From 5a48600b7af0a29e136348f0b96be6a014ced9f9 Mon Sep 17 00:00:00 2001
From: Bohdan Horbeshko <bodqhrohro@gmail.com>
Date: Sun, 6 Feb 2022 08:25:46 -0500
Subject: [PATCH] The Proper Subscriptions Filter

---
 telegram/commands.go |  7 +-----
 telegram/handlers.go | 54 ++++++++++++++++++++++++--------------------
 telegram/utils.go    | 20 ++++++++++++++++
 3 files changed, 51 insertions(+), 30 deletions(-)

diff --git a/telegram/commands.go b/telegram/commands.go
index fbed7cd..e8586d8 100644
--- a/telegram/commands.go
+++ b/telegram/commands.go
@@ -461,12 +461,7 @@ func (c *Client) ProcessChatCommand(chatID int64, cmdline string) (string, bool)
 			return "No error, but chat is nil", true
 		}
 
-		gateway.SendPresence(
-			c.xmpp,
-			c.jid,
-			gateway.SPFrom(strconv.FormatInt(chat.Id, 10)),
-			gateway.SPType("subscribe"),
-		)
+		c.subscribeToID(chat.Id, chat)
 	// join https://t.me/publichat
 	case "join":
 		if len(args) < 1 {
diff --git a/telegram/handlers.go b/telegram/handlers.go
index 1313871..face5dd 100644
--- a/telegram/handlers.go
+++ b/telegram/handlers.go
@@ -73,6 +73,20 @@ func (c *Client) updateHandler() {
 				}
 				c.updateNewChat(typedUpdate)
 				log.Debugf("%#v", typedUpdate.Chat)
+			case client.TypeUpdateChatPosition:
+				typedUpdate, ok := update.(*client.UpdateChatPosition)
+				if !ok {
+					uhOh()
+				}
+				c.updateChatPosition(typedUpdate)
+				log.Debugf("%#v", typedUpdate)
+			case client.TypeUpdateChatLastMessage:
+				typedUpdate, ok := update.(*client.UpdateChatLastMessage)
+				if !ok {
+					uhOh()
+				}
+				c.updateChatLastMessage(typedUpdate)
+				log.Debugf("%#v", typedUpdate)
 			case client.TypeUpdateNewMessage:
 				typedUpdate, ok := update.(*client.UpdateNewMessage)
 				if !ok {
@@ -142,30 +156,8 @@ func (c *Client) updateNewChat(update *client.UpdateNewChat) {
 
 		c.cache.SetChat(update.Chat.Id, update.Chat)
 
-		var isChannel = false
-		chatType := update.Chat.Type.ChatTypeType()
-		if chatType == client.TypeChatTypeSupergroup {
-			typeSupergroup, ok := update.Chat.Type.(*client.ChatTypeSupergroup)
-			if !ok {
-				uhOh()
-			}
-			isChannel = typeSupergroup.IsChannel
-		}
-
-		// don't subscribe to channel posters
-		if !((isChannel && update.Chat.LastReadInboxMessageId == 0) ||
-			// don't subscribe to chats with no conversation
-			// (manual adding will trigger a subscribe anyway)
-			(update.Chat.LastReadInboxMessageId == 0 &&
-				update.Chat.LastReadOutboxMessageId == 0 &&
-				chatType == client.TypeChatTypePrivate)) {
-			gateway.SendPresence(
-				c.xmpp,
-				c.jid,
-				gateway.SPFrom(strconv.FormatInt(update.Chat.Id, 10)),
-				gateway.SPType("subscribe"),
-				gateway.SPNickname(update.Chat.Title),
-			)
+		if update.Chat.Positions != nil && len(update.Chat.Positions) > 0 {
+			c.subscribeToID(update.Chat.Id, update.Chat)
 		}
 
 		if update.Chat.Id < 0 {
@@ -174,6 +166,20 @@ func (c *Client) updateNewChat(update *client.UpdateNewChat) {
 	}()
 }
 
+// chat position is updated
+func (c *Client) updateChatPosition(update *client.UpdateChatPosition) {
+	if update.Position != nil && update.Position.Order != 0 {
+		go c.subscribeToID(update.ChatId, nil)
+	}
+}
+
+// chat last message is updated
+func (c *Client) updateChatLastMessage(update *client.UpdateChatLastMessage) {
+	if update.Positions != nil && len(update.Positions) > 0 {
+		go c.subscribeToID(update.ChatId, nil)
+	}
+}
+
 // message received
 func (c *Client) updateNewMessage(update *client.UpdateNewMessage) {
 	go func() {
diff --git a/telegram/utils.go b/telegram/utils.go
index 66f217a..d6b112d 100644
--- a/telegram/utils.go
+++ b/telegram/utils.go
@@ -774,3 +774,23 @@ func (c *Client) DownloadFile(id int32, priority int32, synchronous bool) (*clie
 		Synchronous: synchronous,
 	})
 }
+
+// subscribe to a Telegram ID
+func (c *Client) subscribeToID(id int64, chat *client.Chat) {
+	var args []args.V
+	args = append(args, gateway.SPFrom(strconv.FormatInt(id, 10)))
+	args = append(args, gateway.SPType("subscribe"))
+
+	if chat == nil {
+		chat, _, _ = c.GetContactByID(id, nil)
+	}
+	if chat != nil {
+		args = append(args, gateway.SPNickname(chat.Title))
+	}
+
+	gateway.SendPresence(
+		c.xmpp,
+		c.jid,
+		args...,
+	)
+}