package v1

import (
	"context"
	stderrors "errors"
	"fmt"
	"log/slog"
	"strings"
	"time"

	"github.com/pkg/errors"
	"google.golang.org/grpc/codes"
	"google.golang.org/grpc/status"
	"google.golang.org/protobuf/proto"
	"google.golang.org/protobuf/types/known/emptypb"

	"github.com/usememos/memos/internal/httpgetter"
	"github.com/usememos/memos/internal/webhook"
	v1pb "github.com/usememos/memos/proto/gen/api/v1"
	storepb "github.com/usememos/memos/proto/gen/store"
	"github.com/usememos/memos/server/runner/memopayload"
	"github.com/usememos/memos/store"
)

// suppressSSEKey is a context key used to suppress the SSE broadcast from
// CreateMemo when it is called internally (e.g., from CreateMemoComment).
type suppressSSEKey struct{}

const maxBatchGetLinkMetadata = 10

var fetchHTMLMeta = httpgetter.GetHTMLMeta

func withSuppressSSE(ctx context.Context) context.Context {
	return context.WithValue(ctx, suppressSSEKey{}, true)
}

func isSSESuppressed(ctx context.Context) bool {
	v, ok := ctx.Value(suppressSSEKey{}).(bool)
	return ok && v
}

func (s *APIV1Service) checkMemoReadAccess(ctx context.Context, memo *store.Memo) error {
	if memo == nil {
		return status.Errorf(codes.NotFound, "memo not found")
	}

	// Archived memos are only visible to their creator.
	if memo.RowStatus == store.Archived {
		user, err := s.fetchCurrentUser(ctx)
		if err != nil {
			return status.Errorf(codes.Internal, "failed to get user")
		}
		if user == nil || memo.CreatorID != user.ID {
			return status.Errorf(codes.NotFound, "memo not found")
		}
	}

	if memo.Visibility != store.Public {
		user, err := s.fetchCurrentUser(ctx)
		if err != nil {
			return status.Errorf(codes.Internal, "failed to get user")
		}
		if user == nil {
			return status.Errorf(codes.Unauthenticated, "user not authenticated")
		}
		if memo.Visibility == store.Private && memo.CreatorID != user.ID {
			return status.Errorf(codes.PermissionDenied, "permission denied")
		}
	}
	return nil
}

func (s *APIV1Service) CreateMemo(ctx context.Context, request *v1pb.CreateMemoRequest) (*v1pb.Memo, error) {
	user, err := s.fetchCurrentUser(ctx)
	if err != nil {
		return nil, status.Errorf(codes.Internal, "failed to get user")
	}
	if user == nil {
		return nil, status.Errorf(codes.Unauthenticated, "user not authenticated")
	}

	memoUID, err := ValidateAndGenerateUID(request.MemoId)
	if err != nil {
		return nil, err
	}

	create := &store.Memo{
		UID:        memoUID,
		CreatorID:  user.ID,
		Content:    request.Memo.Content,
		Visibility: convertVisibilityToStore(request.Memo.Visibility),
	}

	// Set custom timestamps if provided in the request.
	if request.Memo.CreateTime != nil && request.Memo.CreateTime.IsValid() {
		createdTs := request.Memo.CreateTime.AsTime().Unix()
		create.CreatedTs = createdTs
	}
	if request.Memo.UpdateTime != nil && request.Memo.UpdateTime.IsValid() {
		updatedTs := request.Memo.UpdateTime.AsTime().Unix()
		create.UpdatedTs = updatedTs
	}

	contentLengthLimit, err := s.getContentLengthLimit(ctx)
	if err != nil {
		return nil, status.Errorf(codes.Internal, "failed to get content length limit")
	}
	if len(create.Content) > contentLengthLimit {
		return nil, status.Errorf(codes.InvalidArgument, "content too long (max %d characters)", contentLengthLimit)
	}
	if err := memopayload.RebuildMemoPayload(ctx, create, s.MarkdownService); err != nil {
		return nil, status.Errorf(codes.Internal, "failed to rebuild memo payload: %v", err)
	}
	if request.Memo.Location != nil {
		create.Payload.Location = convertLocationToStore(request.Memo.Location)
	}

	memo, err := s.Store.CreateMemo(ctx, create)
	if err != nil {
		// Check for unique constraint violation (AIP-133 compliance)
		errMsg := err.Error()
		if strings.Contains(errMsg, "UNIQUE constraint failed") ||
			strings.Contains(errMsg, "duplicate key") ||
			strings.Contains(errMsg, "Duplicate entry") {
			return nil, status.Errorf(codes.AlreadyExists, "memo with ID %q already exists", memoUID)
		}
		return nil, err
	}

	attachments := []*store.Attachment{}

	if len(request.Memo.Attachments) > 0 {
		if err := s.setMemoAttachmentsInternal(ctx, user, memo, request.Memo.Attachments); err != nil {
			return nil, errors.Wrap(err, "failed to set memo attachments")
		}

		a, err := s.Store.ListAttachments(ctx, &store.FindAttachment{
			MemoID: &memo.ID,
		})
		if err != nil {
			return nil, errors.Wrap(err, "failed to get memo attachments")
		}
		attachments = a
	}
	if len(request.Memo.Relations) > 0 {
		if err := s.setMemoRelationsInternal(ctx, memo, request.Memo.Relations); err != nil {
			return nil, errors.Wrap(err, "failed to set memo relations")
		}
	}

	relations, err := s.loadMemoRelations(ctx, memo)
	if err != nil {
		return nil, errors.Wrap(err, "failed to load memo relations")
	}
	memoMessage, err := s.convertMemoFromStore(ctx, memo, nil, attachments, relations)
	if err != nil {
		return nil, errors.Wrap(err, "failed to convert memo")
	}
	// Try to dispatch webhook when memo is created.
	if err := s.DispatchMemoCreatedWebhook(ctx, memoMessage); err != nil {
		slog.Warn("Failed to dispatch memo created webhook", slog.Any("err", err))
	}

	// Broadcast live refresh event (skipped when called from CreateMemoComment).
	if !isSSESuppressed(ctx) {
		s.SSEHub.Broadcast(&SSEEvent{
			Type:       SSEEventMemoCreated,
			Name:       memoMessage.Name,
			Visibility: memo.Visibility,
			CreatorID:  resolveSSECreatorID(memo, nil),
		})
	}

	if !isMentionNotificationSuppressed(ctx) {
		s.dispatchMemoMentionNotificationsBestEffort(ctx, memo, nil, "")
	}

	return memoMessage, nil
}

func (s *APIV1Service) ListMemos(ctx context.Context, request *v1pb.ListMemosRequest) (*v1pb.ListMemosResponse, error) {
	memoFind := &store.FindMemo{
		// Exclude comments by default.
		ExcludeComments: true,
	}
	currentUser, err := s.fetchCurrentUser(ctx)
	if err != nil {
		return nil, status.Errorf(codes.Internal, "failed to get user")
	}

	if request.State == v1pb.State_ARCHIVED {
		state := store.Archived
		memoFind.RowStatus = &state
		// Archived memos are only visible to their creator.
		if currentUser == nil {
			return &v1pb.ListMemosResponse{}, nil
		}
		memoFind.CreatorID = &currentUser.ID
	} else {
		state := store.Normal
		memoFind.RowStatus = &state
	}

	// Parse order_by field (replaces the old sort and direction fields)
	if request.OrderBy != "" {
		if err := s.parseMemoOrderBy(request.OrderBy, memoFind); err != nil {
			return nil, status.Errorf(codes.InvalidArgument, "invalid order_by: %v", err)
		}
	} else {
		// Default ordering by create_time desc.
		memoFind.OrderByTimeAsc = false
	}

	if request.Filter != "" {
		if err := s.validateFilter(ctx, request.Filter); err != nil {
			return nil, status.Errorf(codes.InvalidArgument, "invalid filter: %v", err)
		}
		memoFind.Filters = append(memoFind.Filters, request.Filter)
	}

	if currentUser == nil {
		memoFind.VisibilityList = []store.Visibility{store.Public}
	} else {
		if memoFind.CreatorID == nil {
			filter := fmt.Sprintf(`creator_id == %d || visibility in ["PUBLIC", "PROTECTED"]`, currentUser.ID)
			memoFind.Filters = append(memoFind.Filters, filter)
		} else if *memoFind.CreatorID != currentUser.ID {
			memoFind.VisibilityList = []store.Visibility{store.Public, store.Protected}
		}
	}

	var limit, offset int
	if request.PageToken != "" {
		var pageToken v1pb.PageToken
		if err := unmarshalPageToken(request.PageToken, &pageToken); err != nil {
			return nil, status.Errorf(codes.InvalidArgument, "invalid page token: %v", err)
		}
		limit = normalizePageSize(pageToken.Limit)
		offset = int(pageToken.Offset)
		if offset < 0 {
			offset = 0
		}
	} else {
		limit = normalizePageSize(request.PageSize)
	}
	limit = min(limit, MaxPageSize)
	limitPlusOne := limit + 1
	memoFind.Limit = &limitPlusOne
	memoFind.Offset = &offset
	memos, err := s.Store.ListMemos(ctx, memoFind)
	if err != nil {
		return nil, status.Errorf(codes.Internal, "failed to list memos: %v", err)
	}

	memoMessages := []*v1pb.Memo{}
	nextPageToken := ""
	if len(memos) == limitPlusOne {
		memos = memos[:limit]
		nextPageToken, err = getPageToken(limit, offset+limit)
		if err != nil {
			return nil, status.Errorf(codes.Internal, "failed to get next page token, error: %v", err)
		}
	}

	if len(memos) == 0 {
		response := &v1pb.ListMemosResponse{
			Memos:         memoMessages,
			NextPageToken: nextPageToken,
		}
		return response, nil
	}

	reactionMap := make(map[string][]*store.Reaction)
	contentIDs := make([]string, 0, len(memos))

	attachmentMap := make(map[int32][]*store.Attachment)
	memoIDs := make([]int32, 0, len(memos))

	for _, m := range memos {
		contentIDs = append(contentIDs, fmt.Sprintf("%s%s", MemoNamePrefix, m.UID))
		memoIDs = append(memoIDs, m.ID)
	}

	// REACTIONS
	reactions, err := s.Store.ListReactions(ctx, &store.FindReaction{ContentIDList: contentIDs})
	if err != nil {
		return nil, status.Errorf(codes.Internal, "failed to list reactions")
	}
	for _, reaction := range reactions {
		reactionMap[reaction.ContentID] = append(reactionMap[reaction.ContentID], reaction)
	}

	// ATTACHMENTS
	attachments, err := s.Store.ListAttachments(ctx, &store.FindAttachment{MemoIDList: memoIDs})
	if err != nil {
		return nil, status.Errorf(codes.Internal, "failed to list attachments")
	}
	for _, attachment := range attachments {
		attachmentMap[*attachment.MemoID] = append(attachmentMap[*attachment.MemoID], attachment)
	}

	// RELATIONS (batch load to avoid N+1)
	relationMap, err := s.batchConvertMemoRelations(ctx, memos, false)
	if err != nil {
		return nil, status.Errorf(codes.Internal, "failed to batch load memo relations")
	}
	creatorIDs := make([]int32, 0, len(memos)+len(reactions))
	for _, memo := range memos {
		creatorIDs = append(creatorIDs, memo.CreatorID)
	}
	for _, reaction := range reactions {
		creatorIDs = append(creatorIDs, reaction.CreatorID)
	}
	creatorMap, err := s.listUsersByID(ctx, creatorIDs)
	if err != nil {
		return nil, status.Errorf(codes.Internal, "failed to list memo creators: %v", err)
	}
	for _, memo := range memos {
		memoName := fmt.Sprintf("%s%s", MemoNamePrefix, memo.UID)
		reactions := reactionMap[memoName]
		attachments := attachmentMap[memo.ID]
		relations := relationMap[memo.ID]

		memoMessage, err := s.convertMemoFromStoreWithCreators(ctx, memo, reactions, attachments, relations, creatorMap)
		if err != nil {
			if stderrors.Is(err, errMemoCreatorNotFound) {
				slog.Warn("Skipping memo with missing creator",
					slog.Int64("memo_id", int64(memo.ID)),
					slog.String("memo_uid", memo.UID),
					slog.Int64("creator_id", int64(memo.CreatorID)),
				)
				continue
			}
			return nil, errors.Wrap(err, "failed to convert memo")
		}

		memoMessages = append(memoMessages, memoMessage)
	}

	response := &v1pb.ListMemosResponse{
		Memos:         memoMessages,
		NextPageToken: nextPageToken,
	}
	return response, nil
}

func (s *APIV1Service) GetMemo(ctx context.Context, request *v1pb.GetMemoRequest) (*v1pb.Memo, error) {
	memoUID, err := ExtractMemoUIDFromName(request.Name)
	if err != nil {
		return nil, status.Errorf(codes.InvalidArgument, "invalid memo name: %v", err)
	}
	memo, err := s.Store.GetMemo(ctx, &store.FindMemo{
		UID: &memoUID,
	})
	if err != nil {
		return nil, err
	}
	if memo == nil {
		return nil, status.Errorf(codes.NotFound, "memo not found")
	}

	if err := s.checkMemoReadAccess(ctx, memo); err != nil {
		return nil, err
	}
	if memo.ParentUID != nil {
		parentMemo, err := s.Store.GetMemo(ctx, &store.FindMemo{UID: memo.ParentUID})
		if err != nil {
			return nil, status.Errorf(codes.Internal, "failed to get parent memo")
		}
		if parentMemo == nil {
			return nil, status.Errorf(codes.NotFound, "memo not found")
		}
		if err := s.checkMemoReadAccess(ctx, parentMemo); err != nil {
			return nil, err
		}
	}

	reactions, err := s.Store.ListReactions(ctx, &store.FindReaction{
		ContentID: &request.Name,
	})
	if err != nil {
		return nil, status.Errorf(codes.Internal, "failed to list reactions")
	}

	attachments, err := s.Store.ListAttachments(ctx, &store.FindAttachment{
		MemoID: &memo.ID,
	})
	if err != nil {
		return nil, status.Errorf(codes.Internal, "failed to list attachments")
	}

	relations, err := s.loadMemoRelations(ctx, memo)
	if err != nil {
		return nil, errors.Wrap(err, "failed to load memo relations")
	}
	memoMessage, err := s.convertMemoFromStore(ctx, memo, reactions, attachments, relations)
	if err != nil {
		if stderrors.Is(err, errMemoCreatorNotFound) {
			return nil, status.Errorf(codes.NotFound, "memo creator not found")
		}
		return nil, errors.Wrap(err, "failed to convert memo")
	}
	return memoMessage, nil
}

// GetLinkMetadata gets metadata for a link.
func (*APIV1Service) GetLinkMetadata(_ context.Context, request *v1pb.GetLinkMetadataRequest) (*v1pb.LinkMetadata, error) {
	return getLinkMetadata(request.GetUrl())
}

// BatchGetLinkMetadata gets metadata for links.
func (*APIV1Service) BatchGetLinkMetadata(_ context.Context, request *v1pb.BatchGetLinkMetadataRequest) (*v1pb.BatchGetLinkMetadataResponse, error) {
	if len(request.Urls) == 0 {
		return nil, status.Errorf(codes.InvalidArgument, "urls are required")
	}
	if len(request.Urls) > maxBatchGetLinkMetadata {
		return nil, status.Errorf(codes.InvalidArgument, "too many urls (max %d)", maxBatchGetLinkMetadata)
	}

	linkMetadata := make([]*v1pb.LinkMetadata, 0, len(request.Urls))
	for _, url := range request.Urls {
		metadata, err := getLinkMetadata(url)
		if err != nil {
			return nil, err
		}
		linkMetadata = append(linkMetadata, metadata)
	}

	return &v1pb.BatchGetLinkMetadataResponse{
		LinkMetadata: linkMetadata,
	}, nil
}

func getLinkMetadata(inputURL string) (*v1pb.LinkMetadata, error) {
	url := strings.TrimSpace(inputURL)
	if url == "" {
		return nil, status.Errorf(codes.InvalidArgument, "url is required")
	}
	htmlMeta, err := fetchHTMLMeta(url)
	if err != nil {
		return nil, status.Errorf(codes.InvalidArgument, "failed to fetch link metadata: %v", err)
	}

	return &v1pb.LinkMetadata{
		Url:         inputURL,
		Title:       htmlMeta.Title,
		Description: htmlMeta.Description,
		Image:       htmlMeta.Image,
	}, nil
}

func (s *APIV1Service) UpdateMemo(ctx context.Context, request *v1pb.UpdateMemoRequest) (*v1pb.Memo, error) {
	memoUID, err := ExtractMemoUIDFromName(request.Memo.Name)
	if err != nil {
		return nil, status.Errorf(codes.InvalidArgument, "invalid memo name: %v", err)
	}
	if request.UpdateMask == nil || len(request.UpdateMask.Paths) == 0 {
		return nil, status.Errorf(codes.InvalidArgument, "update mask is required")
	}

	memo, err := s.Store.GetMemo(ctx, &store.FindMemo{UID: &memoUID})
	if err != nil {
		return nil, status.Errorf(codes.Internal, "failed to get memo: %v", err)
	}
	if memo == nil {
		return nil, status.Errorf(codes.NotFound, "memo not found")
	}

	user, err := s.fetchCurrentUser(ctx)
	if err != nil {
		return nil, status.Errorf(codes.Internal, "failed to get current user")
	}
	if user == nil {
		return nil, status.Errorf(codes.Unauthenticated, "user not authenticated")
	}
	// Only the creator or admin can update the memo.
	if memo.CreatorID != user.ID && !isSuperUser(user) {
		return nil, status.Errorf(codes.PermissionDenied, "permission denied")
	}

	update := &store.UpdateMemo{
		ID: memo.ID,
	}
	var previousContent string
	contentUpdated := false
	for _, path := range request.UpdateMask.Paths {
		if path == "content" {
			contentUpdated = true
			previousContent = memo.Content
			contentLengthLimit, err := s.getContentLengthLimit(ctx)
			if err != nil {
				return nil, status.Errorf(codes.Internal, "failed to get content length limit")
			}
			if len(request.Memo.Content) > contentLengthLimit {
				return nil, status.Errorf(codes.InvalidArgument, "content too long (max %d characters)", contentLengthLimit)
			}
			memo.Content = request.Memo.Content
			if err := memopayload.RebuildMemoPayload(ctx, memo, s.MarkdownService); err != nil {
				return nil, status.Errorf(codes.Internal, "failed to rebuild memo payload: %v", err)
			}
			update.Content = &memo.Content
			update.Payload = memo.Payload
		} else if path == "visibility" {
			visibility := convertVisibilityToStore(request.Memo.Visibility)
			if memo.ParentUID != nil {
				parentMemo, err := s.Store.GetMemo(ctx, &store.FindMemo{UID: memo.ParentUID})
				if err != nil {
					return nil, status.Errorf(codes.Internal, "failed to get parent memo")
				}
				if parentMemo == nil {
					return nil, status.Errorf(codes.NotFound, "memo not found")
				}
				visibility = parentMemo.Visibility
			}
			update.Visibility = &visibility
		} else if path == "pinned" {
			update.Pinned = &request.Memo.Pinned
		} else if path == "state" {
			rowStatus := convertStateToStore(request.Memo.State)
			update.RowStatus = &rowStatus
		} else if path == "create_time" {
			createdTs := request.Memo.CreateTime.AsTime().Unix()
			update.CreatedTs = &createdTs
		} else if path == "update_time" {
			updatedTs := time.Now().Unix()
			if request.Memo.UpdateTime != nil {
				updatedTs = request.Memo.UpdateTime.AsTime().Unix()
			}
			update.UpdatedTs = &updatedTs
		} else if path == "display_time" {
			return nil, status.Errorf(codes.InvalidArgument, "display_time is not supported")
		} else if path == "location" {
			payload := memo.Payload
			payload.Location = convertLocationToStore(request.Memo.Location)
			update.Payload = payload
		} else if path == "attachments" {
			if err := s.setMemoAttachmentsInternal(ctx, user, memo, request.Memo.Attachments); err != nil {
				return nil, errors.Wrap(err, "failed to set memo attachments")
			}
		} else if path == "relations" {
			if err := s.setMemoRelationsInternal(ctx, memo, request.Memo.Relations); err != nil {
				return nil, errors.Wrap(err, "failed to set memo relations")
			}
		}
	}

	if err = s.Store.UpdateMemo(ctx, update); err != nil {
		return nil, status.Errorf(codes.Internal, "failed to update memo")
	}

	memo, err = s.Store.GetMemo(ctx, &store.FindMemo{
		ID: &memo.ID,
	})
	if err != nil {
		return nil, errors.Wrap(err, "failed to get memo")
	}
	memo, parentMemo, memoMessage, err := s.buildUpdatedMemoState(ctx, memo.ID)
	if err != nil {
		return nil, errors.Wrap(err, "failed to build updated memo state")
	}
	if contentUpdated {
		s.dispatchMemoMentionNotificationsBestEffort(ctx, memo, parentMemo, previousContent)
	}
	s.dispatchMemoUpdatedSideEffects(ctx, memo, parentMemo, memoMessage)

	return memoMessage, nil
}

func (s *APIV1Service) DeleteMemo(ctx context.Context, request *v1pb.DeleteMemoRequest) (*emptypb.Empty, error) {
	memoUID, err := ExtractMemoUIDFromName(request.Name)
	if err != nil {
		return nil, status.Errorf(codes.InvalidArgument, "invalid memo name: %v", err)
	}
	memo, err := s.Store.GetMemo(ctx, &store.FindMemo{
		UID: &memoUID,
	})
	if err != nil {
		return nil, err
	}
	if memo == nil {
		return nil, status.Errorf(codes.NotFound, "memo not found")
	}

	user, err := s.fetchCurrentUser(ctx)
	if err != nil {
		return nil, status.Errorf(codes.Internal, "failed to get current user")
	}
	if user == nil {
		return nil, status.Errorf(codes.Unauthenticated, "user not authenticated")
	}
	// Only the creator or admin can update the memo.
	if memo.CreatorID != user.ID && !isSuperUser(user) {
		return nil, status.Errorf(codes.PermissionDenied, "permission denied")
	}

	reactions, err := s.Store.ListReactions(ctx, &store.FindReaction{
		ContentID: &request.Name,
	})
	if err != nil {
		return nil, status.Errorf(codes.Internal, "failed to list reactions")
	}

	attachments, err := s.Store.ListAttachments(ctx, &store.FindAttachment{
		MemoID: &memo.ID,
	})
	if err != nil {
		return nil, status.Errorf(codes.Internal, "failed to list attachments")
	}

	deleteRelations, _ := s.loadMemoRelations(ctx, memo)
	if memoMessage, err := s.convertMemoFromStore(ctx, memo, reactions, attachments, deleteRelations); err == nil {
		// Try to dispatch webhook when memo is deleted.
		if err := s.DispatchMemoDeletedWebhook(ctx, memoMessage); err != nil {
			slog.Warn("Failed to dispatch memo deleted webhook", slog.Any("err", err))
		}
	}

	// Delete memo comments first (store.DeleteMemo handles their relations and attachments)
	commentType := store.MemoRelationComment
	relations, err := s.Store.ListMemoRelations(ctx, &store.FindMemoRelation{RelatedMemoID: &memo.ID, Type: &commentType})
	if err != nil {
		return nil, status.Errorf(codes.Internal, "failed to list memo comments")
	}
	for _, relation := range relations {
		if err := s.Store.DeleteMemo(ctx, &store.DeleteMemo{ID: relation.MemoID}); err != nil {
			return nil, status.Errorf(codes.Internal, "failed to delete memo comment")
		}
	}

	// Delete the memo (store.DeleteMemo handles relation and attachment cleanup)
	if err = s.Store.DeleteMemo(ctx, &store.DeleteMemo{ID: memo.ID}); err != nil {
		return nil, status.Errorf(codes.Internal, "failed to delete memo")
	}

	// Broadcast live refresh event.
	s.SSEHub.Broadcast(&SSEEvent{
		Type:       SSEEventMemoDeleted,
		Name:       request.Name,
		Visibility: memo.Visibility,
		CreatorID:  resolveSSECreatorID(memo, nil),
	})

	return &emptypb.Empty{}, nil
}

func (s *APIV1Service) CreateMemoComment(ctx context.Context, request *v1pb.CreateMemoCommentRequest) (*v1pb.Memo, error) {
	memoUID, err := ExtractMemoUIDFromName(request.Name)
	if err != nil {
		return nil, status.Errorf(codes.InvalidArgument, "invalid memo name: %v", err)
	}
	relatedMemo, err := s.Store.GetMemo(ctx, &store.FindMemo{UID: &memoUID})
	if err != nil {
		return nil, status.Errorf(codes.Internal, "failed to get memo")
	}
	if relatedMemo == nil {
		return nil, status.Errorf(codes.NotFound, "memo not found")
	}

	// Check memo visibility before allowing comment.
	user, err := s.fetchCurrentUser(ctx)
	if err != nil {
		return nil, status.Errorf(codes.Internal, "failed to get user")
	}
	if user == nil {
		return nil, status.Errorf(codes.Unauthenticated, "user not authenticated")
	}
	if relatedMemo.Visibility == store.Private && relatedMemo.CreatorID != user.ID && !isSuperUser(user) {
		return nil, status.Errorf(codes.PermissionDenied, "permission denied")
	}
	if request.Comment == nil {
		return nil, status.Errorf(codes.InvalidArgument, "comment is required")
	}

	comment, ok := proto.Clone(request.Comment).(*v1pb.Memo)
	if !ok {
		return nil, status.Errorf(codes.Internal, "failed to clone memo comment")
	}
	comment.Visibility = convertVisibilityFromStore(relatedMemo.Visibility)

	// Create the memo comment first; suppress the generic memo.created SSE event
	// since CreateMemoComment broadcasts memo.comment.created for the parent instead.
	memoComment, err := s.CreateMemo(withSuppressMentionNotifications(withSuppressSSE(ctx)), &v1pb.CreateMemoRequest{
		Memo:   comment,
		MemoId: request.CommentId,
	})
	if err != nil {
		return nil, status.Errorf(codes.Internal, "failed to create memo")
	}
	memoUID, err = ExtractMemoUIDFromName(memoComment.Name)
	if err != nil {
		return nil, status.Errorf(codes.InvalidArgument, "invalid memo name: %v", err)
	}
	memo, err := s.Store.GetMemo(ctx, &store.FindMemo{UID: &memoUID})
	if err != nil {
		return nil, status.Errorf(codes.Internal, "failed to get memo")
	}

	// Build the relation between the comment memo and the original memo.
	_, err = s.Store.UpsertMemoRelation(ctx, &store.MemoRelation{
		MemoID:        memo.ID,
		RelatedMemoID: relatedMemo.ID,
		Type:          store.MemoRelationComment,
	})
	if err != nil {
		return nil, status.Errorf(codes.Internal, "failed to create memo relation")
	}
	creator, err := ResolveUserByName(ctx, s.Store, memoComment.Creator)
	if err != nil {
		return nil, status.Errorf(codes.InvalidArgument, "invalid memo creator")
	}
	if creator == nil {
		return nil, status.Errorf(codes.NotFound, "memo creator not found")
	}
	creatorID := creator.ID
	if memoComment.Visibility != v1pb.Visibility_PRIVATE && creatorID != relatedMemo.CreatorID {
		if _, err := s.createInboxWithEmailNotification(ctx, &store.Inbox{
			SenderID:   creatorID,
			ReceiverID: relatedMemo.CreatorID,
			Status:     store.UNREAD,
			Message: &storepb.InboxMessage{
				Type: storepb.InboxMessage_MEMO_COMMENT,
				Payload: &storepb.InboxMessage_MemoComment{
					MemoComment: &storepb.InboxMessage_MemoCommentPayload{
						MemoId:        memo.ID,
						RelatedMemoId: relatedMemo.ID,
					},
				},
			},
		}); err != nil {
			return nil, status.Errorf(codes.Internal, "failed to create inbox")
		}
	}

	if err := s.DispatchMemoCommentCreatedWebhook(ctx, memoComment, relatedMemo.CreatorID); err != nil {
		slog.Warn("Failed to dispatch memo comment created webhook", slog.Any("err", err))
	}

	s.dispatchMemoMentionNotificationsBestEffort(ctx, memo, relatedMemo, "")

	// Broadcast live refresh event for the parent memo so subscribers see the new comment.
	s.SSEHub.Broadcast(&SSEEvent{
		Type:       SSEEventMemoCommentCreated,
		Name:       request.Name,
		Visibility: relatedMemo.Visibility,
		CreatorID:  relatedMemo.CreatorID,
	})

	return memoComment, nil
}

func (s *APIV1Service) ListMemoComments(ctx context.Context, request *v1pb.ListMemoCommentsRequest) (*v1pb.ListMemoCommentsResponse, error) {
	memoUID, err := ExtractMemoUIDFromName(request.Name)
	if err != nil {
		return nil, status.Errorf(codes.InvalidArgument, "invalid memo name: %v", err)
	}
	memo, err := s.Store.GetMemo(ctx, &store.FindMemo{UID: &memoUID})
	if err != nil {
		return nil, status.Errorf(codes.Internal, "failed to get memo")
	}
	if memo == nil {
		return nil, status.Errorf(codes.NotFound, "memo not found")
	}
	if err := s.checkMemoReadAccess(ctx, memo); err != nil {
		return nil, err
	}

	currentUser, err := s.fetchCurrentUser(ctx)
	if err != nil {
		return nil, status.Errorf(codes.Internal, "failed to get user")
	}
	var memoFilter string
	if currentUser == nil {
		memoFilter = `visibility == "PUBLIC"`
	} else {
		memoFilter = fmt.Sprintf(`creator_id == %d || visibility in ["PUBLIC", "PROTECTED"]`, currentUser.ID)
	}
	memoRelationComment := store.MemoRelationComment
	var limit, offset int
	if request.PageToken != "" {
		var pageToken v1pb.PageToken
		if err := unmarshalPageToken(request.PageToken, &pageToken); err != nil {
			return nil, status.Errorf(codes.InvalidArgument, "invalid page token: %v", err)
		}
		limit = normalizePageSize(pageToken.Limit)
		offset = int(pageToken.Offset)
		if offset < 0 {
			offset = 0
		}
	} else {
		limit = normalizePageSize(request.PageSize)
	}
	limitPlusOne := limit + 1
	memoRelations, err := s.Store.ListMemoRelations(ctx, &store.FindMemoRelation{
		RelatedMemoID: &memo.ID,
		Type:          &memoRelationComment,
		MemoFilter:    &memoFilter,
		Limit:         &limitPlusOne,
		Offset:        &offset,
	})
	if err != nil {
		return nil, status.Errorf(codes.Internal, "failed to list memo relations")
	}

	nextPageToken := ""
	if len(memoRelations) == limitPlusOne {
		memoRelations = memoRelations[:limit]
		nextPageToken, err = getPageToken(limit, offset+limit)
		if err != nil {
			return nil, status.Errorf(codes.Internal, "failed to get next page token, error: %v", err)
		}
	}

	if len(memoRelations) == 0 {
		response := &v1pb.ListMemoCommentsResponse{
			Memos:         []*v1pb.Memo{},
			NextPageToken: nextPageToken,
		}
		return response, nil
	}

	memoRelationIDs := make([]int32, 0, len(memoRelations))
	for _, m := range memoRelations {
		memoRelationIDs = append(memoRelationIDs, m.MemoID)
	}
	memos, err := s.Store.ListMemos(ctx, &store.FindMemo{IDList: memoRelationIDs})
	if err != nil {
		return nil, status.Errorf(codes.Internal, "failed to list memos")
	}

	memoIDToNameMap := make(map[int32]string)
	contentIDs := make([]string, 0, len(memos))
	memoIDsForAttachments := make([]int32, 0, len(memos))

	for _, memo := range memos {
		memoName := fmt.Sprintf("%s%s", MemoNamePrefix, memo.UID)
		memoIDToNameMap[memo.ID] = memoName
		contentIDs = append(contentIDs, memoName)
		memoIDsForAttachments = append(memoIDsForAttachments, memo.ID)
	}
	reactions, err := s.Store.ListReactions(ctx, &store.FindReaction{ContentIDList: contentIDs})
	if err != nil {
		return nil, status.Errorf(codes.Internal, "failed to list reactions")
	}

	memoReactionsMap := make(map[string][]*store.Reaction)
	for _, reaction := range reactions {
		memoReactionsMap[reaction.ContentID] = append(memoReactionsMap[reaction.ContentID], reaction)
	}

	attachments, err := s.Store.ListAttachments(ctx, &store.FindAttachment{MemoIDList: memoIDsForAttachments})
	if err != nil {
		return nil, status.Errorf(codes.Internal, "failed to list attachments")
	}
	attachmentMap := make(map[int32][]*store.Attachment)
	for _, attachment := range attachments {
		attachmentMap[*attachment.MemoID] = append(attachmentMap[*attachment.MemoID], attachment)
	}

	// RELATIONS (batch load to avoid N+1)
	relationMap, err := s.batchConvertMemoRelations(ctx, memos, false)
	if err != nil {
		return nil, status.Errorf(codes.Internal, "failed to batch load memo relations")
	}
	creatorIDs := make([]int32, 0, len(memos)+len(reactions))
	for _, memo := range memos {
		creatorIDs = append(creatorIDs, memo.CreatorID)
	}
	for _, reaction := range reactions {
		creatorIDs = append(creatorIDs, reaction.CreatorID)
	}
	creatorMap, err := s.listUsersByID(ctx, creatorIDs)
	if err != nil {
		return nil, status.Errorf(codes.Internal, "failed to list memo creators: %v", err)
	}
	var memosResponse []*v1pb.Memo
	for _, m := range memos {
		memoName := memoIDToNameMap[m.ID]
		reactions := memoReactionsMap[memoName]
		attachments := attachmentMap[m.ID]
		relations := relationMap[m.ID]

		memoMessage, err := s.convertMemoFromStoreWithCreators(ctx, m, reactions, attachments, relations, creatorMap)
		if err != nil {
			if stderrors.Is(err, errMemoCreatorNotFound) {
				slog.Warn("Skipping memo comment with missing creator",
					slog.Int64("memo_id", int64(m.ID)),
					slog.String("memo_uid", m.UID),
					slog.Int64("creator_id", int64(m.CreatorID)),
					slog.String("parent_name", request.Name),
				)
				continue
			}
			return nil, errors.Wrap(err, "failed to convert memo")
		}
		memosResponse = append(memosResponse, memoMessage)
	}

	response := &v1pb.ListMemoCommentsResponse{
		Memos:         memosResponse,
		NextPageToken: nextPageToken,
	}
	return response, nil
}

func (s *APIV1Service) getContentLengthLimit(ctx context.Context) (int, error) {
	instanceMemoRelatedSetting, err := s.Store.GetInstanceMemoRelatedSetting(ctx)
	if err != nil {
		return 0, status.Errorf(codes.Internal, "failed to get instance memo related setting")
	}
	return int(instanceMemoRelatedSetting.ContentLengthLimit), nil
}

// DispatchMemoCreatedWebhook dispatches webhook when memo is created.
func (s *APIV1Service) DispatchMemoCreatedWebhook(ctx context.Context, memo *v1pb.Memo) error {
	return s.dispatchMemoRelatedWebhook(ctx, memo, "memos.memo.created")
}

// DispatchMemoUpdatedWebhook dispatches webhook when memo is updated.
func (s *APIV1Service) DispatchMemoUpdatedWebhook(ctx context.Context, memo *v1pb.Memo) error {
	return s.dispatchMemoRelatedWebhook(ctx, memo, "memos.memo.updated")
}

// DispatchMemoDeletedWebhook dispatches webhook when memo is deleted.
func (s *APIV1Service) DispatchMemoDeletedWebhook(ctx context.Context, memo *v1pb.Memo) error {
	return s.dispatchMemoRelatedWebhook(ctx, memo, "memos.memo.deleted")
}

// DispatchMemoCommentCreatedWebhook dispatches webhook to the related memo owner when a comment is created.
func (s *APIV1Service) DispatchMemoCommentCreatedWebhook(ctx context.Context, commentMemo *v1pb.Memo, relatedMemoCreatorID int32) error {
	webhooks, err := s.Store.GetUserWebhooks(ctx, relatedMemoCreatorID)
	if err != nil {
		return err
	}
	for _, hook := range webhooks {
		payload, err := convertMemoToWebhookPayload(commentMemo)
		if err != nil {
			return errors.Wrap(err, "failed to convert memo to webhook payload")
		}
		payload.ActivityType = "memos.memo.comment.created"
		payload.URL = hook.Url
		webhook.PostAsync(payload)
	}
	return nil
}

func (s *APIV1Service) dispatchMemoRelatedWebhook(ctx context.Context, memo *v1pb.Memo, activityType string) error {
	creator, err := ResolveUserByName(ctx, s.Store, memo.Creator)
	if err != nil {
		return status.Errorf(codes.InvalidArgument, "invalid memo creator")
	}
	if creator == nil {
		return status.Errorf(codes.NotFound, "memo creator not found")
	}
	creatorID := creator.ID
	webhooks, err := s.Store.GetUserWebhooks(ctx, creatorID)
	if err != nil {
		return err
	}
	for _, hook := range webhooks {
		payload, err := convertMemoToWebhookPayload(memo)
		if err != nil {
			return errors.Wrap(err, "failed to convert memo to webhook payload")
		}
		payload.ActivityType = activityType
		payload.URL = hook.Url

		// Use asynchronous webhook dispatch
		webhook.PostAsync(payload)
	}
	return nil
}

func convertMemoToWebhookPayload(memo *v1pb.Memo) (*webhook.WebhookRequestPayload, error) {
	return &webhook.WebhookRequestPayload{
		Creator: memo.Creator,
		Memo:    memo,
	}, nil
}

func (s *APIV1Service) getMemoContentSnippet(content string) (string, error) {
	// Use goldmark service for snippet generation
	snippet, err := s.MarkdownService.GenerateSnippet([]byte(content), 64)
	if err != nil {
		return "", errors.Wrap(err, "failed to generate snippet")
	}
	return snippet, nil
}

// parseMemoOrderBy parses the order_by field and sets the appropriate ordering in memoFind.
// Follows AIP-132: supports comma-separated list of fields with optional "desc" suffix.
// Example: "pinned desc, create_time desc" or "update_time asc".
func (*APIV1Service) parseMemoOrderBy(orderBy string, memoFind *store.FindMemo) error {
	if strings.TrimSpace(orderBy) == "" {
		return errors.New("empty order_by")
	}

	// Split by comma to support multiple sort fields per AIP-132.
	fields := strings.Split(orderBy, ",")

	// Track if we've seen pinned field.
	hasPinned := false
	hasExplicitTimeField := false

	for _, field := range fields {
		parts := strings.Fields(strings.TrimSpace(field))
		if len(parts) == 0 {
			continue
		}

		fieldName := parts[0]
		fieldDirection := "desc" // default per AIP-132 (we use desc as default for time fields)
		if len(parts) > 1 {
			fieldDirection = strings.ToLower(parts[1])
			if fieldDirection != "asc" && fieldDirection != "desc" {
				return errors.Errorf("invalid order direction: %s, must be 'asc' or 'desc'", parts[1])
			}
		}

		switch fieldName {
		case "pinned":
			hasPinned = true
			memoFind.OrderByPinned = true
			// Note: pinned is always DESC (true first) regardless of direction specified.
		case "create_time", "name":
			// Only set if this is the first time field we encounter.
			if !hasExplicitTimeField {
				memoFind.OrderByTimeAsc = fieldDirection == "asc"
			}
			hasExplicitTimeField = true
		case "update_time":
			// Only set if this is the first time field we encounter.
			if !hasExplicitTimeField {
				memoFind.OrderByUpdatedTs = true
				memoFind.OrderByTimeAsc = fieldDirection == "asc"
			}
			hasExplicitTimeField = true
		default:
			return errors.Errorf("unsupported order field: %s, supported fields are: pinned, create_time, update_time, name", fieldName)
		}
	}

	// If only pinned was specified, still need to set a default time ordering.
	if hasPinned && !memoFind.OrderByUpdatedTs && len(fields) == 1 {
		memoFind.OrderByTimeAsc = false // default to desc
	}

	return nil
}