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.

client/user/userclient.go

@@ -6,13 +6,17 @@ import (
 
 	"github.com/celestix/gotgproto"
 	"github.com/celestix/gotgproto/dispatcher"
+	"github.com/celestix/gotgproto/dispatcher/handlers"
+	"github.com/celestix/gotgproto/dispatcher/handlers/filters"
 	"github.com/celestix/gotgproto/ext"
 	"github.com/celestix/gotgproto/sessionMaker"
+
 	"github.com/charmbracelet/log"
 	"github.com/gotd/td/telegram/dcs"
 	"github.com/krau/SaveAny-Bot/client/middleware"
 	"github.com/krau/SaveAny-Bot/common/utils/netutil"
 	"github.com/krau/SaveAny-Bot/config"
+	"github.com/krau/SaveAny-Bot/database"
 	"github.com/ncruces/go-sqlite3/gormlite"
 	"golang.org/x/net/proxy"
 )
@@ -106,6 +110,15 @@ func Login(ctx context.Context) (*gotgproto.Client, error) {
 			return nil, r.err
 		}
 		uc = r.client
+		uc.Dispatcher.AddHandler(handlers.NewMessage(filters.Message.Media, func(ctx *ext.Context, u *ext.Update) error {
+			chatId := u.EffectiveChat().GetID()
+			watchChats, err := database.GetWatchChatsByChatID(ctx, chatId)
+			if err != nil || watchChats == nil {
+				return dispatcher.EndGroups
+			}
+			return dispatcher.ContinueGroups
+		}))
+		uc.Dispatcher.AddHandler(handlers.NewMessage(filters.Message.Media, handleMediaMessage))
 		log.FromContext(ctx).Infof("User client logged in successfully: %s", uc.Self.FirstName+" "+uc.Self.LastName)
 		return uc, nil
 	}

client/user/watch.go

@@ -0,0 +1,53 @@
+package user
+
+import (
+	"github.com/celestix/gotgproto/dispatcher"
+	"github.com/celestix/gotgproto/ext"
+	"github.com/gotd/td/tg"
+	"github.com/krau/SaveAny-Bot/common/utils/tgutil"
+	"github.com/krau/SaveAny-Bot/pkg/tfile"
+)
+
+type MediaMessageEvent struct {
+	Ctx    *ext.Context
+	ChatID int64 // from witch the media message was sent
+	File   tfile.TGFileMessage
+}
+
+var mediaMessageCh = make(chan MediaMessageEvent, 100)
+
+func GetMediaMessageCh() chan MediaMessageEvent {
+	return mediaMessageCh
+}
+
+func handleMediaMessage(ctx *ext.Context, update *ext.Update) error {
+	message := update.EffectiveMessage
+	media, ok := message.GetMedia()
+	if !ok || media == nil {
+		return dispatcher.EndGroups
+	}
+	support := func() bool {
+		switch media.(type) {
+		case *tg.MessageMediaDocument, *tg.MessageMediaPhoto:
+			return true
+		default:
+			return false
+		}
+	}()
+	if !support {
+		return dispatcher.EndGroups
+	}
+	file, err := tfile.FromMediaMessage(media, ctx.Raw, message.Message, tfile.WithNameIfEmpty(
+		tgutil.GenFileNameFromMessage(*message.Message),
+	))
+	if err != nil {
+		return err
+	}
+	chatId := update.EffectiveChat().GetID()
+	mediaMessageCh <- MediaMessageEvent{
+		Ctx:    ctx,
+		ChatID: chatId,
+		File:   file,
+	}
+	return dispatcher.EndGroups
+}