Handle private channel post links.

Telegram/Resources/langs/lang.strings

@@ -141,6 +141,7 @@ https://github.com/telegramdesktop/tdesktop/blob/master/LEGAL
 "lng_error_cant_ban_admin" = "Sorry, you can't ban this user because they are an admin in this group and you are not allowed to demote them.";
 "lng_error_admin_limit" = "Sorry, you've reached the maximum number of admins for this group.";
 "lng_error_admin_limit_channel" = "Sorry, you've reached the maximum number of admins for this channel.";
+"lng_error_post_link_invalid" = "Unfortunately, you can't access this message. You are not a member of the chat where it was posted.";
 "lng_sure_add_admin_invite" = "This user is not a member of this group. Add them to the group and promote them to admin?";
 "lng_sure_add_admin_invite_channel" = "This user is not a subscriber of this channel. Add them to the channel and promote them to admin?";
 "lng_sure_add_admin_unremove" = "This user is currently restricted or removed. Are you sure you want to promote them?";

Telegram/SourceFiles/core/click_handler_types.cpp

@@ -64,6 +64,8 @@ QString tryConvertUrlToLocal(QString url) {
 		} else if (auto bgMatch = regex_match(qsl("^bg/([a-zA-Z0-9\\.\\_\\-]+)(\\?(.+)?)?$"), query, matchOptions)) {
 			const auto params = bgMatch->captured(3);
 			return qsl("tg://bg?slug=") + bgMatch->captured(1) + (params.isEmpty() ? QString() : '&' + params);
+		} else if (auto postMatch = regex_match(qsl("^c/(\\-?\\d+)/(\\d+)(#|$)"), query, matchOptions)) {
+			return qsl("tg://privatepost?channel=%1&post=%2").arg(postMatch->captured(1)).arg(postMatch->captured(2));
 		} else if (auto usernameMatch = regex_match(qsl("^([a-zA-Z0-9\\.\\_]+)(/?\\?|/?$|/(\\d+)/?(?:\\?|$))"), query, matchOptions)) {
 			auto params = query.mid(usernameMatch->captured(0).size()).toString();
 			auto postParam = QString();

Telegram/SourceFiles/core/local_url_handlers.cpp

@@ -12,6 +12,7 @@ https://github.com/telegramdesktop/tdesktop/blob/master/LEGAL
 #include "lang/lang_cloud_manager.h"
 #include "lang/lang_keys.h"
 #include "core/update_checker.h"
+#include "core/application.h"
 #include "boxes/confirm_phone_box.h"
 #include "boxes/background_preview_box.h"
 #include "boxes/confirm_box.h"
@@ -21,9 +22,9 @@ https://github.com/telegramdesktop/tdesktop/blob/master/LEGAL
 #include "passport/passport_form_controller.h"
 #include "window/window_controller.h"
 #include "data/data_session.h"
+#include "data/data_channel.h"
 #include "mainwindow.h"
 #include "mainwidget.h"
-#include "core/application.h"
 #include "auth_session.h"
 #include "apiwrap.h"
 
@@ -205,12 +206,14 @@ bool ResolveUsername(const Match &match, const QVariant &context) {
 			start = QString();
 		}
 	}
-	auto post = (start == qsl("startgroup")) ? ShowAtProfileMsgId : ShowAtUnreadMsgId;
+	auto post = (start == qsl("startgroup"))
+		? ShowAtProfileMsgId
+		: ShowAtUnreadMsgId;
 	auto postParam = params.value(qsl("post"));
 	if (auto postId = postParam.toInt()) {
 		post = postId;
 	}
-	auto gameParam = params.value(qsl("game"));
+	const auto gameParam = params.value(qsl("game"));
 	if (!gameParam.isEmpty() && valid(gameParam)) {
 		startToken = gameParam;
 		post = ShowAtGameShareMsgId;
@@ -224,6 +227,51 @@ bool ResolveUsername(const Match &match, const QVariant &context) {
 	return true;
 }
 
+bool ResolvePrivatePost(const Match &match, const QVariant &context) {
+	if (!AuthSession::Exists()) {
+		return false;
+	}
+	const auto params = url_parse_params(
+		match->captured(1),
+		qthelp::UrlParamNameTransform::ToLower);
+	const auto channelId = params.value(qsl("channel")).toInt();
+	const auto msgId = params.value(qsl("post")).toInt();
+	if (!channelId || !IsServerMsgId(msgId)) {
+		return false;
+	}
+	const auto done = [=](not_null<PeerData*> peer) {
+		App::wnd()->controller()->showPeerHistory(
+			peer->id,
+			Window::SectionShow::Way::Forward,
+			msgId);
+	};
+	const auto fail = [=] {
+		Ui::show(Box<InformBox>(lang(lng_error_post_link_invalid)));
+	};
+	const auto auth = &Auth();
+	if (const auto channel = auth->data().channelLoaded(channelId)) {
+		done(channel);
+		return true;
+	}
+	auth->api().request(MTPchannels_GetChannels(
+		MTP_vector<MTPInputChannel>(
+			1,
+			MTP_inputChannel(MTP_int(channelId), MTP_long(0)))
+	)).done([=](const MTPmessages_Chats &result) {
+		result.match([&](const auto &data) {
+			const auto peer = auth->data().processChats(data.vchats);
+			if (peer && peer->id == peerFromChannel(channelId)) {
+				done(peer);
+			} else {
+				fail();
+			}
+		});
+	}).fail([=](const RPCError &error) {
+		fail();
+	}).send();
+	return true;
+}
+
 bool HandleUnknown(const Match &match, const QVariant &context) {
 	if (!AuthSession::Exists()) {
 		return false;
@@ -302,6 +350,10 @@ const std::vector<LocalUrlHandler> &LocalUrlHandlers() {
 			qsl("^resolve/?\\?(.+)(#|$)"),
 			ResolveUsername
 		},
+		{
+			qsl("^privatepost/?\\?(.+)(#|$)"),
+			ResolvePrivatePost
+		},
 		{
 			qsl("^([^\\?]+)(\\?|#|$)"),
 			HandleUnknown