MP: wait at the loading screen until initial lobby data is fetched

This does require some more usability improvements in the future, though. First off, this change was introduced
to get rid of that pause when the lobby is first opened before any contents appears. However, this change only
affects the initial connection, not any subsequent returns to the lobby.

Second, this also means the user doesn't have a way to quit to the titlescreen if the data fetching is taking an
especially long time anymore. It was suggested instead of this, we add some indicator to the lobby that data is
being fetched, but I don't know if that's really feasible with our toolkit. Still, we should add some way to exit
the loading screen if this is taking too long.

Lastly (and building on the above, though this is a more general issue), if at any point the server conks out and
doesn't send the lobby data, or a handshake, or anything, there's no way to exit the loading screen at that point.
Need to come up with a solution for that - either a timeout, or an exit button.

src/game_initialization/multiplayer.cpp

@@ -49,6 +49,8 @@ static lg::log_domain log_mp("mp/main");
 
 namespace
 {
+config initial_lobby_config;
+
 /** Opens a new server connection and prompts the client for login credentials, if necessary. */
 wesnothd_connection_ptr open_connection(CVideo& video, std::string host)
 {
@@ -82,8 +84,6 @@ wesnothd_connection_ptr open_connection(CVideo& video, std::string host)
 		return sock;
 	}
 
-	config data;
-
 	// Start stage
 	gui2::dialogs::loading_screen::progress(loading_stage::connect_to_server);
 
@@ -95,6 +95,16 @@ wesnothd_connection_ptr open_connection(CVideo& video, std::string host)
 
 	gui2::dialogs::loading_screen::progress(loading_stage::waiting);
 
+	config data;
+
+	// Clear the initial saved config to be sure we don't swap old data
+	// into `data` when we grab the new game/user list.
+	initial_lobby_config.clear();
+
+	bool received_join_lobby = false;
+	bool received_join_game = false;
+	bool received_gamelist = false;
+
 	// Then, log in and wait for the lobby/game join prompt.
 	do {
 		if(!sock) {
@@ -149,7 +159,7 @@ wesnothd_connection_ptr open_connection(CVideo& video, std::string host)
 
 		// Continue if we did not get a direction to login
 		if(!data.has_child("mustlogin")) {
-			continue;
+			goto data_check;
 		}
 
 		// Enter login loop
@@ -334,9 +344,27 @@ wesnothd_connection_ptr open_connection(CVideo& video, std::string host)
 			// is still going to be nullptr
 			if(!*error) break;
 		} // end login loop
-	} while(!(data.child("join_lobby") || data.child("join_game")));
 
-	if(!data.has_child("join_lobby")) {
+data_check:
+
+		if(data.has_child("join_lobby")) {
+			received_join_lobby = true;
+
+			gui2::dialogs::loading_screen::progress(loading_stage::download_lobby_data);
+		}
+
+		if(data.has_child("join_game")) {
+			received_join_game = true;
+		}
+
+		if(data.has_child("gamelist")) {
+			received_gamelist = true;
+
+			std::swap(initial_lobby_config, data);
+		}
+	} while(!(received_join_lobby && received_gamelist) && !received_join_game);
+
+	if(!received_join_lobby) {
 		return wesnothd_connection_ptr();
 	}
 
@@ -493,6 +521,11 @@ bool enter_lobby_mode(mp_workflow_helper_ptr helper, const std::vector<std::stri
 		mp::lobby_info li(helper->game_config, installed_addons);
 		helper->lobby_info = &li;
 
+		if(!initial_lobby_config.empty()) {
+			li.process_gamelist(initial_lobby_config);
+			initial_lobby_config.clear();
+		}
+
 		int dlg_retval = 0;
 		int dlg_joined_game_id = 0;
 		{

src/gui/dialogs/loading_screen.cpp

@@ -69,6 +69,7 @@ static const std::map<loading_stage, std::string> stage_names {
 	{ loading_stage::redirect,            N_("Connecting to redirected server") },
 	{ loading_stage::next_scenario,       N_("Waiting for next scenario") },
 	{ loading_stage::download_level_data, N_("Getting game data") },
+	{ loading_stage::download_lobby_data, N_("Downloading lobby data") },
 };
 
 namespace gui2

src/gui/dialogs/loading_screen.hpp

@@ -59,6 +59,7 @@ enum class loading_stage
 	redirect,
 	next_scenario,
 	download_level_data,
+	download_lobby_data,
 	none,
 };
 

src/gui/dialogs/multiplayer/lobby.cpp

@@ -139,7 +139,7 @@ mp_lobby::mp_lobby(const config& game_config, mp::lobby_info& info, wesnothd_con
 	, filter_text_(nullptr)
 	, selected_game_id_()
 	, player_list_()
-	, player_list_dirty_(false)
+	, player_list_dirty_(true)
 	, gamelist_dirty_(true)
 	, last_gamelist_update_(0)
 	, gamelist_diff_update_(true)
@@ -822,7 +822,13 @@ void mp_lobby::pre_show(window& window)
 	game_filter_reload();
 
 	// Force first update to be directly.
-	mp_lobby::network_handler();
+	update_gamelist();
+	update_playerlist();
+
+	// TODO: currently getting a crash in the chatbox if we use this.
+	// -- vultraz, 2017-11-10
+	//mp_lobby::network_handler();
+
 	lobby_update_timer_ = add_timer(
 		game_config::lobby_network_timer, std::bind(&mp_lobby::network_handler, this), true);