Support default General topic in forums.

Telegram/SourceFiles/boxes/peers/edit_peer_info_box.cpp

@@ -248,6 +248,7 @@ public:
 		not_null<Window::SessionNavigation*> navigation,
 		not_null<Ui::BoxContent*> box,
 		not_null<PeerData*> peer);
+	~Controller();
 
 	[[nodiscard]] object_ptr<Ui::VerticalLayout> createContent();
 	void setFocus();
@@ -388,6 +389,8 @@ Controller::Controller(
 	_peer->updateFull();
 }
 
+Controller::~Controller() = default;
+
 void Controller::subscribeToMigration() {
 	SubscribeToMigration(
 		_peer,
@@ -815,7 +818,7 @@ void Controller::fillForumButton() {
 
 	AddButtonWithText(
 		_controls.buttonsLayout,
-		rpl::single(u"Forum"_q), // #TODO forum
+		rpl::single(u"Forum"_q), // #TODO forum lang
 		rpl::single(QString()),
 		[] {},
 		{ &st::settingsIconGroup, Settings::kIconPurple }

Telegram/SourceFiles/data/data_channel.cpp

@@ -60,13 +60,9 @@ Data::ChatBotCommands::Changed MegagroupInfo::setBotCommands(
 	return _botCommands.update(list);
 }
 
-void MegagroupInfo::setIsForum(not_null<ChannelData*> that, bool is) {
-	if (is == (_forum != nullptr)) {
-		return;
-	} else if (is) {
+void MegagroupInfo::ensureForum(not_null<ChannelData*> that) {
+	if (!_forum) {
 		_forum = std::make_unique<Data::Forum>(that->owner().history(that));
-	} else {
-		_forum = nullptr;
 	}
 }
 
@@ -74,35 +70,15 @@ Data::Forum *MegagroupInfo::forum() const {
 	return _forum.get();
 }
 
+std::unique_ptr<Data::Forum> MegagroupInfo::takeForumData() {
+	return std::move(_forum);
+}
+
 ChannelData::ChannelData(not_null<Data::Session*> owner, PeerId id)
 : PeerData(owner, id)
 , inputChannel(
 	MTP_inputChannel(MTP_long(peerToChannel(id).bare), MTP_long(0)))
 , _ptsWaiter(&owner->session().updates()) {
-	_flags.changes(
-	) | rpl::start_with_next([=](const Flags::Change &change) {
-		if (change.diff
-			& (Flag::Left | Flag::Forbidden)) {
-			if (const auto chat = getMigrateFromChat()) {
-				session().changes().peerUpdated(chat, UpdateFlag::Migration);
-				session().changes().peerUpdated(this, UpdateFlag::Migration);
-			}
-		}
-		if (change.diff & Flag::Megagroup) {
-			if (change.value & Flag::Megagroup) {
-				if (!mgInfo) {
-					mgInfo = std::make_unique<MegagroupInfo>();
-				}
-			} else if (mgInfo) {
-				mgInfo = nullptr;
-			}
-		}
-		if (change.diff & Flag::CallNotEmpty) {
-			if (const auto history = this->owner().historyLoaded(this)) {
-				history->updateChatListEntry();
-			}
-		}
-	}, _lifetime);
 }
 
 void ChannelData::setPhoto(const MTPChatPhoto &photo) {
@@ -132,6 +108,44 @@ void ChannelData::setAccessHash(uint64 accessHash) {
 		MTP_long(accessHash));
 }
 
+void ChannelData::setFlags(ChannelDataFlags which) {
+	const auto diff = flags() ^ which;
+	if ((which & Flag::Megagroup) && !mgInfo) {
+		mgInfo = std::make_unique<MegagroupInfo>();
+	}
+
+	// Let Data::Forum live till the end of _flags.set.
+	// That way the data can be used in changes handler.
+	// Example: render frame for forum auto-closing animation.
+	const auto taken = ((diff & Flag::Forum) && !(which & Flag::Forum))
+		? mgInfo->takeForumData()
+		: nullptr;
+
+	if ((diff & Flag::Forum) && (which & Flag::Forum)) {
+		mgInfo->ensureForum(this);
+	}
+	_flags.set(which);
+	if (diff & (Flag::Left | Flag::Forbidden)) {
+		if (const auto chat = getMigrateFromChat()) {
+			session().changes().peerUpdated(chat, UpdateFlag::Migration);
+			session().changes().peerUpdated(this, UpdateFlag::Migration);
+		}
+	}
+	if (diff & Flag::CallNotEmpty) {
+		if (const auto history = this->owner().historyLoaded(this)) {
+			history->updateChatListEntry();
+		}
+	}
+}
+
+void ChannelData::addFlags(ChannelDataFlags which) {
+	setFlags(flags() | which);
+}
+
+void ChannelData::removeFlags(ChannelDataFlags which) {
+	setFlags(flags() & ~which);
+}
+
 void ChannelData::setInviteLink(const QString &newInviteLink) {
 	_inviteLink = newInviteLink;
 }

Telegram/SourceFiles/data/data_channel.h

@@ -96,8 +96,9 @@ public:
 		return _botCommands;
 	}
 
-	void setIsForum(not_null<ChannelData*> that, bool is);
+	void ensureForum(not_null<ChannelData*> that);
 	[[nodiscard]] Data::Forum *forum() const;
+	[[nodiscard]] std::unique_ptr<Data::Forum> takeForumData();
 
 	std::deque<not_null<UserData*>> lastParticipants;
 	base::flat_map<not_null<UserData*>, Admin> lastAdmins;
@@ -148,15 +149,9 @@ public:
 	void setPhoto(const MTPChatPhoto &photo);
 	void setAccessHash(uint64 accessHash);
 
-	void setFlags(ChannelDataFlags which) {
-		_flags.set(which);
-	}
-	void addFlags(ChannelDataFlags which) {
-		_flags.add(which);
-	}
-	void removeFlags(ChannelDataFlags which) {
-		_flags.remove(which);
-	}
+	void setFlags(ChannelDataFlags which);
+	void addFlags(ChannelDataFlags which);
+	void removeFlags(ChannelDataFlags which);
 	[[nodiscard]] auto flags() const {
 		return _flags.current();
 	}
@@ -490,8 +485,6 @@ private:
 	int _slowmodeSeconds = 0;
 	TimeId _slowmodeLastMessage = 0;
 
-	rpl::lifetime _lifetime;
-
 };
 
 namespace Data {

Telegram/SourceFiles/data/data_forum.cpp

@@ -29,12 +29,25 @@ constexpr auto kTopicsPerPage = 500;
 
 } // namespace
 
-Forum::Forum(not_null<History*> forum)
-: _forum(forum)
-, _topicsList(&forum->session(), FilterId(0), rpl::single(1)) {
+Forum::Forum(not_null<History*> history)
+: _history(history)
+, _topicsList(&_history->session(), FilterId(0), rpl::single(1)) {
+	Expects(_history->peer->isChannel());
 }
 
-Forum::~Forum() = default;
+Forum::~Forum() {
+	if (_requestId) {
+		_history->session().api().request(_requestId).cancel();
+	}
+}
+
+not_null<History*> Forum::history() const {
+	return _history;
+}
+
+not_null<ChannelData*> Forum::channel() const {
+	return _history->peer->asChannel();
+}
 
 not_null<Dialogs::MainList*> Forum::topicsList() {
 	return &_topicsList;
@@ -44,28 +57,24 @@ void Forum::requestTopics() {
 	if (_allLoaded || _requestId) {
 		return;
 	}
-	const auto forum = _forum;
 	const auto firstLoad = !_offsetDate;
 	const auto loadCount = firstLoad ? kTopicsFirstLoad : kTopicsPerPage;
-	const auto api = &forum->session().api();
+	const auto api = &_history->session().api();
 	_requestId = api->request(MTPchannels_GetForumTopics(
 		MTP_flags(0),
-		forum->peer->asChannel()->inputChannel,
+		channel()->inputChannel,
 		MTPstring(), // q
 		MTP_int(_offsetDate),
 		MTP_int(_offsetId),
 		MTP_int(_offsetTopicId),
 		MTP_int(loadCount)
 	)).done([=](const MTPmessages_ForumTopics &result) {
-		if (!forum->peer->isForum()) {
-			return;
-		}
 		const auto &data = result.data();
-		const auto owner = &forum->owner();
+		const auto owner = &channel()->owner();
 		owner->processUsers(data.vusers());
 		owner->processChats(data.vchats());
 		owner->processMessages(data.vmessages(), NewMessageType::Existing);
-		forum->peer->asChannel()->ptsReceived(data.vpts().v);
+		channel()->ptsReceived(data.vpts().v);
 		const auto &list = data.vtopics().v;
 		for (const auto &topic : list) {
 			const auto rootId = MsgId(topic.data().vid().v);
@@ -74,7 +83,7 @@ void Forum::requestTopics() {
 			const auto raw = creating
 				? _topics.emplace(
 					rootId,
-					std::make_unique<ForumTopic>(forum, rootId)
+					std::make_unique<ForumTopic>(_history, rootId)
 				).first->second.get()
 				: i->second.get();
 			raw->applyTopic(topic);
@@ -107,7 +116,7 @@ void Forum::applyTopicAdded(MsgId rootId, const QString &title) {
 	} else {
 		const auto raw = _topics.emplace(
 			rootId,
-			std::make_unique<ForumTopic>(_forum, rootId)
+			std::make_unique<ForumTopic>(_history, rootId)
 		).first->second.get();
 		raw->applyTitle(title);
 		raw->addToChatList(FilterId(), topicsList());
@@ -122,10 +131,18 @@ void Forum::applyTopicRemoved(MsgId rootId) {
 }
 
 ForumTopic *Forum::topicFor(not_null<HistoryItem*> item) {
-	if (const auto rootId = item->replyToTop()) {
+	return topicFor(item->topicRootId());
+}
+
+ForumTopic *Forum::topicFor(MsgId rootId) {
+	if (rootId != ForumTopic::kGeneralId) {
 		if (const auto i = _topics.find(rootId); i != end(_topics)) {
 			return i->second.get();
 		}
+	} else {
+		// #TODO forum lang
+		applyTopicAdded(rootId, "General! Created.");
+		return _topics.find(rootId)->second.get();
 	}
 	return nullptr;
 }
@@ -148,13 +165,13 @@ void ShowAddForumTopic(
 			object_ptr<Ui::InputField>(
 				box,
 				st::defaultInputField,
-				rpl::single(u"Topic Title"_q))); // #TODO forum
+				rpl::single(u"Topic Title"_q))); // #TODO forum lang
 		const auto message = box->addRow(
 			object_ptr<Ui::InputField>(
 				box,
 				st::newGroupDescription,
 				Ui::InputField::Mode::MultiLine,
-				rpl::single(u"Message"_q))); // #TODO forum
+				rpl::single(u"Message"_q))); // #TODO forum lang
 		box->setFocusCallback([=] {
 			title->setFocusFast();
 		});

Telegram/SourceFiles/data/data_forum.h

@@ -20,9 +20,11 @@ namespace Data {
 
 class Forum final {
 public:
-	explicit Forum(not_null<History*> forum);
+	explicit Forum(not_null<History*> history);
 	~Forum();
 
+	[[nodiscard]] not_null<History*> history() const;
+	[[nodiscard]] not_null<ChannelData*> channel() const;
 	[[nodiscard]] not_null<Dialogs::MainList*> topicsList();
 
 	void requestTopics();
@@ -32,9 +34,10 @@ public:
 	void applyTopicAdded(MsgId rootId, const QString &title);
 	void applyTopicRemoved(MsgId rootId);
 	[[nodiscard]] ForumTopic *topicFor(not_null<HistoryItem*> item);
+	[[nodiscard]] ForumTopic *topicFor(MsgId rootId);
 
 private:
-	const not_null<History*> _forum;
+	const not_null<History*> _history;
 
 	base::flat_map<MsgId, std::unique_ptr<ForumTopic>> _topics;
 	Dialogs::MainList _topicsList;

Telegram/SourceFiles/data/data_forum_topic.cpp

@@ -198,6 +198,9 @@ void ForumTopic::requestChatListMessage() {
 }
 
 TimeId ForumTopic::adjustedChatListTimeId() const {
+	if (isGeneral()) {
+		return TimeId(1);
+	}
 	const auto result = chatListTimeId();
 #if 0 // #TODO forum
 	if (const auto draft = cloudDraft()) {
@@ -236,10 +239,10 @@ bool ForumTopic::lastServerMessageKnown() const {
 }
 
 void ForumTopic::applyTitle(const QString &title) {
-	if (_title == title) {
+	if (_title == title || (isGeneral() && !_title.isEmpty())) {
 		return;
 	}
-	_title = title;
+	_title = isGeneral() ? "General! Topic." : title; // #TODO forum lang
 	++_titleVersion;
 	indexTitleParts();
 	updateChatListEntry();

Telegram/SourceFiles/data/data_forum_topic.h

@@ -26,6 +26,8 @@ class Session;
 
 class ForumTopic final : public Dialogs::Entry {
 public:
+	static constexpr auto kGeneralId = 1;
+
 	ForumTopic(not_null<History*> forum, MsgId rootId);
 
 	ForumTopic(const ForumTopic &) = delete;
@@ -33,6 +35,9 @@ public:
 
 	[[nodiscard]] not_null<History*> forum() const;
 	[[nodiscard]] MsgId rootId() const;
+	[[nodiscard]] bool isGeneral() const {
+		return (_rootId == kGeneralId);
+	}
 
 	void applyTopic(const MTPForumTopic &topic);
 
@@ -88,7 +93,6 @@ private:
 		int unreadCount,
 		MsgId maxInboxRead,
 		MsgId maxOutboxRead);
-	void applyChatListMessage(HistoryItem *item);
 
 	void setLastMessage(HistoryItem *item);
 	void setLastServerMessage(HistoryItem *item);

Telegram/SourceFiles/data/data_replies_list.cpp

@@ -16,6 +16,7 @@ https://github.com/telegramdesktop/tdesktop/blob/master/LEGAL
 #include "data/data_changes.h"
 #include "data/data_channel.h"
 #include "data/data_messages.h"
+#include "data/data_forum_topic.h"
 #include "lang/lang_keys.h"
 #include "apiwrap.h"
 
@@ -125,7 +126,10 @@ void RepliesList::appendClientSideMessages(MessagesSlice &slice) {
 		}
 		slice.ids.reserve(messages.size());
 		for (const auto &item : messages) {
-			if (item->replyToTop() != _rootId) {
+			const auto checkId = (_rootId == ForumTopic::kGeneralId)
+				? item->topicRootId()
+				: item->replyToTop();
+			if (!item->inThread(_rootId)) {
 				continue;
 			}
 			slice.ids.push_back(item->fullId());
@@ -143,7 +147,7 @@ void RepliesList::appendClientSideMessages(MessagesSlice &slice) {
 		dates.push_back(message->date());
 	}
 	for (const auto &item : messages) {
-		if (item->replyToTop() != _rootId) {
+		if (!item->inThread(_rootId)) {
 			continue;
 		}
 		const auto date = item->date();
@@ -341,12 +345,15 @@ bool RepliesList::buildFromData(not_null<Viewer*> viewer) {
 	auto nearestToAround = std::optional<MsgId>();
 	slice->ids.reserve(useAfter + useBefore);
 	for (auto j = i - useAfter, e = i + useBefore; j != e; ++j) {
-		if (!nearestToAround && *j < around) {
+		const auto id = *j;
+		if (id == _rootId) {
+			continue;
+		} else if (!nearestToAround && id < around) {
 			nearestToAround = (j == i - useAfter)
-				? *j
+				? id
 				: *(j - 1);
 		}
-		slice->ids.emplace_back(peerId, *j);
+		slice->ids.emplace_back(peerId, id);
 	}
 	slice->nearestToAround = FullMsgId(
 		peerId,
@@ -380,7 +387,7 @@ bool RepliesList::applyUpdate(
 			}
 		}
 	}
-	if (update.item->replyToTop() != _rootId) {
+	if (!update.item->inThread(_rootId)) {
 		return false;
 	}
 	const auto id = update.item->id;
@@ -613,7 +620,7 @@ bool RepliesList::processMessagesIsEmpty(const MTPmessages_Messages &result) {
 	auto skipped = 0;
 	for (const auto &message : list) {
 		if (const auto item = owner.addNewMessage(message, localFlags, type)) {
-			if (item->replyToTop() == _rootId) {
+			if (item->inThread(_rootId)) {
 				if (toFront && item->id > _list.front()) {
 					refreshed.push_back(item->id);
 				} else if (_list.empty() || item->id < _list.back()) {

Telegram/SourceFiles/data/data_session.cpp

@@ -807,12 +807,7 @@ not_null<PeerData*> Session::processChat(const MTPChat &data) {
 			| ((data.is_forum() && data.is_megagroup())
 				? Flag::Forum
 				: Flag());
-		const auto wasForum = channel->isForum();
 		channel->setFlags((channel->flags() & ~flagsMask) | flagsSet);
-		if (const auto nowForum = channel->isForum(); nowForum != wasForum) {
-			Assert(channel->mgInfo != nullptr);
-			channel->mgInfo->setIsForum(channel, nowForum);
-		}
 
 		channel->setName(
 			qs(data.vtitle()),

Telegram/SourceFiles/dialogs/dialogs_inner_widget.cpp

@@ -404,12 +404,13 @@ void InnerWidget::changeOpenedFolder(Data::Folder *folder) {
 }
 
 void InnerWidget::changeOpenedForum(ChannelData *forum) {
-	if (_openedForum == forum) {
+	const auto now = _openedForum ? _openedForum->channel().get() : nullptr;
+	if (now == forum) {
 		return;
 	}
 	stopReorderPinned();
 	clearSelection();
-	_openedForum = forum;
+	_openedForum = forum ? forum->forum() : nullptr;
 
 	_openedForumLifetime.destroy();
 	if (forum) {
@@ -1791,7 +1792,7 @@ not_null<IndexedList*> InnerWidget::shownDialogs() const {
 	return _filterId
 		? session().data().chatsFilters().chatsList(_filterId)->indexed()
 		: _openedForum
-		? _openedForum->forum()->topicsList()->indexed()
+		? _openedForum->topicsList()->indexed()
 		: session().data().chatsList(_openedFolder)->indexed();
 }
 
@@ -2296,7 +2297,7 @@ Data::Folder *InnerWidget::shownFolder() const {
 	return _openedFolder;
 }
 
-ChannelData *InnerWidget::shownForum() const {
+Data::Forum *InnerWidget::shownForum() const {
 	return _openedForum;
 }
 
@@ -2410,7 +2411,7 @@ void InnerWidget::refreshEmptyLabel() {
 		} else if (_emptyState == EmptyState::EmptyFolder) {
 			editOpenedFilter();
 		} else if (_emptyState == EmptyState::EmptyForum) {
-			Data::ShowAddForumTopic(_controller, _openedForum);
+			Data::ShowAddForumTopic(_controller, _openedForum->channel());
 		}
 	});
 	_empty->setVisible(_state == WidgetState::Default);
@@ -3286,7 +3287,9 @@ void InnerWidget::setupShortcuts() {
 		});
 		request->check(Command::ChatSelf) && request->handle([=] {
 			if (_openedForum) {
-				Data::ShowAddForumTopic(_controller, _openedForum);
+				Data::ShowAddForumTopic(
+					_controller,
+					_openedForum->channel());
 			} else {
 				_controller->content()->choosePeer(
 					session().userPeerId(),

Telegram/SourceFiles/dialogs/dialogs_inner_widget.h

@@ -36,6 +36,8 @@ class SessionController;
 
 namespace Data {
 class CloudImageView;
+class Folder;
+class Forum;
 } // namespace Data
 
 namespace Dialogs::Ui {
@@ -110,7 +112,7 @@ public:
 	void scrollToEntry(const RowDescriptor &entry);
 
 	Data::Folder *shownFolder() const;
-	ChannelData *shownForum() const;
+	Data::Forum *shownForum() const;
 	int32 lastSearchDate() const;
 	PeerData *lastSearchPeer() const;
 	MsgId lastSearchId() const;
@@ -351,7 +353,7 @@ private:
 	Qt::MouseButton _pressButton = Qt::LeftButton;
 
 	Data::Folder *_openedFolder = nullptr;
-	ChannelData *_openedForum = nullptr;
+	Data::Forum *_openedForum = nullptr;
 	rpl::lifetime _openedForumLifetime;
 
 	std::vector<std::unique_ptr<CollapsedRow>> _collapsedRows;

Telegram/SourceFiles/dialogs/dialogs_widget.cpp

@@ -260,50 +260,7 @@ Widget::Widget(
 	}, lifetime());
 	_inner->chosenRow(
 	) | rpl::start_with_next([=](const ChosenRow &row) {
-		const auto openSearchResult = !controller->selectingPeer()
-			&& row.filteredRow;
-		const auto history = row.key.history();
-		if (const auto topic = row.key.topic()) {
-			controller->showRepliesForMessage(
-				topic->forum(),
-				topic->rootId());
-		} else if (history && history->peer->isForum()) {
-			controller->openForum(history->peer->asChannel());
-		} else if (history) {
-			const auto peer = history->peer;
-			const auto showAtMsgId = controller->uniqueChatsInSearchResults()
-				? ShowAtUnreadMsgId
-				: row.message.fullId.msg;
-			if (row.newWindow && controller->canShowSeparateWindow(peer)) {
-				const auto active = controller->activeChatCurrent();
-				const auto fromActive = active.history()
-					? (active.history()->peer == peer)
-					: false;
-				const auto toSeparate = [=] {
-					Core::App().ensureSeparateWindowForPeer(
-						peer,
-						showAtMsgId);
-				};
-				if (fromActive) {
-					controller->window().preventOrInvoke([=] {
-						controller->content()->ui_showPeerHistory(
-							0,
-							Window::SectionShow::Way::ClearStack,
-							0);
-						toSeparate();
-					});
-				} else {
-					toSeparate();
-				}
-			} else {
-				controller->content()->choosePeer(peer->id, showAtMsgId);
-			}
-		} else if (const auto folder = row.key.folder()) {
-			controller->openFolder(folder);
-		}
-		if (openSearchResult && !session().supportMode()) {
-			escape();
-		}
+		chosenRow(row);
 	}, lifetime());
 
 	_scroll->geometryChanged(
@@ -422,6 +379,53 @@ Widget::Widget(
 	setupDownloadBar();
 }
 
+void Widget::chosenRow(const ChosenRow &row) {
+	const auto openSearchResult = !controller()->selectingPeer()
+		&& row.filteredRow;
+	const auto history = row.key.history();
+	if (const auto topic = row.key.topic()) {
+		controller()->showRepliesForMessage(
+			topic->forum(),
+			topic->rootId());
+	} else if (history && history->peer->isForum()) {
+		controller()->openForum(history->peer->asChannel());
+	} else if (history) {
+		const auto peer = history->peer;
+		const auto showAtMsgId = controller()->uniqueChatsInSearchResults()
+			? ShowAtUnreadMsgId
+			: row.message.fullId.msg;
+		if (row.newWindow && controller()->canShowSeparateWindow(peer)) {
+			const auto active = controller()->activeChatCurrent();
+			const auto fromActive = active.history()
+				? (active.history()->peer == peer)
+				: false;
+			const auto toSeparate = [=] {
+				Core::App().ensureSeparateWindowForPeer(
+					peer,
+					showAtMsgId);
+			};
+			if (fromActive) {
+				controller()->window().preventOrInvoke([=] {
+					controller()->content()->ui_showPeerHistory(
+						0,
+						Window::SectionShow::Way::ClearStack,
+						0);
+					toSeparate();
+				});
+			} else {
+				toSeparate();
+			}
+		} else {
+			controller()->content()->choosePeer(peer->id, showAtMsgId);
+		}
+	} else if (const auto folder = row.key.folder()) {
+		controller()->openFolder(folder);
+	}
+	if (openSearchResult && !session().supportMode()) {
+		escape();
+	}
+}
+
 void Widget::setGeometryWithTopMoved(
 		const QRect &newGeometry,
 		int topDelta) {

Telegram/SourceFiles/dialogs/dialogs_widget.h

@@ -116,6 +116,7 @@ private:
 		Internal,
 	};
 
+	void chosenRow(const ChosenRow &row);
 	void listScrollUpdated();
 	void cancelSearchInChat();
 	void filterCursorMoved(int from = -1, int to = -1);

Telegram/SourceFiles/history/history_item.cpp

@@ -47,6 +47,7 @@ https://github.com/telegramdesktop/tdesktop/blob/master/LEGAL
 #include "data/data_messages.h"
 #include "data/data_media_types.h"
 #include "data/data_folder.h"
+#include "data/data_forum_topic.h"
 #include "data/data_channel.h"
 #include "data/data_chat.h"
 #include "data/data_user.h"
@@ -1058,6 +1059,21 @@ MsgId HistoryItem::replyToTop() const {
 	return 0;
 }
 
+MsgId HistoryItem::topicRootId() const {
+	if (const auto reply = Get<HistoryMessageReply>()
+		; reply && reply->topicPost) {
+		return reply->replyToTop();
+	}
+	return Data::ForumTopic::kGeneralId;
+}
+
+MsgId HistoryItem::inThread(MsgId rootId) const {
+	const auto checkId = (rootId == Data::ForumTopic::kGeneralId)
+		? topicRootId()
+		: replyToTop();
+	return (checkId == rootId);
+}
+
 not_null<PeerData*> HistoryItem::author() const {
 	return (isPost() && !isSponsored()) ? history()->peer : from();
 }

Telegram/SourceFiles/history/history_item.h

@@ -410,6 +410,8 @@ public:
 
 	[[nodiscard]] MsgId replyToId() const;
 	[[nodiscard]] MsgId replyToTop() const;
+	[[nodiscard]] MsgId topicRootId() const;
+	[[nodiscard]] MsgId inThread(MsgId rootId) const;
 
 	[[nodiscard]] not_null<PeerData*> author() const;
 

Telegram/SourceFiles/history/history_item_components.cpp

@@ -259,7 +259,7 @@ bool HistoryMessageReply::updateData(
 			} else {
 				holder->history()->owner().registerDependentMessage(
 					holder,
-					replyToMsg);
+					replyToMsg.get());
 			}
 		}
 	}
@@ -298,7 +298,7 @@ bool HistoryMessageReply::updateData(
 void HistoryMessageReply::setReplyToLinkFrom(
 		not_null<HistoryMessage*> holder) {
 	replyToLnk = replyToMsg
-		? goToMessageClickHandler(replyToMsg, holder->fullId())
+		? goToMessageClickHandler(replyToMsg.get(), holder->fullId())
 		: nullptr;
 }
 
@@ -307,7 +307,7 @@ void HistoryMessageReply::clearData(not_null<HistoryMessage*> holder) {
 	if (replyToMsg) {
 		holder->history()->owner().unregisterDependentMessage(
 			holder,
-			replyToMsg);
+			replyToMsg.get());
 		replyToMsg = nullptr;
 	}
 	replyToMsgId = 0;
@@ -399,7 +399,7 @@ void HistoryMessageReply::resize(int width) const {
 void HistoryMessageReply::itemRemoved(
 		HistoryMessage *holder,
 		HistoryItem *removed) {
-	if (replyToMsg == removed) {
+	if (replyToMsg.get() == removed) {
 		clearData(holder);
 		holder->history()->owner().requestItemResize(holder);
 	}

Telegram/SourceFiles/history/history_item_components.h

@@ -132,29 +132,55 @@ struct HistoryMessageSponsored : public RuntimeComponent<HistoryMessageSponsored
 	bool recommended = false;
 };
 
-struct HistoryMessageReply : public RuntimeComponent<HistoryMessageReply, HistoryItem> {
+class ReplyToMessagePointer final {
+public:
+	ReplyToMessagePointer(HistoryItem *item = nullptr) : _data(item) {
+	}
+	ReplyToMessagePointer(ReplyToMessagePointer &&other)
+	: _data(base::take(other._data)) {
+	}
+	ReplyToMessagePointer &operator=(ReplyToMessagePointer &&other) {
+		_data = base::take(other._data);
+		return *this;
+	}
+	ReplyToMessagePointer &operator=(HistoryItem *item) {
+		_data = item;
+		return *this;
+	}
+
+	[[nodiscard]] bool empty() const {
+		return !_data;
+	}
+	[[nodiscard]] HistoryItem *get() const {
+		return _data;
+	}
+	explicit operator bool() const {
+		return !empty();
+	}
+
+	[[nodiscard]] HistoryItem *operator->() const {
+		return _data;
+	}
+	[[nodiscard]] HistoryItem &operator*() const {
+		return *_data;
+	}
+
+private:
+	HistoryItem *_data = nullptr;
+
+};
+
+struct HistoryMessageReply
+	: public RuntimeComponent<HistoryMessageReply, HistoryItem> {
 	HistoryMessageReply() = default;
 	HistoryMessageReply(const HistoryMessageReply &other) = delete;
 	HistoryMessageReply(HistoryMessageReply &&other) = delete;
-	HistoryMessageReply &operator=(const HistoryMessageReply &other) = delete;
-	HistoryMessageReply &operator=(HistoryMessageReply &&other) {
-		replyToPeerId = other.replyToPeerId;
-		replyToMsgId = other.replyToMsgId;
-		replyToMsgTop = other.replyToMsgTop;
-		replyToDocumentId = other.replyToDocumentId;
-		replyToWebPageId = other.replyToWebPageId;
-		std::swap(replyToMsg, other.replyToMsg);
-		replyToLnk = std::move(other.replyToLnk);
-		replyToName = std::move(other.replyToName);
-		replyToText = std::move(other.replyToText);
-		replyToVersion = other.replyToVersion;
-		maxReplyWidth = other.maxReplyWidth;
-		replyToVia = std::move(other.replyToVia);
-		return *this;
-	}
+	HistoryMessageReply &operator=(
+		const HistoryMessageReply &other) = delete;
+	HistoryMessageReply &operator=(HistoryMessageReply &&other) = default;
 	~HistoryMessageReply() {
 		// clearData() should be called by holder.
-		Expects(replyToMsg == nullptr);
+		Expects(replyToMsg.empty());
 		Expects(replyToVia == nullptr);
 	}
 
@@ -205,15 +231,16 @@ struct HistoryMessageReply : public RuntimeComponent<HistoryMessageReply, Histor
 	PeerId replyToPeerId = 0;
 	MsgId replyToMsgId = 0;
 	MsgId replyToMsgTop = 0;
-	HistoryItem *replyToMsg = nullptr;
 	DocumentId replyToDocumentId = 0;
 	WebPageId replyToWebPageId = 0;
+	ReplyToMessagePointer replyToMsg;
+	std::unique_ptr<HistoryMessageVia> replyToVia;
 	ClickHandlerPtr replyToLnk;
 	mutable Ui::Text::String replyToName, replyToText;
 	mutable int replyToVersion = 0;
 	mutable int maxReplyWidth = 0;
-	std::unique_ptr<HistoryMessageVia> replyToVia;
 	int toWidth = 0;
+	bool topicPost = false;
 
 };
 

Telegram/SourceFiles/history/history_item_text.cpp

@@ -52,7 +52,7 @@ TextForMimeData WrapAsItem(
 		not_null<HistoryItem*> item,
 		TextForMimeData &&result) {
 	if (const auto reply = item->Get<HistoryMessageReply>()) {
-		if (const auto message = reply->replyToMsg) {
+		if (const auto message = reply->replyToMsg.get()) {
 			result = WrapAsReply(std::move(result), message);
 		}
 	}

Telegram/SourceFiles/history/history_message.cpp

@@ -247,6 +247,7 @@ struct HistoryMessage::CreateConfig {
 	PeerId replyToPeer = 0;
 	MsgId replyTo = 0;
 	MsgId replyToTop = 0;
+	bool replyIsTopicPost = false;
 	UserId viaBotId = 0;
 	int viewsCount = -1;
 	QString author;
@@ -963,6 +964,7 @@ void HistoryMessage::createComponents(CreateConfig &&config) {
 		reply->replyToPeerId = config.replyToPeer;
 		reply->replyToMsgId = config.replyTo;
 		reply->replyToMsgTop = isScheduled() ? 0 : config.replyToTop;
+		reply->topicPost = config.replyIsTopicPost;
 		if (!reply->updateData(this)) {
 			RequestDependentMessageData(
 				this,

Telegram/SourceFiles/history/view/history_view_replies_section.cpp

@@ -57,6 +57,8 @@ https://github.com/telegramdesktop/tdesktop/blob/master/LEGAL
 #include "data/data_user.h"
 #include "data/data_chat.h"
 #include "data/data_channel.h"
+#include "data/data_forum.h"
+#include "data/data_forum_topic.h"
 #include "data/data_replies_list.h"
 #include "data/data_peer_values.h"
 #include "data/data_changes.h"
@@ -160,6 +162,7 @@ RepliesWidget::RepliesWidget(
 , _history(history)
 , _rootId(rootId)
 , _root(lookupRoot())
+, _topic(lookupTopic())
 , _areComments(computeAreComments())
 , _sendAction(history->owner().sendActionManager().repliesPainter(
 	history,
@@ -332,6 +335,7 @@ RepliesWidget::~RepliesWidget() {
 	if (_readRequestTimer.isActive()) {
 		sendReadTillRequest();
 	}
+	_history->session().api().request(_resolveTopicRequestId).cancel();
 	base::take(_sendAction);
 	_history->owner().sendActionManager().repliesPainterRemoved(
 		_history,
@@ -437,6 +441,58 @@ HistoryItem *RepliesWidget::lookupRoot() const {
 	return _history->owner().message(_history->peer, _rootId);
 }
 
+Data::ForumTopic *RepliesWidget::lookupTopic() {
+	if (const auto forum = _history->peer->forum()) {
+		const auto result = forum->topicFor(_rootId);
+		if (!result && !_resolveTopicRequestId) {
+			const auto api = &_history->session().api();
+			_resolveTopicRequestId = api->request(
+				MTPchannels_GetForumTopicsByID(
+					forum->channel()->inputChannel,
+					MTP_vector<MTPint>(1, MTP_int(_rootId.bare)))
+			).done([=](const MTPmessages_ForumTopics &result) {
+				const auto &data = result.data();
+				const auto owner = &_history->owner();
+				owner->processUsers(data.vusers());
+				owner->processChats(data.vchats());
+				owner->processMessages(data.vmessages(), NewMessageType::Existing);
+				channel()->ptsReceived(data.vpts().v);
+				const auto &list = data.vtopics().v;
+				for (const auto &topic : list) {
+					const auto rootId = MsgId(topic.data().vid().v);
+					const auto i = _topics.find(rootId);
+					const auto creating = (i == end(_topics));
+					const auto raw = creating
+						? _topics.emplace(
+							rootId,
+							std::make_unique<ForumTopic>(_history, rootId)
+						).first->second.get()
+						: i->second.get();
+					raw->applyTopic(topic);
+					if (creating) {
+						raw->addToChatList(FilterId(), topicsList());
+					}
+					if (const auto last = raw->lastServerMessage()) {
+						_offsetDate = last->date();
+						_offsetId = last->id;
+					}
+					_offsetTopicId = rootId;
+				}
+				if (list.isEmpty() || list.size() == data.vcount().v) {
+					_allLoaded = true;
+				}
+				_requestId = 0;
+				_chatsListChanges.fire({});
+				if (_allLoaded) {
+					_chatsListLoadedEvents.fire({});
+				}
+			}).send();
+		}
+		return result;
+	}
+	return nullptr;
+}
+
 bool RepliesWidget::computeAreComments() const {
 	return _root && _root->isDiscussionPost();
 }
@@ -1294,7 +1350,11 @@ void RepliesWidget::refreshTopBarActiveChat() {
 
 MsgId RepliesWidget::replyToId() const {
 	const auto custom = _composeControls->replyingToMessage().msg;
-	return custom ? custom : _rootId;
+	return custom
+		? custom
+		: (_rootId == Data::ForumTopic::kGeneralId)
+		? MsgId(0)
+		: _rootId;
 }
 
 void RepliesWidget::setupScrollDownButton() {
@@ -1578,23 +1638,34 @@ bool RepliesWidget::showMessage(
 	}
 	const auto id = FullMsgId(_history->peer->id, messageId);
 	const auto message = _history->owner().message(id);
-	if (!message || message->replyToTop() != _rootId) {
+	if (!message) {
 		return false;
 	}
-
-	const auto originItem = [&]() -> HistoryItem* {
+	auto originFound = false;
+	const auto general = (_rootId == Data::ForumTopic::kGeneralId);
+	const auto originMessage = [&]() -> HistoryItem* {
 		using OriginMessage = Window::SectionShow::OriginMessage;
 		if (const auto origin = std::get_if<OriginMessage>(&params.origin)) {
 			if (const auto returnTo = session().data().message(origin->id)) {
-				if (returnTo->history() == _history
-					&& returnTo->replyToTop() == _rootId
-					&& _replyReturn != returnTo) {
+				if (returnTo->history() != _history) {
+					return nullptr;
+				} else if (general
+					&& _inner->viewByPosition(returnTo->position())
+					&& returnTo->replyToId() == messageId) {
+					return returnTo;
+				} else if (!general && (returnTo->replyToTop() == _rootId)) {
 					return returnTo;
 				}
 			}
 		}
 		return nullptr;
 	}();
+	if (!originMessage) {
+		return false;
+	}
+	const auto originItem = (!originMessage || _replyReturn == originMessage)
+		? nullptr
+		: originMessage;
 	showAtPosition(message->position(), originItem);
 	return true;
 }
@@ -1756,8 +1827,8 @@ void RepliesWidget::updateInnerVisibleArea() {
 void RepliesWidget::updatePinnedVisibility() {
 	if (!_loaded) {
 		return;
-	} else if (!_root) {
-		setPinnedVisibility(true);
+	} else if (!_root || _root->isEmpty()) {
+		setPinnedVisibility(!_root);
 		return;
 	}
 	const auto item = [&] {

Telegram/SourceFiles/history/view/history_view_replies_section.h

@@ -49,6 +49,7 @@ class Result;
 
 namespace Data {
 class RepliesList;
+class ForumTopic;
 } // namespace Data
 
 namespace HistoryView {
@@ -208,6 +209,7 @@ private:
 	[[nodiscard]] SendMenu::Type sendMenuType() const;
 	[[nodiscard]] MsgId replyToId() const;
 	[[nodiscard]] HistoryItem *lookupRoot() const;
+	[[nodiscard]] Data::ForumTopic *lookupTopic();
 	[[nodiscard]] bool computeAreComments() const;
 	[[nodiscard]] std::optional<int> computeUnreadCount() const;
 	void orderWidgets();
@@ -270,6 +272,8 @@ private:
 	const MsgId _rootId = 0;
 	std::shared_ptr<Ui::ChatTheme> _theme;
 	HistoryItem *_root = nullptr;
+	Data::ForumTopic *_topic = nullptr;
+
 	std::shared_ptr<Data::RepliesList> _replies;
 	rpl::variable<bool> _areComments = false;
 	std::shared_ptr<SendActionPainter> _sendAction;
@@ -301,6 +305,8 @@ private:
 	bool _readRequestPending = false;
 	mtpRequestId _readRequestId = 0;
 
+	mtpRequestId _resolveTopicRequestId = 0;
+
 	mtpRequestId _reloadUnreadCountRequestId = 0;
 	bool _loaded = false;
 

Telegram/SourceFiles/window/window_session_controller.cpp

@@ -676,19 +676,6 @@ SessionController::SessionController(
 		closeFolder();
 	}, lifetime());
 
-	_openedForum.changes(
-	) | rpl::filter([](ChannelData *forum) {
-		return (forum != nullptr);
-	}) | rpl::map([](ChannelData *forum) {
-		return forum->flagsValue(
-		) | rpl::filter([](ChannelData::Flags::Change change) {
-			return (change.diff & ChannelData::Flag::Forum)
-				&& !(change.value & ChannelData::Flag::Forum);
-		});
-	}) | rpl::flatten_latest() | rpl::start_with_next([=] {
-		closeForum();
-	}, lifetime());
-
 	session->data().chatsFilters().changed(
 	) | rpl::start_with_next([=] {
 		checkOpenedFilter();
@@ -842,7 +829,9 @@ void SessionController::checkOpenedFilter() {
 		const auto &list = session().data().chatsFilters().list();
 		const auto i = ranges::find(list, filterId, &Data::ChatFilter::id);
 		if (i == end(list)) {
-			setActiveChatsFilter(0);
+			setActiveChatsFilter(
+				0,
+				{ anim::type::normal, anim::activation::background });
 		}
 	}
 }
@@ -874,18 +863,35 @@ void SessionController::closeFolder() {
 	_openedFolder = nullptr;
 }
 
-void SessionController::openForum(not_null<ChannelData*> forum) {
+void SessionController::openForum(
+		not_null<ChannelData*> forum,
+		const SectionShow &params) {
 	Expects(forum->isForum());
 
+	_openedForumLifetime.destroy();
 	if (_openedForum.current() != forum) {
 		resetFakeUnreadWhileOpened();
 	}
-	setActiveChatsFilter(0);
+	setActiveChatsFilter(0, params);
 	closeFolder();
 	_openedForum = forum.get();
+	if (_openedForum.current() == forum) {
+		forum->flagsValue(
+		) | rpl::filter([=](const ChannelData::Flags::Change &update) {
+			using Flag = ChannelData::Flag;
+			return (update.diff & Flag::Forum)
+				&& !(update.value & Flag::Forum);
+		}) | rpl::start_with_next([=] {
+			closeForum();
+			showPeerHistory(
+				forum,
+				{ anim::type::normal, anim::activation::background });
+		}, _openedForumLifetime);
+	}
 }
 
 void SessionController::closeForum() {
+	_openedForumLifetime.destroy();
 	_openedForum = nullptr;
 }
 
@@ -926,12 +932,27 @@ void SessionController::setActiveChatEntry(Dialogs::RowDescriptor row) {
 	const auto was = _activeChatEntry.current().key.history();
 	const auto now = row.key.history();
 	if (was && was != now) {
+		_activeHistoryLifetime.destroy();
 		was->setFakeUnreadWhileOpened(false);
 		_invitePeekTimer.cancel();
 	}
 	_activeChatEntry = row;
 	if (now) {
 		now->setFakeUnreadWhileOpened(true);
+		if (const auto channel = now->peer->asChannel()
+			; channel && !channel->isForum()) {
+			channel->flagsValue(
+			) | rpl::filter([=](const ChannelData::Flags::Change &update) {
+				using Flag = ChannelData::Flag;
+				return (update.diff & Flag::Forum)
+					&& (update.value & Flag::Forum);
+			}) | rpl::start_with_next([=] {
+				clearSectionStack(
+					{ anim::type::normal, anim::activation::background });
+				openForum(channel,
+					{ anim::type::normal, anim::activation::background });
+			}, _openedForumLifetime);
+		}
 	}
 	if (session().supportMode()) {
 		pushToChatEntryHistory(row);
@@ -1601,7 +1622,9 @@ FilterId SessionController::activeChatsFilterCurrent() const {
 	return _activeChatsFilter.current();
 }
 
-void SessionController::setActiveChatsFilter(FilterId id) {
+void SessionController::setActiveChatsFilter(
+		FilterId id,
+		const SectionShow &params) {
 	if (activeChatsFilterCurrent() != id) {
 		resetFakeUnreadWhileOpened();
 	}
@@ -1610,7 +1633,7 @@ void SessionController::setActiveChatsFilter(FilterId id) {
 		closeFolder();
 	}
 	if (adaptive().isOneColumn()) {
-		Ui::showChatsList(&session());
+		clearSectionStack(params);
 	}
 }
 

Telegram/SourceFiles/window/window_session_controller.h

@@ -345,7 +345,9 @@ public:
 	void closeFolder();
 	const rpl::variable<Data::Folder*> &openedFolder() const;
 
-	void openForum(not_null<ChannelData*> forum);
+	void openForum(
+		not_null<ChannelData*> forum,
+		const SectionShow &params = SectionShow::Way::ClearStack);
 	void closeForum();
 	const rpl::variable<ChannelData*> &openedForum() const;
 
@@ -474,7 +476,9 @@ public:
 	[[nodiscard]] int filtersWidth() const;
 	[[nodiscard]] rpl::producer<FilterId> activeChatsFilter() const;
 	[[nodiscard]] FilterId activeChatsFilterCurrent() const;
-	void setActiveChatsFilter(FilterId id);
+	void setActiveChatsFilter(
+		FilterId id,
+		const SectionShow &params = SectionShow::Way::ClearStack);
 
 	void toggleFiltersMenu(bool enabled);
 	[[nodiscard]] rpl::producer<> filtersMenuChanged() const;
@@ -582,6 +586,7 @@ private:
 	const std::unique_ptr<ChatHelpers::TabbedSelector> _tabbedSelector;
 
 	rpl::variable<Dialogs::RowDescriptor> _activeChatEntry;
+	rpl::lifetime _activeHistoryLifetime;
 	base::Variable<bool> _dialogsListFocused = { false };
 	base::Variable<bool> _dialogsListDisplayForced = { false };
 	std::deque<Dialogs::RowDescriptor> _chatEntryHistory;
@@ -600,6 +605,7 @@ private:
 	PeerData *_showEditPeer = nullptr;
 	rpl::variable<Data::Folder*> _openedFolder;
 	rpl::variable<ChannelData*> _openedForum;
+	rpl::lifetime _openedForumLifetime;
 
 	rpl::event_stream<> _filtersMenuChanged;