name: Validate pull request rules

on:
  pull_request:

permissions:
  contents: read
  pull-requests: read

jobs:
  validate-main-source-branch:
    name: Require development as source branch for main
    runs-on: ubuntu-latest
    if: github.base_ref == 'main'

    steps:
      - name: Validate source branch
        shell: bash
        env:
          HEAD_REF: ${{ github.head_ref }}
        run: |
          set -euo pipefail

          if [ "${HEAD_REF}" != "development" ]; then
            echo "::error::Pull requests into main must come from development. Current source branch: ${HEAD_REF}"
            exit 1
          fi