validate-student-pr.yml

name: validate student pr branches

on:
  pull_request:
    types: [opened, reopened, synchronize, edited, ready_for_review]

jobs:
  validate-branch-rules:
    runs-on: ubuntu-latest
    steps:
      - name: Validate PR base and head branch names
        shell: bash
        env:
          BASE_REF: ${{ github.event.pull_request.base.ref }}
          HEAD_REF: ${{ github.event.pull_request.head.ref }}
        run: |
          set -euo pipefail

          if [[ "$BASE_REF" == "main" ]]; then
            echo "::error::PRs to 'main' are not allowed. Open PRs to your personal handle branch."
            exit 1
          fi

          escaped_base="$(printf '%s' "$BASE_REF" | sed -e 's/[][(){}.^$*+?|\\/]/\\&/g')"
          expected_pattern="^${escaped_base}-.+$"

          if [[ ! "$HEAD_REF" =~ $expected_pattern ]]; then
            echo "::error::Invalid branch mapping. Expected '<base>-*' -> '<base>' (head must start with base name)."
            echo "::error::Current mapping: '$HEAD_REF' -> '$BASE_REF'."
            exit 1
          fi

          echo "Branch validation passed: '$HEAD_REF' -> '$BASE_REF'."