Track real latest message in the folder.

Telegram/SourceFiles/data/data_folder.cpp

@@ -90,12 +90,55 @@ void Folder::registerOne(not_null<History*> history) {
 	if (_chatsList.indexed()->size() == 1) {
 		updateChatListSortPosition();
 	}
+	applyChatListMessage(history->chatListMessage());
 }
 
 void Folder::unregisterOne(not_null<History*> history) {
 	if (_chatsList.empty()) {
 		updateChatListExistence();
 	}
+	if (_chatListMessage && _chatListMessage->history() == history) {
+		computeChatListMessage();
+	}
+}
+
+void Folder::oneListMessageChanged(HistoryItem *from, HistoryItem *to) {
+	if (!applyChatListMessage(to) && _chatListMessage == from) {
+		computeChatListMessage();
+	}
+}
+
+bool Folder::applyChatListMessage(HistoryItem *item) {
+	if (!item) {
+		return false;
+	} else if (_chatListMessage
+		&& _chatListMessage->date() >= item->date()) {
+		return false;
+	}
+	_chatListMessage = item;
+	updateChatListEntry();
+	return true;
+}
+
+void Folder::computeChatListMessage() {
+	auto &&items = ranges::view::all(
+		*_chatsList.indexed()
+	) | ranges::view::filter([](not_null<Dialogs::Row*> row) {
+		return row->entry()->chatListMessage() != nullptr;
+	});
+	const auto chatListDate = [](not_null<Dialogs::Row*> row) {
+		return row->entry()->chatListMessage()->date();
+	};
+	const auto top = ranges::max_element(
+		items,
+		ranges::less(),
+		chatListDate);
+	if (top == items.end()) {
+		_chatListMessage = nullptr;
+	} else {
+		_chatListMessage = (*top)->entry()->chatListMessage();
+	}
+	updateChatListEntry();
 }
 
 not_null<Dialogs::MainList*> Folder::chatsList() {
@@ -158,10 +201,7 @@ void Folder::requestChatListMessage() {
 }
 
 TimeId Folder::adjustedChatListTimeId() const {
-	const auto list = _chatsList.indexed();
-	return list->empty()
-		? TimeId(0)
-		: (*list->begin())->entry()->adjustedChatListTimeId();
+	return _chatListMessage ? _chatListMessage->date() : chatListTimeId();
 }
 
 void Folder::applyDialog(const MTPDdialogFolder &data) {
@@ -291,16 +331,11 @@ bool Folder::chatListMutedBadge() const {
 }
 
 HistoryItem *Folder::chatListMessage() const {
-	const auto list = _chatsList.indexed();
-	return list->empty()
-		? nullptr
-		: (*list->begin())->key().entry()->chatListMessage();
+	return _chatListMessage;
 }
 
 bool Folder::chatListMessageKnown() const {
-	const auto list = _chatsList.indexed();
-	return list->empty()
-		|| (*list->begin())->key().entry()->chatListMessageKnown();
+	return true;
 }
 
 const QString &Folder::chatListName() const {

Telegram/SourceFiles/data/data_folder.h

@@ -32,6 +32,7 @@ public:
 	FolderId id() const;
 	void registerOne(not_null<History*> history);
 	void unregisterOne(not_null<History*> history);
+	void oneListMessageChanged(HistoryItem *from, HistoryItem *to);
 
 	not_null<Dialogs::MainList*> chatsList();
 
@@ -75,6 +76,8 @@ public:
 
 private:
 	void indexNameParts();
+	bool applyChatListMessage(HistoryItem *item);
+	void computeChatListMessage();
 
 	FolderId _id = 0;
 	Dialogs::MainList _chatsList;
@@ -84,6 +87,7 @@ private:
 	base::flat_set<QChar> _nameFirstLetters;
 
 	Dialogs::UnreadState _cloudUnread;
+	HistoryItem *_chatListMessage = nullptr;
 	//rpl::variable<MessagePosition> _unreadPosition;
 
 };

Telegram/SourceFiles/history/history.cpp

@@ -154,7 +154,7 @@ void History::checkChatListMessageRemoved(not_null<HistoryItem*> item) {
 	if (chatListMessage() != item) {
 		return;
 	}
-	_chatListMessage = std::nullopt;
+	setChatListMessageUnknown();
 	refreshChatListMessage();
 	//if (const auto channel = peer->asChannel()) { // #feed
 	//	if (const auto feed = channel->feed()) {
@@ -2201,12 +2201,16 @@ void History::setLastMessage(HistoryItem *item) {
 		}
 	}
 	_lastMessage = item;
-	_chatListMessage = std::nullopt;
-	if (!peer->migrateTo()) {
+	if (peer->migrateTo()) {
 		// We don't want to request last message for all deactivated chats.
 		// This is a heavy request for them, because we need to get last
 		// two items by messages.getHistory to skip the migration message.
-		requestChatListMessage();
+		setChatListMessageUnknown();
+	} else {
+		setChatListMessageFromLast();
+		if (!chatListMessageKnown()) {
+			setFakeChatListMessage();
+		}
 	}
 }
 
@@ -2222,6 +2226,7 @@ void History::setChatListMessage(HistoryItem *item) {
 	if (_chatListMessage && *_chatListMessage == item) {
 		return;
 	}
+	const auto was = _chatListMessage.value_or(nullptr);
 	if (item) {
 		if (!_chatListMessage || !*_chatListMessage) {
 			Local::removeSavedPeer(peer);
@@ -2235,6 +2240,9 @@ void History::setChatListMessage(HistoryItem *item) {
 		_chatListMessage = nullptr;
 		updateChatListEntry();
 	}
+	if (const auto folder = this->folder()) {
+		folder->oneListMessageChanged(was, item);
+	}
 	if (const auto to = peer->migrateTo()) {
 		if (const auto history = owner().historyLoaded(to)) {
 			if (!history->chatListMessageKnown()) {
@@ -2297,7 +2305,18 @@ void History::setChatListMessageFromLast() {
 	if (const auto good = computeChatListMessageFromLast()) {
 		setChatListMessage(*good);
 	} else {
+		setChatListMessageUnknown();
+	}
+}
+
+void History::setChatListMessageUnknown() {
+	if (!_chatListMessage.has_value()) {
+		return;
+	}
+	const auto was = *_chatListMessage;
 	_chatListMessage = std::nullopt;
+	if (const auto folder = this->folder()) {
+		folder->oneListMessageChanged(was, nullptr);
 	}
 }
 

Telegram/SourceFiles/history/history.h

@@ -439,6 +439,7 @@ private:
 	void setChatListMessage(HistoryItem *item);
 	std::optional<HistoryItem*> computeChatListMessageFromLast() const;
 	void setChatListMessageFromLast();
+	void setChatListMessageUnknown();
 	void setFakeChatListMessage();
 
 	// Add all items to the unread mentions if we were not loaded at bottom and now are.