PR
          github_token: ${{ secrets.BOT_GITHUB_TOKEN }}
          # Match labels with a pattern `backport:<target-branch>`
          label_pattern: '^backport:([^ ]+)$'
          # A bit shorter pull-request title than the default
          pull_title: '[${target_branch}] ${pull_title}'
          # Simpler PR description than default
          pull_description: |-
            Automated backport to `${target_branch}`, triggered by a label in #${pull_number}.