redirect-external-pr.yml

name: Redirect external PRs

on:
    pull_request_target:
        types: [opened, reopened]
        branches: [main, dev]

permissions:
    contents: write
    pull-requests: write

jobs:
    redirect:
        # Only run for PRs coming from forks
        if: github.event.pull_request.head.repo.full_name != github.repository
        runs-on: ubuntu-latest

        steps:
            - name: Resolve dev branch SHA
              id: devsha
              env:
                  GH_TOKEN: ${{ secrets.GITHUB_TOKEN }}
              run: |
                  DEV_SHA=$(gh api repos/${{ github.repository }}/git/ref/heads/dev --jq '.object.sha')
                  echo "sha=$DEV_SHA" >> $GITHUB_OUTPUT

            - name: Create internal feature branch from dev
              env:
                  GH_TOKEN: ${{ secrets.GITHUB_TOKEN }}
              run: |
                  PR_NUMBER="${{ github.event.pull_request.number }}"
                  SOURCE_BRANCH="${{ github.event.pull_request.head.ref }}"

                  SAFE_SOURCE_BRANCH=$(echo "$SOURCE_BRANCH" | tr '/' '-')
                  NEW_BRANCH="feature/external/pr-${PR_NUMBER}-${SAFE_SOURCE_BRANCH}"

                  echo "Creating branch $NEW_BRANCH from dev"

                  gh api repos/${{ github.repository }}/git/refs \
                    -f ref="refs/heads/$NEW_BRANCH" \
                    -f sha="${{ steps.devsha.outputs.sha }}"

            - name: Retarget PR to new branch
              env:
                  GH_TOKEN: ${{ secrets.GITHUB_TOKEN }}
              run: |
                  PR_NUMBER="${{ github.event.pull_request.number }}"
                  SOURCE_BRANCH="${{ github.event.pull_request.head.ref }}"

                  SAFE_SOURCE_BRANCH=$(echo "$SOURCE_BRANCH" | tr '/' '-')
                  NEW_BRANCH="feature/external/pr-${PR_NUMBER}-${SAFE_SOURCE_BRANCH}"

                  echo "Updating PR #$PR_NUMBER base to $NEW_BRANCH"

                  gh api repos/${{ github.repository }}/pulls/$PR_NUMBER \
                    -X PATCH \
                    -f base="$NEW_BRANCH"