feat: implement watch for monitoring chat messages

- Added a new command handler for /watch that allows users to listen to messages from a specified chat and save them according to storage rules.
- Introduced filtering options for messages using regular expressions.
- Implemented functionality to start and stop watching chats, including error handling for invalid inputs and user settings.
- Created a new utility package for message element handling related to the watch feature.
- Updated the user model to manage watched chats, including methods to add, remove, and check if a chat is being watched.

database/chat.go

@@ -0,0 +1,39 @@
+package database
+
+import "context"
+
+func (user *User) WatchChat(ctx context.Context, chat WatchChat) error {
+	if user.WatchChats == nil {
+		user.WatchChats = make([]WatchChat, 0)
+	}
+
+	user.WatchChats = append(user.WatchChats, chat)
+	return db.WithContext(ctx).Save(user.WatchChats).Error
+}
+
+func (user *User) UnwatchChat(ctx context.Context, chatID int64) error {
+	var watchChat WatchChat
+	err := db.WithContext(ctx).Where("chat_id = ? AND user_id = ?", chatID, user.ID).First(&watchChat).Error
+	if err != nil {
+		return err
+	}
+	return db.WithContext(ctx).Unscoped().Delete(&watchChat).Error
+}
+
+func (user *User) WatchingChat(ctx context.Context, chatID int64) (bool, error) {
+	var count int64
+	err := db.WithContext(ctx).Model(&WatchChat{}).Where("chat_id = ? AND user_id = ?", chatID, user.ID).Count(&count).Error
+	if err != nil {
+		return false, err
+	}
+	return count > 0, nil
+}
+
+func GetWatchChatsByChatID(ctx context.Context, chatID int64) ([]*WatchChat, error) {
+	var watchChats []*WatchChat
+	err := db.WithContext(ctx).Where("chat_id = ?", chatID).Find(&watchChats).Error
+	if err != nil {
+		return nil, err
+	}
+	return watchChats, nil
+}

database/db.go

@@ -37,7 +37,7 @@ func Init(ctx context.Context) {
 		logger.Fatal("Failed to open database: ", err)
 	}
 	logger.Debug("Database connected")
-	if err := db.AutoMigrate(&User{}, &Dir{}, &Rule{}); err != nil {
+	if err := db.AutoMigrate(&User{}, &Dir{}, &Rule{}, &WatchChat{}); err != nil {
 		logger.Fatal("迁移数据库失败, 如果您从旧版本升级, 建议手动删除数据库文件后重试: ", err)
 	}
 	if err := syncUsers(ctx); err != nil {

database/model.go

@@ -12,6 +12,14 @@ type User struct {
 	Dirs           []Dir
 	ApplyRule      bool
 	Rules          []Rule
+	WatchChats     []WatchChat
+}
+
+type WatchChat struct {
+	gorm.Model
+	UserID uint // User's database ID (not chat ID)
+	ChatID int64
+	Filter string
 }
 
 type Dir struct {

database/user.go

@@ -1,6 +1,10 @@
 package database
 
-import "context"
+import (
+	"context"
+
+	"gorm.io/gorm/clause"
+)
 
 func CreateUser(ctx context.Context, chatID int64) error {
 	if _, err := GetUserByChatID(ctx, chatID); err == nil {
@@ -11,19 +15,16 @@ func CreateUser(ctx context.Context, chatID int64) error {
 
 func GetAllUsers(ctx context.Context) ([]User, error) {
 	var users []User
-	err := db.Preload("Dirs").
-		WithContext(ctx).
-		Preload("Rules").
+	err := db.WithContext(ctx).
+		Preload(clause.Associations).
 		Find(&users).Error
 	return users, err
 }
 
 func GetUserByChatID(ctx context.Context, chatID int64) (*User, error) {
 	var user User
-	err := db.
-		Preload("Dirs").
-		WithContext(ctx).
-		Preload("Rules").
+	err := db.WithContext(ctx).
+		Preload(clause.Associations).
 		Where("chat_id = ?", chatID).First(&user).Error
 	return &user, err
 }
@@ -36,5 +37,16 @@ func UpdateUser(ctx context.Context, user *User) error {
 }
 
 func DeleteUser(ctx context.Context, user *User) error {
-	return db.WithContext(ctx).Unscoped().Select("Dirs", "Rules").Delete(user).Error
+	return db.WithContext(ctx).
+		Unscoped().
+		Select(clause.Associations).
+		Delete(user).Error
 }
+
+func GetUserByID(ctx context.Context, id uint) (*User, error) {
+	var user User
+	err := db.WithContext(ctx).
+		Preload(clause.Associations).
+		Where("id = ?", id).First(&user).Error
+	return &user, err
+}