cherry-pick.yml

name: Cherry Pick

on:
  pull_request_target:
    types: [closed, labeled]

permissions:
  contents: write
  pull-requests: write

jobs:
  cherry-pick:
    if: github.event.pull_request.merged == true
    runs-on: ubuntu-latest
    steps:
      - name: Checkout
        uses: actions/checkout@v4
        with:
          fetch-depth: 0

      - name: Cherry Pick
        env:
          GH_TOKEN: ${{ secrets.GITHUB_TOKEN }}
          PR_NUMBER: ${{ github.event.pull_request.number }}
          PR_TITLE: ${{ github.event.pull_request.title }}
          PR_AUTHOR: ${{ github.event.pull_request.user.login }}
          MERGE_COMMIT_SHA: ${{ github.event.pull_request.merge_commit_sha }}
        run: |
          # Function to post comment
          post_comment() {
            gh pr comment "$PR_NUMBER" --body "$1"
          }

          # Configure git for the original author
          echo "Fetching author info for $PR_AUTHOR..."
          AUTHOR_INFO=$(gh api "/users/$PR_AUTHOR" --jq '{email: .email, name: .name}')
          AUTHOR_EMAIL=$(echo "$AUTHOR_INFO" | jq -r '.email')
          AUTHOR_NAME=$(echo "$AUTHOR_INFO" | jq -r '.name')

          if [ "$AUTHOR_EMAIL" = "null" ] || [ -z "$AUTHOR_EMAIL" ]; then
            AUTHOR_EMAIL="${PR_AUTHOR}@users.noreply.github.com"
            echo "Author email not found, using default: $AUTHOR_EMAIL"
          fi
          if [ "$AUTHOR_NAME" = "null" ] || [ -z "$AUTHOR_NAME" ]; then
            AUTHOR_NAME="${PR_AUTHOR}"
            echo "Author name not found, using username: $AUTHOR_NAME"
          fi

          git config user.name "$AUTHOR_NAME"
          git config user.email "$AUTHOR_EMAIL"

          # Capture current SHA to return to later
          ORIGINAL_HEAD_SHA=$(git rev-parse HEAD)

          # Get labels
          LABELS=$(gh pr view "$PR_NUMBER" --json labels --jq '.labels[].name')

          if [ -z "$LABELS" ]; then
            echo "No labels found."
            exit 0
          fi

          # Loop through labels
          echo "$LABELS" | while read -r label; do
            if [[ "$label" == cherry-pick:* ]]; then
              TARGET_BRANCH=$(echo "${label#cherry-pick:}" | xargs)

              if [ -z "$TARGET_BRANCH" ]; then
                 echo "Empty target branch for label '$label', skipping."
                 continue
              fi

              echo "Processing cherry-pick to $TARGET_BRANCH"

              # Check if target branch exists on remote
              if ! git ls-remote --exit-code --heads origin "$TARGET_BRANCH"; then
                echo "Target branch $TARGET_BRANCH does not exist."
                post_comment "❌ Cherry-pick failed: Target branch \`$TARGET_BRANCH\` does not exist."
                continue
              fi

              # Create a new branch for the cherry-pick
              NEW_BRANCH="cherry-pick/$PR_NUMBER/$TARGET_BRANCH"

              # Clean up local branch if it exists (from previous run)
              if git show-ref --verify --quiet "refs/heads/$NEW_BRANCH"; then
                git branch -D "$NEW_BRANCH"
              fi

              # Fetch the target branch and checkout a new branch from it
              git fetch origin "$TARGET_BRANCH"
              git checkout -b "$NEW_BRANCH" "origin/$TARGET_BRANCH"

              # Cherry pick
              # Try standard cherry-pick first (for squash merges or single commits)
              if git cherry-pick "$MERGE_COMMIT_SHA"; then
                echo "Cherry-pick successful."
              else
                echo "Standard cherry-pick failed, trying with -m 1 (for merge commits)..."
                git cherry-pick --abort
                if git cherry-pick -m 1 "$MERGE_COMMIT_SHA"; then
                   echo "Cherry-pick with -m 1 successful."
                else
                   echo "Cherry-pick failed."
                   git cherry-pick --abort
                   post_comment "❌ Cherry-pick failed: Conflicts detected when cherry-picking to \`$TARGET_BRANCH\`. Please resolve manually."

                   # Cleanup
                   git checkout "$ORIGINAL_HEAD_SHA"
                   git branch -D "$NEW_BRANCH"
                   continue
                fi
              fi

              # Push
              # Check if remote branch already exists, if so, force push? Or maybe fail?
              # Force push is better to update the PR if we are re-running.
              git push origin "$NEW_BRANCH" --force

              # Create PR
              NEW_TITLE="[$TARGET_BRANCH] $PR_TITLE"

              # Check if PR already exists
              EXISTING_PR=$(gh pr list --base "$TARGET_BRANCH" --head "$NEW_BRANCH" --json url --jq '.[0].url')

              if [ -n "$EXISTING_PR" ]; then
                echo "PR already exists: $EXISTING_PR"
                post_comment "ℹ️ Cherry-pick PR already exists: $EXISTING_PR"
              else
                CREATED_PR_URL=$(gh pr create --base "$TARGET_BRANCH" --head "$NEW_BRANCH" --title "$NEW_TITLE" --body "Cherry-pick of #$PR_NUMBER" --reviewer "$PR_AUTHOR")
                echo "Created PR: $CREATED_PR_URL"
                post_comment "✅ Cherry-pick successful! Created PR: $CREATED_PR_URL"
              fi

              # Cleanup for next loop
              git checkout "$ORIGINAL_HEAD_SHA"
              git branch -D "$NEW_BRANCH"
            fi
          done