name: Close master-targeted PRs
on:
  pull_request_target:
    types: [opened]
    branches:
      - 'master'

permissions:
  contents: read

jobs:
  run:
    permissions:
      pull-requests: write # Needs to be able to close a PR.
    runs-on: ubuntu-latest
    steps:
      - name: Harden Runner
        uses: step-security/harden-runner@eb238b55efaa70779f274895e782ed17c84f2895 # v2.6.1
        with:
          egress-policy: audit

      - name: Close PRs
        uses: superbrothers/close-pull-request@9c18513d320d7b2c7185fb93396d0c664d5d8448 # v3.1.2
        with:
          comment: "Thank you for your contribution, but PRs must be raised against the `dev` branch. Please log your pull request against the `dev` branch not `master`. You can also retarget this pull request, then reopen it."