Add "View Discussion" button to third column.

Telegram/SourceFiles/dialogs/dialogs_key.h

@@ -121,8 +121,12 @@ struct EntryState {
 	FilterId filterId = 0;
 	FullReplyTo currentReplyTo;
 
-	friend inline auto operator<=>(EntryState, EntryState) noexcept
+	friend inline auto operator<=>(
-		= default;
+		const EntryState&,
+		const EntryState&) = default;
+	friend inline bool operator==(
+		const EntryState&,
+		const EntryState&) = default;
 };
 
 struct SearchState {

Telegram/SourceFiles/history/history_widget.cpp

@@ -1014,7 +1014,7 @@ void HistoryWidget::refreshTopBarActiveChat() {
 	const auto state = computeDialogsEntryState();
 	_topBar->setActiveChat(state, _history->sendActionPainter());
 	if (state.key) {
-		controller()->setCurrentDialogsEntryState(state);
+		controller()->setDialogsEntryState(state);
 	}
 }
 
@@ -1989,7 +1989,7 @@ bool HistoryWidget::notify_switchInlineBotButtonReceived(
 		UserData *samePeerBot,
 		MsgId samePeerReplyTo) {
 	if (samePeerBot) {
-		const auto to = controller()->currentDialogsEntryState();
+		const auto to = controller()->dialogsEntryStateCurrent();
 		if (!to.key.owningHistory()) {
 			return false;
 		}
@@ -2222,7 +2222,7 @@ void HistoryWidget::showHistory(
 	_showAtMsgHighlightPart = {};
 	_showAtMsgHighlightPartOffsetHint = 0;
 
-	const auto wasState = controller()->currentDialogsEntryState();
+	const auto wasState = controller()->dialogsEntryStateCurrent();
 	const auto startBot = (showAtMsgId == ShowAndStartBotMsgId);
 	_showAndMaybeSendStart = (showAtMsgId == ShowAndMaybeStartBotMsgId);
 	if (startBot || _showAndMaybeSendStart) {

Telegram/SourceFiles/history/view/history_view_replies_section.cpp

@@ -1521,7 +1521,7 @@ void RepliesWidget::refreshTopBarActiveChat() {
 	};
 	_topBar->setActiveChat(state, _sendAction.get());
 	_composeControls->setCurrentDialogsEntryState(state);
-	controller()->setCurrentDialogsEntryState(state);
+	controller()->setDialogsEntryState(state);
 }
 
 void RepliesWidget::refreshUnreadCountBadge(std::optional<int> count) {

Telegram/SourceFiles/history/view/history_view_scheduled_section.cpp

@@ -186,7 +186,7 @@ ScheduledWidget::ScheduledWidget(
 	};
 	_topBar->setActiveChat(state, nullptr);
 	_composeControls->setCurrentDialogsEntryState(state);
-	controller->setCurrentDialogsEntryState(state);
+	controller->setDialogsEntryState(state);
 
 	_topBar->move(0, 0);
 	_topBar->resizeToWidth(width());

Telegram/SourceFiles/info/profile/info_profile_actions.cpp

@@ -967,6 +967,8 @@ private:
 		not_null<UserData*> user);
 	Ui::MultiSlideTracker fillChannelButtons(
 		not_null<ChannelData*> channel);
+	Ui::MultiSlideTracker fillDiscussionButtons(
+		not_null<ChannelData*> channel);
 
 	void addReportReaction(Ui::MultiSlideTracker &tracker);
 	void addReportReaction(
@@ -1915,7 +1917,11 @@ void DetailsFiller::setupMainButtons() {
 			return fillUserButtons(user);
 		});
 	} else if (const auto channel = _peer->asChannel()) {
-		if (!channel->isMegagroup()) {
+		if (channel->isMegagroup()) {
+			wrapButtons([=] {
+				return fillDiscussionButtons(channel);
+			});
+		} else {
 			wrapButtons([=] {
 				return fillChannelButtons(channel);
 			});
@@ -2080,6 +2086,37 @@ Ui::MultiSlideTracker DetailsFiller::fillChannelButtons(
 	return tracker;
 }
 
+Ui::MultiSlideTracker DetailsFiller::fillDiscussionButtons(
+		not_null<ChannelData*> channel) {
+	using namespace rpl::mappers;
+
+	Ui::MultiSlideTracker tracker;
+	auto window = _controller->parentController();
+	auto viewDiscussionVisible = rpl::combine(
+		_controller->wrapValue(),
+		window->dialogsEntryStateValue()
+	) | rpl::map([=](Wrap wrap, const Dialogs::EntryState &state) {
+		const auto history = state.key.history();
+		return (wrap == Wrap::Side)
+			&& (state.section == Dialogs::EntryState::Section::Replies)
+			&& history
+			&& (history->peer == channel);
+	});
+	auto viewDiscussion = [=] {
+		window->showPeerHistory(
+			channel,
+			Window::SectionShow::Way::Forward);
+	};
+	AddMainButton(
+		_wrap,
+		tr::lng_profile_view_discussion(),
+		std::move(viewDiscussionVisible),
+		std::move(viewDiscussion),
+		tracker);
+
+	return tracker;
+}
+
 object_ptr<Ui::RpWidget> DetailsFiller::fill() {
 	Expects(!_topic || !_topic->creating());
 

Telegram/SourceFiles/inline_bots/bot_attach_web_view.cpp

@@ -348,7 +348,7 @@ WebViewContext ResolveContext(
 		WebViewContext context) {
 	if (!context.dialogsEntryState.key) {
 		if (const auto strong = context.controller.get()) {
-			context.dialogsEntryState = strong->currentDialogsEntryState();
+			context.dialogsEntryState = strong->dialogsEntryStateCurrent();
 		}
 	}
 	if (!context.action) {

Telegram/SourceFiles/inline_bots/inline_results_inner.cpp

@@ -700,7 +700,7 @@ void Inner::switchPm() {
 	} else {
 		_inlineBot->botInfo->startToken = _switchPmStartToken;
 		_inlineBot->botInfo->inlineReturnTo
-			= _controller->currentDialogsEntryState();
+			= _controller->dialogsEntryStateCurrent();
 		_controller->showPeerHistory(
 			_inlineBot,
 			Window::SectionShow::Way::ClearStack,

Telegram/SourceFiles/window/window_session_controller.cpp

@@ -1847,13 +1847,18 @@ bool SessionController::jumpToChatListEntry(Dialogs::RowDescriptor row) {
 	return false;
 }
 
-void SessionController::setCurrentDialogsEntryState(
+void SessionController::setDialogsEntryState(
 		Dialogs::EntryState state) {
-	_currentDialogsEntryState = state;
+	_dialogsEntryState = state;
 }
 
-Dialogs::EntryState SessionController::currentDialogsEntryState() const {
+Dialogs::EntryState SessionController::dialogsEntryStateCurrent() const {
-	return _currentDialogsEntryState;
+	return _dialogsEntryState.current();
+}
+
+auto SessionController::dialogsEntryStateValue() const
+-> rpl::producer<Dialogs::EntryState> {
+	return _dialogsEntryState.value();
 }
 
 bool SessionController::switchInlineQuery(

Telegram/SourceFiles/window/window_session_controller.h

@@ -394,8 +394,10 @@ public:
 	rpl::producer<Dialogs::Key> activeChatValue() const;
 	bool jumpToChatListEntry(Dialogs::RowDescriptor row);
 
-	void setCurrentDialogsEntryState(Dialogs::EntryState state);
+	void setDialogsEntryState(Dialogs::EntryState state);
-	[[nodiscard]] Dialogs::EntryState currentDialogsEntryState() const;
+	[[nodiscard]] Dialogs::EntryState dialogsEntryStateCurrent() const;
+	[[nodiscard]] auto dialogsEntryStateValue() const
+		-> rpl::producer<Dialogs::EntryState>;
 	bool switchInlineQuery(
 		Dialogs::EntryState to,
 		not_null<UserData*> bot,
@@ -708,7 +710,7 @@ private:
 	int _chatEntryHistoryPosition = -1;
 	bool _filtersActivated = false;
 
-	Dialogs::EntryState _currentDialogsEntryState;
+	rpl::variable<Dialogs::EntryState> _dialogsEntryState;
 
 	base::Timer _invitePeekTimer;