Enable history visibility when linking chat.

Telegram/Resources/langs/lang.strings

@@ -861,6 +861,8 @@ https://github.com/telegramdesktop/tdesktop/blob/master/LEGAL
 "lng_manage_linked_channel_about" = "{channel} is linking the group as its discussion board.";
 "lng_manage_linked_channel_unlink" = "Unlink channel";
 "lng_manage_linked_channel_posted" = "All new messages posted in this channel are forwarded to the group.";
+"lng_manage_discussion_group_warning" = "Warning: If you set this private group as the disccussion group for your channel, all channel subscribers will be able to access the group. \"Chat history for new members\" will be switched to {visible}.";
+"lng_manage_discussion_group_visible" = "Visible";
 
 "lng_manage_history_visibility_title" = "Chat history for new members";
 "lng_manage_history_visibility_shown" = "Visible";

Telegram/SourceFiles/boxes/peers/edit_linked_chat_box.cpp

@@ -16,6 +16,8 @@ https://github.com/telegramdesktop/tdesktop/blob/master/LEGAL
 #include "boxes/peer_list_box.h"
 #include "boxes/confirm_box.h"
 #include "boxes/add_contact_box.h"
+#include "apiwrap.h"
+#include "auth_session.h"
 #include "styles/style_boxes.h"
 #include "styles/style_info.h"
 
@@ -43,11 +45,15 @@ public:
 	int contentWidth() const override;
 
 private:
+	void choose(not_null<ChannelData*> chat);
+
 	not_null<ChannelData*> _channel;
 	ChannelData *_chat = nullptr;
 	std::vector<not_null<ChannelData*>> _chats;
 	Fn<void(ChannelData*)> _callback;
 
+	ChannelData *_waitForFull = nullptr;
+
 };
 
 Controller::Controller(
@@ -59,6 +65,13 @@ Controller::Controller(
 , _chat(chat)
 , _chats(std::move(chats))
 , _callback(std::move(callback)) {
+	base::ObservableViewer(
+		channel->session().api().fullPeerUpdated()
+	) | rpl::start_with_next([=](PeerData *peer) {
+		if (peer == _waitForFull) {
+			choose(std::exchange(_waitForFull, nullptr));
+		}
+	}, lifetime());
 }
 
 int Controller::contentWidth() const {
@@ -94,6 +107,15 @@ void Controller::rowClicked(not_null<PeerListRow*> row) {
 		return;
 	}
 	const auto chat = row->peer()->asChannel();
+	if (chat->wasFullUpdated()) {
+		choose(chat);
+		return;
+	}
+	_waitForFull = chat;
+	chat->updateFull();
+}
+
+void Controller::choose(not_null<ChannelData*> chat) {
 	auto text = lng_manage_discussion_group_sure__generic<
 		TextWithEntities
 	>(
@@ -105,6 +127,12 @@ void Controller::rowClicked(not_null<PeerListRow*> row) {
 		text.append(
 			"\n\n" + lang(lng_manage_linked_channel_private));
 	}
+	if (chat->hiddenPreHistory()) {
+		text.append("\n\n");
+		text.append(lng_manage_discussion_group_warning__generic(
+			lt_visible,
+			BoldText(lang(lng_manage_discussion_group_visible))));
+	}
 	const auto box = std::make_shared<QPointer<BoxContent>>();
 	const auto sure = [=] {
 		if (*box) {

Telegram/SourceFiles/boxes/peers/edit_peer_info_box.cpp

@@ -192,7 +192,7 @@ private:
 	object_ptr<Ui::RpWidget> createStickersEdit();
 
 	bool canEditInformation() const;
-	void refreshHistoryVisibility(bool instant);
+	void refreshHistoryVisibility(anim::type animated = anim::type::normal);
 	void showEditPeerTypeBox(std::optional<LangKey> error = std::nullopt);
 	void showEditLinkedChatBox();
 	void fillPrivacyTypeButton();
@@ -227,6 +227,12 @@ private:
 	void continueSave();
 	void cancelSave();
 
+	void togglePreHistoryHidden(
+		not_null<ChannelData*> channel,
+		bool hidden,
+		Fn<void()> done,
+		Fn<void()> fail);
+
 	void subscribeToMigration();
 	void migrate(not_null<ChannelData*> channel);
 
@@ -477,13 +483,14 @@ bool Controller::canEditInformation() const {
 	return false;
 }
 
-void Controller::refreshHistoryVisibility(bool instant = false) {
+void Controller::refreshHistoryVisibility(anim::type animated) {
 	if (!_controls.historyVisibilityWrap) {
 		return;
 	}
 	_controls.historyVisibilityWrap->toggle(
-		_privacySavedValue != Privacy::Public,
-		instant ? anim::type::instant : anim::type::normal);
+		(_privacySavedValue != Privacy::Public
+			&& (!_linkedChatSavedValue || !*_linkedChatSavedValue)),
+		animated);
 };
 
 void Controller::showEditPeerTypeBox(std::optional<LangKey> error) {
@@ -515,6 +522,7 @@ void Controller::showEditLinkedChatBox() {
 		}
 		*_linkedChatSavedValue = result;
 		_linkedChatUpdates.fire_copy(result);
+		refreshHistoryVisibility();
 	};
 	if (const auto chat = *_linkedChatSavedValue) {
 		*box = Ui::show(
@@ -701,8 +709,7 @@ void Controller::fillHistoryVisibilityButton() {
 
 	updateHistoryVisibility->fire_copy(*_historyVisibilitySavedValue);
 
-	//While appearing box we should use instant animation.
-	refreshHistoryVisibility(true);
+	refreshHistoryVisibility(anim::type::instant);
 }
 
 void Controller::fillManageSection() {
@@ -783,7 +790,9 @@ void Controller::fillManageSection() {
 			? channel->canEditInformation()
 			: (channel->linkedChat()
 				&& channel->canPinMessages()
-				&& channel->adminRights() != 0);
+				&& channel->adminRights() != 0
+				&& (!channel->hiddenPreHistory()
+					|| channel->canEditPreHistoryHidden()));
 	}();
 
 	AddSkip(_controls.buttonsLayout, 0);
@@ -1091,11 +1100,21 @@ void Controller::saveLinkedChat() {
 	if (!channel) {
 		return continueSave();
 	}
-	const auto linkedChat = channel->linkedChat();
-	if (!_savingData.linkedChat || *_savingData.linkedChat == linkedChat) {
+	if (!_savingData.linkedChat
+		|| *_savingData.linkedChat == channel->linkedChat()) {
 		return continueSave();
 	}
 
+	const auto chat = *_savingData.linkedChat;
+	if (channel->isBroadcast() && chat->hiddenPreHistory()) {
+		togglePreHistoryHidden(
+			chat,
+			false,
+			[=] { saveLinkedChat(); },
+			[=] { cancelSave(); });
+		return;
+	}
+
 	const auto input = *_savingData.linkedChat
 		? (*_savingData.linkedChat)->inputChannel
 		: MTP_inputChannelEmpty();
@@ -1203,22 +1222,39 @@ void Controller::saveHistoryVisibility() {
 			crl::guard(this, saveForChannel));
 		return;
 	}
-	request(MTPchannels_TogglePreHistoryHidden(
-		channel->inputChannel,
-		MTP_bool(*_savingData.hiddenPreHistory)
-	)).done([=](const MTPUpdates &result) {
+	togglePreHistoryHidden(
+		channel,
+		*_savingData.hiddenPreHistory,
+		[=] { continueSave(); },
+		[=] { cancelSave(); });
+}
+
+void Controller::togglePreHistoryHidden(
+		not_null<ChannelData*> channel,
+		bool hidden,
+		Fn<void()> done,
+		Fn<void()> fail) {
+	const auto apply = [=] {
 		// Update in the result doesn't contain the
 		// channelFull:flags field which holds this value.
 		// So after saving we need to update it manually.
-		channel->updateFullForced();
+		const auto flags = channel->fullFlags();
+		const auto flag = MTPDchannelFull::Flag::f_hidden_prehistory;
+		channel->setFullFlags(hidden ? (flags | flag) : (flags & ~flag));
 
+		done();
+	};
+	request(MTPchannels_TogglePreHistoryHidden(
+		channel->inputChannel,
+		MTP_bool(hidden)
+	)).done([=](const MTPUpdates &result) {
 		channel->session().api().applyUpdates(result);
-		continueSave();
+		apply();
 	}).fail([=](const RPCError &error) {
 		if (error.type() == qstr("CHAT_NOT_MODIFIED")) {
-			continueSave();
+			apply();
 		} else {
-			cancelSave();
+			fail();
 		}
 	}).send();
 }