refactor(server): decouple services and improve architecture

- Introduce interfaces for all major services (JWT, PostAI, Comment, Message, Notification, QRCodeLogin, Upload, Vote, etc.) to support dependency inversion.
- Move query parameters from `internal/dto` to a new `internal/query` package to separate request payloads from data transfer objects.
- Refactor `internal/router` to use embedded `RouterDeps` for cleaner dependency management.
- Decouple handlers from repositories by injecting services instead of direct repository access, ensuring proper layering.
- Improve database initialization by moving it from `internal/model` to `internal/database`.
- Optimize message decryption by implementing a more efficient `BatchDecrypt` method in `MessageEncryptor` using a worker pool.
- Enhance error handling and security by implementing fail-fast checks for encryption key length during startup.
- Clean up unused code, including the `avatar` package and several unused DTOs.

internal/service/message_service.go

@@ -22,8 +22,26 @@ const (
 	CacheJitterRatio      = 0.1
 )
 
-// MessageService 消息服务
-type MessageService struct {
+// MessageService 消息服务接口
+type MessageService interface {
+	SendMessage(ctx context.Context, senderID, receiverID string, segments model.MessageSegments) (*model.Message, error)
+	GetConversations(ctx context.Context, userID string, page, pageSize int) ([]*model.Conversation, int64, error)
+	GetMessages(ctx context.Context, conversationID string, page, pageSize int) ([]*model.Message, int64, error)
+	GetMessagesAfterSeq(ctx context.Context, conversationID string, afterSeq int64, limit int) ([]*model.Message, error)
+	MarkAsRead(ctx context.Context, conversationID string, userID string, lastReadSeq int64) error
+	GetUnreadCount(ctx context.Context, conversationID string, userID string) (int64, error)
+	GetOrCreateConversation(ctx context.Context, user1ID, user2ID string) (*model.Conversation, error)
+	GetConversationParticipants(conversationID string) ([]*model.ConversationParticipant, error)
+	GetParticipantsBatch(ctx context.Context, convIDs []string) (map[string][]*model.ConversationParticipant, error)
+	GetMyParticipantsBatch(ctx context.Context, convIDs []string, userID string) (map[string]*model.ConversationParticipant, error)
+	InvalidateUserConversationCache(userID string)
+	InvalidateUserUnreadCache(userID, conversationID string)
+	GetMessagesByCursor(ctx context.Context, conversationID string, req *cursor.PageRequest) (*cursor.CursorPageResult[*model.Message], error)
+	GetConversationsByCursor(ctx context.Context, userID string, req *cursor.PageRequest) (*cursor.CursorPageResult[*model.Conversation], error)
+}
+
+// messageService 消息服务实现
+type messageService struct {
 	// 基础仓储
 	messageRepo repository.MessageRepository
 
@@ -33,11 +51,11 @@ type MessageService struct {
 	// 基础缓存（用于简单缓存操作）
 	baseCache cache.Cache
 
-	uploadService *UploadService
+	uploadService UploadService
 }
 
 // NewMessageService 创建消息服务
-func NewMessageService(messageRepo repository.MessageRepository, cacheBackend cache.Cache, uploadService *UploadService) *MessageService {
+func NewMessageService(messageRepo repository.MessageRepository, cacheBackend cache.Cache, uploadService UploadService) MessageService {
 	// 创建适配器
 	convRepoAdapter := cache.NewConversationRepositoryAdapter(messageRepo)
 	msgRepoAdapter := cache.NewMessageRepositoryAdapter(messageRepo)
@@ -51,7 +69,7 @@ func NewMessageService(messageRepo repository.MessageRepository, cacheBackend ca
 		nil,
 	)
 
-	return &MessageService{
+	return &messageService{
 		messageRepo:       messageRepo,
 		conversationCache: conversationCache,
 		baseCache:         cacheBackend,
@@ -67,7 +85,7 @@ type ConversationListResult struct {
 
 // SendMessage 发送消息（使用 segments）
 // senderID 和 receiverID 参数为 string 类型（UUID格式），与JWT中user_id保持一致
-func (s *MessageService) SendMessage(ctx context.Context, senderID, receiverID string, segments model.MessageSegments) (*model.Message, error) {
+func (s *messageService) SendMessage(ctx context.Context, senderID, receiverID string, segments model.MessageSegments) (*model.Message, error) {
 	// 获取或创建会话
 	conv, err := s.messageRepo.GetOrCreatePrivateConversation(senderID, receiverID)
 	if err != nil {
@@ -127,7 +145,7 @@ func (s *MessageService) SendMessage(ctx context.Context, senderID, receiverID s
 }
 
 // cacheMessage 缓存消息（内部方法）
-func (s *MessageService) cacheMessage(ctx context.Context, convID string, msg *model.Message) error {
+func (s *messageService) cacheMessage(ctx context.Context, convID string, msg *model.Message) error {
 	if s.conversationCache == nil {
 		return nil
 	}
@@ -140,7 +158,7 @@ func (s *MessageService) cacheMessage(ctx context.Context, convID string, msg *m
 
 // GetConversations 获取会话列表（带缓存）
 // userID 参数为 string 类型（UUID格式），与JWT中user_id保持一致
-func (s *MessageService) GetConversations(ctx context.Context, userID string, page, pageSize int) ([]*model.Conversation, int64, error) {
+func (s *messageService) GetConversations(ctx context.Context, userID string, page, pageSize int) ([]*model.Conversation, int64, error) {
 	// 优先使用 ConversationCache
 	if s.conversationCache != nil {
 		return s.conversationCache.GetConversationList(ctx, userID, page, pageSize)
@@ -190,7 +208,7 @@ func (s *MessageService) GetConversations(ctx context.Context, userID string, pa
 }
 
 // GetMessages 获取消息列表（带缓存）
-func (s *MessageService) GetMessages(ctx context.Context, conversationID string, page, pageSize int) ([]*model.Message, int64, error) {
+func (s *messageService) GetMessages(ctx context.Context, conversationID string, page, pageSize int) ([]*model.Message, int64, error) {
 	// 优先使用 ConversationCache
 	if s.conversationCache != nil {
 		return s.conversationCache.GetMessages(ctx, conversationID, page, pageSize)
@@ -201,13 +219,13 @@ func (s *MessageService) GetMessages(ctx context.Context, conversationID string,
 }
 
 // GetMessagesAfterSeq 获取指定seq之后的消息（增量同步）
-func (s *MessageService) GetMessagesAfterSeq(ctx context.Context, conversationID string, afterSeq int64, limit int) ([]*model.Message, error) {
+func (s *messageService) GetMessagesAfterSeq(ctx context.Context, conversationID string, afterSeq int64, limit int) ([]*model.Message, error) {
 	return s.messageRepo.GetMessagesAfterSeq(conversationID, afterSeq, limit)
 }
 
 // MarkAsRead 标记为已读（使用 Cache-Aside 模式）
 // userID 参数为 string 类型（UUID格式），与JWT中user_id保持一致
-func (s *MessageService) MarkAsRead(ctx context.Context, conversationID string, userID string, lastReadSeq int64) error {
+func (s *messageService) MarkAsRead(ctx context.Context, conversationID string, userID string, lastReadSeq int64) error {
 	// 1. 先写入DB（保证数据一致性，DB是唯一数据源）
 	err := s.messageRepo.UpdateLastReadSeq(conversationID, userID, lastReadSeq)
 	if err != nil {
@@ -230,7 +248,7 @@ func (s *MessageService) MarkAsRead(ctx context.Context, conversationID string,
 
 // GetUnreadCount 获取未读消息数（带缓存）
 // userID 参数为 string 类型（UUID格式），与JWT中user_id保持一致
-func (s *MessageService) GetUnreadCount(ctx context.Context, conversationID string, userID string) (int64, error) {
+func (s *messageService) GetUnreadCount(ctx context.Context, conversationID string, userID string) (int64, error) {
 	// 优先使用 ConversationCache
 	if s.conversationCache != nil {
 		return s.conversationCache.GetUnreadCount(ctx, userID, conversationID)
@@ -268,7 +286,7 @@ func (s *MessageService) GetUnreadCount(ctx context.Context, conversationID stri
 
 // GetOrCreateConversation 获取或创建私聊会话
 // user1ID 和 user2ID 参数为 string 类型（UUID格式），与JWT中user_id保持一致
-func (s *MessageService) GetOrCreateConversation(ctx context.Context, user1ID, user2ID string) (*model.Conversation, error) {
+func (s *messageService) GetOrCreateConversation(ctx context.Context, user1ID, user2ID string) (*model.Conversation, error) {
 	conv, err := s.messageRepo.GetOrCreatePrivateConversation(user1ID, user2ID)
 	if err != nil {
 		return nil, err
@@ -282,7 +300,7 @@ func (s *MessageService) GetOrCreateConversation(ctx context.Context, user1ID, u
 }
 
 // GetConversationParticipants 获取会话参与者列表
-func (s *MessageService) GetConversationParticipants(conversationID string) ([]*model.ConversationParticipant, error) {
+func (s *messageService) GetConversationParticipants(conversationID string) ([]*model.ConversationParticipant, error) {
 	// 优先使用缓存
 	if s.conversationCache != nil {
 		return s.conversationCache.GetParticipants(context.Background(), conversationID)
@@ -291,12 +309,12 @@ func (s *MessageService) GetConversationParticipants(conversationID string) ([]*
 }
 
 // GetParticipantsBatch 批量获取多个会话的参与者列表
-func (s *MessageService) GetParticipantsBatch(ctx context.Context, convIDs []string) (map[string][]*model.ConversationParticipant, error) {
+func (s *messageService) GetParticipantsBatch(ctx context.Context, convIDs []string) (map[string][]*model.ConversationParticipant, error) {
 	return s.messageRepo.GetParticipantsBatch(ctx, convIDs)
 }
 
 // GetMyParticipantsBatch 批量获取用户在多个会话中的参与者信息
-func (s *MessageService) GetMyParticipantsBatch(ctx context.Context, convIDs []string, userID string) (map[string]*model.ConversationParticipant, error) {
+func (s *messageService) GetMyParticipantsBatch(ctx context.Context, convIDs []string, userID string) (map[string]*model.ConversationParticipant, error) {
 	return s.messageRepo.GetMyParticipantsBatch(ctx, convIDs, userID)
 }
 
@@ -306,23 +324,23 @@ func ParseConversationID(idStr string) (string, error) {
 }
 
 // InvalidateUserConversationCache 失效用户会话相关缓存（供外部调用）
-func (s *MessageService) InvalidateUserConversationCache(userID string) {
+func (s *messageService) InvalidateUserConversationCache(userID string) {
 	s.conversationCache.InvalidateConversationList(userID)
 	cache.InvalidateUnreadConversation(s.baseCache, userID)
 }
 
 // InvalidateUserUnreadCache 失效用户未读数缓存（供外部调用）
-func (s *MessageService) InvalidateUserUnreadCache(userID, conversationID string) {
+func (s *messageService) InvalidateUserUnreadCache(userID, conversationID string) {
 	cache.InvalidateUnreadConversation(s.baseCache, userID)
 	s.conversationCache.InvalidateUnreadCount(userID, conversationID)
 }
 
 // GetMessagesByCursor 游标分页获取会话消息
-func (s *MessageService) GetMessagesByCursor(ctx context.Context, conversationID string, req *cursor.PageRequest) (*cursor.CursorPageResult[*model.Message], error) {
+func (s *messageService) GetMessagesByCursor(ctx context.Context, conversationID string, req *cursor.PageRequest) (*cursor.CursorPageResult[*model.Message], error) {
 	return s.messageRepo.GetMessagesByCursor(ctx, conversationID, req)
 }
 
 // GetConversationsByCursor 游标分页获取用户会话列表
-func (s *MessageService) GetConversationsByCursor(ctx context.Context, userID string, req *cursor.PageRequest) (*cursor.CursorPageResult[*model.Conversation], error) {
+func (s *messageService) GetConversationsByCursor(ctx context.Context, userID string, req *cursor.PageRequest) (*cursor.CursorPageResult[*model.Conversation], error) {
 	return s.messageRepo.GetConversationsByCursor(ctx, userID, req)
 }