Sort contacts by last seen by default.

Fixes #5515.

Telegram/SourceFiles/boxes/boxes.style

@@ -160,6 +160,21 @@ contactsAboutFg: windowSubTextFgOver;
 contactsAboutTop: 60px;
 contactsAboutBottom: 19px;
 
+contactsSortButton: IconButton(defaultIconButton) {
+	width: 48px;
+	height: 54px;
+	icon: icon{{ "contacts_alphabet", boxTitleCloseFg }};
+	iconOver: icon{{ "contacts_alphabet", boxTitleCloseFgOver }};
+	iconPosition: point(10px, -1px);
+	rippleAreaPosition: point(1px, 6px);
+	rippleAreaSize: 42px;
+	ripple: RippleAnimation(defaultRippleAnimation) {
+		color: windowBgOver;
+	}
+}
+contactsSortOnlineIcon: icon{{ "contacts_online", boxTitleCloseFg }};
+contactsSortOnlineIconOver: icon{{ "contacts_online", boxTitleCloseFgOver }};
+
 contactsMarginTop: 4px;
 contactsMarginBottom: 4px;
 membersMarginTop: 10px;

Telegram/SourceFiles/boxes/peer_list_controllers.cpp

@@ -19,6 +19,7 @@ https://github.com/telegramdesktop/tdesktop/blob/master/LEGAL
 #include "data/data_user.h"
 #include "data/data_folder.h"
 #include "data/data_histories.h"
+#include "data/data_changes.h"
 #include "apiwrap.h"
 #include "mainwidget.h"
 #include "mainwindow.h"
@@ -26,12 +27,15 @@ https://github.com/telegramdesktop/tdesktop/blob/master/LEGAL
 #include "history/history.h"
 #include "dialogs/dialogs_main_list.h"
 #include "window/window_session_controller.h" // showAddContact()
+#include "base/unixtime.h"
 #include "facades.h"
 #include "styles/style_boxes.h"
 #include "styles/style_profile.h"
 
 namespace {
 
+constexpr auto kSortByOnlineThrottle = 3 * crl::time(1000);
+
 void ShareBotGame(not_null<UserData*> bot, not_null<PeerData*> chat) {
 	const auto history = chat->owner().history(chat);
 	auto &histories = history->owner().histories();
@@ -110,17 +114,31 @@ void AddBotToGroup(not_null<UserData*> bot, not_null<PeerData*> chat) {
 
 object_ptr<Ui::BoxContent> PrepareContactsBox(
 		not_null<Window::SessionController*> sessionController) {
-	const auto controller = sessionController;
-	auto delegate = [=](not_null<PeerListBox*> box) {
+	using Mode = ContactsBoxController::SortMode;
+	auto controller = std::make_unique<ContactsBoxController>(
+		&sessionController->session());
+	const auto raw = controller.get();
+	auto init = [=](not_null<PeerListBox*> box) {
+		struct State {
+			QPointer<Ui::IconButton> toggleSort;
+			Mode mode = ContactsBoxController::SortMode::Online;
+		};
+		const auto state = box->lifetime().make_state<State>();
 		box->addButton(tr::lng_close(), [=] { box->closeBox(); });
 		box->addLeftButton(
 			tr::lng_profile_add_contact(),
-			[=] { controller->showAddContact(); });
+			[=] { sessionController->showAddContact(); });
+		state->toggleSort = box->addTopButton(st::contactsSortButton, [=] {
+			const auto online = (state->mode == Mode::Online);
+			state->mode = online ? Mode::Alphabet : Mode::Online;
+			raw->setSortMode(state->mode);
+			state->toggleSort->setIconOverride(
+				online ? &st::contactsSortOnlineIcon : nullptr,
+				online ? &st::contactsSortOnlineIconOver : nullptr);
+		});
+		raw->setSortMode(Mode::Online);
 	};
-	return Box<PeerListBox>(
-		std::make_unique<ContactsBoxController>(
-			&sessionController->session()),
-		std::move(delegate));
+	return Box<PeerListBox>(std::move(controller), std::move(init));
 }
 
 void PeerListRowWithLink::setActionLink(const QString &action) {
@@ -368,7 +386,8 @@ ContactsBoxController::ContactsBoxController(
 	not_null<Main::Session*> session,
 	std::unique_ptr<PeerListSearchController> searchController)
 : PeerListController(std::move(searchController))
-, _session(session) {
+, _session(session)
+, _sortByOnlineTimer([=] { sort(); }) {
 }
 
 Main::Session &ContactsBoxController::session() const {
@@ -404,6 +423,7 @@ void ContactsBoxController::rebuildRows() {
 	};
 	appendList(session().data().contactsList());
 	checkForEmptyRows();
+	sort();
 	delegate()->peerListRefreshRows();
 }
 
@@ -427,6 +447,66 @@ void ContactsBoxController::rowClicked(not_null<PeerListRow*> row) {
 	Ui::showPeerHistory(row->peer(), ShowAtUnreadMsgId);
 }
 
+void ContactsBoxController::setSortMode(SortMode mode) {
+	if (_sortMode == mode) {
+		return;
+	}
+	_sortMode = mode;
+	sort();
+	if (_sortMode == SortMode::Online) {
+		session().changes().peerUpdates(
+			Data::PeerUpdate::Flag::OnlineStatus
+		) | rpl::filter([=](const Data::PeerUpdate &update) {
+			return !_sortByOnlineTimer.isActive()
+				&& delegate()->peerListFindRow(update.peer->id.value);
+		}) | rpl::start_with_next([=] {
+			_sortByOnlineTimer.callOnce(kSortByOnlineThrottle);
+		}, _sortByOnlineLifetime);
+	} else {
+		_sortByOnlineTimer.cancel();
+		_sortByOnlineLifetime.destroy();
+	}
+}
+
+void ContactsBoxController::sort() {
+	switch (_sortMode) {
+	case SortMode::Alphabet: sortByName(); break;
+	case SortMode::Online: sortByOnline(); break;
+	default: Unexpected("SortMode in ContactsBoxController.");
+	}
+}
+
+void ContactsBoxController::sortByName() {
+	auto keys = base::flat_map<PeerListRowId, QString>();
+	keys.reserve(delegate()->peerListFullRowsCount());
+	const auto key = [&](const PeerListRow &row) {
+		const auto id = row.id();
+		const auto i = keys.find(id);
+		if (i != end(keys)) {
+			return i->second;
+		}
+		const auto peer = row.peer();
+		const auto history = peer->owner().history(peer);
+		return keys.emplace(id, history->chatListNameSortKey()).first->second;
+	};
+	const auto predicate = [&](const PeerListRow &a, const PeerListRow &b) {
+		return (key(a).compare(key(b)) < 0);
+	};
+	delegate()->peerListSortRows(predicate);
+}
+
+void ContactsBoxController::sortByOnline() {
+	const auto now = base::unixtime::now();
+	const auto key = [&](const PeerListRow &row) {
+		const auto user = row.peer()->asUser();
+		return user ? (std::min(user->onlineTill, now) + 1) : TimeId();
+	};
+	const auto predicate = [&](const PeerListRow &a, const PeerListRow &b) {
+		return key(a) > key(b);
+	};
+	delegate()->peerListSortRows(predicate);
+}
+
 bool ContactsBoxController::appendRow(not_null<UserData*> user) {
 	if (auto row = delegate()->peerListFindRow(user->id.value)) {
 		updateRowHook(row);

Telegram/SourceFiles/boxes/peer_list_controllers.h

@@ -10,6 +10,7 @@ https://github.com/telegramdesktop/tdesktop/blob/master/LEGAL
 #include "boxes/peer_list_box.h"
 #include "base/flat_set.h"
 #include "base/weak_ptr.h"
+#include "base/timer.h"
 
 // Not used for now.
 //
@@ -136,6 +137,12 @@ public:
 		not_null<PeerData*> peer) override final;
 	void rowClicked(not_null<PeerListRow*> row) override;
 
+	enum class SortMode {
+		Alphabet,
+		Online,
+	};
+	void setSortMode(SortMode mode);
+
 protected:
 	virtual std::unique_ptr<PeerListRow> createRow(not_null<UserData*> user);
 	virtual void prepareViewHook() {
@@ -144,11 +151,17 @@ protected:
 	}
 
 private:
+	void sort();
+	void sortByName();
+	void sortByOnline();
 	void rebuildRows();
 	void checkForEmptyRows();
 	bool appendRow(not_null<UserData*> user);
 
 	const not_null<Main::Session*> _session;
+	SortMode _sortMode = SortMode::Alphabet;
+	base::Timer _sortByOnlineTimer;
+	rpl::lifetime _sortByOnlineLifetime;
 
 };