name: "Sync with Upstream and Create PR"

on:
    workflow_dispatch:
    workflow_call:

jobs:
  sync-upstream:
    runs-on: ubuntu-latest

    steps:
      - name: Checkout repository
        uses: actions/checkout@v3
        with:
          token: ${{ secrets.GITHUB_TOKEN }}
          fetch-depth: 0  # Retrieve full history to allow merging

      - name: Set default values for UPSTREAM_REPO and TARGET_BRANCH if not set
        run: |
          # Use the current repository name if UPSTREAM_REPO is not set
          : "${UPSTREAM_REPO:=${{ github.repository }} }"
          : "${TARGET_BRANCH:=master}"

          # Format the repository name for flathub
          UPSTREAM_REPO="https://github.com/flathub/${UPSTREAM_REPO}"

          echo "UPSTREAM_REPO=$UPSTREAM_REPO" >> $GITHUB_ENV
          echo "TARGET_BRANCH=$TARGET_BRANCH" >> $GITHUB_ENV
          
      - name: Sync from Upstream Repository
        run: |
          echo "Syncing from upstream repository $UPSTREAM_REPO on branch $TARGET_BRANCH"
          
          # Perform fetch and merge, attempting to resolve conflicts by preferring the upstream changes
          git fetch "$UPSTREAM_REPO" "$TARGET_BRANCH"
          git merge FETCH_HEAD -m "Merge changes from upstream $UPSTREAM_REPO/$TARGET_BRANCH" || {
            echo "Conflict detected. Resolving by preferring upstream changes..."
            git merge --strategy-option theirs --no-edit FETCH_HEAD
          }


      - name: Push changes if there are updates
        env:
          BRANCH_NAME: "sync-${{ github.run_id }}"  # Temporary branch name for the PR
        run: |
          if [ "$(git status --porcelain)" ]; then
            git checkout -b "$BRANCH_NAME"
            git push origin "$BRANCH_NAME"
          else
            echo "No changes to push."
          fi

      - name: Create Pull Request
        if: success() && steps.push.outputs.BRANCH_NAME != ''  # Only run if there are changes
        uses: peter-evans/create-pull-request@v4
        with:
          token: ${{ secrets.GITHUB_TOKEN }}
          commit-message: "Sync with upstream changes from $UPSTREAM_REPO"
          branch: ${{ steps.push.outputs.BRANCH_NAME }}
          title: "Sync with upstream $UPSTREAM_REPO"
          body: |
            This PR merges the latest changes from the upstream repository:
            - **Repository**: $UPSTREAM_REPO
            - **Branch**: $TARGET_BRANCH

            ## Conflict Resolution Instructions
            If there are conflicts in this PR, you can resolve them locally by following these steps:

            1. **Fetch the remote branch**:
               ```bash
               git fetch origin ${{ steps.push.outputs.BRANCH_NAME }}
               ```

            2. **Checkout the branch**:
               ```bash
               git checkout ${{ steps.push.outputs.BRANCH_NAME }}
               ```

            3. **Merge the upstream branch manually**:
               ```bash
               git fetch https://github.com/flathub/$UPSTREAM_REPO $TARGET_BRANCH
               git merge FETCH_HEAD
               ```

            4. **Resolve any conflicts**:
               Open each conflicted file and manually resolve the conflicts. Then mark each file as resolved:
               ```bash
               git add <file-with-conflicts>
               ```

            5. **Complete the merge**:
               ```bash
               git commit
               ```

            6. **Push the resolved branch**:
               ```bash
               git push origin ${{ steps.push.outputs.BRANCH_NAME }}
               ```
          base: $TARGET_BRANCH
          labels: ["sync", "upstream"]