From 9cf4cf6dcaf6f7b4bff34d0245e2d25707aaf27c Mon Sep 17 00:00:00 2001
From: John Preston <johnprestonmail@gmail.com>
Date: Wed, 24 Jul 2019 10:46:23 +0200
Subject: [PATCH] Move MTP::Instance to Main::Account.

---
 Telegram/SourceFiles/auth_session.cpp         |   6 +-
 Telegram/SourceFiles/auth_session.h           |   1 +
 Telegram/SourceFiles/boxes/connection_box.cpp |   3 +-
 Telegram/SourceFiles/boxes/language_box.cpp   |   8 +-
 .../chat_helpers/emoji_sets_manager.cpp       |   3 +-
 Telegram/SourceFiles/core/application.cpp     | 450 ++----------------
 Telegram/SourceFiles/core/application.h       |  50 +-
 Telegram/SourceFiles/core/update_checker.cpp  |   5 +-
 Telegram/SourceFiles/data/data_folder.cpp     |   8 +-
 Telegram/SourceFiles/data/data_session.cpp    |   8 +-
 Telegram/SourceFiles/intro/introcode.cpp      |  10 +-
 Telegram/SourceFiles/intro/introcode.h        |   5 +-
 Telegram/SourceFiles/intro/introphone.cpp     |  13 +-
 Telegram/SourceFiles/intro/introphone.h       |   5 +-
 Telegram/SourceFiles/intro/intropwdcheck.cpp  |   5 +-
 Telegram/SourceFiles/intro/intropwdcheck.h    |   5 +-
 Telegram/SourceFiles/intro/introsignup.cpp    |   6 +-
 Telegram/SourceFiles/intro/introsignup.h      |   5 +-
 Telegram/SourceFiles/intro/introstart.cpp     |   8 +-
 Telegram/SourceFiles/intro/introstart.h       |   5 +-
 Telegram/SourceFiles/intro/introwidget.cpp    |  33 +-
 Telegram/SourceFiles/intro/introwidget.h      |  53 ++-
 Telegram/SourceFiles/main/main_account.cpp    | 434 ++++++++++++++++-
 Telegram/SourceFiles/main/main_account.h      |  60 ++-
 Telegram/SourceFiles/mainwidget.cpp           |   2 +-
 Telegram/SourceFiles/mainwindow.cpp           |  13 +-
 Telegram/SourceFiles/mtproto/dc_options.cpp   |   4 +
 Telegram/SourceFiles/mtproto/dc_options.h     |   2 +
 Telegram/SourceFiles/mtproto/facade.cpp       |   5 +-
 Telegram/SourceFiles/mtproto/mtp_instance.cpp |   9 +-
 .../SourceFiles/settings/settings_codes.cpp   |   2 +-
 Telegram/SourceFiles/storage/localstorage.cpp |  15 +-
 32 files changed, 715 insertions(+), 526 deletions(-)

diff --git a/Telegram/SourceFiles/auth_session.cpp b/Telegram/SourceFiles/auth_session.cpp
index 3054dbbe6f..2b47176c9d 100644
--- a/Telegram/SourceFiles/auth_session.cpp
+++ b/Telegram/SourceFiles/auth_session.cpp
@@ -534,7 +534,7 @@ bool AuthSession::validateSelf(const MTPUser &user) {
 		return false;
 	} else if (user.c_user().vid().v != userId()) {
 		LOG(("Auth Error: wrong self user received."));
-		crl::on_main(this, [] { Core::App().logOut(); });
+		crl::on_main(this, [=] { _account->logOut(); });
 		return false;
 	}
 	return true;
@@ -558,6 +558,10 @@ void AuthSession::saveSettingsDelayed(crl::time delay) {
 	_saveDataTimer.callOnce(delay);
 }
 
+not_null<MTP::Instance*> AuthSession::mtp() {
+	return _account->mtp();
+}
+
 void AuthSession::localPasscodeChanged() {
 	_shouldLockAt = 0;
 	_autoLockTimer.cancel();
diff --git a/Telegram/SourceFiles/auth_session.h b/Telegram/SourceFiles/auth_session.h
index 76557acc89..201882fc24 100644
--- a/Telegram/SourceFiles/auth_session.h
+++ b/Telegram/SourceFiles/auth_session.h
@@ -333,6 +333,7 @@ public:
 	void moveSettingsFrom(AuthSessionSettings &&other);
 	void saveSettingsDelayed(crl::time delay = kDefaultSaveDelay);
 
+	not_null<MTP::Instance*> mtp();
 	ApiWrap &api() {
 		return *_api;
 	}
diff --git a/Telegram/SourceFiles/boxes/connection_box.cpp b/Telegram/SourceFiles/boxes/connection_box.cpp
index 8ea0c82a93..5622cf2d7c 100644
--- a/Telegram/SourceFiles/boxes/connection_box.cpp
+++ b/Telegram/SourceFiles/boxes/connection_box.cpp
@@ -12,6 +12,7 @@ https://github.com/telegramdesktop/tdesktop/blob/master/LEGAL
 #include "storage/localstorage.h"
 #include "base/qthelp_url.h"
 #include "core/application.h"
+#include "main/main_account.h"
 #include "ui/widgets/checkbox.h"
 #include "ui/widgets/buttons.h"
 #include "ui/widgets/input_fields.h"
@@ -1045,7 +1046,7 @@ void ProxiesBoxController::refreshChecker(Item &item) {
 	const auto type = (item.data.type == Type::Http)
 		? Variants::Http
 		: Variants::Tcp;
-	const auto mtproto = Core::App().mtp();
+	const auto mtproto = Core::App().activeAccount().mtp();
 	const auto dcId = mtproto->mainDcId();
 
 	item.state = ItemState::Checking;
diff --git a/Telegram/SourceFiles/boxes/language_box.cpp b/Telegram/SourceFiles/boxes/language_box.cpp
index a45cd07efe..46e73d1695 100644
--- a/Telegram/SourceFiles/boxes/language_box.cpp
+++ b/Telegram/SourceFiles/boxes/language_box.cpp
@@ -1155,13 +1155,13 @@ not_null<Ui::MultiSelect*> LanguageBox::createMultiSelect() {
 base::binary_guard LanguageBox::Show() {
 	auto result = base::binary_guard();
 
-	const auto manager = Core::App().langCloudManager();
-	if (manager->languageList().empty()) {
+	auto &manager = Lang::CurrentCloudManager();
+	if (manager.languageList().empty()) {
 		auto guard = std::make_shared<base::binary_guard>(
 			result.make_guard());
 		auto alive = std::make_shared<std::unique_ptr<base::Subscription>>(
 			std::make_unique<base::Subscription>());
-		**alive = manager->languageListChanged().add_subscription([=] {
+		**alive = manager.languageListChanged().add_subscription([=] {
 			const auto show = guard->alive();
 			*alive = nullptr;
 			if (show) {
@@ -1171,7 +1171,7 @@ base::binary_guard LanguageBox::Show() {
 	} else {
 		Ui::show(Box<LanguageBox>());
 	}
-	manager->requestLanguageList();
+	manager.requestLanguageList();
 
 	return result;
 }
diff --git a/Telegram/SourceFiles/chat_helpers/emoji_sets_manager.cpp b/Telegram/SourceFiles/chat_helpers/emoji_sets_manager.cpp
index 40e1ffb92d..47493a65d3 100644
--- a/Telegram/SourceFiles/chat_helpers/emoji_sets_manager.cpp
+++ b/Telegram/SourceFiles/chat_helpers/emoji_sets_manager.cpp
@@ -19,6 +19,7 @@ https://github.com/telegramdesktop/tdesktop/blob/master/LEGAL
 #include "base/zlib_help.h"
 #include "layout.h"
 #include "core/application.h"
+#include "main/main_account.h"
 #include "mainwidget.h"
 #include "styles/style_boxes.h"
 #include "styles/style_chat_helpers.h"
@@ -245,7 +246,7 @@ Loader::Loader(QObject *parent, int id)
 , _id(id)
 , _size(GetDownloadSize(_id))
 , _state(Loading{ 0, _size })
-, _mtproto(Core::App().mtp()) {
+, _mtproto(Core::App().activeAccount().mtp()) {
 	const auto ready = [=](std::unique_ptr<MTP::DedicatedLoader> loader) {
 		if (loader) {
 			setImplementation(std::move(loader));
diff --git a/Telegram/SourceFiles/core/application.cpp b/Telegram/SourceFiles/core/application.cpp
index 702531ae69..bc1addfb87 100644
--- a/Telegram/SourceFiles/core/application.cpp
+++ b/Telegram/SourceFiles/core/application.cpp
@@ -72,12 +72,6 @@ constexpr auto kQuitPreventTimeoutMs = 1500;
 Application *Application::Instance = nullptr;
 
 struct Application::Private {
-	UserId authSessionUserId = 0;
-	QByteArray authSessionUserSerialized;
-	int32 authSessionUserStreamVersion = 0;
-	std::unique_ptr<AuthSessionSettings> storedAuthSession;
-	MTP::Instance::Config mtpConfig;
-	MTP::AuthKeysList mtpKeysToDestroy;
 	base::Timer quitTimer;
 };
 
@@ -87,6 +81,7 @@ Application::Application(not_null<Launcher*> launcher)
 , _private(std::make_unique<Private>())
 , _databases(std::make_unique<Storage::Databases>())
 , _animationsManager(std::make_unique<Ui::Animations::Manager>())
+, _dcOptions(std::make_unique<MTP::DcOptions>())
 , _account(std::make_unique<Main::Account>(cDataFile()))
 , _langpack(std::make_unique<Lang::Instance>())
 , _emojiKeywords(std::make_unique<ChatHelpers::EmojiKeywords>())
@@ -95,9 +90,26 @@ Application::Application(not_null<Launcher*> launcher)
 , _logoNoMargin(Window::LoadLogoNoMargin()) {
 	Expects(!_logo.isNull());
 	Expects(!_logoNoMargin.isNull());
-	Expects(Instance == nullptr);
 
-	Instance = this;
+	activeAccount().sessionChanges(
+	) | rpl::start_with_next([=] {
+		if (_mediaView) {
+			hideMediaView();
+			_mediaView->clearData();
+		}
+	}, _lifetime);
+
+	activeAccount().mtpChanges(
+	) | rpl::filter([=](MTP::Instance *instance) {
+		return instance != nullptr;
+	}) | rpl::start_with_next([=](not_null<MTP::Instance*> mtp) {
+		_langCloudManager = std::make_unique<Lang::CloudManager>(
+			langpack(),
+			mtp);
+		if (!UpdaterDisabled()) {
+			UpdateChecker().setMtproto(mtp.get());
+		}
+	}, _lifetime);
 }
 
 Application::~Application() {
@@ -109,14 +121,14 @@ Application::~Application() {
 	Local::finish();
 
 	// Some MTP requests can be cancelled from data clearing.
-	authSessionDestroy();
+	unlockTerms();
+	activeAccount().destroySession();
 
 	// The langpack manager should be destroyed before MTProto instance,
 	// because it is MTP::Sender and it may have pending requests.
 	_langCloudManager.reset();
 
-	_mtproto.reset();
-	_mtprotoForKeysDestroy.reset();
+	activeAccount().clearMtp();
 
 	Shortcuts::Finish();
 
@@ -199,7 +211,7 @@ void Application::run() {
 		DEBUG_LOG(("Application Info: passcode needed..."));
 	} else {
 		DEBUG_LOG(("Application Info: local map read..."));
-		startMtp();
+		activeAccount().startMtp();
 		DEBUG_LOG(("Application Info: MTP started..."));
 		if (activeAccount().sessionExists()) {
 			_window->setupMain();
@@ -327,31 +339,24 @@ bool Application::eventFilter(QObject *object, QEvent *e) {
 void Application::setCurrentProxy(
 		const ProxyData &proxy,
 		ProxyData::Settings settings) {
-	const auto key = [&](const ProxyData &proxy) {
-		if (proxy.type == ProxyData::Type::Mtproto) {
-			return std::make_pair(proxy.host, proxy.port);
-		}
-		return std::make_pair(QString(), uint32(0));
-	};
-	const auto previousKey = key(
-		(Global::ProxySettings() == ProxyData::Settings::Enabled
+	const auto current = [&] {
+		return (Global::ProxySettings() == ProxyData::Settings::Enabled)
 			? Global::SelectedProxy()
-			: ProxyData()));
+			: ProxyData();
+	};
+	const auto was = current();
 	Global::SetSelectedProxy(proxy);
 	Global::SetProxySettings(settings);
+	const auto now = current();
 	refreshGlobalProxy();
-	if (_mtproto) {
-		_mtproto->restart();
-		if (previousKey != key(proxy)) {
-			_mtproto->reInitConnection(_mtproto->mainDcId());
-		}
-	}
-	if (_mtprotoForKeysDestroy) {
-		_mtprotoForKeysDestroy->restart();
-	}
+	_proxyChanges.fire({ was, now });
 	Global::RefConnectionTypeChanged().notify();
 }
 
+auto Application::proxyChanges() const -> rpl::producer<ProxyChange> {
+	return _proxyChanges.events();
+}
+
 void Application::badMtprotoConfigurationError() {
 	if (Global::ProxySettings() == ProxyData::Settings::Enabled
 		&& !_badProxyDisableBox) {
@@ -366,311 +371,16 @@ void Application::badMtprotoConfigurationError() {
 	}
 }
 
-void Application::setMtpMainDcId(MTP::DcId mainDcId) {
-	Expects(!_mtproto);
-
-	_private->mtpConfig.mainDcId = mainDcId;
-}
-
-void Application::setMtpKey(MTP::DcId dcId, const MTP::AuthKey::Data &keyData) {
-	Expects(!_mtproto);
-
-	_private->mtpConfig.keys.push_back(std::make_shared<MTP::AuthKey>(MTP::AuthKey::Type::ReadFromFile, dcId, keyData));
-}
-
-QByteArray Application::serializeMtpAuthorization() const {
-	auto serialize = [this](auto mainDcId, auto &keys, auto &keysToDestroy) {
-		auto keysSize = [](auto &list) {
-			return sizeof(qint32) + list.size() * (sizeof(qint32) + MTP::AuthKey::Data().size());
-		};
-		auto writeKeys = [](QDataStream &stream, auto &keys) {
-			stream << qint32(keys.size());
-			for (auto &key : keys) {
-				stream << qint32(key->dcId());
-				key->write(stream);
-			}
-		};
-
-		auto result = QByteArray();
-		auto size = sizeof(qint32) + sizeof(qint32); // userId + mainDcId
-		size += keysSize(keys) + keysSize(keysToDestroy);
-		result.reserve(size);
-		{
-			QDataStream stream(&result, QIODevice::WriteOnly);
-			stream.setVersion(QDataStream::Qt_5_1);
-
-			auto currentUserId = activeAccount().sessionExists()
-				? activeAccount().session().userId()
-				: 0;
-			stream << qint32(currentUserId) << qint32(mainDcId);
-			writeKeys(stream, keys);
-			writeKeys(stream, keysToDestroy);
-
-			DEBUG_LOG(("MTP Info: Keys written, userId: %1, dcId: %2").arg(currentUserId).arg(mainDcId));
-		}
-		return result;
-	};
-	if (_mtproto) {
-		auto keys = _mtproto->getKeysForWrite();
-		auto keysToDestroy = _mtprotoForKeysDestroy ? _mtprotoForKeysDestroy->getKeysForWrite() : MTP::AuthKeysList();
-		return serialize(_mtproto->mainDcId(), keys, keysToDestroy);
-	}
-	auto &keys = _private->mtpConfig.keys;
-	auto &keysToDestroy = _private->mtpKeysToDestroy;
-	return serialize(_private->mtpConfig.mainDcId, keys, keysToDestroy);
-}
-
-void Application::setAuthSessionUserId(UserId userId) {
-	Expects(!activeAccount().sessionExists());
-
-	_private->authSessionUserId = userId;
-}
-
-void Application::setAuthSessionFromStorage(
-		std::unique_ptr<AuthSessionSettings> data,
-		QByteArray &&selfSerialized,
-		int32 selfStreamVersion) {
-	Expects(!activeAccount().sessionExists());
-
-	DEBUG_LOG(("authSessionUserSerialized set: %1"
-		).arg(selfSerialized.size()));
-
-	_private->storedAuthSession = std::move(data);
-	_private->authSessionUserSerialized = std::move(selfSerialized);
-	_private->authSessionUserStreamVersion = selfStreamVersion;
-}
-
-AuthSessionSettings *Application::getAuthSessionSettings() {
-	if (_private->authSessionUserId) {
-		return _private->storedAuthSession
-			? _private->storedAuthSession.get()
-			: nullptr;
-	} else if (activeAccount().sessionExists()) {
-		return &activeAccount().session().settings();
-	}
-	return nullptr;
-}
-
-void Application::setMtpAuthorization(const QByteArray &serialized) {
-	Expects(!_mtproto);
-
-	QDataStream stream(serialized);
-	stream.setVersion(QDataStream::Qt_5_1);
-
-	auto userId = Serialize::read<qint32>(stream);
-	auto mainDcId = Serialize::read<qint32>(stream);
-	if (stream.status() != QDataStream::Ok) {
-		LOG(("MTP Error: could not read main fields from serialized mtp authorization."));
-		return;
-	}
-
-	setAuthSessionUserId(userId);
-	_private->mtpConfig.mainDcId = mainDcId;
-
-	auto readKeys = [&stream](auto &keys) {
-		auto count = Serialize::read<qint32>(stream);
-		if (stream.status() != QDataStream::Ok) {
-			LOG(("MTP Error: could not read keys count from serialized mtp authorization."));
-			return;
-		}
-		keys.reserve(count);
-		for (auto i = 0; i != count; ++i) {
-			auto dcId = Serialize::read<qint32>(stream);
-			auto keyData = Serialize::read<MTP::AuthKey::Data>(stream);
-			if (stream.status() != QDataStream::Ok) {
-				LOG(("MTP Error: could not read key from serialized mtp authorization."));
-				return;
-			}
-			keys.push_back(std::make_shared<MTP::AuthKey>(MTP::AuthKey::Type::ReadFromFile, dcId, keyData));
-		}
-	};
-	readKeys(_private->mtpConfig.keys);
-	readKeys(_private->mtpKeysToDestroy);
-	LOG(("MTP Info: read keys, current: %1, to destroy: %2").arg(_private->mtpConfig.keys.size()).arg(_private->mtpKeysToDestroy.size()));
-}
-
-void Application::startMtp() {
-	Expects(!_mtproto);
-
-	auto config = base::take(_private->mtpConfig);
-	config.deviceModel = _launcher->deviceModel();
-	config.systemVersion = _launcher->systemVersion();
-	_mtproto = std::make_unique<MTP::Instance>(
-		_dcOptions.get(),
-		MTP::Instance::Mode::Normal,
-		std::move(config));
-	_mtproto->setUserPhone(cLoggedPhoneNumber());
-	_private->mtpConfig.mainDcId = _mtproto->mainDcId();
-
-	_mtproto->setStateChangedHandler([](MTP::ShiftedDcId dc, int32 state) {
-		if (dc == MTP::maindc()) {
-			Global::RefConnectionTypeChanged().notify();
-		}
-	});
-	_mtproto->setSessionResetHandler([](MTP::ShiftedDcId shiftedDcId) {
-		if (App::main() && shiftedDcId == MTP::maindc()) {
-			App::main()->getDifference();
-		}
-	});
-
-	if (!_private->mtpKeysToDestroy.empty()) {
-		destroyMtpKeys(base::take(_private->mtpKeysToDestroy));
-	}
-
-	if (_private->authSessionUserId) {
-		DEBUG_LOG(("authSessionUserSerialized.size: %1"
-			).arg(_private->authSessionUserSerialized.size()));
-		QDataStream peekStream(_private->authSessionUserSerialized);
-		const auto phone = Serialize::peekUserPhone(
-			_private->authSessionUserStreamVersion,
-			peekStream);
-		const auto flags = MTPDuser::Flag::f_self | (phone.isEmpty()
-			? MTPDuser::Flag()
-			: MTPDuser::Flag::f_phone);
-		authSessionCreate(MTP_user(
-			MTP_flags(flags),
-			MTP_int(base::take(_private->authSessionUserId)),
-			MTPlong(), // access_hash
-			MTPstring(), // first_name
-			MTPstring(), // last_name
-			MTPstring(), // username
-			MTP_string(phone),
-			MTPUserProfilePhoto(),
-			MTPUserStatus(),
-			MTPint(), // bot_info_version
-			MTPstring(), // restriction_reason
-			MTPstring(), // bot_inline_placeholder
-			MTPstring())); // lang_code
-		Local::readSelf(
-			base::take(_private->authSessionUserSerialized),
-			base::take(_private->authSessionUserStreamVersion));
-	}
-	if (_private->storedAuthSession) {
-		if (activeAccount().sessionExists()) {
-			activeAccount().session().moveSettingsFrom(
-				std::move(*_private->storedAuthSession));
-		}
-		_private->storedAuthSession.reset();
-	}
-
-	_langCloudManager = std::make_unique<Lang::CloudManager>(
-		langpack(),
-		mtp());
-	if (!UpdaterDisabled()) {
-		UpdateChecker().setMtproto(mtp());
-	}
-
-	if (activeAccount().sessionExists()) {
-		// Skip all pending self updates so that we won't Local::writeSelf.
-		Notify::peerUpdatedSendDelayed();
-	}
-}
-
-void Application::destroyMtpKeys(MTP::AuthKeysList &&keys) {
-	if (keys.empty()) {
-		return;
-	}
-	if (_mtprotoForKeysDestroy) {
-		_mtprotoForKeysDestroy->addKeysForDestroy(std::move(keys));
-		Local::writeMtpData();
-		return;
-	}
-	auto destroyConfig = MTP::Instance::Config();
-	destroyConfig.mainDcId = MTP::Instance::Config::kNoneMainDc;
-	destroyConfig.keys = std::move(keys);
-	destroyConfig.deviceModel = _launcher->deviceModel();
-	destroyConfig.systemVersion = _launcher->systemVersion();
-	_mtprotoForKeysDestroy = std::make_unique<MTP::Instance>(
-		_dcOptions.get(),
-		MTP::Instance::Mode::KeysDestroyer,
-		std::move(destroyConfig));
-	connect(
-		_mtprotoForKeysDestroy.get(),
-		&MTP::Instance::allKeysDestroyed,
-		[=] { allKeysDestroyed(); });
-}
-
-void Application::allKeysDestroyed() {
-	LOG(("MTP Info: all keys scheduled for destroy are destroyed."));
-	crl::on_main(this, [=] {
-		_mtprotoForKeysDestroy = nullptr;
-		Local::writeMtpData();
-	});
-}
-
-void Application::suggestMainDcId(MTP::DcId mainDcId) {
-	Expects(_mtproto != nullptr);
-
-	_mtproto->suggestMainDcId(mainDcId);
-	if (_private->mtpConfig.mainDcId != MTP::Instance::Config::kNotSetMainDc) {
-		_private->mtpConfig.mainDcId = mainDcId;
-	}
-}
-
-void Application::destroyStaleAuthorizationKeys() {
-	Expects(_mtproto != nullptr);
-
-	for (const auto &key : _mtproto->getKeysForWrite()) {
-		// Disable this for now.
-		if (key->type() == MTP::AuthKey::Type::ReadFromFile) {
-			_private->mtpKeysToDestroy = _mtproto->getKeysForWrite();
-			LOG(("MTP Info: destroying stale keys, count: %1"
-				).arg(_private->mtpKeysToDestroy.size()));
-			resetAuthorizationKeys();
-			return;
-		}
-	}
-}
-
-void Application::configUpdated() {
-	_configUpdates.fire({});
-}
-
-rpl::producer<> Application::configUpdates() const {
-	return _configUpdates.events();
-}
-
-void Application::resetAuthorizationKeys() {
-	_mtproto = nullptr;
-	startMtp();
-	Local::writeMtpData();
-}
-
 void Application::startLocalStorage() {
-	_dcOptions = std::make_unique<MTP::DcOptions>();
-	_dcOptions->constructFromBuiltIn();
 	Local::start();
 	subscribe(_dcOptions->changed(), [this](const MTP::DcOptions::Ids &ids) {
 		Local::writeSettings();
-		if (auto instance = mtp()) {
-			for (auto id : ids) {
+		if (const auto instance = activeAccount().mtp()) {
+			for (const auto id : ids) {
 				instance->restart(id);
 			}
 		}
 	});
-	activeAccount().sessionChanges(
-	) | rpl::start_with_next([=] {
-		crl::on_main(this, [=] {
-			const auto phone = activeAccount().sessionExists()
-					? activeAccount().session().user()->phone()
-					: QString();
-			const auto support = activeAccount().sessionExists()
-				&& activeAccount().session().supportMode();
-			if (cLoggedPhoneNumber() != phone) {
-				cSetLoggedPhoneNumber(phone);
-				if (_mtproto) {
-					_mtproto->setUserPhone(phone);
-				}
-				Local::writeSettings();
-			}
-			if (_mtproto) {
-				_mtproto->requestConfig();
-			}
-			Platform::SetApplicationIcon(
-				Window::CreateIcon(&activeAccount()));
-			Shortcuts::ToggleSupportShortcuts(support);
-		});
-	}, _lifetime);
 }
 
 void Application::forceLogOut(const TextWithEntities &explanation) {
@@ -681,10 +391,7 @@ void Application::forceLogOut(const TextWithEntities &explanation) {
 	box->setCloseByOutsideClick(false);
 	connect(box, &QObject::destroyed, [=] {
 		crl::on_main(this, [=] {
-			if (AuthSession::Exists()) {
-				resetAuthorizationKeys();
-				loggedOut();
-			}
+			activeAccount().forcedLogOut();
 		});
 	});
 }
@@ -773,41 +480,6 @@ void Application::writeInstallBetaVersionsSetting() {
 	_launcher->writeInstallBetaVersionsSetting();
 }
 
-void Application::authSessionCreate(const MTPUser &user) {
-	Expects(_mtproto != nullptr);
-
-	_mtproto->setUpdatesHandler(::rpcDone([](
-			const mtpPrime *from,
-			const mtpPrime *end) {
-		if (const auto main = App::main()) {
-			return main->updateReceived(from, end);
-		}
-		return true;
-	}));
-	_mtproto->setGlobalFailHandler(::rpcFail([=](const RPCError &error) {
-		if (activeAccount().sessionExists()) {
-			crl::on_main(&activeAccount().session(), [=] { logOut(); });
-		}
-		return true;
-	}));
-
-	activeAccount().createSession(user);
-}
-
-void Application::authSessionDestroy() {
-	_private->storedAuthSession.reset();
-	_private->authSessionUserId = 0;
-	_private->authSessionUserSerialized = {};
-	if (activeAccount().sessionExists()) {
-		unlockTerms();
-		_mtproto->clearGlobalHandlers();
-
-		activeAccount().destroySession();
-
-		Notify::unreadCounterUpdated();
-	}
-}
-
 int Application::unreadBadge() const {
 	return activeAccount().sessionExists()
 		? activeAccount().session().data().unreadBadge()
@@ -897,7 +569,9 @@ void Application::lockByPasscode() {
 
 void Application::unlockPasscode() {
 	clearPasscodeLock();
-	_window->clearPasscodeLock();
+	if (_window) {
+		_window->clearPasscodeLock();
+	}
 }
 
 void Application::clearPasscodeLock() {
@@ -1011,48 +685,6 @@ void Application::checkMediaViewActivation() {
 	}
 }
 
-void Application::logOut() {
-	if (_mtproto) {
-		_mtproto->logout(::rpcDone([=] {
-			loggedOut();
-		}), ::rpcFail([=] {
-			loggedOut();
-			return true;
-		}));
-	} else {
-		// We log out because we've forgotten passcode.
-		// So we just start mtproto from scratch.
-		startMtp();
-		loggedOut();
-	}
-}
-
-void Application::loggedOut() {
-	if (Global::LocalPasscode()) {
-		Global::SetLocalPasscode(false);
-		Global::RefLocalPasscodeChanged().notify();
-	}
-	clearPasscodeLock();
-	Media::Player::mixer()->stopAndClear();
-	Global::SetVoiceMsgPlaybackDoubled(false);
-	if (const auto window = activeWindow()) {
-		window->tempDirDelete(Local::ClearManagerAll);
-		window->setupIntro();
-	}
-	if (activeAccount().sessionExists()) {
-		activeAccount().session().data().clearLocalStorage();
-		authSessionDestroy();
-	}
-	if (_mediaView) {
-		hideMediaView();
-		_mediaView->clearData();
-	}
-	Local::reset();
-
-	cSetOtherOnline(0);
-	Images::ClearRemote();
-}
-
 QPoint Application::getPointForCallPanelCenter() const {
 	if (const auto window = activeWindow()) {
 		return window->getPointForCallPanelCenter();
diff --git a/Telegram/SourceFiles/core/application.h b/Telegram/SourceFiles/core/application.h
index dfa66803aa..a86b2b849e 100644
--- a/Telegram/SourceFiles/core/application.h
+++ b/Telegram/SourceFiles/core/application.h
@@ -120,34 +120,16 @@ public:
 	MTP::DcOptions *dcOptions() {
 		return _dcOptions.get();
 	}
+	struct ProxyChange {
+		ProxyData was;
+		ProxyData now;
+	};
 	void setCurrentProxy(
 		const ProxyData &proxy,
 		ProxyData::Settings settings);
+	[[nodiscard]] rpl::producer<ProxyChange> proxyChanges() const;
 	void badMtprotoConfigurationError();
 
-	// Set from legacy storage.
-	void setMtpMainDcId(MTP::DcId mainDcId);
-	void setMtpKey(MTP::DcId dcId, const MTP::AuthKey::Data &keyData);
-	void setAuthSessionUserId(UserId userId);
-	void setAuthSessionFromStorage(
-		std::unique_ptr<AuthSessionSettings> data,
-		QByteArray &&selfSerialized,
-		int32 selfStreamVersion);
-	AuthSessionSettings *getAuthSessionSettings();
-
-	// Serialization.
-	QByteArray serializeMtpAuthorization() const;
-	void setMtpAuthorization(const QByteArray &serialized);
-
-	void startMtp();
-	MTP::Instance *mtp() {
-		return _mtproto.get();
-	}
-	void suggestMainDcId(MTP::DcId mainDcId);
-	void destroyStaleAuthorizationKeys();
-	void configUpdated();
-	[[nodiscard]] rpl::producer<> configUpdates() const;
-
 	// Databases.
 	Storage::Databases &databases() {
 		return *_databases;
@@ -159,10 +141,8 @@ public:
 	}
 
 	// AuthSession component.
-	void authSessionCreate(const MTPUser &user);
 	int unreadBadge() const;
 	bool unreadBadgeMuted() const;
-	void logOut();
 
 	// Media component.
 	Media::Audio::Instance &audio() {
@@ -244,9 +224,6 @@ private:
 	friend bool IsAppLaunched();
 	friend Application &App();
 
-	void destroyMtpKeys(MTP::AuthKeysList &&keys);
-	void allKeysDestroyed();
-
 	void startLocalStorage();
 	void startShortcuts();
 
@@ -256,14 +233,20 @@ private:
 	static void QuitAttempt();
 	void quitDelayed();
 
-	void resetAuthorizationKeys();
-	void authSessionDestroy();
 	void clearPasscodeLock();
-	void loggedOut();
 
 	static Application *Instance;
+	struct InstanceSetter {
+		InstanceSetter(not_null<Application*> instance) {
+			Expects(Instance == nullptr);
+
+			Instance = instance;
+		}
+	};
+	InstanceSetter _setter = { this };
 
 	not_null<Launcher*> _launcher;
+	rpl::event_stream<ProxyChange> _proxyChanges;
 
 	// Some fields are just moved from the declaration.
 	struct Private;
@@ -273,6 +256,7 @@ private:
 
 	const std::unique_ptr<Storage::Databases> _databases;
 	const std::unique_ptr<Ui::Animations::Manager> _animationsManager;
+	const std::unique_ptr<MTP::DcOptions> _dcOptions;
 	const std::unique_ptr<Main::Account> _account;
 	std::unique_ptr<Window::Controller> _window;
 	std::unique_ptr<Media::View::OverlayWidget> _mediaView;
@@ -280,10 +264,6 @@ private:
 	std::unique_ptr<Lang::CloudManager> _langCloudManager;
 	const std::unique_ptr<ChatHelpers::EmojiKeywords> _emojiKeywords;
 	std::unique_ptr<Lang::Translator> _translator;
-	std::unique_ptr<MTP::DcOptions> _dcOptions;
-	std::unique_ptr<MTP::Instance> _mtproto;
-	std::unique_ptr<MTP::Instance> _mtprotoForKeysDestroy;
-	rpl::event_stream<> _configUpdates;
 	base::Observable<void> _passcodedChanged;
 	QPointer<BoxContent> _badProxyDisableBox;
 
diff --git a/Telegram/SourceFiles/core/update_checker.cpp b/Telegram/SourceFiles/core/update_checker.cpp
index 800f7824cf..bff6dcd77d 100644
--- a/Telegram/SourceFiles/core/update_checker.cpp
+++ b/Telegram/SourceFiles/core/update_checker.cpp
@@ -13,8 +13,9 @@ https://github.com/telegramdesktop/tdesktop/blob/master/LEGAL
 #include "base/unixtime.h"
 #include "storage/localstorage.h"
 #include "core/application.h"
-#include "mainwindow.h"
 #include "core/click_handler_types.h"
+#include "mainwindow.h"
+#include "main/main_account.h"
 #include "info/info_memento.h"
 #include "info/settings/info_settings_widget.h"
 #include "window/window_session_controller.h"
@@ -1390,7 +1391,7 @@ Updater::~Updater() {
 UpdateChecker::UpdateChecker()
 : _updater(GetUpdaterInstance()) {
 	if (IsAppLaunched()) {
-		if (const auto mtproto = Core::App().mtp()) {
+		if (const auto mtproto = Core::App().activeAccount().mtp()) {
 			_updater->setMtproto(mtproto);
 		}
 	}
diff --git a/Telegram/SourceFiles/data/data_folder.cpp b/Telegram/SourceFiles/data/data_folder.cpp
index 5916cb2c65..7fb776e8d4 100644
--- a/Telegram/SourceFiles/data/data_folder.cpp
+++ b/Telegram/SourceFiles/data/data_folder.cpp
@@ -15,6 +15,7 @@ https://github.com/telegramdesktop/tdesktop/blob/master/LEGAL
 #include "lang/lang_keys.h"
 #include "storage/storage_facade.h"
 #include "core/application.h"
+#include "main/main_account.h"
 //#include "storage/storage_feed_messages.h" // #feed
 #include "auth_session.h"
 #include "observer_peer.h"
@@ -28,11 +29,12 @@ namespace {
 constexpr auto kLoadedChatsMinCount = 20;
 constexpr auto kShowChatNamesCount = 8;
 
-rpl::producer<int> PinnedDialogsInFolderMaxValue() {
+rpl::producer<int> PinnedDialogsInFolderMaxValue(
+		not_null<AuthSession*> session) {
 	return rpl::single(
 		rpl::empty_value()
 	) | rpl::then(
-		Core::App().configUpdates()
+		session->account().configUpdates()
 	) | rpl::map([=] {
 		return Global::PinnedDialogsInFolderMax();
 	});
@@ -53,7 +55,7 @@ rpl::producer<int> PinnedDialogsInFolderMaxValue() {
 Folder::Folder(not_null<Data::Session*> owner, FolderId id)
 : Entry(owner, this)
 , _id(id)
-, _chatsList(PinnedDialogsInFolderMaxValue())
+, _chatsList(PinnedDialogsInFolderMaxValue(&owner->session()))
 , _name(tr::lng_archived_name(tr::now)) {
 	indexNameParts();
 
diff --git a/Telegram/SourceFiles/data/data_session.cpp b/Telegram/SourceFiles/data/data_session.cpp
index 61c7caf5dd..fec417e576 100644
--- a/Telegram/SourceFiles/data/data_session.cpp
+++ b/Telegram/SourceFiles/data/data_session.cpp
@@ -25,6 +25,7 @@ https://github.com/telegramdesktop/tdesktop/blob/master/LEGAL
 #include "inline_bots/inline_bot_layout_item.h"
 #include "storage/localstorage.h"
 #include "storage/storage_encrypted_file.h"
+#include "main/main_account.h"
 #include "media/player/media_player_instance.h" // instance()->play()
 #include "media/streaming/media_streaming_loader.h" // unique_ptr<Loader>
 #include "media/streaming/media_streaming_reader.h" // make_shared<Reader>
@@ -155,11 +156,12 @@ MTPPhotoSize FindDocumentThumbnail(const MTPDdocument &data) {
 		: MTPPhotoSize(MTP_photoSizeEmpty(MTP_string()));
 }
 
-rpl::producer<int> PinnedDialogsCountMaxValue() {
+rpl::producer<int> PinnedDialogsCountMaxValue(
+		not_null<AuthSession*> session) {
 	return rpl::single(
 		rpl::empty_value()
 	) | rpl::then(
-		Core::App().configUpdates()
+		session->account().configUpdates()
 	) | rpl::map([=] {
 		return Global::PinnedDialogsCountMax();
 	});
@@ -195,7 +197,7 @@ Session::Session(not_null<AuthSession*> session)
 , _bigFileCache(Core::App().databases().get(
 	Local::cacheBigFilePath(),
 	Local::cacheBigFileSettings()))
-, _chatsList(PinnedDialogsCountMaxValue())
+, _chatsList(PinnedDialogsCountMaxValue(session))
 , _contactsList(Dialogs::SortMode::Name)
 , _contactsNoChatsList(Dialogs::SortMode::Name)
 , _selfDestructTimer([=] { checkSelfDestructItems(); })
diff --git a/Telegram/SourceFiles/intro/introcode.cpp b/Telegram/SourceFiles/intro/introcode.cpp
index 14731086d0..356f8ce7b9 100644
--- a/Telegram/SourceFiles/intro/introcode.cpp
+++ b/Telegram/SourceFiles/intro/introcode.cpp
@@ -73,7 +73,11 @@ void CodeInput::correctValue(const QString &was, int wasCursor, QString &now, in
 	}
 }
 
-CodeWidget::CodeWidget(QWidget *parent, Widget::Data *data) : Step(parent, data)
+CodeWidget::CodeWidget(
+	QWidget *parent,
+	not_null<Main::Account*> account,
+	not_null<Widget::Data*> data)
+: Step(parent, account, data)
 , _noTelegramCode(this, tr::lng_code_no_telegram(tr::now), st::introLink)
 , _code(this, st::introCode, tr::lng_code_ph())
 , _callTimer(this)
@@ -244,7 +248,7 @@ void CodeWidget::codeSubmitDone(const MTPauth_Authorization &result) {
 		} else {
 			getData()->termsLock = Window::TermsLock();
 		}
-		goReplace(new Intro::SignupWidget(parentWidget(), getData()));
+		goReplace<SignupWidget>();
 	});
 }
 
@@ -342,7 +346,7 @@ void CodeWidget::gotPassword(const MTPaccount_Password &result) {
 	getData()->hasRecovery = d.is_has_recovery();
 	getData()->pwdHint = qs(d.vhint().value_or_empty());
 	getData()->pwdNotEmptyPassport = d.is_has_secure_values();
-	goReplace(new Intro::PwdCheckWidget(parentWidget(), getData()));
+	goReplace<PwdCheckWidget>();
 }
 
 void CodeWidget::submit() {
diff --git a/Telegram/SourceFiles/intro/introcode.h b/Telegram/SourceFiles/intro/introcode.h
index 2b8d99d74a..527715035d 100644
--- a/Telegram/SourceFiles/intro/introcode.h
+++ b/Telegram/SourceFiles/intro/introcode.h
@@ -39,7 +39,10 @@ class CodeWidget : public Widget::Step {
 	Q_OBJECT
 
 public:
-	CodeWidget(QWidget *parent, Widget::Data *data);
+	CodeWidget(
+		QWidget *parent,
+		not_null<Main::Account*> account,
+		not_null<Widget::Data*> data);
 
 	bool hasBack() const override {
 		return true;
diff --git a/Telegram/SourceFiles/intro/introphone.cpp b/Telegram/SourceFiles/intro/introphone.cpp
index 135681e9e1..8bd1716b7d 100644
--- a/Telegram/SourceFiles/intro/introphone.cpp
+++ b/Telegram/SourceFiles/intro/introphone.cpp
@@ -13,6 +13,7 @@ https://github.com/telegramdesktop/tdesktop/blob/master/LEGAL
 #include "ui/widgets/buttons.h"
 #include "ui/widgets/labels.h"
 #include "ui/wrap/fade_wrap.h"
+#include "main/main_account.h"
 #include "boxes/confirm_phone_box.h"
 #include "boxes/confirm_box.h"
 #include "core/application.h"
@@ -29,7 +30,11 @@ bool AllowPhoneAttempt(const QString &phone) {
 
 } // namespace
 
-PhoneWidget::PhoneWidget(QWidget *parent, Widget::Data *data) : Step(parent, data)
+PhoneWidget::PhoneWidget(
+	QWidget *parent,
+	not_null<Main::Account*> account,
+	not_null<Widget::Data*> data)
+: Step(parent, account, data)
 , _country(this, st::introCountry)
 , _code(this, st::introCountryCode)
 , _phone(this, st::introPhone)
@@ -54,7 +59,7 @@ PhoneWidget::PhoneWidget(QWidget *parent, Widget::Data *data) : Step(parent, dat
 	}
 	_changed = false;
 
-	Core::App().destroyStaleAuthorizationKeys();
+	account->destroyStaleAuthorizationKeys();
 }
 
 void PhoneWidget::resizeEvent(QResizeEvent *e) {
@@ -111,7 +116,7 @@ void PhoneWidget::submit() {
 	_checkRequest->start(1000);
 
 	_sentPhone = phone;
-	Core::App().mtp()->setUserPhone(_sentPhone);
+	account().mtp()->setUserPhone(_sentPhone);
 	_sentRequest = MTP::send(
 		MTPauth_SendCode(
 			MTP_string(_sentPhone),
@@ -162,7 +167,7 @@ void PhoneWidget::phoneSubmitDone(const MTPauth_SentCode &result) {
 		getData()->callStatus = Widget::Data::CallStatus::Disabled;
 		getData()->callTimeout = 0;
 	}
-	goNext(new Intro::CodeWidget(parentWidget(), getData()));
+	goNext<CodeWidget>();
 }
 
 bool PhoneWidget::phoneSubmitFail(const RPCError &error) {
diff --git a/Telegram/SourceFiles/intro/introphone.h b/Telegram/SourceFiles/intro/introphone.h
index 6dd6598b1e..60e706345e 100644
--- a/Telegram/SourceFiles/intro/introphone.h
+++ b/Telegram/SourceFiles/intro/introphone.h
@@ -23,7 +23,10 @@ class PhoneWidget : public Widget::Step {
 	Q_OBJECT
 
 public:
-	PhoneWidget(QWidget *parent, Widget::Data *data);
+	PhoneWidget(
+		QWidget *parent,
+		not_null<Main::Account*> account,
+		not_null<Widget::Data*> data);
 
 	void selectCountry(const QString &country);
 
diff --git a/Telegram/SourceFiles/intro/intropwdcheck.cpp b/Telegram/SourceFiles/intro/intropwdcheck.cpp
index 94ee2c3aee..f6d1728a63 100644
--- a/Telegram/SourceFiles/intro/intropwdcheck.cpp
+++ b/Telegram/SourceFiles/intro/intropwdcheck.cpp
@@ -23,8 +23,9 @@ namespace Intro {
 
 PwdCheckWidget::PwdCheckWidget(
 	QWidget *parent,
-	Widget::Data *data)
-: Step(parent, data)
+	not_null<Main::Account*> account,
+	not_null<Widget::Data*> data)
+: Step(parent, account, data)
 , _request(getData()->pwdRequest)
 , _hasRecovery(getData()->hasRecovery)
 , _notEmptyPassport(getData()->pwdNotEmptyPassport)
diff --git a/Telegram/SourceFiles/intro/intropwdcheck.h b/Telegram/SourceFiles/intro/intropwdcheck.h
index 0036d6f9a2..a0fc7b5558 100644
--- a/Telegram/SourceFiles/intro/intropwdcheck.h
+++ b/Telegram/SourceFiles/intro/intropwdcheck.h
@@ -23,7 +23,10 @@ class PwdCheckWidget : public Widget::Step, private MTP::Sender {
 	Q_OBJECT
 
 public:
-	PwdCheckWidget(QWidget *parent, Widget::Data *data);
+	PwdCheckWidget(
+		QWidget *parent,
+		not_null<Main::Account*> account,
+		not_null<Widget::Data*> data);
 
 	void setInnerFocus() override;
 	void activate() override;
diff --git a/Telegram/SourceFiles/intro/introsignup.cpp b/Telegram/SourceFiles/intro/introsignup.cpp
index c09e15e8d3..01d71d369d 100644
--- a/Telegram/SourceFiles/intro/introsignup.cpp
+++ b/Telegram/SourceFiles/intro/introsignup.cpp
@@ -20,7 +20,11 @@ https://github.com/telegramdesktop/tdesktop/blob/master/LEGAL
 
 namespace Intro {
 
-SignupWidget::SignupWidget(QWidget *parent, Widget::Data *data) : Step(parent, data)
+SignupWidget::SignupWidget(
+	QWidget *parent,
+	not_null<Main::Account*> account,
+	not_null<Widget::Data*> data)
+: Step(parent, account, data)
 , _photo(
 	this,
 	tr::lng_settings_crop_profile(tr::now),
diff --git a/Telegram/SourceFiles/intro/introsignup.h b/Telegram/SourceFiles/intro/introsignup.h
index ee5b9a1418..7eadd5ae85 100644
--- a/Telegram/SourceFiles/intro/introsignup.h
+++ b/Telegram/SourceFiles/intro/introsignup.h
@@ -21,7 +21,10 @@ class SignupWidget : public Widget::Step {
 	Q_OBJECT
 
 public:
-	SignupWidget(QWidget *parent, Widget::Data *data);
+	SignupWidget(
+		QWidget *parent,
+		not_null<Main::Account*> account,
+		not_null<Widget::Data*> data);
 
 	void finishInit() override;
 	void setInnerFocus() override;
diff --git a/Telegram/SourceFiles/intro/introstart.cpp b/Telegram/SourceFiles/intro/introstart.cpp
index 9822f3678a..8ee0b1e5ce 100644
--- a/Telegram/SourceFiles/intro/introstart.cpp
+++ b/Telegram/SourceFiles/intro/introstart.cpp
@@ -14,7 +14,11 @@ https://github.com/telegramdesktop/tdesktop/blob/master/LEGAL
 
 namespace Intro {
 
-StartWidget::StartWidget(QWidget *parent, Widget::Data *data) : Step(parent, data, true) {
+StartWidget::StartWidget(
+	QWidget *parent,
+	not_null<Main::Account*> account,
+	not_null<Widget::Data*> data)
+: Step(parent, account, data, true) {
 	setMouseTracking(true);
 	setTitleText(rpl::single(qsl("Telegram Desktop")));
 	setDescriptionText(tr::lng_intro_about());
@@ -22,7 +26,7 @@ StartWidget::StartWidget(QWidget *parent, Widget::Data *data) : Step(parent, dat
 }
 
 void StartWidget::submit() {
-	goNext(new Intro::PhoneWidget(parentWidget(), getData()));
+	goNext<PhoneWidget>();
 }
 
 rpl::producer<QString> StartWidget::nextButtonText() const {
diff --git a/Telegram/SourceFiles/intro/introstart.h b/Telegram/SourceFiles/intro/introstart.h
index 1a0489151e..9f7048f6f6 100644
--- a/Telegram/SourceFiles/intro/introstart.h
+++ b/Telegram/SourceFiles/intro/introstart.h
@@ -19,7 +19,10 @@ namespace Intro {
 
 class StartWidget : public Widget::Step {
 public:
-	StartWidget(QWidget *parent, Widget::Data *data);
+	StartWidget(
+		QWidget *parent,
+		not_null<Main::Account*> account,
+		not_null<Widget::Data*> data);
 
 	void submit() override;
 	rpl::producer<QString> nextButtonText() const override;
diff --git a/Telegram/SourceFiles/intro/introwidget.cpp b/Telegram/SourceFiles/intro/introwidget.cpp
index 5136a888e7..1567ee5652 100644
--- a/Telegram/SourceFiles/intro/introwidget.cpp
+++ b/Telegram/SourceFiles/intro/introwidget.cpp
@@ -15,6 +15,7 @@ https://github.com/telegramdesktop/tdesktop/blob/master/LEGAL
 #include "intro/introcode.h"
 #include "intro/introsignup.h"
 #include "intro/intropwdcheck.h"
+#include "main/main_account.h"
 #include "mainwidget.h"
 #include "apiwrap.h"
 #include "mainwindow.h"
@@ -59,7 +60,9 @@ void PrepareSupportMode() {
 
 } // namespace
 
-Widget::Widget(QWidget *parent) : RpWidget(parent)
+Widget::Widget(QWidget *parent, not_null<Main::Account*> account)
+: RpWidget(parent)
+, _account(account)
 , _back(this, object_ptr<Ui::IconButton>(this, st::introBackButton))
 , _settings(
 	this,
@@ -84,7 +87,7 @@ Widget::Widget(QWidget *parent) : RpWidget(parent)
 	getNearestDC();
 	setupConnectingWidget();
 
-	appendStep(new StartWidget(this, getData()));
+	appendStep(new StartWidget(this, _account, getData()));
 	fixOrder();
 
 	subscribe(Lang::CurrentCloudManager().firstLanguageSuggestion(), [this] { createLanguageLink(); });
@@ -367,11 +370,13 @@ void Widget::resetAccount() {
 			_resetRequest = 0;
 
 			Ui::hideLayer();
-			moveToStep(new SignupWidget(this, getData()), Direction::Replace);
+			moveToStep(
+				new SignupWidget(this, _account, getData()),
+				Direction::Replace);
 		}).fail([this](const RPCError &error) {
 			_resetRequest = 0;
 
-			auto type = error.type();
+			const auto &type = error.type();
 			if (type.startsWith(qstr("2FA_CONFIRM_WAIT_"))) {
 				const auto seconds = type.mid(qstr("2FA_CONFIRM_WAIT_").size()).toInt();
 				const auto days = (seconds + 59) / 86400;
@@ -434,7 +439,7 @@ void Widget::getNearestDC() {
 			).arg(qs(nearest.vcountry())
 			).arg(nearest.vnearest_dc().v
 			).arg(nearest.vthis_dc().v));
-		Core::App().suggestMainDcId(nearest.vnearest_dc().v);
+		_account->suggestMainDcId(nearest.vnearest_dc().v);
 		auto nearestCountry = qs(nearest.vcountry());
 		if (getData()->country != nearestCountry) {
 			getData()->country = nearestCountry;
@@ -664,16 +669,19 @@ void Widget::Step::finish(const MTPUser &user, QImage &&photo) {
 		Local::writeLangPack();
 	}
 
-	Core::App().authSessionCreate(user);
+	const auto account = _account;
+	const auto weak = base::make_weak(account.get());
+	account->createSession(user);
 	Local::writeMtpData();
 	App::wnd()->setupMain();
 
 	// "this" is already deleted here by creating the main widget.
-	if (AuthSession::Exists()) {
+	if (weak && account->sessionExists()) {
+		auto &session = account->session();
 		if (!photo.isNull()) {
-			Auth().api().uploadPeerPhoto(Auth().user(), std::move(photo));
+			session.api().uploadPeerPhoto(session.user(), std::move(photo));
 		}
-		if (Auth().supportMode()) {
+		if (session.supportMode()) {
 			PrepareSupportMode();
 		}
 	}
@@ -919,8 +927,13 @@ void Widget::Step::refreshError(const QString &text) {
 	}
 }
 
-Widget::Step::Step(QWidget *parent, Data *data, bool hasCover)
+Widget::Step::Step(
+	QWidget *parent,
+	not_null<Main::Account*> account,
+	not_null<Data*> data,
+	bool hasCover)
 : RpWidget(parent)
+, _account(account)
 , _data(data)
 , _hasCover(hasCover)
 , _title(this, _hasCover ? st::introCoverTitle : st::introTitle)
diff --git a/Telegram/SourceFiles/intro/introwidget.h b/Telegram/SourceFiles/intro/introwidget.h
index ab051829d1..58d49d524f 100644
--- a/Telegram/SourceFiles/intro/introwidget.h
+++ b/Telegram/SourceFiles/intro/introwidget.h
@@ -13,6 +13,10 @@ https://github.com/telegramdesktop/tdesktop/blob/master/LEGAL
 #include "window/window_lock_widgets.h"
 #include "core/core_cloud_password.h"
 
+namespace Main {
+class Account;
+} // namespace Main
+
 namespace Ui {
 class IconButton;
 class RoundButton;
@@ -34,7 +38,7 @@ class Widget : public Ui::RpWidget, private MTP::Sender, private base::Subscribe
 	Q_OBJECT
 
 public:
-	Widget(QWidget *parent);
+	Widget(QWidget *parent, not_null<Main::Account*> account);
 
 	void showAnimated(const QPixmap &bgAnimCache, bool back = false);
 
@@ -90,7 +94,15 @@ public:
 	};
 	class Step : public Ui::RpWidget, public RPCSender, protected base::Subscriber {
 	public:
-		Step(QWidget *parent, Data *data, bool hasCover = false);
+		Step(
+			QWidget *parent,
+			not_null<Main::Account*> account,
+			not_null<Data*> data,
+			bool hasCover = false);
+
+		Main::Account &account() const {
+			return *_account;
+		}
 
 		virtual void finishInit() {
 		}
@@ -147,19 +159,33 @@ public:
 		void showDescription();
 		void hideDescription();
 
-		Data *getData() const {
+		not_null<Data*> getData() const {
 			return _data;
 		}
 		void finish(const MTPUser &user, QImage &&photo = QImage());
 
 		void goBack() {
-			if (_goCallback) _goCallback(nullptr, Direction::Back);
+			if (_goCallback) {
+				_goCallback(nullptr, Direction::Back);
+			}
 		}
-		void goNext(Step *step) {
-			if (_goCallback) _goCallback(step, Direction::Forward);
+
+		template <typename StepType>
+		void goNext() {
+			if (_goCallback) {
+				_goCallback(
+					new StepType(parentWidget(), _account, _data),
+					Direction::Forward);
+			}
 		}
-		void goReplace(Step *step) {
-			if (_goCallback) _goCallback(step, Direction::Replace);
+
+		template <typename StepType>
+		void goReplace() {
+			if (_goCallback) {
+				_goCallback(
+					new StepType(parentWidget(), _account, _data),
+					Direction::Replace);
+			}
 		}
 		void showResetButton() {
 			if (_showResetCallback) _showResetCallback();
@@ -190,9 +216,6 @@ public:
 		void updateLabelsPosition();
 		void paintContentSnapshot(Painter &p, const QPixmap &snapshot, float64 alpha, float64 howMuchHidden);
 		void refreshError(const QString &text);
-		void refreshTitle();
-		void refreshDescription();
-		void refreshLang();
 
 		CoverAnimation prepareCoverAnimation(Step *step);
 		QPixmap prepareContentSnapshot();
@@ -202,7 +225,9 @@ public:
 		void prepareCoverMask();
 		void paintCover(Painter &p, int top);
 
-		Data *_data = nullptr;
+		const not_null<Main::Account*> _account;
+		const not_null<Data*> _data;
+
 		bool _hasCover = false;
 		Fn<void(Step *step, Direction direction)> _goCallback;
 		Fn<void()> _showResetCallback;
@@ -233,7 +258,7 @@ private:
 	void createLanguageLink();
 
 	void updateControlsGeometry();
-	Data *getData() {
+	not_null<Data*> getData() {
 		return &_data;
 	}
 
@@ -260,6 +285,8 @@ private:
 	void getNearestDC();
 	void showTerms(Fn<void()> callback);
 
+	not_null<Main::Account*> _account;
+
 	Ui::Animations::Simple _a_show;
 	bool _showBack = false;
 	QPixmap _cacheUnder, _cacheOver;
diff --git a/Telegram/SourceFiles/main/main_account.cpp b/Telegram/SourceFiles/main/main_account.cpp
index 6bb88b3e59..79aaa775b3 100644
--- a/Telegram/SourceFiles/main/main_account.cpp
+++ b/Telegram/SourceFiles/main/main_account.cpp
@@ -7,28 +7,113 @@ https://github.com/telegramdesktop/tdesktop/blob/master/LEGAL
 */
 #include "main/main_account.h"
 
-#include "auth_session.h"
 #include "core/application.h"
+#include "core/launcher.h"
+#include "core/shortcuts.h"
+#include "storage/serialize_common.h"
+#include "storage/localstorage.h"
+#include "data/data_session.h"
+#include "data/data_user.h"
+#include "window/window_controller.h"
+#include "media/audio/media_audio.h"
+#include "mainwidget.h"
+#include "observer_peer.h"
+#include "auth_session.h"
 
 namespace Main {
 
 Account::Account(const QString &dataName) {
+	watchProxyChanges();
+	watchSessionChanges();
 }
 
-Account::~Account() {
+Account::~Account() = default;
+
+void Account::watchProxyChanges() {
+	using ProxyChange = Core::Application::ProxyChange;
+
+	Core::App().proxyChanges(
+	) | rpl::start_with_next([=](const ProxyChange &change) {
+		const auto key = [&](const ProxyData &proxy) {
+			return (proxy.type == ProxyData::Type::Mtproto)
+				? std::make_pair(proxy.host, proxy.port)
+				: std::make_pair(QString(), uint32(0));
+		};
+		if (_mtp) {
+			_mtp->restart();
+			if (key(change.was) != key(change.now)) {
+				_mtp->reInitConnection(_mtp->mainDcId());
+			}
+		}
+		if (_mtpForKeysDestroy) {
+			_mtpForKeysDestroy->restart();
+		}
+	}, _lifetime);
+}
+
+void Account::watchSessionChanges() {
+	sessionChanges(
+	) | rpl::start_with_next([=] {
+		crl::on_main(this, [=] {
+			const auto phone = sessionExists()
+				? session().user()->phone()
+				: QString();
+			const auto support = sessionExists() && session().supportMode();
+			if (cLoggedPhoneNumber() != phone) {
+				cSetLoggedPhoneNumber(phone);
+				if (_mtp) {
+					_mtp->setUserPhone(phone);
+				}
+				Local::writeSettings();
+			}
+			if (_mtp) {
+				_mtp->requestConfig();
+			}
+			Shortcuts::ToggleSupportShortcuts(support);
+			Platform::SetApplicationIcon(Window::CreateIcon(this));
+		});
+	}, _lifetime);
 }
 
 void Account::createSession(const MTPUser &user) {
+	Expects(_mtp != nullptr);
 	Expects(_session == nullptr);
 	Expects(_sessionValue.current() == nullptr);
 
+	_mtp->setUpdatesHandler(::rpcDone([](
+			const mtpPrime *from,
+			const mtpPrime *end) {
+		if (const auto main = App::main()) {
+			return main->updateReceived(from, end);
+		}
+		return true;
+	}));
+	_mtp->setGlobalFailHandler(::rpcFail([=](const RPCError &error) {
+		if (sessionExists()) {
+			crl::on_main(&session(), [=] { logOut(); });
+		}
+		return true;
+	}));
+
 	_session = std::make_unique<AuthSession>(this, user);
 	_sessionValue = _session.get();
 }
 
 void Account::destroySession() {
+	_storedAuthSession.reset();
+	_authSessionUserId = 0;
+	_authSessionUserSerialized = {};
+	if (!sessionExists()) {
+		return;
+	}
+	session().data().clearLocalStorage();
+
+	_mtp->clearGlobalHandlers();
+
 	_sessionValue = nullptr;
 	_session = nullptr;
+
+	Notify::unreadCounterUpdated();
 }
 
 bool Account::sessionExists() const {
@@ -41,6 +126,12 @@ AuthSession &Account::session() {
 	return *_sessionValue.current();
 }
 
+const AuthSession &Account::session() const {
+	Expects(sessionExists());
+
+	return *_sessionValue.current();
+}
+
 rpl::producer<AuthSession*> Account::sessionValue() const {
 	return _sessionValue.value();
 }
@@ -49,8 +140,343 @@ rpl::producer<AuthSession*> Account::sessionChanges() const {
 	return _sessionValue.changes();
 }
 
-MTP::Instance *Account::mtp() {
-	return MTP::MainInstance();
+rpl::producer<MTP::Instance*> Account::mtpValue() const {
+	return _mtpValue.value();
+}
+
+rpl::producer<MTP::Instance*> Account::mtpChanges() const {
+	return _mtpValue.changes();
+}
+
+void Account::setMtpMainDcId(MTP::DcId mainDcId) {
+	Expects(!_mtp);
+
+	_mtpConfig.mainDcId = mainDcId;
+}
+
+void Account::setMtpKey(MTP::DcId dcId, const MTP::AuthKey::Data &keyData) {
+	Expects(!_mtp);
+
+	_mtpConfig.keys.push_back(std::make_shared<MTP::AuthKey>(
+		MTP::AuthKey::Type::ReadFromFile,
+		dcId,
+		keyData));
+}
+
+QByteArray Account::serializeMtpAuthorization() const {
+	const auto serialize = [&](
+			MTP::DcId mainDcId,
+			const MTP::AuthKeysList &keys,
+			const MTP::AuthKeysList &keysToDestroy) {
+		const auto keysSize = [](auto &list) {
+			const auto keyDataSize = MTP::AuthKey::Data().size();
+			return sizeof(qint32)
+				+ list.size() * (sizeof(qint32) + keyDataSize);
+		};
+		const auto writeKeys = [](
+				QDataStream &stream,
+				const MTP::AuthKeysList &keys) {
+			stream << qint32(keys.size());
+			for (const auto &key : keys) {
+				stream << qint32(key->dcId());
+				key->write(stream);
+			}
+		};
+
+		auto result = QByteArray();
+		auto size = sizeof(qint32) + sizeof(qint32); // userId + mainDcId
+		size += keysSize(keys) + keysSize(keysToDestroy);
+		result.reserve(size);
+		{
+			QDataStream stream(&result, QIODevice::WriteOnly);
+			stream.setVersion(QDataStream::Qt_5_1);
+
+			const auto currentUserId = sessionExists()
+				? session().userId()
+				: 0;
+			stream << qint32(currentUserId) << qint32(mainDcId);
+			writeKeys(stream, keys);
+			writeKeys(stream, keysToDestroy);
+
+			DEBUG_LOG(("MTP Info: Keys written, userId: %1, dcId: %2").arg(currentUserId).arg(mainDcId));
+		}
+		return result;
+	};
+	if (_mtp) {
+		const auto keys = _mtp->getKeysForWrite();
+		const auto keysToDestroy = _mtpForKeysDestroy
+			? _mtpForKeysDestroy->getKeysForWrite()
+			: MTP::AuthKeysList();
+		return serialize(_mtp->mainDcId(), keys, keysToDestroy);
+	}
+	const auto &keys = _mtpConfig.keys;
+	const auto &keysToDestroy = _mtpKeysToDestroy;
+	return serialize(_mtpConfig.mainDcId, keys, keysToDestroy);
+}
+
+void Account::setAuthSessionUserId(UserId userId) {
+	Expects(!sessionExists());
+
+	_authSessionUserId = userId;
+}
+
+void Account::setAuthSessionFromStorage(
+		std::unique_ptr<AuthSessionSettings> data,
+		QByteArray &&selfSerialized,
+		int32 selfStreamVersion) {
+	Expects(!sessionExists());
+
+	DEBUG_LOG(("authSessionUserSerialized set: %1"
+		).arg(selfSerialized.size()));
+
+	_storedAuthSession = std::move(data);
+	_authSessionUserSerialized = std::move(selfSerialized);
+	_authSessionUserStreamVersion = selfStreamVersion;
+}
+
+AuthSessionSettings *Account::getAuthSessionSettings() {
+	if (_authSessionUserId) {
+		return _storedAuthSession ? _storedAuthSession.get() : nullptr;
+	} else if (sessionExists()) {
+		return &session().settings();
+	}
+	return nullptr;
+}
+
+void Account::setMtpAuthorization(const QByteArray &serialized) {
+	Expects(!_mtp);
+
+	QDataStream stream(serialized);
+	stream.setVersion(QDataStream::Qt_5_1);
+
+	auto userId = Serialize::read<qint32>(stream);
+	auto mainDcId = Serialize::read<qint32>(stream);
+	if (stream.status() != QDataStream::Ok) {
+		LOG(("MTP Error: "
+			"Could not read main fields from mtp authorization."));
+		return;
+	}
+
+	setAuthSessionUserId(userId);
+	_mtpConfig.mainDcId = mainDcId;
+
+	const auto readKeys = [&stream](auto &keys) {
+		const auto count = Serialize::read<qint32>(stream);
+		if (stream.status() != QDataStream::Ok) {
+			LOG(("MTP Error: "
+				"Could not read keys count from mtp authorization."));
+			return;
+		}
+		keys.reserve(count);
+		for (auto i = 0; i != count; ++i) {
+			const auto dcId = Serialize::read<qint32>(stream);
+			const auto keyData = Serialize::read<MTP::AuthKey::Data>(stream);
+			if (stream.status() != QDataStream::Ok) {
+				LOG(("MTP Error: "
+					"Could not read key from mtp authorization."));
+				return;
+			}
+			keys.push_back(std::make_shared<MTP::AuthKey>(MTP::AuthKey::Type::ReadFromFile, dcId, keyData));
+		}
+	};
+	readKeys(_mtpConfig.keys);
+	readKeys(_mtpKeysToDestroy);
+	LOG(("MTP Info: "
+		"read keys, current: %1, to destroy: %2"
+		).arg(_mtpConfig.keys.size()
+		).arg(_mtpKeysToDestroy.size()));
+}
+
+void Account::startMtp() {
+	Expects(!_mtp);
+
+	auto config = base::take(_mtpConfig);
+	config.deviceModel = Core::App().launcher()->deviceModel();
+	config.systemVersion = Core::App().launcher()->systemVersion();
+	_mtp = std::make_unique<MTP::Instance>(
+		Core::App().dcOptions(),
+		MTP::Instance::Mode::Normal,
+		std::move(config));
+	_mtp->setUserPhone(cLoggedPhoneNumber());
+	_mtpConfig.mainDcId = _mtp->mainDcId();
+
+	_mtp->setStateChangedHandler([](MTP::ShiftedDcId dc, int32 state) {
+		if (dc == MTP::maindc()) {
+			Global::RefConnectionTypeChanged().notify();
+		}
+	});
+	_mtp->setSessionResetHandler([](MTP::ShiftedDcId shiftedDcId) {
+		if (App::main() && shiftedDcId == MTP::maindc()) {
+			App::main()->getDifference();
+		}
+	});
+
+	if (!_mtpKeysToDestroy.empty()) {
+		destroyMtpKeys(base::take(_mtpKeysToDestroy));
+	}
+
+	if (_authSessionUserId) {
+		DEBUG_LOG(("authSessionUserSerialized.size: %1"
+			).arg(_authSessionUserSerialized.size()));
+		QDataStream peekStream(_authSessionUserSerialized);
+		const auto phone = Serialize::peekUserPhone(
+			_authSessionUserStreamVersion,
+			peekStream);
+		const auto flags = MTPDuser::Flag::f_self | (phone.isEmpty()
+			? MTPDuser::Flag()
+			: MTPDuser::Flag::f_phone);
+		createSession(MTP_user(
+			MTP_flags(flags),
+			MTP_int(base::take(_authSessionUserId)),
+			MTPlong(), // access_hash
+			MTPstring(), // first_name
+			MTPstring(), // last_name
+			MTPstring(), // username
+			MTP_string(phone),
+			MTPUserProfilePhoto(),
+			MTPUserStatus(),
+			MTPint(), // bot_info_version
+			MTPstring(), // restriction_reason
+			MTPstring(), // bot_inline_placeholder
+			MTPstring())); // lang_code
+		Local::readSelf(
+			base::take(_authSessionUserSerialized),
+			base::take(_authSessionUserStreamVersion));
+	}
+	if (_storedAuthSession) {
+		if (sessionExists()) {
+			session().moveSettingsFrom(std::move(*_storedAuthSession));
+		}
+		_storedAuthSession.reset();
+	}
+
+	if (sessionExists()) {
+		// Skip all pending self updates so that we won't Local::writeSelf.
+		Notify::peerUpdatedSendDelayed();
+	}
+
+	_mtpValue = _mtp.get();
+}
+
+
+void Account::logOut() {
+	if (_mtp) {
+		_mtp->logout(::rpcDone([=] {
+			loggedOut();
+		}), ::rpcFail([=] {
+			loggedOut();
+			return true;
+		}));
+	} else {
+		// We log out because we've forgotten passcode.
+		// So we just start mtproto from scratch.
+		startMtp();
+		loggedOut();
+	}
+}
+
+void Account::forcedLogOut() {
+	if (sessionExists()) {
+		resetAuthorizationKeys();
+		loggedOut();
+	}
+}
+
+void Account::loggedOut() {
+	if (Global::LocalPasscode()) {
+		Global::SetLocalPasscode(false);
+		Global::RefLocalPasscodeChanged().notify();
+	}
+	Core::App().unlockPasscode();
+	Core::App().unlockTerms();
+	Media::Player::mixer()->stopAndClear();
+	Global::SetVoiceMsgPlaybackDoubled(false);
+	if (const auto window = Core::App().activeWindow()) {
+		window->tempDirDelete(Local::ClearManagerAll);
+		window->setupIntro();
+	}
+	destroySession();
+	Local::reset();
+
+	cSetOtherOnline(0);
+	Images::ClearRemote();
+}
+
+void Account::destroyMtpKeys(MTP::AuthKeysList &&keys) {
+	if (keys.empty()) {
+		return;
+	}
+	if (_mtpForKeysDestroy) {
+		_mtpForKeysDestroy->addKeysForDestroy(std::move(keys));
+		Local::writeMtpData();
+		return;
+	}
+	auto destroyConfig = MTP::Instance::Config();
+	destroyConfig.mainDcId = MTP::Instance::Config::kNoneMainDc;
+	destroyConfig.keys = std::move(keys);
+	destroyConfig.deviceModel = Core::App().launcher()->deviceModel();
+	destroyConfig.systemVersion = Core::App().launcher()->systemVersion();
+	_mtpForKeysDestroy = std::make_unique<MTP::Instance>(
+		Core::App().dcOptions(),
+		MTP::Instance::Mode::KeysDestroyer,
+		std::move(destroyConfig));
+	QObject::connect(
+		_mtpForKeysDestroy.get(),
+		&MTP::Instance::allKeysDestroyed,
+		[=] { allKeysDestroyed(); });
+}
+
+void Account::allKeysDestroyed() {
+	LOG(("MTP Info: all keys scheduled for destroy are destroyed."));
+	crl::on_main(this, [=] {
+		_mtpForKeysDestroy = nullptr;
+		Local::writeMtpData();
+	});
+}
+
+void Account::suggestMainDcId(MTP::DcId mainDcId) {
+	Expects(_mtp != nullptr);
+
+	_mtp->suggestMainDcId(mainDcId);
+	if (_mtpConfig.mainDcId != MTP::Instance::Config::kNotSetMainDc) {
+		_mtpConfig.mainDcId = mainDcId;
+	}
+}
+
+void Account::destroyStaleAuthorizationKeys() {
+	Expects(_mtp != nullptr);
+
+	for (const auto &key : _mtp->getKeysForWrite()) {
+		// Disable this for now.
+		if (key->type() == MTP::AuthKey::Type::ReadFromFile) {
+			_mtpKeysToDestroy = _mtp->getKeysForWrite();
+			LOG(("MTP Info: destroying stale keys, count: %1"
+				).arg(_mtpKeysToDestroy.size()));
+			resetAuthorizationKeys();
+			return;
+		}
+	}
+}
+
+void Account::configUpdated() {
+	_configUpdates.fire({});
+}
+
+rpl::producer<> Account::configUpdates() const {
+	return _configUpdates.events();
+}
+
+void Account::resetAuthorizationKeys() {
+	_mtp = nullptr;
+	_mtpValue = _mtp.get();
+	startMtp();
+	Local::writeMtpData();
+}
+
+void Account::clearMtp() {
+	_mtp = nullptr;
+	_mtpForKeysDestroy = nullptr;
+	_mtpValue = _mtp.get();
 }
 
 } // namespace Main
diff --git a/Telegram/SourceFiles/main/main_account.h b/Telegram/SourceFiles/main/main_account.h
index 2e02813f15..2c98d07032 100644
--- a/Telegram/SourceFiles/main/main_account.h
+++ b/Telegram/SourceFiles/main/main_account.h
@@ -7,11 +7,15 @@ https://github.com/telegramdesktop/tdesktop/blob/master/LEGAL
 */
 #pragma once
 
+#include "mtproto/auth_key.h"
+#include "base/weak_ptr.h"
+
 class AuthSession;
+class AuthSessionSettings;
 
 namespace Main {
 
-class Account final {
+class Account final : public base::has_weak_ptr {
 public:
 	explicit Account(const QString &dataName);
 	~Account();
@@ -22,17 +26,69 @@ public:
 	void createSession(const MTPUser &user);
 	void destroySession();
 
+	void logOut();
+	void forcedLogOut();
+
 	[[nodiscard]] bool sessionExists() const;
 	[[nodiscard]] AuthSession &session();
+	[[nodiscard]] const AuthSession &session() const;
 	[[nodiscard]] rpl::producer<AuthSession*> sessionValue() const;
 	[[nodiscard]] rpl::producer<AuthSession*> sessionChanges() const;
 
-	[[nodiscard]] MTP::Instance *mtp();
+	[[nodiscard]] MTP::Instance *mtp() {
+		return _mtp.get();
+	}
+	[[nodiscard]] rpl::producer<MTP::Instance*> mtpValue() const;
+	[[nodiscard]] rpl::producer<MTP::Instance*> mtpChanges() const;
+
+	// Set from legacy storage.
+	void setMtpMainDcId(MTP::DcId mainDcId);
+	void setMtpKey(MTP::DcId dcId, const MTP::AuthKey::Data &keyData);
+	void setAuthSessionUserId(UserId userId);
+	void setAuthSessionFromStorage(
+		std::unique_ptr<AuthSessionSettings> data,
+		QByteArray &&selfSerialized,
+		int32 selfStreamVersion);
+	[[nodiscard]] AuthSessionSettings *getAuthSessionSettings();
+
+	// Serialization.
+	[[nodiscard]] QByteArray serializeMtpAuthorization() const;
+	void setMtpAuthorization(const QByteArray &serialized);
+
+	void startMtp();
+	void suggestMainDcId(MTP::DcId mainDcId);
+	void destroyStaleAuthorizationKeys();
+	void configUpdated();
+	[[nodiscard]] rpl::producer<> configUpdates() const;
+	void clearMtp();
 
 private:
+	void watchProxyChanges();
+	void watchSessionChanges();
+
+	void destroyMtpKeys(MTP::AuthKeysList &&keys);
+	void allKeysDestroyed();
+	void resetAuthorizationKeys();
+
+	void loggedOut();
+
+	std::unique_ptr<MTP::Instance> _mtp;
+	rpl::variable<MTP::Instance*> _mtpValue;
+	std::unique_ptr<MTP::Instance> _mtpForKeysDestroy;
+	rpl::event_stream<> _configUpdates;
+
 	std::unique_ptr<AuthSession> _session;
 	rpl::variable<AuthSession*> _sessionValue;
 
+	UserId _authSessionUserId = 0;
+	QByteArray _authSessionUserSerialized;
+	int32 _authSessionUserStreamVersion = 0;
+	std::unique_ptr<AuthSessionSettings> _storedAuthSession;
+	MTP::Instance::Config _mtpConfig;
+	MTP::AuthKeysList _mtpKeysToDestroy;
+
+	rpl::lifetime _lifetime;
+
 };
 
 } // namespace Main
diff --git a/Telegram/SourceFiles/mainwidget.cpp b/Telegram/SourceFiles/mainwidget.cpp
index 26f19fd4b4..47f11df2cb 100644
--- a/Telegram/SourceFiles/mainwidget.cpp
+++ b/Telegram/SourceFiles/mainwidget.cpp
@@ -4244,7 +4244,7 @@ void MainWidget::feedUpdate(const MTPUpdate &update) {
 	} break;
 
 	case mtpc_updateConfig: {
-		Core::App().mtp()->requestConfig();
+		session().mtp()->requestConfig();
 	} break;
 
 	case mtpc_updateUserPhone: {
diff --git a/Telegram/SourceFiles/mainwindow.cpp b/Telegram/SourceFiles/mainwindow.cpp
index 481a7912f3..6e30495367 100644
--- a/Telegram/SourceFiles/mainwindow.cpp
+++ b/Telegram/SourceFiles/mainwindow.cpp
@@ -200,7 +200,7 @@ void MainWindow::clearPasscodeLock() {
 		_main->showAnimated(bg, true);
 		Core::App().checkStartUrl();
 	} else {
-		Core::App().startMtp();
+		account().startMtp();
 		if (account().sessionExists()) {
 			setupMain();
 		} else {
@@ -216,7 +216,7 @@ void MainWindow::setupIntro() {
 	auto bg = animated ? grabInner() : QPixmap();
 
 	clearWidgets();
-	_intro.create(bodyWidget());
+	_intro.create(bodyWidget(), &account());
 	updateControlsGeometry();
 
 	if (animated) {
@@ -619,16 +619,15 @@ void MainWindow::onLogout() {
 		showFromTray();
 	}
 
-	const auto logout = [] {
-		Core::App().logOut();
-	};
 	const auto callback = [=] {
 		if (account().sessionExists()
 			&& account().session().data().exportInProgress()) {
 			Ui::hideLayer();
-			account().session().data().stopExportWithConfirmation(logout);
+			account().session().data().stopExportWithConfirmation([=] {
+				account().logOut();
+			});
 		} else {
-			logout();
+			account().logOut();
 		}
 	};
 	Ui::show(Box<ConfirmBox>(
diff --git a/Telegram/SourceFiles/mtproto/dc_options.cpp b/Telegram/SourceFiles/mtproto/dc_options.cpp
index 992482f748..4dda904163 100644
--- a/Telegram/SourceFiles/mtproto/dc_options.cpp
+++ b/Telegram/SourceFiles/mtproto/dc_options.cpp
@@ -88,6 +88,10 @@ private:
 
 };
 
+DcOptions::DcOptions() {
+	constructFromBuiltIn();
+}
+
 bool DcOptions::ValidateSecret(bytes::const_span secret) {
 	// See also TcpConnection::Protocol::Create.
 	return (secret.size() >= 21 && secret[0] == bytes::type(0xEE))
diff --git a/Telegram/SourceFiles/mtproto/dc_options.h b/Telegram/SourceFiles/mtproto/dc_options.h
index 288822d337..cbd20d68ad 100644
--- a/Telegram/SourceFiles/mtproto/dc_options.h
+++ b/Telegram/SourceFiles/mtproto/dc_options.h
@@ -48,6 +48,8 @@ public:
 
 	};
 
+	DcOptions();
+
 	[[nodiscard]] static bool ValidateSecret(bytes::const_span secret);
 
 	// construct methods don't notify "changed" subscribers.
diff --git a/Telegram/SourceFiles/mtproto/facade.cpp b/Telegram/SourceFiles/mtproto/facade.cpp
index 6f1f0ec48f..920a2c723e 100644
--- a/Telegram/SourceFiles/mtproto/facade.cpp
+++ b/Telegram/SourceFiles/mtproto/facade.cpp
@@ -9,6 +9,7 @@ https://github.com/telegramdesktop/tdesktop/blob/master/LEGAL
 
 #include "storage/localstorage.h"
 #include "core/application.h"
+#include "main/main_account.h"
 
 namespace MTP {
 namespace internal {
@@ -38,7 +39,9 @@ void unpause() {
 } // namespace internal
 
 Instance *MainInstance() {
-	return Core::IsAppLaunched() ? Core::App().mtp() : nullptr;
+	return Core::IsAppLaunched()
+		? Core::App().activeAccount().mtp()
+		: nullptr;
 }
 
 } // namespace MTP
diff --git a/Telegram/SourceFiles/mtproto/mtp_instance.cpp b/Telegram/SourceFiles/mtproto/mtp_instance.cpp
index 7a2c7fe15f..496fe72284 100644
--- a/Telegram/SourceFiles/mtproto/mtp_instance.cpp
+++ b/Telegram/SourceFiles/mtproto/mtp_instance.cpp
@@ -17,6 +17,7 @@ https://github.com/telegramdesktop/tdesktop/blob/master/LEGAL
 #include "mtproto/rsa_public_key.h"
 #include "storage/localstorage.h"
 #include "calls/calls_instance.h"
+#include "main/main_account.h"
 #include "auth_session.h"
 #include "apiwrap.h"
 #include "core/application.h"
@@ -167,9 +168,9 @@ private:
 
 	void checkDelayedRequests();
 
-	not_null<Instance*> _instance;
-	not_null<DcOptions*> _dcOptions;
-	Instance::Mode _mode = Instance::Mode::Normal;
+	const not_null<Instance*> _instance;
+	const not_null<DcOptions*> _dcOptions;
+	const Instance::Mode _mode = Instance::Mode::Normal;
 
 	DcId _mainDcId = Config::kDefaultMainDc;
 	bool _mainDcIdForced = false;
@@ -808,7 +809,7 @@ void Instance::Private::configLoadDone(const MTPConfig &result) {
 		data.vlang_pack_version().value_or_empty(),
 		data.vbase_lang_pack_version().value_or_empty());
 
-	Core::App().configUpdated();
+	Core::App().activeAccount().configUpdated();
 
 	if (const auto prefix = data.vautoupdate_url_prefix()) {
 		Local::writeAutoupdatePrefix(qs(*prefix));
diff --git a/Telegram/SourceFiles/settings/settings_codes.cpp b/Telegram/SourceFiles/settings/settings_codes.cpp
index 49df1059f3..2220cd8878 100644
--- a/Telegram/SourceFiles/settings/settings_codes.cpp
+++ b/Telegram/SourceFiles/settings/settings_codes.cpp
@@ -108,7 +108,7 @@ auto GenerateCodes() {
 	codes.emplace(qsl("endpoints"), [] {
 		FileDialog::GetOpenPath(Core::App().getFileDialogParent(), "Open DC endpoints", "DC Endpoints (*.tdesktop-endpoints)", [](const FileDialog::OpenResult &result) {
 			if (!result.paths.isEmpty()) {
-				if (!Core::App().mtp()->dcOptions()->loadFromFile(result.paths.front())) {
+				if (!Core::App().dcOptions()->loadFromFile(result.paths.front())) {
 					Ui::show(Box<InformBox>("Could not load endpoints :( Errors in 'log.txt'."));
 				}
 			}
diff --git a/Telegram/SourceFiles/storage/localstorage.cpp b/Telegram/SourceFiles/storage/localstorage.cpp
index 9d00f3c769..5d6f025615 100644
--- a/Telegram/SourceFiles/storage/localstorage.cpp
+++ b/Telegram/SourceFiles/storage/localstorage.cpp
@@ -26,6 +26,7 @@ https://github.com/telegramdesktop/tdesktop/blob/master/LEGAL
 #include "mainwindow.h"
 #include "lang/lang_keys.h"
 #include "lang/lang_cloud_manager.h"
+#include "main/main_account.h"
 #include "media/audio/media_audio.h"
 #include "mtproto/dc_options.h"
 #include "core/application.h"
@@ -972,8 +973,8 @@ bool _readSetting(quint32 blockId, QDataStream &stream, int version, ReadSetting
 		if (!_checkStreamStatus(stream)) return false;
 
 		DEBUG_LOG(("MTP Info: user found, dc %1, uid %2").arg(dcId).arg(userId));
-		Core::App().setMtpMainDcId(dcId);
-		Core::App().setAuthSessionUserId(userId);
+		Core::App().activeAccount().setMtpMainDcId(dcId);
+		Core::App().activeAccount().setAuthSessionUserId(userId);
 	} break;
 
 	case dbiKey: {
@@ -982,7 +983,7 @@ bool _readSetting(quint32 blockId, QDataStream &stream, int version, ReadSetting
 		auto key = Serialize::read<MTP::AuthKey::Data>(stream);
 		if (!_checkStreamStatus(stream)) return false;
 
-		Core::App().setMtpKey(dcId, key);
+		Core::App().activeAccount().setMtpKey(dcId, key);
 	} break;
 
 	case dbiMtpAuthorization: {
@@ -990,7 +991,7 @@ bool _readSetting(quint32 blockId, QDataStream &stream, int version, ReadSetting
 		stream >> serialized;
 		if (!_checkStreamStatus(stream)) return false;
 
-		Core::App().setMtpAuthorization(serialized);
+		Core::App().activeAccount().setMtpAuthorization(serialized);
 	} break;
 
 	case dbiAutoStart: {
@@ -2034,7 +2035,7 @@ void _writeUserSettings() {
 	}
 	auto userDataInstance = StoredAuthSessionCache
 		? StoredAuthSessionCache.get()
-		: Core::App().getAuthSessionSettings();
+		: Core::App().activeAccount().getAuthSessionSettings();
 	auto userData = userDataInstance
 		? userDataInstance->serialize()
 		: QByteArray();
@@ -2157,7 +2158,7 @@ void _writeMtpData() {
 		return;
 	}
 
-	auto mtpAuthorizationSerialized = Core::App().serializeMtpAuthorization();
+	auto mtpAuthorizationSerialized = Core::App().activeAccount().serializeMtpAuthorization();
 
 	quint32 size = sizeof(quint32) + Serialize::bytearraySize(mtpAuthorizationSerialized);
 
@@ -2388,7 +2389,7 @@ ReadMapState _readMap(const QByteArray &pass) {
 	_readMtpData();
 
 	DEBUG_LOG(("selfSerialized set: %1").arg(selfSerialized.size()));
-	Core::App().setAuthSessionFromStorage(
+	Core::App().activeAccount().setAuthSessionFromStorage(
 		std::move(StoredAuthSessionCache),
 		std::move(selfSerialized),
 		_oldMapVersion);