Support message links for forum topics.

td/generate/scheme/td_api.tl

@@ -3912,11 +3912,11 @@ messageLink link:string is_public:Bool = MessageLink;
 //@description Contains information about a link to a message in a chat
 //@is_public True, if the link is a public link for a message in a chat
 //@chat_id If found, identifier of the chat to which the message belongs, 0 otherwise
+//@message_thread_id If found, identifier of the message thread in which to open the message, or which to open in case of a missing message
 //@message If found, the linked message; may be null
 //@media_timestamp Timestamp from which the video/audio/video note/voice note playing must start, in seconds; 0 if not specified. The media can be in the message content or in its web page preview
 //@for_album True, if the whole media album to which the message belongs is linked
-//@for_comment True, if the message is linked as a channel post comment or from a message thread
+messageLinkInfo is_public:Bool chat_id:int53 message_thread_id:int53 message:message media_timestamp:int32 for_album:Bool = MessageLinkInfo;
-messageLinkInfo is_public:Bool chat_id:int53 message:message media_timestamp:int32 for_album:Bool for_comment:Bool = MessageLinkInfo;
 
 
 //@description Contains a part of a file @data File bytes

td/telegram/LinkManager.cpp

@@ -1752,6 +1752,7 @@ Result<MessageLinkInfo> LinkManager::get_message_link_info(Slice url) {
   Slice channel_id_slice;
   Slice message_id_slice;
   Slice comment_message_id_slice = "0";
+  Slice top_thread_message_id_slice;
   Slice media_timestamp_slice;
   bool is_single = false;
   bool for_comment = false;
@@ -1803,10 +1804,12 @@ Result<MessageLinkInfo> LinkManager::get_message_link_info(Slice url) {
       }
       if (key_value.first == "thread") {
         for_comment = true;
+        top_thread_message_id_slice = key_value.second;
       }
     }
   } else {
     // /c/123456789/12345
+    // /c/123456789/1234/12345
     // /username/12345?single
 
     CHECK(!url.empty() && url[0] == '/');
@@ -1845,9 +1848,15 @@ Result<MessageLinkInfo> LinkManager::get_message_link_info(Slice url) {
         }
         if (key_value.first == "thread") {
           for_comment = true;
+          top_thread_message_id_slice = key_value.second;
         }
       }
     }
+    auto slash_pos = message_id_slice.find('/');
+    if (slash_pos != Slice::npos) {
+      top_thread_message_id_slice = message_id_slice.substr(0, slash_pos);
+      message_id_slice.remove_prefix(slash_pos + 1);
+    }
   }
 
   ChannelId channel_id;
@@ -1864,6 +1873,18 @@ Result<MessageLinkInfo> LinkManager::get_message_link_info(Slice url) {
     return Status::Error("Wrong message ID");
   }
 
+  int32 top_thread_message_id = 0;
+  if (!top_thread_message_id_slice.empty()) {
+    auto r_top_thread_message_id = to_integer_safe<int32>(top_thread_message_id_slice);
+    if (r_top_thread_message_id.is_error()) {
+      return Status::Error("Wrong message thread ID");
+    }
+    top_thread_message_id = r_top_thread_message_id.ok();
+    if (!ServerMessageId(top_thread_message_id).is_valid()) {
+      return Status::Error("Invalid message thread ID");
+    }
+  }
+
   auto r_comment_message_id = to_integer_safe<int32>(comment_message_id_slice);
   if (r_comment_message_id.is_error() ||
       !(r_comment_message_id.ok() == 0 || ServerMessageId(r_comment_message_id.ok()).is_valid())) {
@@ -1912,6 +1933,7 @@ Result<MessageLinkInfo> LinkManager::get_message_link_info(Slice url) {
   info.channel_id = channel_id;
   info.message_id = MessageId(ServerMessageId(r_message_id.ok()));
   info.comment_message_id = MessageId(ServerMessageId(r_comment_message_id.ok()));
+  info.top_thread_message_id = MessageId(ServerMessageId(top_thread_message_id));
   info.media_timestamp = is_media_timestamp_invalid ? 0 : media_timestamp;
   info.is_single = is_single;
   info.for_comment = for_comment;

td/telegram/MessageLinkInfo.h

@@ -23,6 +23,8 @@ struct MessageLinkInfo {
   bool is_single = false;
   int32 media_timestamp = 0;
 
+  MessageId top_thread_message_id;
+
   DialogId comment_dialog_id;
   MessageId comment_message_id;
   bool for_comment = false;

td/telegram/MessagesManager.cpp

@@ -19513,32 +19513,45 @@ td_api::object_ptr<td_api::messageLinkInfo> MessagesManager::get_message_link_in
   DialogId dialog_id = info.comment_dialog_id.is_valid()
                            ? info.comment_dialog_id
                            : (is_public ? resolve_dialog_username(info.username) : DialogId(info.channel_id));
+  MessageId top_thread_message_id;
   MessageId message_id = info.comment_dialog_id.is_valid() ? info.comment_message_id : info.message_id;
   td_api::object_ptr<td_api::message> message;
   int32 media_timestamp = 0;
   bool for_album = false;
-  bool for_comment = false;
 
   const Dialog *d = get_dialog(dialog_id);
   if (d == nullptr) {
     dialog_id = DialogId();
+    top_thread_message_id = MessageId();
   } else {
     const Message *m = get_message(d, message_id);
     if (m != nullptr) {
       message = get_message_object(dialog_id, m, "get_message_link_info_object");
       for_album = !info.is_single && m->media_album_id != 0;
-      for_comment = (info.comment_dialog_id.is_valid() || info.for_comment) && m->top_thread_message_id.is_valid();
+      if (info.comment_dialog_id.is_valid() || info.for_comment || m->is_topic_message) {
+        top_thread_message_id = m->top_thread_message_id;
+      } else {
+        top_thread_message_id = MessageId();
+      }
       if (can_message_content_have_media_timestamp(m->content.get())) {
         auto duration = get_message_content_media_duration(m->content.get(), td_);
         if (duration == 0 || info.media_timestamp <= duration) {
           media_timestamp = info.media_timestamp;
         }
       }
+      if (m->content->get_type() == MessageContentType::TopicCreate && m->top_thread_message_id.is_valid()) {
+        message = nullptr;
+        CHECK(!for_album);
+        CHECK(media_timestamp == 0);
+      }
+    } else if (!info.comment_dialog_id.is_valid() && dialog_id.get_type() == DialogType::Channel &&
+               !is_broadcast_channel(dialog_id)) {
+      top_thread_message_id = info.top_thread_message_id;
     }
   }
 
-  return td_api::make_object<td_api::messageLinkInfo>(is_public, dialog_id.get(), std::move(message), media_timestamp,
+  return td_api::make_object<td_api::messageLinkInfo>(is_public, dialog_id.get(), top_thread_message_id.get(),
-                                                      for_album, for_comment);
+                                                      std::move(message), media_timestamp, for_album);
 }
 
 InputDialogId MessagesManager::get_input_dialog_id(DialogId dialog_id) const {