Use service message instead of unread bar.

Telegram/Resources/langs/lang.strings

@@ -1359,6 +1359,8 @@ https://github.com/telegramdesktop/tdesktop/blob/master/LEGAL
 "lng_comments_open_none" = "Leave a comment";
 "lng_replies_view_original" = "View in chat";
 "lng_replies_messages" = "Replies";
+"lng_replies_discussion_started" = "Discussion started";
+"lng_replies_no_comments" = "No comments here yet...";
 
 "lng_archived_name" = "Archived chats";
 "lng_archived_add" = "Archive";

Telegram/SourceFiles/data/data_replies_list.cpp

@@ -9,12 +9,14 @@ https://github.com/telegramdesktop/tdesktop/blob/master/LEGAL
 
 #include "history/history.h"
 #include "history/history_item.h"
+#include "history/history_service.h"
 #include "main/main_session.h"
 #include "data/data_histories.h"
 #include "data/data_session.h"
 #include "data/data_changes.h"
 #include "data/data_channel.h"
 #include "data/data_messages.h"
+#include "lang/lang_keys.h"
 #include "apiwrap.h"
 
 namespace Data {
@@ -22,6 +24,17 @@ namespace {
 
 constexpr auto kMessagesPerPage = 50;
 
+[[nodiscard]] HistoryService *GenerateDivider(
+		not_null<History*> history,
+		TimeId date,
+		const QString &text) {
+	return history->makeServiceMessage(
+		history->session().data().nextNonHistoryEntryId(),
+		MTPDmessage_ClientFlag::f_fake_history_item,
+		date,
+		HistoryService::PreparedText{ text });
+}
+
 } // namespace
 
 struct RepliesList::Viewer {
@@ -40,6 +53,9 @@ RepliesList::RepliesList(not_null<History*> history, MsgId rootId)
 RepliesList::~RepliesList() {
 	histories().cancelRequest(base::take(_beforeId));
 	histories().cancelRequest(base::take(_afterId));
+	if (_divider) {
+		_divider->destroy();
+	}
 }
 
 rpl::producer<MessagesSlice> RepliesList::source(
@@ -157,13 +173,21 @@ rpl::producer<int> RepliesList::fullCount() const {
 	return _fullCount.value() | rpl::filter_optional();
 }
 
+void RepliesList::injectRootMessageAndReverse(
+		not_null<MessagesSlice*> slice) {
+	injectRootMessage(slice);
+	ranges::reverse(slice->ids);
+}
+
 void RepliesList::injectRootMessage(not_null<MessagesSlice*> slice) {
 	if (slice->skippedBefore != 0) {
 		return;
 	}
 	if (const auto root = lookupRoot()) {
+		injectRootDivider(root, slice);
+
 		if (const auto group = _history->owner().groups().find(root)) {
-			for (const auto item : group->items) {
+			for (const auto item : ranges::view::reverse(group->items)) {
 				slice->ids.push_back(item->fullId());
 			}
 			if (slice->fullCount) {
@@ -178,6 +202,28 @@ void RepliesList::injectRootMessage(not_null<MessagesSlice*> slice) {
 	}
 }
 
+void RepliesList::injectRootDivider(
+		not_null<HistoryItem*> root,
+		not_null<MessagesSlice*> slice) {
+	const auto withComments = !slice->ids.empty();
+	const auto text = [&] {
+		return withComments
+			? tr::lng_replies_discussion_started(tr::now)
+			: tr::lng_replies_no_comments(tr::now);
+	};
+	if (!_divider) {
+		_dividerWithComments = withComments;
+		_divider = GenerateDivider(
+			_history,
+			root->date(),
+			text());
+	} else if (_dividerWithComments != withComments) {
+		_dividerWithComments = withComments;
+		_divider->setServiceText(HistoryService::PreparedText{ text() });
+	}
+	slice->ids.push_back(_divider->fullId());
+}
+
 bool RepliesList::buildFromData(not_null<Viewer*> viewer) {
 	if (_list.empty() && _skippedBefore == 0 && _skippedAfter == 0) {
 		viewer->slice.ids.clear();
@@ -185,7 +231,7 @@ bool RepliesList::buildFromData(not_null<Viewer*> viewer) {
 			= viewer->slice.skippedBefore
 			= viewer->slice.skippedAfter
 			= 0;
-		injectRootMessage(&viewer->slice);
+		injectRootMessageAndReverse(&viewer->slice);
 		return true;
 	}
 	const auto around = [&] {
@@ -230,9 +276,7 @@ bool RepliesList::buildFromData(not_null<Viewer*> viewer) {
 	}
 	slice->fullCount = _fullCount.current();
 
-	injectRootMessage(slice);
-
-	ranges::reverse(slice->ids);
+	injectRootMessageAndReverse(slice);
 
 	if (_skippedBefore != 0 && useBefore < viewer->limitBefore + 1) {
 		loadBefore();

Telegram/SourceFiles/data/data_replies_list.h

@@ -10,6 +10,7 @@ https://github.com/telegramdesktop/tdesktop/blob/master/LEGAL
 #include "base/weak_ptr.h"
 
 class History;
+class HistoryService;
 
 namespace Data {
 
@@ -46,7 +47,11 @@ private:
 	[[nodiscard]] bool applyUpdate(
 		not_null<Viewer*> viewer,
 		const MessageUpdate &update);
+	void injectRootMessageAndReverse(not_null<MessagesSlice*> slice);
 	void injectRootMessage(not_null<MessagesSlice*> slice);
+	void injectRootDivider(
+		not_null<HistoryItem*> root,
+		not_null<MessagesSlice*> slice);
 	bool processMessagesIsEmpty(const MTPmessages_Messages &result);
 	void loadAround(MsgId id);
 	void loadBefore();
@@ -60,6 +65,8 @@ private:
 	rpl::variable<std::optional<int>> _fullCount;
 	rpl::event_stream<> _partLoaded;
 	std::optional<MsgId> _loadingAround;
+	HistoryService *_divider = nullptr;
+	bool _dividerWithComments = false;
 	int _beforeId = 0;
 	int _afterId = 0;
 

Telegram/SourceFiles/history/history_service.h

@@ -108,6 +108,8 @@ public:
 		not_null<HistoryView::ElementDelegate*> delegate,
 		HistoryView::Element *replacing = nullptr) override;
 
+	void setServiceText(const PreparedText &prepared);
+
 	~HistoryService();
 
 protected:
@@ -115,8 +117,6 @@ protected:
 
 	void markMediaAsReadHook() override;
 
-	void setServiceText(const PreparedText &prepared);
-
 	QString fromLinkText() const;
 	ClickHandlerPtr fromLink() const;
 

Telegram/SourceFiles/history/view/history_view_replies_section.cpp

@@ -123,7 +123,6 @@ RepliesWidget::RepliesWidget(
 , _root(lookupRoot())
 , _commentsRoot(lookupCommentsRoot())
 , _areComments(computeAreComments())
-, _scroll(this, st::historyScroll, false)
 , _topBar(this, controller)
 , _topBarShadow(this)
 , _composeControls(std::make_unique<ComposeControls>(
@@ -132,7 +131,8 @@ RepliesWidget::RepliesWidget(
 	ComposeControls::Mode::Normal))
 , _rootView(this, object_ptr<Ui::RpWidget>(this))
 , _rootShadow(this)
-, _scrollDown(_scroll, st::historyToDown)
+, _scroll(std::make_unique<Ui::ScrollArea>(this, st::historyScroll, false))
+, _scrollDown(_scroll.get(), st::historyToDown)
 , _readRequestTimer([=] { sendReadTillRequest(); }) {
 	setupRoot();
 	setupRootView();
@@ -162,8 +162,9 @@ RepliesWidget::RepliesWidget(
 		clearSelected();
 	}, _topBar->lifetime());
 
-	_topBarShadow->raise();
+	_rootView->raise();
 	_rootShadow->raise();
+	_topBarShadow->raise();
 	updateAdaptiveLayout();
 	subscribe(Adaptive::Changed(), [=] { updateAdaptiveLayout(); });
 
@@ -173,7 +174,7 @@ RepliesWidget::RepliesWidget(
 		static_cast<ListDelegate*>(this)));
 	_scroll->move(0, _topBar->height());
 	_scroll->show();
-	connect(_scroll, &Ui::ScrollArea::scrolled, [=] { onScroll(); });
+	connect(_scroll.get(), &Ui::ScrollArea::scrolled, [=] { onScroll(); });
 
 	_inner->editMessageRequested(
 	) | rpl::start_with_next([=](auto fullId) {
@@ -1366,7 +1367,13 @@ void RepliesWidget::updatePinnedVisibility() {
 		setPinnedVisibility(true);
 		return;
 	}
-	const auto view = _inner->viewByPosition(_root->position());
+	const auto item = [&] {
+		if (const auto group = _history->owner().groups().find(_root)) {
+			return group->items.front().get();
+		}
+		return _root;
+	}();
+	const auto view = _inner->viewByPosition(item->position());
 	setPinnedVisibility(!view
 		|| (view->y() + view->height() <= _scroll->scrollTop()));
 }
@@ -1502,40 +1509,11 @@ void RepliesWidget::listVisibleItemsChanged(HistoryItemsList &&items) {
 MessagesBarData RepliesWidget::listMessagesBar(
 		const std::vector<not_null<Element*>> &elements) {
 	if (!_commentsRoot || elements.empty()) {
-		return MessagesBarData();
+		return {};
 	}
-	const auto rootBar = [&] {
-		const auto fromRoot = (elements.front()->data().get() == _root);
-		if (elements.size() < 2 || !fromRoot) {
-			return MessagesBarData();
-		}
-		auto text = rpl::combine(
-			_replies->fullCount(),
-			_areComments.value()
-		) | rpl::map([=](int count, bool areComments) {
-			return count
-				? (areComments
-					? tr::lng_comments_header
-					: tr::lng_replies_header)(
-						lt_count,
-						rpl::single(count) | tr::to_count())
-				: (areComments
-					? tr::lng_comments_header_none
-					: tr::lng_replies_header_none)();
-		}) | rpl::flatten_latest();
-
-		return MessagesBarData{
-			// Designated initializers here crash MSVC 16.7.3.
-			MessagesBar{
-				.element = elements[1],
-				.focus = false,
-			},
-			std::move(text),
-		};
-	};
 	const auto till = _commentsRoot->commentsReadTill();
 	if (till < 2) {
-		return rootBar();
+		return {};
 	}
 	for (auto i = 0, count = int(elements.size()); i != count; ++i) {
 		const auto item = elements[i]->data();
@@ -1554,7 +1532,7 @@ MessagesBarData RepliesWidget::listMessagesBar(
 			}
 		}
 	}
-	return rootBar();
+	return {};
 }
 
 void RepliesWidget::listContentRefreshed() {

Telegram/SourceFiles/history/view/history_view_replies_section.h

@@ -237,7 +237,6 @@ private:
 	HistoryItem *_commentsRoot = nullptr;
 	std::shared_ptr<Data::RepliesList> _replies;
 	rpl::variable<bool> _areComments = false;
-	object_ptr<Ui::ScrollArea> _scroll;
 	QPointer<ListWidget> _inner;
 	object_ptr<TopBarWidget> _topBar;
 	object_ptr<Ui::PlainShadow> _topBarShadow;
@@ -249,6 +248,8 @@ private:
 	object_ptr<Ui::SlideWrap<Ui::RpWidget>> _rootView;
 	object_ptr<Ui::PlainShadow> _rootShadow;
 
+	std::unique_ptr<Ui::ScrollArea> _scroll;
+
 	std::vector<MsgId> _replyReturns;
 	HistoryItem *_replyReturn = nullptr;