From ab0d2bf9c68d016a71aab248b1173dbf0454eca3 Mon Sep 17 00:00:00 2001
From: John Preston <johnprestonmail@gmail.com>
Date: Fri, 24 Sep 2021 19:10:25 +0400
Subject: [PATCH] Initial chat theme changing.

---
 Telegram/CMakeLists.txt                       |   2 +
 Telegram/Resources/langs/lang.strings         |   8 +
 .../SourceFiles/data/data_cloud_themes.cpp    |  30 +-
 Telegram/SourceFiles/data/data_cloud_themes.h |   8 +-
 Telegram/SourceFiles/data/data_peer.cpp       |  15 +-
 Telegram/SourceFiles/data/data_peer.h         |   4 +-
 .../SourceFiles/history/history_widget.cpp    | 188 +++++---
 Telegram/SourceFiles/history/history_widget.h |  31 +-
 Telegram/SourceFiles/mainwidget.cpp           |   4 +
 Telegram/SourceFiles/mainwidget.h             |   2 +
 Telegram/SourceFiles/ui/chat/chat_theme.cpp   |   5 +
 Telegram/SourceFiles/ui/chat/chat_theme.h     |   2 +-
 .../ui/chat/choose_theme_controller.cpp       | 424 ++++++++++++++++++
 .../ui/chat/choose_theme_controller.h         |  73 +++
 .../SourceFiles/window/section_widget.cpp     |  25 +-
 .../window/themes/window_theme.cpp            |  11 +
 .../SourceFiles/window/themes/window_theme.h  |   2 +
 .../SourceFiles/window/window_peer_menu.cpp   |   5 +
 .../window/window_session_controller.cpp      |  33 +-
 .../window/window_session_controller.h        |  21 +-
 20 files changed, 773 insertions(+), 120 deletions(-)
 create mode 100644 Telegram/SourceFiles/ui/chat/choose_theme_controller.cpp
 create mode 100644 Telegram/SourceFiles/ui/chat/choose_theme_controller.h

diff --git a/Telegram/CMakeLists.txt b/Telegram/CMakeLists.txt
index 5f0e135f7..d9133905d 100644
--- a/Telegram/CMakeLists.txt
+++ b/Telegram/CMakeLists.txt
@@ -1040,6 +1040,8 @@ PRIVATE
     ui/chat/attach/attach_item_single_file_preview.h
     ui/chat/attach/attach_item_single_media_preview.cpp
     ui/chat/attach/attach_item_single_media_preview.h
+    ui/chat/choose_theme_controller.cpp
+    ui/chat/choose_theme_controller.h
     ui/effects/fireworks_animation.cpp
     ui/effects/fireworks_animation.h
     ui/effects/round_checkbox.cpp
diff --git a/Telegram/Resources/langs/lang.strings b/Telegram/Resources/langs/lang.strings
index b59129ef6..d66174c5a 100644
--- a/Telegram/Resources/langs/lang.strings
+++ b/Telegram/Resources/langs/lang.strings
@@ -2871,6 +2871,14 @@ https://github.com/telegramdesktop/tdesktop/blob/master/LEGAL
 "lng_filters_remove_sure" = "This will remove the folder, your chats will not be deleted.";
 "lng_filters_remove_yes" = "Remove";
 
+"lng_chat_theme_change" = "Change colors";
+"lng_chat_theme_none" = "No\nTheme";
+"lng_chat_theme_apply" = "Apply Theme";
+"lng_chat_theme_reset" = "Reset Theme";
+"lng_chat_theme_dont" = "Do Not Set Theme";
+"lng_chat_theme_title" = "Select theme";
+"lng_chat_theme_cant_voice" = "Sorry, you can't change the chat theme while you're having an unsent voice message.";
+
 "lng_photo_editor_menu_delete" = "Delete";
 "lng_photo_editor_menu_flip" = "Flip";
 "lng_photo_editor_menu_duplicate" = "Duplicate";
diff --git a/Telegram/SourceFiles/data/data_cloud_themes.cpp b/Telegram/SourceFiles/data/data_cloud_themes.cpp
index 22e803c84..d6b015af8 100644
--- a/Telegram/SourceFiles/data/data_cloud_themes.cpp
+++ b/Telegram/SourceFiles/data/data_cloud_themes.cpp
@@ -387,26 +387,29 @@ rpl::producer<> CloudThemes::chatThemesUpdated() const {
 }
 
 std::optional<ChatTheme> CloudThemes::themeForEmoji(
-		const QString &emoji) const {
-	if (emoji.isEmpty()) {
+		const QString &emoticon) const {
+	const auto emoji = Ui::Emoji::Find(emoticon);
+	if (!emoji) {
 		return {};
 	}
-	const auto i = ranges::find(_chatThemes, emoji, &ChatTheme::emoji);
+	const auto i = ranges::find(_chatThemes, emoji, [](const ChatTheme &v) {
+		return Ui::Emoji::Find(v.emoticon);
+	});
 	return (i != end(_chatThemes)) ? std::make_optional(*i) : std::nullopt;
 }
 
 rpl::producer<std::optional<ChatTheme>> CloudThemes::themeForEmojiValue(
-		const QString &emoji) {
+		const QString &emoticon) {
 	const auto testing = TestingColors();
-	if (emoji.isEmpty()) {
+	if (!Ui::Emoji::Find(emoticon)) {
 		return rpl::single<std::optional<ChatTheme>>(std::nullopt);
-	} else if (auto result = themeForEmoji(emoji)) {
+	} else if (auto result = themeForEmoji(emoticon)) {
 		if (testing) {
 			return rpl::single(
 				std::move(result)
 			) | rpl::then(chatThemesUpdated(
 			) | rpl::map([=] {
-				return themeForEmoji(emoji);
+				return themeForEmoji(emoticon);
 			}) | rpl::filter([](const std::optional<ChatTheme> &theme) {
 				return theme.has_value();
 			}));
@@ -419,7 +422,7 @@ rpl::producer<std::optional<ChatTheme>> CloudThemes::themeForEmojiValue(
 		std::nullopt
 	) | rpl::then(chatThemesUpdated(
 	) | rpl::map([=] {
-		return themeForEmoji(emoji);
+		return themeForEmoji(emoticon);
 	}) | rpl::filter([](const std::optional<ChatTheme> &theme) {
 		return theme.has_value();
 	}) | rpl::take(limit));
@@ -482,12 +485,15 @@ QString CloudThemes::prepareTestingLink(const CloudTheme &theme) const {
 }
 
 std::optional<CloudTheme> CloudThemes::updateThemeFromLink(
-		const QString &emoji,
+		const QString &emoticon,
 		const QMap<QString, QString> &params) {
-	if (!TestingColors()) {
+	const auto emoji = Ui::Emoji::Find(emoticon);
+	if (!TestingColors() || !emoji) {
 		return std::nullopt;
 	}
-	const auto i = ranges::find(_chatThemes, emoji, &ChatTheme::emoji);
+	const auto i = ranges::find(_chatThemes, emoji, [](const ChatTheme &v) {
+		return Ui::Emoji::Find(v.emoticon);
+	});
 	if (i == end(_chatThemes)) {
 		return std::nullopt;
 	}
@@ -552,7 +558,7 @@ void CloudThemes::parseChatThemes(const QVector<MTPChatTheme> &list) {
 	for (const auto &theme : list) {
 		theme.match([&](const MTPDchatTheme &data) {
 			_chatThemes.push_back({
-				.emoji = qs(data.vemoticon()),
+				.emoticon = qs(data.vemoticon()),
 				.light = CloudTheme::Parse(_session, data.vtheme(), true),
 				.dark = CloudTheme::Parse(_session, data.vdark_theme(), true),
 			});
diff --git a/Telegram/SourceFiles/data/data_cloud_themes.h b/Telegram/SourceFiles/data/data_cloud_themes.h
index e6a1b3ca9..0976e4e90 100644
--- a/Telegram/SourceFiles/data/data_cloud_themes.h
+++ b/Telegram/SourceFiles/data/data_cloud_themes.h
@@ -50,7 +50,7 @@ struct CloudTheme {
 };
 
 struct ChatTheme {
-	QString emoji;
+	QString emoticon;
 	CloudTheme light;
 	CloudTheme dark;
 };
@@ -71,15 +71,15 @@ public:
 	[[nodiscard]] const std::vector<ChatTheme> &chatThemes() const;
 	[[nodiscard]] rpl::producer<> chatThemesUpdated() const;
 	[[nodiscard]] std::optional<ChatTheme> themeForEmoji(
-		const QString &emoji) const;
+		const QString &emoticon) const;
 	[[nodiscard]] rpl::producer<std::optional<ChatTheme>> themeForEmojiValue(
-		const QString &emoji);
+		const QString &emoticon);
 
 	[[nodiscard]] static bool TestingColors();
 	static void SetTestingColors(bool testing);
 	[[nodiscard]] QString prepareTestingLink(const CloudTheme &theme) const;
 	[[nodiscard]] std::optional<CloudTheme> updateThemeFromLink(
-		const QString &emoji,
+		const QString &emoticon,
 		const QMap<QString, QString> &params);
 
 	void applyUpdate(const MTPTheme &theme);
diff --git a/Telegram/SourceFiles/data/data_peer.cpp b/Telegram/SourceFiles/data/data_peer.cpp
index 7d9f31ea1..c0144bc4e 100644
--- a/Telegram/SourceFiles/data/data_peer.cpp
+++ b/Telegram/SourceFiles/data/data_peer.cpp
@@ -1004,19 +1004,24 @@ PeerId PeerData::groupCallDefaultJoinAs() const {
 	return 0;
 }
 
-void PeerData::setThemeEmoji(const QString &emoji) {
-	if (_themeEmoji == emoji) {
+void PeerData::setThemeEmoji(const QString &emoticon) {
+	if (_themeEmoticon == emoticon) {
 		return;
 	}
-	_themeEmoji = emoji;
-	if (!emoji.isEmpty() && !owner().cloudThemes().themeForEmoji(emoji)) {
+	if (Ui::Emoji::Find(_themeEmoticon) == Ui::Emoji::Find(emoticon)) {
+		_themeEmoticon = emoticon;
+		return;
+	}
+	_themeEmoticon = emoticon;
+	if (!emoticon.isEmpty()
+		&& !owner().cloudThemes().themeForEmoji(emoticon)) {
 		owner().cloudThemes().refreshChatThemes();
 	}
 	session().changes().peerUpdated(this, UpdateFlag::ChatThemeEmoji);
 }
 
 const QString &PeerData::themeEmoji() const {
-	return _themeEmoji;
+	return _themeEmoticon;
 }
 
 void PeerData::setIsBlocked(bool is) {
diff --git a/Telegram/SourceFiles/data/data_peer.h b/Telegram/SourceFiles/data/data_peer.h
index a4dd2b0f1..55d940200 100644
--- a/Telegram/SourceFiles/data/data_peer.h
+++ b/Telegram/SourceFiles/data/data_peer.h
@@ -459,7 +459,7 @@ public:
 	[[nodiscard]] Data::GroupCall *groupCall() const;
 	[[nodiscard]] PeerId groupCallDefaultJoinAs() const;
 
-	void setThemeEmoji(const QString &emoji);
+	void setThemeEmoji(const QString &emoticon);
 	[[nodiscard]] const QString &themeEmoji() const;
 
 	const PeerId id;
@@ -506,7 +506,7 @@ private:
 	LoadedStatus _loadedStatus = LoadedStatus::Not;
 
 	QString _about;
-	QString _themeEmoji;
+	QString _themeEmoticon;
 
 };
 
diff --git a/Telegram/SourceFiles/history/history_widget.cpp b/Telegram/SourceFiles/history/history_widget.cpp
index b12867f6f..ee0e3f4ca 100644
--- a/Telegram/SourceFiles/history/history_widget.cpp
+++ b/Telegram/SourceFiles/history/history_widget.cpp
@@ -23,6 +23,7 @@ https://github.com/telegramdesktop/tdesktop/blob/master/LEGAL
 #include "ui/special_buttons.h"
 #include "ui/emoji_config.h"
 #include "ui/chat/attach/attach_prepare.h"
+#include "ui/chat/choose_theme_controller.h"
 #include "ui/widgets/buttons.h"
 #include "ui/widgets/inner_dropdown.h"
 #include "ui/widgets/dropdown_menu.h"
@@ -1282,11 +1283,39 @@ void HistoryWidget::insertHashtagOrBotCommand(
 	}
 }
 
+
+InlineBotQuery HistoryWidget::parseInlineBotQuery() const {
+	return (isChoosingTheme() || _editMsgId)
+		? InlineBotQuery()
+		: ParseInlineBotQuery(&session(), _field);
+}
+
+AutocompleteQuery HistoryWidget::parseMentionHashtagBotCommandQuery() const {
+	const auto result = (isChoosingTheme()
+		|| (_inlineBot && !_inlineLookingUpBot))
+		? AutocompleteQuery()
+		: ParseMentionHashtagBotCommandQuery(_field);
+	if (result.query.isEmpty()) {
+		return result;
+	} else if (result.query[0] == '#'
+		&& cRecentWriteHashtags().isEmpty()
+		&& cRecentSearchHashtags().isEmpty()) {
+		session().local().readRecentHashtagsAndBots();
+	} else if (result.query[0] == '@'
+		&& cRecentInlineBots().isEmpty()) {
+		session().local().readRecentHashtagsAndBots();
+	} else if (result.query[0] == '/'
+		&& ((_peer->isUser() && !_peer->asUser()->isBot()) || _editMsgId)) {
+		return AutocompleteQuery();
+	}
+	return result;
+}
+
 void HistoryWidget::updateInlineBotQuery() {
 	if (!_history) {
 		return;
 	}
-	const auto query = ParseInlineBotQuery(&session(), _field);
+	const auto query = parseInlineBotQuery();
 	if (_inlineBotUsername != query.username) {
 		_inlineBotUsername = query.username;
 		if (_inlineBotResolveRequestId) {
@@ -1369,10 +1398,11 @@ void HistoryWidget::orderWidgets() {
 	if (_groupCallBar) {
 		_groupCallBar->raise();
 	}
-	_topShadow->raise();
-	if (_fieldAutocomplete) {
-		_fieldAutocomplete->raise();
+	if (_chooseTheme) {
+		_chooseTheme->raise();
 	}
+	_topShadow->raise();
+	_fieldAutocomplete->raise();
 	if (_membersDropdown) {
 		_membersDropdown->raise();
 	}
@@ -1410,6 +1440,34 @@ bool HistoryWidget::updateStickersByEmoji() {
 	return (emoji != nullptr);
 }
 
+void HistoryWidget::toggleChooseChatTheme(not_null<PeerData*> peer) {
+	const auto update = [=] {
+		updateInlineBotQuery();
+		updateControlsGeometry();
+		updateControlsVisibility();
+	};
+	if (peer.get() != _peer) {
+		return;
+	} else if (_chooseTheme) {
+		if (isChoosingTheme()) {
+			_chooseTheme = nullptr;
+			update();
+		}
+		return;
+	} else if (_voiceRecordBar->isActive()) {
+		Ui::ShowMultilineToast({
+			.text = { tr::lng_chat_theme_cant_voice(tr::now) },
+		});
+		return;
+	}
+	_chooseTheme = std::make_unique<Ui::ChooseThemeController>(
+		this,
+		controller(),
+		peer);
+	_chooseTheme->shouldBeShownValue(
+	) | rpl::start_with_next(update, _chooseTheme->lifetime());
+}
+
 void HistoryWidget::fieldChanged() {
 	const auto updateTyping = (_textUpdateEvents & TextUpdateEvent::SendTyping);
 
@@ -1925,6 +1983,7 @@ void HistoryWidget::showHistory(
 		_pinnedTracker = nullptr;
 		_groupCallBar = nullptr;
 		_groupCallTracker = nullptr;
+		_chooseTheme = nullptr;
 		_membersDropdown.destroy();
 		_scrollToAnimation.stop();
 
@@ -2322,52 +2381,41 @@ void HistoryWidget::updateControlsVisibility() {
 	if (_contactStatus) {
 		_contactStatus->show();
 	}
-	if (!editingMessage() && (isBlocked() || isJoinChannel() || isMuteUnmute() || isBotStart() || isReportMessages())) {
-		if (isReportMessages()) {
-			_unblock->hide();
-			_joinChannel->hide();
-			_muteUnmute->hide();
-			_botStart->hide();
-			if (_reportMessages->isHidden()) {
-				_reportMessages->clearState();
-				_reportMessages->show();
-			}
+	if (isChoosingTheme()
+		|| (!editingMessage()
+			&& (isBlocked()
+				|| isJoinChannel()
+				|| isMuteUnmute()
+				|| isBotStart()
+				|| isReportMessages()))) {
+		const auto toggle = [&](Ui::FlatButton *shown) {
+			const auto toggleOne = [&](not_null<Ui::FlatButton*> button) {
+				if (button.get() != shown) {
+					button->hide();
+				} else if (button->isHidden()) {
+					button->clearState();
+					button->show();
+				}
+			};
+			toggleOne(_reportMessages);
+			toggleOne(_joinChannel);
+			toggleOne(_muteUnmute);
+			toggleOne(_botStart);
+			toggleOne(_unblock);
+		};
+		if (isChoosingTheme()) {
+			toggle(nullptr);
+			_chooseTheme->show();
+		} else if (isReportMessages()) {
+			toggle(_reportMessages);
 		} else if (isBlocked()) {
-			_reportMessages->hide();
-			_joinChannel->hide();
-			_muteUnmute->hide();
-			_botStart->hide();
-			if (_unblock->isHidden()) {
-				_unblock->clearState();
-				_unblock->show();
-			}
+			toggle(_unblock);
 		} else if (isJoinChannel()) {
-			_reportMessages->hide();
-			_unblock->hide();
-			_muteUnmute->hide();
-			_botStart->hide();
-			if (_joinChannel->isHidden()) {
-				_joinChannel->clearState();
-				_joinChannel->show();
-			}
+			toggle(_joinChannel);
 		} else if (isMuteUnmute()) {
-			_reportMessages->hide();
-			_unblock->hide();
-			_joinChannel->hide();
-			_botStart->hide();
-			if (_muteUnmute->isHidden()) {
-				_muteUnmute->clearState();
-				_muteUnmute->show();
-			}
+			toggle(_muteUnmute);
 		} else if (isBotStart()) {
-			_reportMessages->hide();
-			_unblock->hide();
-			_joinChannel->hide();
-			_muteUnmute->hide();
-			if (_botStart->isHidden()) {
-				_botStart->clearState();
-				_botStart->show();
-			}
+			toggle(_botStart);
 		}
 		_kbShown = false;
 		_fieldAutocomplete->hide();
@@ -3289,6 +3337,9 @@ void HistoryWidget::hideChildWidgets() {
 	if (_voiceRecordBar) {
 		_voiceRecordBar->hideFast();
 	}
+	if (_chooseTheme) {
+		_chooseTheme->hide();
+	}
 	hideChildren();
 }
 
@@ -3908,7 +3959,7 @@ void HistoryWidget::inlineBotResolveDone(
 	}();
 	session().data().processChats(data.vchats());
 
-	const auto query = ParseInlineBotQuery(&session(), _field);
+	const auto query = parseInlineBotQuery();
 	if (_inlineBotUsername == query.username) {
 		applyInlineBotQuery(
 			query.lookingUpBot ? resolvedBot : query.bot,
@@ -3953,6 +4004,10 @@ bool HistoryWidget::isJoinChannel() const {
 	return _peer && _peer->isChannel() && !_peer->asChannel()->amIn();
 }
 
+bool HistoryWidget::isChoosingTheme() const {
+	return _chooseTheme && _chooseTheme->shouldBeShown();
+}
+
 bool HistoryWidget::isMuteUnmute() const {
 	return _peer
 		&& ((_peer->isBroadcast() && !_peer->asChannel()->canPublish())
@@ -4337,24 +4392,7 @@ void HistoryWidget::checkFieldAutocomplete() {
 		return;
 	}
 
-	const auto isInlineBot = _inlineBot && !_inlineLookingUpBot;
-	const auto autocomplete = isInlineBot
-		? AutocompleteQuery()
-		: ParseMentionHashtagBotCommandQuery(_field);
-	if (!autocomplete.query.isEmpty()) {
-		if (autocomplete.query[0] == '#'
-			&& cRecentWriteHashtags().isEmpty()
-			&& cRecentSearchHashtags().isEmpty()) {
-			session().local().readRecentHashtagsAndBots();
-		} else if (autocomplete.query[0] == '@'
-			&& cRecentInlineBots().isEmpty()) {
-			session().local().readRecentHashtagsAndBots();
-		} else if (autocomplete.query[0] == '/'
-			&& ((_peer->isUser() && !_peer->asUser()->isBot())
-				|| _editMsgId)) {
-			return;
-		}
-	}
+	const auto autocomplete = parseMentionHashtagBotCommandQuery();
 	_fieldAutocomplete->showFiltered(
 		_peer,
 		autocomplete.query,
@@ -4922,7 +4960,14 @@ void HistoryWidget::updateHistoryGeometry(
 	if (_contactStatus) {
 		newScrollHeight -= _contactStatus->height();
 	}
-	if (!editingMessage() && (isBlocked() || isBotStart() || isJoinChannel() || isMuteUnmute() || isReportMessages())) {
+	if (isChoosingTheme()) {
+		newScrollHeight -= _chooseTheme->height();
+	} else if (!editingMessage()
+		&& (isBlocked()
+			|| isBotStart()
+			|| isJoinChannel()
+			|| isMuteUnmute()
+			|| isReportMessages())) {
 		newScrollHeight -= _unblock->height();
 	} else {
 		if (editingMessage() || _canSendMessages) {
@@ -6136,16 +6181,17 @@ void HistoryWidget::editMessage(FullMsgId itemId) {
 }
 
 void HistoryWidget::editMessage(not_null<HistoryItem*> item) {
-	if (_voiceRecordBar->isActive()) {
-		controller()->show(
-			Box<InformBox>(tr::lng_edit_caption_voice(tr::now)));
-		return;
-	}
 	if (const auto media = item->media()) {
 		if (media->allowsEditCaption()) {
 			controller()->show(Box<EditCaptionBox>(controller(), item));
 			return;
 		}
+	} else if (_chooseTheme) {
+		toggleChooseChatTheme(_peer);
+	} else if (_voiceRecordBar->isActive()) {
+		controller()->show(
+			Box<InformBox>(tr::lng_edit_caption_voice(tr::now)));
+		return;
 	}
 
 	if (isRecording()) {
diff --git a/Telegram/SourceFiles/history/history_widget.h b/Telegram/SourceFiles/history/history_widget.h
index dd69a77fa..8bd0c68ea 100644
--- a/Telegram/SourceFiles/history/history_widget.h
+++ b/Telegram/SourceFiles/history/history_widget.h
@@ -25,6 +25,8 @@ struct FileLoadResult;
 struct SendingAlbum;
 enum class SendMediaType;
 class MessageLinksParser;
+struct InlineBotQuery;
+struct AutocompleteQuery;
 
 namespace MTP {
 class Error;
@@ -77,6 +79,7 @@ enum class ReportReason;
 namespace Toast {
 class Instance;
 } // namespace Toast
+class ChooseThemeController;
 } // namespace Ui
 
 namespace Window {
@@ -237,6 +240,8 @@ public:
 	void clearDelayedShowAt();
 	void saveFieldToHistoryLocalDraft();
 
+	void toggleChooseChatTheme(not_null<PeerData*> peer);
+
 	void applyCloudDraft(History *history);
 
 	void updateHistoryDownPosition();
@@ -454,6 +459,10 @@ private:
 	std::optional<QString> writeRestriction() const;
 	void orderWidgets();
 
+	[[nodiscard]] InlineBotQuery parseInlineBotQuery() const;
+	[[nodiscard]] auto parseMentionHashtagBotCommandQuery() const
+		-> AutocompleteQuery;
+
 	void clearInlineBot();
 	void inlineBotChanged();
 
@@ -585,19 +594,21 @@ private:
 	void inlineBotResolveDone(const MTPcontacts_ResolvedPeer &result);
 	void inlineBotResolveFail(const MTP::Error &error, const QString &username);
 
-	bool isRecording() const;
+	[[nodiscard]] bool isRecording() const;
 
-	bool isBotStart() const;
-	bool isBlocked() const;
-	bool isJoinChannel() const;
-	bool isMuteUnmute() const;
-	bool isReportMessages() const;
+	[[nodiscard]] bool isBotStart() const;
+	[[nodiscard]] bool isBlocked() const;
+	[[nodiscard]] bool isJoinChannel() const;
+	[[nodiscard]] bool isMuteUnmute() const;
+	[[nodiscard]] bool isReportMessages() const;
 	bool updateCmdStartShown();
 	void updateSendButtonType();
-	bool showRecordButton() const;
-	bool showInlineBotCancel() const;
+	[[nodiscard]] bool showRecordButton() const;
+	[[nodiscard]] bool showInlineBotCancel() const;
 	void refreshSilentToggle();
 
+	[[nodiscard]] bool isChoosingTheme() const;
+
 	void setupScheduledToggle();
 	void refreshScheduledToggle();
 
@@ -689,7 +700,7 @@ private:
 	bool _unreadMentionsIsShown = false;
 	object_ptr<Ui::HistoryDownButton> _unreadMentions;
 
-	object_ptr<FieldAutocomplete> _fieldAutocomplete;
+	const object_ptr<FieldAutocomplete> _fieldAutocomplete;
 	object_ptr<Support::Autocomplete> _supportAutocomplete;
 	std::unique_ptr<MessageLinksParser> _fieldLinksParser;
 
@@ -726,6 +737,8 @@ private:
 	object_ptr<Ui::ScrollArea> _kbScroll;
 	const not_null<BotKeyboard*> _keyboard;
 
+	std::unique_ptr<Ui::ChooseThemeController> _chooseTheme;
+
 	object_ptr<Ui::InnerDropdown> _membersDropdown = { nullptr };
 	base::Timer _membersDropdownShowTimer;
 
diff --git a/Telegram/SourceFiles/mainwidget.cpp b/Telegram/SourceFiles/mainwidget.cpp
index 2205b98ff..bb1e5d76f 100644
--- a/Telegram/SourceFiles/mainwidget.cpp
+++ b/Telegram/SourceFiles/mainwidget.cpp
@@ -1353,6 +1353,10 @@ void MainWidget::clearChooseReportMessages() {
 	_history->setChooseReportMessagesDetails({}, nullptr);
 }
 
+void MainWidget::toggleChooseChatTheme(not_null<PeerData*> peer) {
+	_history->toggleChooseChatTheme(peer);
+}
+
 void MainWidget::ui_showPeerHistory(
 		PeerId peerId,
 		const SectionShow &params,
diff --git a/Telegram/SourceFiles/mainwidget.h b/Telegram/SourceFiles/mainwidget.h
index 7266b413e..2aa0e42ef 100644
--- a/Telegram/SourceFiles/mainwidget.h
+++ b/Telegram/SourceFiles/mainwidget.h
@@ -213,6 +213,8 @@ public:
 		Fn<void(MessageIdsList)> done);
 	void clearChooseReportMessages();
 
+	void toggleChooseChatTheme(not_null<PeerData*> peer);
+
 	void ui_showPeerHistory(
 		PeerId peer,
 		const SectionShow &params,
diff --git a/Telegram/SourceFiles/ui/chat/chat_theme.cpp b/Telegram/SourceFiles/ui/chat/chat_theme.cpp
index 61c898de0..ffdf8a8ac 100644
--- a/Telegram/SourceFiles/ui/chat/chat_theme.cpp
+++ b/Telegram/SourceFiles/ui/chat/chat_theme.cpp
@@ -511,6 +511,11 @@ const BackgroundState &ChatTheme::backgroundState(QSize area) {
 	return _backgroundState;
 }
 
+void ChatTheme::clearBackgroundState() {
+	_backgroundState = BackgroundState();
+	_backgroundFade.stop();
+}
+
 bool ChatTheme::readyForBackgroundRotation() const {
 	Expects(_cacheBackgroundTimer.has_value());
 
diff --git a/Telegram/SourceFiles/ui/chat/chat_theme.h b/Telegram/SourceFiles/ui/chat/chat_theme.h
index 75bb4c787..bcc357fbd 100644
--- a/Telegram/SourceFiles/ui/chat/chat_theme.h
+++ b/Telegram/SourceFiles/ui/chat/chat_theme.h
@@ -137,6 +137,7 @@ public:
 		QRect viewport,
 		QRect clip);
 	[[nodiscard]] const BackgroundState &backgroundState(QSize area);
+	void clearBackgroundState();
 	[[nodiscard]] rpl::producer<> repaintBackgroundRequests() const;
 	void rotateComplexGradientBackground();
 
@@ -157,7 +158,6 @@ private:
 	void cacheBubblesNow();
 	void cacheBubblesAsync(
 		const CacheBackgroundRequest &request);
-	void setCachedBubbles(CacheBackgroundResult &&cached);
 	[[nodiscard]] CacheBackgroundRequest cacheBubblesRequest(
 		QSize area) const;
 
diff --git a/Telegram/SourceFiles/ui/chat/choose_theme_controller.cpp b/Telegram/SourceFiles/ui/chat/choose_theme_controller.cpp
new file mode 100644
index 000000000..15742b7e0
--- /dev/null
+++ b/Telegram/SourceFiles/ui/chat/choose_theme_controller.cpp
@@ -0,0 +1,424 @@
+/*
+This file is part of Telegram Desktop,
+the official desktop application for the Telegram messaging service.
+
+For license and copyright information please follow this link:
+https://github.com/telegramdesktop/tdesktop/blob/master/LEGAL
+*/
+#include "ui/chat/choose_theme_controller.h"
+
+#include "ui/rp_widget.h"
+#include "ui/widgets/shadow.h"
+#include "ui/widgets/labels.h"
+#include "ui/widgets/buttons.h"
+#include "ui/chat/chat_theme.h"
+#include "ui/wrap/vertical_layout.h"
+#include "main/main_session.h"
+#include "window/window_session_controller.h"
+#include "window/themes/window_theme.h"
+#include "data/data_session.h"
+#include "data/data_peer.h"
+#include "data/data_cloud_themes.h"
+#include "data/data_document.h"
+#include "data/data_document_media.h"
+#include "lang/lang_keys.h"
+#include "apiwrap.h"
+#include "styles/style_widgets.h"
+#include "styles/style_layers.h" // boxTitle.
+#include "styles/style_settings.h"
+
+namespace Ui {
+namespace {
+
+constexpr auto kDisableElement = "disable"_cs;
+
+[[nodiscard]] QImage GeneratePreview(not_null<Ui::ChatTheme*> theme) {
+	const auto &colors = theme->background().colors;
+	auto result = Images::GenerateGradient(
+		st::settingsThemePreviewSize * style::DevicePixelRatio(),
+		colors.empty() ? std::vector{ 1, QColor(0, 0, 0) } : colors
+	).convertToFormat(QImage::Format_ARGB32_Premultiplied);
+	Images::prepareRound(result, ImageRoundRadius::Large);
+	return result;
+}
+
+[[nodiscard]] QImage GenerateEmptyPreview() {
+	auto result = QImage(
+		st::settingsThemePreviewSize * style::DevicePixelRatio(),
+		QImage::Format_ARGB32_Premultiplied);
+	result.fill(st::settingsThemeNotSupportedBg->c);
+	Images::prepareRound(result, ImageRoundRadius::Large);
+	return result;
+}
+
+} // namespace
+
+struct ChooseThemeController::Entry {
+	uint64 id = 0;
+	std::shared_ptr<Ui::ChatTheme> theme;
+	std::shared_ptr<Data::DocumentMedia> media;
+	QImage preview;
+	EmojiPtr emoji = nullptr;
+	QRect geometry;
+};
+
+ChooseThemeController::ChooseThemeController(
+	not_null<RpWidget*> parent,
+	not_null<Window::SessionController*> window,
+	not_null<PeerData*> peer)
+: _controller(window)
+, _peer(peer)
+, _wrap(std::make_unique<VerticalLayout>(parent))
+, _topShadow(std::make_unique<PlainShadow>(parent))
+, _content(_wrap->add(object_ptr<RpWidget>(_wrap.get())))
+, _inner(CreateChild<RpWidget>(_content.get()))
+, _dark(Window::Theme::IsThemeDarkValue()) {
+	init(parent->sizeValue());
+}
+
+ChooseThemeController::~ChooseThemeController() {
+	_controller->clearPeerThemeOverride(_peer);
+}
+
+void ChooseThemeController::init(rpl::producer<QSize> outer) {
+	using namespace rpl::mappers;
+
+	const auto themes = &_controller->session().data().cloudThemes();
+	const auto &list = themes->chatThemes();
+	if (!list.empty()) {
+		fill(list);
+	} else {
+		themes->refreshChatThemes();
+		themes->chatThemesUpdated(
+		) | rpl::take(1) | rpl::start_with_next([=] {
+			fill(themes->chatThemes());
+		}, lifetime());
+	}
+
+	const auto skip = st::normalFont->spacew * 2;
+	_wrap->insert(
+		0,
+		object_ptr<FlatLabel>(
+			_wrap.get(),
+			tr::lng_chat_theme_title(),
+			st::boxTitle),
+		style::margins{ skip * 2, skip, skip * 2, skip });
+	_wrap->paintRequest(
+	) | rpl::start_with_next([=](QRect clip) {
+		QPainter(_wrap.get()).fillRect(clip, st::windowBg);
+	}, lifetime());
+
+	initButtons();
+	initList();
+
+	std::move(
+		outer
+	) | rpl::start_with_next([=](QSize outer) {
+		_wrap->resizeToWidth(outer.width());
+		_wrap->move(0, outer.height() - _wrap->height());
+		const auto line = st::lineWidth;
+		_topShadow->setGeometry(0, _wrap->y() - line, outer.width(), line);
+	}, lifetime());
+
+	rpl::combine(
+		_shouldBeShown.value(),
+		_forceHidden.value(),
+		_1 && !_2
+	) | rpl::start_with_next([=](bool shown) {
+		_wrap->setVisible(shown);
+		_topShadow->setVisible(shown);
+	}, lifetime());
+}
+
+void ChooseThemeController::initButtons() {
+	const auto controls = _wrap->add(object_ptr<RpWidget>(_wrap.get()));
+	const auto cancel = CreateChild<RoundButton>(
+		controls,
+		tr::lng_cancel(),
+		st::defaultLightButton);
+	const auto apply = CreateChild<RoundButton>(
+		controls,
+		tr::lng_chat_theme_apply(),
+		st::defaultActiveButton);
+	const auto skip = st::normalFont->spacew * 2;
+	controls->resize(
+		skip + cancel->width() + skip + apply->width() + skip,
+		skip + apply->height() + skip);
+	rpl::combine(
+		controls->widthValue(),
+		cancel->widthValue(),
+		apply->widthValue()
+	) | rpl::start_with_next([=](
+			int outer,
+			int cancelWidth,
+			int applyWidth) {
+		const auto inner = skip + cancelWidth + skip + applyWidth + skip;
+		const auto left = (outer - inner) / 2;
+		cancel->moveToLeft(left, skip);
+		apply->moveToRight(left, skip);
+	}, controls->lifetime());
+
+	const auto findChosen = [=]() -> const Entry* {
+		if (_chosen.isEmpty()) {
+			return nullptr;
+		}
+		for (const auto &entry : _entries) {
+			if (!entry.id && _chosen == kDisableElement.utf16()) {
+				return &entry;
+			} else if (_chosen == entry.emoji->text()) {
+				return &entry;
+			}
+		}
+		return nullptr;
+	};
+	const auto changed = [=] {
+		if (_chosen.isEmpty()) {
+			return false;
+		}
+		const auto now = Ui::Emoji::Find(_peer->themeEmoji());
+		if (_chosen == kDisableElement.utf16()) {
+			return !now;
+		}
+		for (const auto &entry : _entries) {
+			if (entry.id && entry.emoji->text() == _chosen) {
+				return (now != entry.emoji);
+			}
+		}
+		return false;
+	};
+	cancel->setClickedCallback([=] {
+		if (const auto chosen = findChosen()) {
+			if (Ui::Emoji::Find(_peer->themeEmoji()) != chosen->emoji) {
+				clearCurrentBackgroundState();
+			}
+		}
+		_controller->toggleChooseChatTheme(_peer);
+	});
+	apply->setClickedCallback([=] {
+		if (const auto chosen = findChosen()) {
+			if (Ui::Emoji::Find(_peer->themeEmoji()) != chosen->emoji) {
+				const auto now = chosen->id ? _chosen : QString();
+				_peer->setThemeEmoji(now);
+				if (chosen->theme) {
+					// Remember while changes propagate through event loop.
+					_controller->pushLastUsedChatTheme(chosen->theme);
+				}
+				const auto api = &_peer->session().api();
+				api->request(MTPmessages_SetChatTheme(
+					_peer->input,
+					MTP_string(now)
+				)).done([=](const MTPUpdates &result) {
+					api->applyUpdates(result);
+				}).send();
+			}
+		}
+		_controller->toggleChooseChatTheme(_peer);
+	});
+}
+
+void ChooseThemeController::paintEntry(QPainter &p, const Entry &entry) {
+	const auto geometry = entry.geometry;
+	p.drawImage(geometry, entry.preview);
+
+	if (entry.theme) {
+		const auto received = QRect(
+			st::settingsThemeBubblePosition,
+			st::settingsThemeBubbleSize);
+		const auto sent = QRect(
+			(geometry.width()
+				- received.width()
+				- st::settingsThemeBubblePosition.x()),
+			received.y() + received.height() + st::settingsThemeBubbleSkip,
+			received.width(),
+			received.height());
+		const auto radius = st::settingsThemeBubbleRadius;
+
+		const auto sentBg = entry.theme->palette()->msgOutBg()->c;
+		const auto receivedBg = entry.theme->palette()->msgInBg()->c;
+
+		PainterHighQualityEnabler hq(p);
+		p.setPen(Qt::NoPen);
+
+		p.setBrush(receivedBg);
+		p.drawRoundedRect(received.translated(geometry.topLeft()), radius, radius);
+		p.setBrush(sentBg);
+		p.drawRoundedRect(sent.translated(geometry.topLeft()), radius, radius);
+	}
+	const auto size = Ui::Emoji::GetSizeLarge();
+	const auto factor = style::DevicePixelRatio();
+	const auto skip = st::normalFont->spacew * 2;
+	Ui::Emoji::Draw(
+		p,
+		entry.emoji,
+		size,
+		(geometry.x()
+			+ (geometry.width() - (size / factor)) / 2),
+		(geometry.y() + geometry.height() - (size / factor) - skip));
+
+}
+
+void ChooseThemeController::initList() {
+	_content->resize(
+		_content->width(),
+		st::settingsThemePreviewSize.height());
+	_inner->setMouseTracking(true);
+
+	_inner->paintRequest(
+	) | rpl::start_with_next([=](QRect clip) {
+		auto p = QPainter(_inner.get());
+		for (const auto &entry : _entries) {
+			if (entry.preview.isNull() || !clip.intersects(entry.geometry)) {
+				continue;
+			}
+			paintEntry(p, entry);
+		}
+	}, lifetime());
+	const auto byPoint = [=](QPoint position) -> const Entry* {
+		for (const auto &entry : _entries) {
+			if (entry.geometry.contains(position)) {
+				return &entry;
+			}
+		}
+		return nullptr;
+	};
+	const auto chosenText = [=](const Entry *entry) {
+		if (!entry) {
+			return QString();
+		} else if (entry->id) {
+			return entry->emoji->text();
+		} else {
+			return kDisableElement.utf16();
+		}
+	};
+	_inner->events(
+	) | rpl::start_with_next([=](not_null<QEvent*> event) {
+		const auto type = event->type();
+		if (type == QEvent::MouseMove) {
+			const auto mouse = static_cast<QMouseEvent*>(event.get());
+			_inner->setCursor(byPoint(mouse->pos())
+				? style::cur_pointer
+				: style::cur_default);
+		} else if (type == QEvent::MouseButtonPress) {
+			const auto mouse = static_cast<QMouseEvent*>(event.get());
+			_pressed = chosenText(byPoint(mouse->pos()));
+		} else if (type == QEvent::MouseButtonRelease) {
+			const auto mouse = static_cast<QMouseEvent*>(event.get());
+			const auto entry = byPoint(mouse->pos());
+			const auto chosen = chosenText(entry);
+			if (entry && chosen == _pressed && chosen != _chosen) {
+				clearCurrentBackgroundState();
+				_chosen = chosen;
+				if (entry->theme || !entry->id) {
+					_controller->overridePeerTheme(_peer, entry->theme);
+				}
+			}
+			_pressed = QString();
+		}
+	}, lifetime());
+}
+
+void ChooseThemeController::clearCurrentBackgroundState() {
+	for (const auto &entry : _entries) {
+		if (entry.theme && entry.emoji && entry.emoji->text() == _chosen) {
+			entry.theme->clearBackgroundState();
+		}
+	}
+}
+
+void ChooseThemeController::fill(
+		const std::vector<Data::ChatTheme> &themes) {
+	if (themes.empty()) {
+		return;
+	}
+	const auto count = int(themes.size()) + 1;
+	const auto single = st::settingsThemePreviewSize;
+	const auto skip = st::normalFont->spacew * 2;
+	const auto full = single.width() * count + skip * (count + 1);
+	_inner->resize(full, single.height());
+
+	_dark.value(
+	) | rpl::start_with_next([=](bool dark) {
+		clearCurrentBackgroundState();
+
+		_cachingLifetime.destroy();
+		const auto old = base::take(_entries);
+		auto x = skip;
+		_entries.push_back({
+			.preview = GenerateEmptyPreview(),
+			.emoji = Ui::Emoji::Find(QString::fromUtf8("\xe2\x9d\x8c")),
+			.geometry = QRect(QPoint(x, 0), single),
+		});
+		Assert(_entries.front().emoji != nullptr);
+		style::PaletteChanged(
+		) | rpl::start_with_next([=] {
+			_entries.front().preview = GenerateEmptyPreview();
+		}, _cachingLifetime);
+
+		x += single.width() + skip;
+		for (const auto &theme : themes) {
+			const auto emoji = Ui::Emoji::Find(theme.emoticon);
+			if (!emoji) {
+				continue;
+			}
+			const auto &used = dark ? theme.dark : theme.light;
+			const auto id = used.id;
+			_entries.push_back({
+				.id = id,
+				.emoji = emoji,
+				.geometry = QRect(QPoint(x, 0), single),
+			});
+			_controller->cachedChatThemeValue(
+				used
+			) | rpl::filter([=](const std::shared_ptr<ChatTheme> &data) {
+				return data && (data->key() == id);
+			}) | rpl::take(
+				1
+			) | rpl::start_with_next([=](std::shared_ptr<ChatTheme> &&data) {
+				const auto id = data->key();
+				const auto i = ranges::find(_entries, id, &Entry::id);
+				if (i != end(_entries)) {
+					i->theme = std::move(data);
+					i->preview = GeneratePreview(i->theme.get());
+					if (_chosen == i->emoji->text()) {
+						_controller->overridePeerTheme(_peer, i->theme);
+					}
+					_inner->update();
+				}
+			}, _cachingLifetime);
+			_entries.back().preview;
+			x += single.width() + skip;
+		}
+	}, lifetime());
+	_shouldBeShown = true;
+}
+
+bool ChooseThemeController::shouldBeShown() const {
+	return _shouldBeShown.current();
+}
+
+rpl::producer<bool> ChooseThemeController::shouldBeShownValue() const {
+	return _shouldBeShown.value();
+}
+
+int ChooseThemeController::height() const {
+	return shouldBeShown() ? _wrap->height() : 0;
+}
+
+void ChooseThemeController::hide() {
+	_forceHidden = true;
+}
+
+void ChooseThemeController::show() {
+	_forceHidden = false;
+}
+
+void ChooseThemeController::raise() {
+	_wrap->raise();
+	_topShadow->raise();
+}
+
+rpl::lifetime &ChooseThemeController::lifetime() {
+	return _wrap->lifetime();
+}
+
+} // namespace Ui
diff --git a/Telegram/SourceFiles/ui/chat/choose_theme_controller.h b/Telegram/SourceFiles/ui/chat/choose_theme_controller.h
new file mode 100644
index 000000000..daec775a7
--- /dev/null
+++ b/Telegram/SourceFiles/ui/chat/choose_theme_controller.h
@@ -0,0 +1,73 @@
+/*
+This file is part of Telegram Desktop,
+the official desktop application for the Telegram messaging service.
+
+For license and copyright information please follow this link:
+https://github.com/telegramdesktop/tdesktop/blob/master/LEGAL
+*/
+#pragma once
+
+class PeerData;
+
+namespace Window {
+class SessionController;
+} // namespace Window
+
+namespace Data {
+struct ChatTheme;
+} // namespace Data
+
+namespace Ui {
+
+class RpWidget;
+class PlainShadow;
+class VerticalLayout;
+
+class ChooseThemeController final {
+public:
+	ChooseThemeController(
+		not_null<RpWidget*> parent,
+		not_null<Window::SessionController*> window,
+		not_null<PeerData*> peer);
+	~ChooseThemeController();
+
+	[[nodiscard]] bool shouldBeShown() const;
+	[[nodiscard]] rpl::producer<bool> shouldBeShownValue() const;
+	[[nodiscard]] int height() const;
+
+	void hide();
+	void show();
+	void raise();
+
+	[[nodiscard]] rpl::lifetime &lifetime();
+
+private:
+	struct Entry;
+
+	void init(rpl::producer<QSize> outer);
+	void initButtons();
+	void initList();
+	void fill(const std::vector<Data::ChatTheme> &themes);
+
+	void clearCurrentBackgroundState();
+	void paintEntry(QPainter &p, const Entry &entry);
+
+	const not_null<Window::SessionController*> _controller;
+	const not_null<PeerData*> _peer;
+	const std::unique_ptr<VerticalLayout> _wrap;
+	const std::unique_ptr<PlainShadow> _topShadow;
+
+	const not_null<RpWidget*> _content;
+	const not_null<RpWidget*> _inner;
+	std::vector<Entry> _entries;
+	QString _pressed;
+	QString _chosen;
+
+	rpl::variable<bool> _shouldBeShown = false;
+	rpl::variable<bool> _forceHidden = false;
+	rpl::variable<bool> _dark = false;
+	rpl::lifetime _cachingLifetime;
+
+};
+
+} // namespace Ui
diff --git a/Telegram/SourceFiles/window/section_widget.cpp b/Telegram/SourceFiles/window/section_widget.cpp
index 02801126d..f86a8c879 100644
--- a/Telegram/SourceFiles/window/section_widget.cpp
+++ b/Telegram/SourceFiles/window/section_widget.cpp
@@ -25,8 +25,6 @@ https://github.com/telegramdesktop/tdesktop/blob/master/LEGAL
 namespace Window {
 namespace {
 
-constexpr auto kDarkValueThreshold = 0.5;
-
 [[nodiscard]] rpl::producer<QString> PeerThemeEmojiValue(
 		not_null<PeerData*> peer) {
 	return peer->session().changes().peerFlagsValue(
@@ -51,17 +49,9 @@ constexpr auto kDarkValueThreshold = 0.5;
 [[nodiscard]] auto MaybeCloudThemeValueFromPeer(
 	not_null<PeerData*> peer)
 -> rpl::producer<std::optional<Data::CloudTheme>> {
-	auto isThemeDarkValue = rpl::single(
-		rpl::empty_value()
-	) | rpl::then(
-		style::PaletteChanged()
-	) | rpl::map([] {
-		return (st::dialogsBg->c.valueF() < kDarkValueThreshold);
-	}) | rpl::distinct_until_changed();
-
 	return rpl::combine(
 		MaybeChatThemeDataValueFromPeer(peer),
-		std::move(isThemeDarkValue)
+		Theme::IsThemeDarkValue() | rpl::distinct_until_changed()
 	) | rpl::map([](std::optional<Data::ChatTheme> theme, bool night) {
 		return !theme
 			? std::nullopt
@@ -304,7 +294,7 @@ auto ChatThemeValueFromPeer(
 	not_null<SessionController*> controller,
 	not_null<PeerData*> peer)
 -> rpl::producer<std::shared_ptr<Ui::ChatTheme>> {
-	return MaybeCloudThemeValueFromPeer(
+	auto cloud = MaybeCloudThemeValueFromPeer(
 		peer
 	) | rpl::map([=](std::optional<Data::CloudTheme> theme)
 	-> rpl::producer<std::shared_ptr<Ui::ChatTheme>> {
@@ -314,6 +304,17 @@ auto ChatThemeValueFromPeer(
 		return controller->cachedChatThemeValue(*theme);
 	}) | rpl::flatten_latest(
 	) | rpl::distinct_until_changed();
+
+	return rpl::combine(
+		std::move(cloud),
+		controller->peerThemeOverrideValue()
+	) | rpl::map([=](
+			std::shared_ptr<Ui::ChatTheme> &&cloud,
+			PeerThemeOverride &&overriden) {
+		return (overriden.peer == peer.get())
+			? std::move(overriden.theme)
+			: std::move(cloud);
+	});
 }
 
 } // namespace Window
diff --git a/Telegram/SourceFiles/window/themes/window_theme.cpp b/Telegram/SourceFiles/window/themes/window_theme.cpp
index fbed3c8ec..affb0a03b 100644
--- a/Telegram/SourceFiles/window/themes/window_theme.cpp
+++ b/Telegram/SourceFiles/window/themes/window_theme.cpp
@@ -46,6 +46,7 @@ namespace {
 constexpr auto kThemeFileSizeLimit = 5 * 1024 * 1024;
 constexpr auto kBackgroundSizeLimit = 25 * 1024 * 1024;
 constexpr auto kNightThemeFile = ":/gui/night.tdesktop-theme"_cs;
+constexpr auto kDarkValueThreshold = 0.5;
 
 struct Applying {
 	Saved data;
@@ -1450,6 +1451,16 @@ bool LoadFromContent(
 		out);
 }
 
+rpl::producer<bool> IsThemeDarkValue() {
+	return rpl::single(
+		rpl::empty_value()
+	) | rpl::then(
+		style::PaletteChanged()
+	) | rpl::map([] {
+		return (st::dialogsBg->c.valueF() < kDarkValueThreshold);
+	});
+}
+
 QString EditingPalettePath() {
 	return cWorkingDir() + "tdata/editing-theme.tdesktop-palette";
 }
diff --git a/Telegram/SourceFiles/window/themes/window_theme.h b/Telegram/SourceFiles/window/themes/window_theme.h
index 02cd7ee0e..22cd32f97 100644
--- a/Telegram/SourceFiles/window/themes/window_theme.h
+++ b/Telegram/SourceFiles/window/themes/window_theme.h
@@ -97,6 +97,8 @@ void ResetToSomeDefault();
 [[nodiscard]] bool IsNonDefaultBackground();
 void Revert();
 
+[[nodiscard]] rpl::producer<bool> IsThemeDarkValue();
+
 [[nodiscard]] QString EditingPalettePath();
 
 // NB! This method looks to Core::App().settings() to get colorizer by 'file'.
diff --git a/Telegram/SourceFiles/window/window_peer_menu.cpp b/Telegram/SourceFiles/window/window_peer_menu.cpp
index 7dab65674..9182a4442 100644
--- a/Telegram/SourceFiles/window/window_peer_menu.cpp
+++ b/Telegram/SourceFiles/window/window_peer_menu.cpp
@@ -487,6 +487,11 @@ void Filler::addUserActions(not_null<UserData*> user) {
 				[=] { AddBotToGroup::Start(user); });
 		}
 		addPollAction(user);
+		if (!user->isBot()) {
+			_addAction(
+				tr::lng_chat_theme_change(tr::now),
+				[=] { controller->toggleChooseChatTheme(user); });
+		}
 		if (user->canExportChatHistory()) {
 			_addAction(
 				tr::lng_profile_export_chat(tr::now),
diff --git a/Telegram/SourceFiles/window/window_session_controller.cpp b/Telegram/SourceFiles/window/window_session_controller.cpp
index 839ed2e12..e676c3303 100644
--- a/Telegram/SourceFiles/window/window_session_controller.cpp
+++ b/Telegram/SourceFiles/window/window_session_controller.cpp
@@ -125,6 +125,14 @@ void ActivateWindow(not_null<SessionController*> controller) {
 	Ui::ActivateWindowDelayed(window);
 }
 
+bool operator==(const PeerThemeOverride &a, const PeerThemeOverride &b) {
+	return (a.peer == b.peer) && (a.theme == b.theme);
+}
+
+bool operator!=(const PeerThemeOverride &a, const PeerThemeOverride &b) {
+	return !(a == b);
+}
+
 DateClickHandler::DateClickHandler(Dialogs::Key chat, QDate date)
 : _chat(chat)
 , _date(date) {
@@ -1208,6 +1216,10 @@ void SessionController::clearChooseReportMessages() {
 	content()->clearChooseReportMessages();
 }
 
+void SessionController::toggleChooseChatTheme(not_null<PeerData*> peer) {
+	content()->toggleChooseChatTheme(peer);
+}
+
 void SessionController::updateColumnLayout() {
 	content()->updateColumnLayout();
 }
@@ -1397,7 +1409,7 @@ auto SessionController::cachedChatThemeValue(
 	const auto i = _customChatThemes.find(key);
 	if (i != end(_customChatThemes)) {
 		if (auto strong = i->second.theme.lock()) {
-			pushToLastUsed(strong);
+			pushLastUsedChatTheme(strong);
 			return rpl::single(std::move(strong));
 		}
 	}
@@ -1413,12 +1425,12 @@ auto SessionController::cachedChatThemeValue(
 		if (theme->key() != key) {
 			return false;
 		}
-		pushToLastUsed(theme);
+		pushLastUsedChatTheme(theme);
 		return true;
 	}) | rpl::take(limit));
 }
 
-void SessionController::pushToLastUsed(
+void SessionController::pushLastUsedChatTheme(
 		const std::shared_ptr<Ui::ChatTheme> &theme) {
 	const auto i = ranges::find(_lastUsedCustomChatThemes, theme);
 	if (i == end(_lastUsedCustomChatThemes)) {
@@ -1444,6 +1456,21 @@ void SessionController::clearCachedChatThemes() {
 	_customChatThemes.clear();
 }
 
+void SessionController::overridePeerTheme(
+		not_null<PeerData*> peer,
+		std::shared_ptr<Ui::ChatTheme> theme) {
+	_peerThemeOverride = PeerThemeOverride{
+		peer,
+		theme ? theme : _defaultChatTheme,
+	};
+}
+
+void SessionController::clearPeerThemeOverride(not_null<PeerData*> peer) {
+	if (_peerThemeOverride.current().peer == peer.get()) {
+		_peerThemeOverride = PeerThemeOverride();
+	}
+}
+
 void SessionController::pushDefaultChatBackground() {
 	const auto background = Theme::Background();
 	const auto &paper = background->paper();
diff --git a/Telegram/SourceFiles/window/window_session_controller.h b/Telegram/SourceFiles/window/window_session_controller.h
index 81d6697d6..c524f1bc2 100644
--- a/Telegram/SourceFiles/window/window_session_controller.h
+++ b/Telegram/SourceFiles/window/window_session_controller.h
@@ -75,6 +75,13 @@ enum class GifPauseReason {
 using GifPauseReasons = base::flags<GifPauseReason>;
 inline constexpr bool is_flag_type(GifPauseReason) { return true; };
 
+struct PeerThemeOverride {
+	PeerData *peer = nullptr;
+	std::shared_ptr<Ui::ChatTheme> theme;
+};
+bool operator==(const PeerThemeOverride &a, const PeerThemeOverride &b);
+bool operator!=(const PeerThemeOverride &a, const PeerThemeOverride &b);
+
 class DateClickHandler : public ClickHandler {
 public:
 	DateClickHandler(Dialogs::Key chat, QDate date);
@@ -378,6 +385,8 @@ public:
 		Fn<void(MessageIdsList)> done);
 	void clearChooseReportMessages();
 
+	void toggleChooseChatTheme(not_null<PeerData*> peer);
+
 	base::Variable<bool> &dialogsListFocused() {
 		return _dialogsListFocused;
 	}
@@ -412,6 +421,16 @@ public:
 	-> rpl::producer<std::shared_ptr<Ui::ChatTheme>>;
 	void setChatStyleTheme(const std::shared_ptr<Ui::ChatTheme> &theme);
 	void clearCachedChatThemes();
+	void pushLastUsedChatTheme(const std::shared_ptr<Ui::ChatTheme> &theme);
+
+	void overridePeerTheme(
+		not_null<PeerData*> peer,
+		std::shared_ptr<Ui::ChatTheme> theme);
+	void clearPeerThemeOverride(not_null<PeerData*> peer);
+	[[nodiscard]] auto peerThemeOverrideValue() const
+		-> rpl::producer<PeerThemeOverride> {
+		return _peerThemeOverride.value();
+	}
 
 	struct PaintContextArgs {
 		not_null<Ui::ChatTheme*> theme;
@@ -464,7 +483,6 @@ private:
 	[[nodiscard]] Ui::ChatThemeBackgroundData backgroundData(
 		CachedTheme &theme,
 		bool generateGradient = true) const;
-	void pushToLastUsed(const std::shared_ptr<Ui::ChatTheme> &theme);
 
 	const not_null<Controller*> _window;
 	const std::unique_ptr<ChatHelpers::EmojiInteractions> _emojiInteractions;
@@ -500,6 +518,7 @@ private:
 	const std::unique_ptr<Ui::ChatStyle> _chatStyle;
 	std::weak_ptr<Ui::ChatTheme> _chatStyleTheme;
 	std::deque<std::shared_ptr<Ui::ChatTheme>> _lastUsedCustomChatThemes;
+	rpl::variable<PeerThemeOverride> _peerThemeOverride;
 
 	rpl::lifetime _lifetime;