# =============================================================================
# Upstream Sync Workflow
# =============================================================================
# Automatically syncs this repository with the upstream repository.
# Creates a PR when new changes are detected from upstream.
#
# Local repository: current default branch (main)
# Upstream source: CJackHwang/AIstudioProxyAPI (main)
#
# CONFLICT HANDLING:
# README.md can conflict when this repository keeps custom docs/content.
# The workflow auto-resolves README.md conflicts by keeping local version.
# Other conflicts will fail the workflow and require manual intervention.
# =============================================================================

name: Sync with Upstream

on:
  # Run every 6 hours (at 00:00, 06:00, 12:00, 18:00 UTC)
  # This ensures timely detection of upstream changes while avoiding excessive API calls
  schedule:
    - cron: '0 */6 * * *'

  # Allow manual trigger from GitHub Actions UI
  workflow_dispatch:
    inputs:
      force_sync:
        description: 'Force sync even if no new commits detected'
        required: false
        default: false
        type: boolean

# Ensure only one sync workflow runs at a time
concurrency:
  group: upstream-sync
  cancel-in-progress: true

jobs:
  sync:
    name: Sync Repository with Upstream
    runs-on: ubuntu-latest

    # Required permissions for creating PRs and pushing branches
    permissions:
      contents: write
      pull-requests: write

    steps:
      # -----------------------------------------------------------------------
      # Step 1: Checkout current repository
      # -----------------------------------------------------------------------
      - name: Checkout Repository
        uses: actions/checkout@v4
        with:
          # Fetch all history to properly compare with upstream
          fetch-depth: 0
          # Use the default GITHUB_TOKEN
          token: ${{ secrets.GITHUB_TOKEN }}

      # -----------------------------------------------------------------------
      # Step 2: Configure Git identity for commits
      # -----------------------------------------------------------------------
      - name: Configure Git Identity
        run: |
          git config user.name "github-actions[bot]"
          git config user.email "41898282+github-actions[bot]@users.noreply.github.com"

      # -----------------------------------------------------------------------
      # Step 3: Add upstream remote and fetch latest changes
      # -----------------------------------------------------------------------
      - name: Add Upstream Remote
        run: |
          echo "Adding upstream remote..."
          git remote add upstream https://github.com/CJackHwang/AIstudioProxyAPI.git
          
          echo "Fetching upstream changes..."
          git fetch upstream main --tags
          
          echo "Upstream remote added and fetched successfully."

      # -----------------------------------------------------------------------
      # Step 4: Check for new commits from upstream
      # -----------------------------------------------------------------------
      - name: Check for Upstream Changes
        id: check_changes
        run: |
          echo "Comparing local main with upstream/main..."
          
          # Get commit counts
          LOCAL_COMMIT=$(git rev-parse HEAD)
          UPSTREAM_COMMIT=$(git rev-parse upstream/main)
          
          echo "Local HEAD: $LOCAL_COMMIT"
          echo "Upstream HEAD: $UPSTREAM_COMMIT"
          
          # Count commits ahead and behind
          COMMITS_BEHIND=$(git rev-list --count HEAD..upstream/main)
          COMMITS_AHEAD=$(git rev-list --count upstream/main..HEAD)
          
          echo "Commits behind upstream: $COMMITS_BEHIND"
          echo "Commits ahead of upstream: $COMMITS_AHEAD"
          
          # Determine if sync is needed
          if [ "$COMMITS_BEHIND" -gt 0 ]; then
            echo "has_changes=true" >> $GITHUB_OUTPUT
            echo "commits_behind=$COMMITS_BEHIND" >> $GITHUB_OUTPUT
            echo "::notice::Found $COMMITS_BEHIND new commit(s) from upstream"
          else
            echo "has_changes=false" >> $GITHUB_OUTPUT
            echo "commits_behind=0" >> $GITHUB_OUTPUT
            echo "::notice::Fork is up to date with upstream"
          fi
          
          # Get the date for PR title
          echo "sync_date=$(date +'%Y-%m-%d')" >> $GITHUB_OUTPUT
          
          # Get recent upstream commit messages for PR body
          if [ "$COMMITS_BEHIND" -gt 0 ]; then
            echo "Getting recent upstream commits..."
            COMMIT_LOG=$(git log --oneline HEAD..upstream/main | head -20)
            
            # Write commit log to file for multi-line output
            echo "$COMMIT_LOG" > /tmp/commit_log.txt
            
            # Use delimiter for multi-line output
            {
              echo 'commit_log<<EOF'
              cat /tmp/commit_log.txt
              echo 'EOF'
            } >> $GITHUB_OUTPUT
          fi

      # -----------------------------------------------------------------------
      # Step 5: Create sync branch with upstream changes
      # -----------------------------------------------------------------------
      # CONFLICT RESOLUTION STRATEGY:
      # 1. Attempt merge with upstream
      # 2. If conflicts occur, check if ONLY expected files conflict (README.md)
      # 3. Auto-resolve expected conflicts by keeping fork's version (--ours)
      # 4. Fail only if unexpected files have conflicts
      # -----------------------------------------------------------------------
      - name: Create Sync Branch
        id: create_branch
        if: steps.check_changes.outputs.has_changes == 'true' || github.event.inputs.force_sync == 'true'
        run: |
          BRANCH_NAME="sync/upstream-${{ steps.check_changes.outputs.sync_date }}"
          echo "branch_name=$BRANCH_NAME" >> $GITHUB_OUTPUT
          
          echo "Creating sync branch: $BRANCH_NAME"
          
          # Check if branch already exists remotely
          if git ls-remote --heads origin "$BRANCH_NAME" | grep -q "$BRANCH_NAME"; then
            echo "::warning::Sync branch already exists. Deleting and recreating..."
            git push origin --delete "$BRANCH_NAME" || true
          fi
          
          # Create new branch from current main
          git checkout -b "$BRANCH_NAME"
          
          echo "Merging upstream/main into sync branch..."
          
          # =====================================================================
          # EXPECTED CONFLICT FILES (Translation Fork)
          # These files are expected to conflict because they are intentionally
          # different in this English fork vs the Chinese upstream.
          # =====================================================================
          EXPECTED_CONFLICT_FILES="README.md"
          
          # Attempt merge with upstream
          # Using --no-edit to auto-generate merge commit message
          if git merge upstream/main --no-edit --allow-unrelated-histories; then
            echo "merge_success=true" >> $GITHUB_OUTPUT
            echo "auto_resolved=false" >> $GITHUB_OUTPUT
            echo "::notice::Merge successful (no conflicts)"
          else
            echo "::warning::Merge conflicts detected. Checking if auto-resolvable..."
            
            # Get list of conflicting files
            CONFLICTING_FILES=$(git diff --name-only --diff-filter=U)
            echo "Conflicting files:"
            echo "$CONFLICTING_FILES"
            
            # Check if all conflicts are in expected files
            UNEXPECTED_CONFLICTS=""
            for file in $CONFLICTING_FILES; do
              IS_EXPECTED=false
              for expected in $EXPECTED_CONFLICT_FILES; do
                if [ "$file" = "$expected" ]; then
                  IS_EXPECTED=true
                  break
                fi
              done
              
              if [ "$IS_EXPECTED" = false ]; then
                UNEXPECTED_CONFLICTS="$UNEXPECTED_CONFLICTS $file"
              fi
            done
            
            # Trim whitespace
            UNEXPECTED_CONFLICTS=$(echo "$UNEXPECTED_CONFLICTS" | xargs)
            
            if [ -n "$UNEXPECTED_CONFLICTS" ]; then
              # Unexpected conflicts found - fail the workflow
              echo "merge_success=false" >> $GITHUB_OUTPUT
              echo "auto_resolved=false" >> $GITHUB_OUTPUT
              echo "::error::Unexpected conflicts in: $UNEXPECTED_CONFLICTS"
              echo "::error::Manual intervention required for these files."
              
              # Abort the merge to leave clean state
              git merge --abort
              exit 1
            else
              # Only expected conflicts - auto-resolve by keeping fork's version
              echo "::notice::All conflicts are in expected files. Auto-resolving..."
              
              for file in $CONFLICTING_FILES; do
                echo "  Resolving $file by keeping fork's version (--ours)..."
                git checkout --ours "$file"
                git add "$file"
              done
              
              # Complete the merge with resolved conflicts
              git commit --no-edit
              
              echo "merge_success=true" >> $GITHUB_OUTPUT
              echo "auto_resolved=true" >> $GITHUB_OUTPUT
              echo "::notice::Merge successful (auto-resolved expected conflicts)"
            fi
          fi

      # -----------------------------------------------------------------------
      # Step 6: Push sync branch to origin
      # -----------------------------------------------------------------------
      - name: Push Sync Branch
        if: steps.create_branch.outputs.merge_success == 'true'
        run: |
          echo "Pushing sync branch to origin..."
          git push origin "${{ steps.create_branch.outputs.branch_name }}"
          echo "::notice::Sync branch pushed successfully"

      # -----------------------------------------------------------------------
      # Step 7: Create Pull Request
      # -----------------------------------------------------------------------
      - name: Create Pull Request
        if: steps.create_branch.outputs.merge_success == 'true'
        uses: peter-evans/create-pull-request@v7
        id: create_pr
        with:
          token: ${{ secrets.GITHUB_TOKEN }}
          branch: ${{ steps.create_branch.outputs.branch_name }}
          base: main
          title: "chore: Sync with upstream [${{ steps.check_changes.outputs.sync_date }}]"
          body: |
            ## Upstream Sync

            This PR syncs the fork with the upstream repository.

            ### Summary
            - **Upstream Repository**: [CJackHwang/AIstudioProxyAPI](https://github.com/CJackHwang/AIstudioProxyAPI)
            - **Commits Behind**: ${{ steps.check_changes.outputs.commits_behind }}
            - **Sync Date**: ${{ steps.check_changes.outputs.sync_date }}
            - **Auto-resolved Conflicts**: ${{ steps.create_branch.outputs.auto_resolved == 'true' && '✅ Yes (README.md kept from fork)' || '❌ None' }}

            ### Recent Upstream Commits
            ```
            ${{ steps.check_changes.outputs.commit_log }}
            ```

            ### Review Notes
            - Please review changes carefully before merging
            - Check for any conflicts with fork-specific modifications
            - Ensure translation/localization files are preserved
            ${{ steps.create_branch.outputs.auto_resolved == 'true' && '- ⚠️ **README.md conflict was auto-resolved** - The English README from this fork was preserved' || '' }}

            ---
            *This PR was automatically generated by the [Upstream Sync Workflow](${{ github.server_url }}/${{ github.repository }}/actions/runs/${{ github.run_id }})*
          labels: |
            upstream-sync
            automated
          draft: false
          delete-branch: false

      # -----------------------------------------------------------------------
      # Step 8: Output Results
      # -----------------------------------------------------------------------
      - name: Output Results
        if: always()
        run: |
          echo "=========================================="
          echo "Upstream Sync Workflow Complete"
          echo "=========================================="
          echo ""
          
          if [ "${{ steps.check_changes.outputs.has_changes }}" == "true" ]; then
            echo "Status: Changes detected from upstream"
            echo "Commits behind: ${{ steps.check_changes.outputs.commits_behind }}"
            
            if [ "${{ steps.create_branch.outputs.merge_success }}" == "true" ]; then
              echo "Merge: Successful"
              
              if [ "${{ steps.create_branch.outputs.auto_resolved }}" == "true" ]; then
                echo "Conflicts: Auto-resolved (expected files only)"
                echo "  - README.md: Kept fork's English version"
              else
                echo "Conflicts: None"
              fi
              
              echo "PR Created: Yes"
              echo "Branch: ${{ steps.create_branch.outputs.branch_name }}"
            else
              echo "Merge: Failed (unexpected conflicts detected)"
              echo "PR Created: No"
              echo ""
              echo "Manual intervention required to resolve conflicts."
              echo "Expected conflict files (auto-resolved): README.md"
              echo "Unexpected conflicts require manual resolution."
            fi
          else
            echo "Status: Fork is up to date with upstream"
            echo "No action required."
          fi
          
          echo ""
          echo "=========================================="