name: Sync upstream

# Weekly check for new commits in acnicholas/scaddins. If there are any,
# attempts a merge into a sync/upstream-YYYY-MM-DD branch and opens a PR.
# If the merge has conflicts, the PR is opened anyway with the conflict
# markers committed so a human can resolve them — see docs/SYNCING.md.

on:
  schedule:
    - cron: '0 6 * * 1'   # Every Monday 06:00 UTC
  workflow_dispatch:

jobs:
  sync:
    runs-on: ubuntu-latest
    permissions:
      contents: write
      pull-requests: write

    steps:
      - uses: actions/checkout@v4
        with:
          fetch-depth: 0
          ref: dev   # base sync branches off dev so the PR diff stays clean

      - name: Configure git
        run: |
          git config user.name  "github-actions[bot]"
          git config user.email "41898282+github-actions[bot]@users.noreply.github.com"
          git config merge.ours.driver true

      - name: Add upstream remote
        run: |
          git remote add upstream https://github.com/acnicholas/scaddins.git
          git fetch upstream --tags

      - name: Check if there's anything to sync
        id: check
        run: |
          AHEAD=$(git rev-list --count HEAD..upstream/master)
          echo "ahead=$AHEAD" >> $GITHUB_OUTPUT
          echo "Upstream is $AHEAD commits ahead."

      - name: Create sync branch
        if: steps.check.outputs.ahead != '0'
        id: branch
        run: |
          BRANCH="sync/upstream-$(date -u +%Y-%m-%d)"
          echo "name=$BRANCH" >> $GITHUB_OUTPUT
          git checkout -b "$BRANCH"

      - name: Merge upstream
        if: steps.check.outputs.ahead != '0'
        id: merge
        continue-on-error: true
        run: |
          git merge --no-edit upstream/master

      - name: Commit conflict markers (if conflicts)
        if: steps.merge.outcome == 'failure'
        run: |
          git add -A
          git commit -m "sync: upstream merge has conflicts — needs manual resolution"

      - name: Push branch
        if: steps.check.outputs.ahead != '0'
        run: git push -u origin ${{ steps.branch.outputs.name }}

      - name: Open PR
        if: steps.check.outputs.ahead != '0'
        env:
          GH_TOKEN: ${{ secrets.GITHUB_TOKEN }}
        run: |
          STATUS="clean merge"
          if [ "${{ steps.merge.outcome }}" = "failure" ]; then
            STATUS="HAS CONFLICTS — see docs/SYNCING.md"
          fi
          gh pr create \
            --base dev \
            --head ${{ steps.branch.outputs.name }} \
            --title "Sync upstream ($(date -u +%Y-%m-%d))" \
            --body "Automated weekly sync from acnicholas/scaddins. Status: **$STATUS**. ${{ steps.check.outputs.ahead }} upstream commits."