Restore supergroup convert

Telegram/Resources/langs/lang.strings

@@ -1049,6 +1049,7 @@ https://github.com/telegramdesktop/tdesktop/blob/master/LEGAL
 "lng_action_changed_title_channel" = "Channel name was changed to «{title}»";
 "lng_action_created_chat" = "{from} created group «{title}»";
 "lng_action_created_channel" = "Channel created";
+"lng_action_group_migrate" = "The group was upgraded to a supergroup";
 "lng_action_pinned_message" = "{from} pinned «{text}»";
 "lng_action_pinned_media" = "{from} pinned {media}";
 "lng_action_pinned_media_photo" = "a photo";

Telegram/SourceFiles/boxes/confirm_box.cpp

@@ -426,6 +426,61 @@ void MaxInviteBox::resizeEvent(QResizeEvent *e) {
 	_invitationLink = myrtlrect(st::boxPadding.left(), st::boxPadding.top() + _textHeight + st::boxTextFont->height, width() - st::boxPadding.left() - st::boxPadding.right(), 2 * st::boxTextFont->height);
 }
 
+ConvertToSupergroupBox::ConvertToSupergroupBox(QWidget*, not_null<ChatData*> chat)
+: _chat(chat) {
+}
+
+void ConvertToSupergroupBox::prepare() {
+	setTitle(tr::lng_profile_convert_title());
+
+	addButton(tr::lng_profile_convert_confirm(), [=] { convertToSupergroup(); });
+	addButton(tr::lng_cancel(), [=] { closeBox(); });
+
+	auto details = TextWithEntities();
+	const auto appendDetails = [&](TextWithEntities &&text) {
+		details.append(qs("\n")).append(std::move(text));
+	};
+
+	details.text = tr::lng_profile_convert_feature1(tr::now);
+	appendDetails({ tr::lng_profile_convert_feature2(tr::now) });
+	appendDetails({ tr::lng_profile_convert_feature3(tr::now) });
+	appendDetails({ tr::lng_profile_convert_feature4(tr::now) });
+	appendDetails({ qs("\n") + tr::lng_profile_convert_warning(tr::now, lt_bold_start, textcmdStartSemibold(), lt_bold_end, textcmdStopSemibold()) });
+
+	_text.create(this, rpl::single(std::move(details)), st::boxLabel);
+
+	const auto fullHeight = st::boxPadding.top() + _text->height() + st::boxPadding.bottom();
+	setDimensions(st::boxWideWidth, fullHeight);
+}
+
+void ConvertToSupergroupBox::convertToSupergroup() {
+	MTP::send(MTPmessages_MigrateChat(_chat->inputChat), rpcDone(&ConvertToSupergroupBox::convertDone), rpcFail(&ConvertToSupergroupBox::convertFail));
+}
+
+void ConvertToSupergroupBox::convertDone(const MTPUpdates &updates) {
+	_chat->session().api().applyUpdates(updates);
+	Ui::hideLayer();
+}
+
+bool ConvertToSupergroupBox::convertFail(const RPCError &error) {
+	if (MTP::isDefaultHandledError(error)) return false;
+	Ui::hideLayer();
+	return true;
+}
+
+void ConvertToSupergroupBox::resizeEvent(QResizeEvent *e) {
+	BoxContent::resizeEvent(e);
+	_text->moveToLeft(st::boxPadding.left(), st::boxPadding.top());
+}
+
+void ConvertToSupergroupBox::keyPressEvent(QKeyEvent *e) {
+	if (e->key() == Qt::Key_Enter || e->key() == Qt::Key_Return) {
+		convertToSupergroup();
+	} else {
+		BoxContent::keyPressEvent(e);
+	}
+}
+
 PinMessageBox::PinMessageBox(
 	QWidget*,
 	not_null<PeerData*> peer,

Telegram/SourceFiles/boxes/confirm_box.h

@@ -124,6 +124,25 @@ class MaxInviteBox : public Ui::BoxContent, private base::Subscriber {
 
 };
 
+class ConvertToSupergroupBox : public Ui::BoxContent, public RPCSender {
+public:
+	ConvertToSupergroupBox(QWidget*, not_null<ChatData*> chat);
+
+protected:
+	void prepare() override;
+
+	void resizeEvent(QResizeEvent *e) override;
+	void keyPressEvent(QKeyEvent *e) override;
+
+private:
+	void convertToSupergroup();
+	void convertDone(const MTPUpdates &updates);
+	bool convertFail(const RPCError &error);
+
+	not_null<ChatData*> _chat;
+	object_ptr<Ui::FlatLabel> _text = { nullptr };
+};
+
 class PinMessageBox : public Ui::BoxContent, public RPCSender {
 public:
 	PinMessageBox(QWidget*, not_null<PeerData*> peer, MsgId msgId);

Telegram/SourceFiles/history/history_service.cpp

@@ -232,9 +232,9 @@ void HistoryService::setMessageByAction(const MTPmessageAction &action) {
 	}, [&](const MTPDmessageActionChatCreate &data) {
 		return prepareChatCreate(data);
 	}, [](const MTPDmessageActionChatMigrateTo &) {
-		return PreparedText();
+		return PreparedText{ tr::lng_action_group_migrate(tr::now) };
 	}, [](const MTPDmessageActionChannelMigrateFrom &) {
-		return PreparedText();
+		return PreparedText{ tr::lng_action_group_migrate(tr::now) };
 	}, [](const MTPDmessageActionHistoryClear &) {
 		return PreparedText();
 	}, [&](const MTPDmessageActionChannelCreate &data) {