Handle forum / topic links.

Telegram/SourceFiles/apiwrap.cpp

@@ -659,6 +659,7 @@ QString ApiWrap::exportDirectMessageLink(
 		auto linkItemId = item->id;
 		auto linkCommentId = MsgId();
 		auto linkThreadId = MsgId();
+		auto linkThreadIsTopic = false;
 		if (inRepliesContext) {
 			if (const auto rootId = item->replyToTop()) {
 				const auto root = item->history()->owner().message(
@@ -680,6 +681,7 @@ QString ApiWrap::exportDirectMessageLink(
 				} else {
 					// Reply in a thread, maybe comment in a private channel.
 					linkThreadId = rootId;
+					linkThreadIsTopic = (item->topicRootId() == rootId);
 				}
 			}
 		}
@@ -692,7 +694,8 @@ QString ApiWrap::exportDirectMessageLink(
 			+ (linkCommentId
 				? "?comment=" + QString::number(linkCommentId.bare)
 				: linkThreadId
-				? "?thread=" + QString::number(linkThreadId.bare)
+				? ((linkThreadIsTopic ? "?topic=" : "?thread=")
+					+ QString::number(linkThreadId.bare))
 				: "");
 		if (linkChannel->hasUsername()
 			&& !linkChannel->isMegagroup()

Telegram/SourceFiles/core/application.cpp

@@ -12,6 +12,7 @@ https://github.com/telegramdesktop/tdesktop/blob/master/LEGAL
 #include "data/data_document.h"
 #include "data/data_session.h"
 #include "data/data_user.h"
+#include "data/data_channel.h"
 #include "data/data_download_manager.h"
 #include "base/timer.h"
 #include "base/event_filter.h"
@@ -1229,6 +1230,9 @@ void Application::closeChatFromWindows(not_null<PeerData*> peer) {
 				PeerId(0),
 				Window::SectionShow::Way::ClearStack);
 		}
+		if (primary->openedForum().current() == peer) {
+			primary->closeForum();
+		}
 	}
 }
 

Telegram/SourceFiles/core/local_url_handlers.cpp

@@ -362,8 +362,10 @@ bool ResolveUsernameOrPhone(
 	}
 	const auto commentParam = params.value(qsl("comment"));
 	const auto commentId = commentParam.toInt();
+	const auto topicParam = params.value(qsl("topic"));
+	const auto topicId = topicParam.toInt();
 	const auto threadParam = params.value(qsl("thread"));
-	const auto threadId = threadParam.toInt();
+	const auto threadId = topicId ? topicId : threadParam.toInt();
 	const auto gameParam = params.value(qsl("game"));
 	if (!gameParam.isEmpty() && validDomain(gameParam)) {
 		startToken = gameParam;
@@ -422,8 +424,10 @@ bool ResolvePrivatePost(
 	const auto msgId = params.value(qsl("post")).toInt();
 	const auto commentParam = params.value(qsl("comment"));
 	const auto commentId = commentParam.toInt();
+	const auto topicParam = params.value(qsl("topic"));
+	const auto topicId = topicParam.toInt();
 	const auto threadParam = params.value(qsl("thread"));
-	const auto threadId = threadParam.toInt();
+	const auto threadId = topicId ? topicId : threadParam.toInt();
 	if (!channelId || !IsServerMsgId(msgId)) {
 		return false;
 	}

Telegram/SourceFiles/history/view/history_view_list_widget.cpp

@@ -685,9 +685,12 @@ bool ListWidget::showAtPositionNow(
 			&& position != Data::UnreadMessagePosition) {
 			highlightMessage(position.fullId);
 		}
-		done(!position.fullId.peer
-			|| !position.fullId.msg
-			|| viewForItem(position.fullId));
+		if (done) {
+			const auto found = !position.fullId.peer
+				|| !position.fullId.msg
+				|| viewForItem(position.fullId);
+			done(found);
+		}
 		return true;
 	}
 	return false;

Telegram/SourceFiles/history/view/history_view_replies_section.cpp

@@ -1174,7 +1174,9 @@ void RepliesWidget::refreshJoinGroupButton() {
 		}
 	};
 	const auto channel = _history->peer->asChannel();
-	if (channel->amIn() || !channel->joinToWrite() || channel->amCreator()) {
+	if (channel->amIn()
+		|| !channel->joinToWrite()
+		|| (channel->amCreator() && channel->canWrite())) {
 		set(nullptr);
 	} else {
 		if (!_joinGroup) {

Telegram/SourceFiles/window/window_session_controller.cpp

@@ -343,6 +343,8 @@ void SessionNavigation::showPeerByLinkResolved(
 			info.messageId,
 			commentId->id,
 			params);
+	} else if (peer->isForum()) {
+		parentController()->openForum(peer->asChannel(), params);
 	} else if (bot
 		&& (info.resolveType == ResolveType::AddToGroup
 			|| info.resolveType == ResolveType::AddToChannel