feat: add stickers

internal/service/chat_service.go

@@ -418,6 +418,9 @@ type SendRequest struct {
 	PreviewURL *string
 	// Entity is something else in the app — a post — shared as a card.
 	Entity *EntityAttachment
+	// StickerKey sends a piece of reward artwork. Ownership is checked
+	// server-side; the key alone proves nothing.
+	StickerKey *string
 	// Quote is a passage shared from the library, rendered as a quote the
 	// reader can tap to return to the exact phrase.
 	Quote *QuoteAttachment
@@ -458,7 +461,8 @@ func (s *ChatService) Send(ctx context.Context, userID, conversationID string, r
 	body := strings.TrimSpace(req.Body)
 	// A photo or a shared passage with no caption is an ordinary message; only
 	// a message with nothing at all in it is empty.
-	if body == "" && len(req.Attachments) == 0 && req.Quote == nil && req.Entity == nil {
+	if body == "" && len(req.Attachments) == 0 && req.Quote == nil &&
+		req.Entity == nil && req.StickerKey == nil {
 		return nil, ErrChatEmptyBody
 	}
 	if len([]rune(body)) > maxBodyRunes {
@@ -493,6 +497,12 @@ func (s *ChatService) Send(ctx context.Context, userID, conversationID string, r
 		return s.hydrateSent(ctx, userID, conversationID, msg), nil
 	}
 
+	if req.StickerKey != nil {
+		if err := s.attachSticker(ctx, conversationID, userID, msg, *req.StickerKey); err != nil {
+			s.logger.Warn("chat: sticker refused",
+				zap.String("user_id", userID), zap.Error(err))
+		}
+	}
 	if err := s.attachEntity(ctx, conversationID, userID, msg, req.Entity); err != nil {
 		s.logger.Warn("chat: entity share refused", zap.String("user_id", userID), zap.Error(err))
 	}
@@ -1624,6 +1634,40 @@ func (s *ChatService) Message(ctx context.Context, userID, conversationID, messa
 	return s.withAttachments(ctx, userID, msg)
 }
 
+// Stickers lists what the caller can send: sādhana rewards they earned, plus
+// stickers they saved from a chat.
+func (s *ChatService) Stickers(ctx context.Context, userID string) ([]model.Sticker, error) {
+	return s.chat.Stickers(ctx, userID)
+}
+
+// SaveSticker keeps one someone sent, after checking it really is on that
+// message and the caller is in the thread.
+func (s *ChatService) SaveSticker(ctx context.Context, userID, messageID, key string) error {
+	return s.chat.SaveSticker(ctx, userID, key, messageID)
+}
+
+// attachSticker stores the artwork on a message.
+//
+// Ownership is checked here, not trusted from the client: the key comes over
+// the wire, and without this anyone could send any sticker in the catalog by
+// guessing its key. The image and name are denormalized because the catalog
+// is static art — there is nothing viewer-dependent to re-resolve on read.
+func (s *ChatService) attachSticker(ctx context.Context, conversationID, userID string, msg *model.Message, key string) error {
+	sticker, err := s.chat.Sticker(ctx, userID, key)
+	if err != nil {
+		return err
+	}
+	entityType := model.EntitySticker
+	if _, err := s.chat.AddAttachment(ctx, repository.AddAttachmentParams{
+		MessageID: msg.ID, ConversationID: conversationID, Ord: 0,
+		Kind: model.AttachmentSticker, EntityType: &entityType,
+		EntityID: &sticker.Key, ImageURL: &sticker.ImageURL, Title: &sticker.Name,
+	}); err != nil {
+		s.logger.Warn("chat: attach sticker failed", zap.Error(err))
+	}
+	return nil
+}
+
 // Typing broadcasts that someone is composing.
 //
 // Never persisted and never pushed: a typing indicator is only meaningful to