name: Sync main to next

on:
  schedule:
    - cron: '0 3 * * *'
  workflow_dispatch:

permissions:
  contents: write
  pull-requests: write

concurrency:
  group: sync-main-to-next
  cancel-in-progress: false

jobs:
  sync:
    name: Merge main into next
    runs-on: ubuntu-latest
    steps:
      - name: Checkout next
        uses: actions/checkout@v5
        with:
          ref: next
          fetch-depth: 0

      - name: Merge main into next
        env:
          GH_TOKEN: ${{ github.token }}
        run: |
          git config user.name 'github-actions[bot]'
          git config user.email '41898282+github-actions[bot]@users.noreply.github.com'
          git fetch origin main next

          if git merge --no-edit origin/main; then
            git push origin HEAD:next
            exit 0
          fi

          conflicts=$(git diff --name-only --diff-filter=U)
          git merge --abort

          if [ -z "$conflicts" ]; then
            echo 'The merge failed without conflicts, so no pull request was created.'
            exit 1
          fi

          sync_branch='automation/sync-main-to-next'
          existing_pr=$(gh pr list --base next --head "$sync_branch" --state open --json url --jq '.[0].url')
          if [ -n "$existing_pr" ]; then
            echo "A main to next pull request already exists: $existing_pr"
          else
            git push --force origin origin/main:"refs/heads/$sync_branch"
            gh pr create \
              --base next \
              --head "$sync_branch" \
              --title 'chore: merge main into next' \
              --body 'This pull request was created automatically because main could not be merged into next without conflicts. Resolve conflicts on this temporary branch; never update main with next.'
          fi

          echo 'main could not be merged into next without conflicts.'
          exit 1