[Server] Add game lifecycle strategy hook (#7130)

Took 30 minutes

Co-authored-by: Lukas Brübach <Bruebach.Lukas@bdosecurity.de>

libcockatrice_network/libcockatrice/network/server/remote/CMakeLists.txt

@@ -13,6 +13,7 @@ set(HEADERS
     game/game_config.h
     game/server_deck_validation_strategy.h
     game/server_game.h
+    game/server_game_lifecycle_strategy.h
     game/server_player.h
     game/server_spectator.h
     server.h

libcockatrice_network/libcockatrice/network/server/remote/game/server_game.cpp

@@ -63,7 +63,7 @@ Server_Game::Server_Game(const GameConfig &config, Server_Room *_room)
       startingLifeTotal(config.startingLifeTotal), shareDecklistsOnLoad(config.shareDecklistsOnLoad),
       inactivityCounter(0), startTimeOfThisGame(0), secondsElapsed(0), firstGameStarted(false),
       turnOrderReversed(false), startTime(QDateTime::currentDateTime()), pingClock(nullptr),
-      deckValidationStrategy(new Server_DefaultDeckValidationStrategy), gameMutex()
+      lifecycleStrategy(new Server_DefaultLifecycleStrategy), gameMutex()
 {
     currentReplay = new GameReplay;
     currentReplay->set_replay_id(room->getServer()->getDatabaseInterface()->getNextReplayId());
@@ -329,6 +329,11 @@ void Server_Game::doStartGameIfReady(bool forceStartGame)
     }
 
     players = getPlayers(); // players could have been kicked, get new list of players
+    if (lifecycleStrategy->onGameStarting(this) == Server_GameLifecycleStrategy::StartAction::Handled) {
+        locker.unlock();
+        return;
+    }
+
     for (Server_AbstractPlayer *player : players.values()) {
         player->setupZones();
     }

libcockatrice_network/libcockatrice/network/server/remote/game/server_game.h

@@ -23,6 +23,7 @@
 #include "../server_response_containers.h"
 #include "game_config.h"
 #include "server_deck_validation_strategy.h"
+#include "server_game_lifecycle_strategy.h"
 
 #include <QDateTime>
 #include <QMap>
@@ -83,6 +84,8 @@ private:
 
     QScopedPointer<Server_DeckValidationStrategy> deckValidationStrategy;
 
+    QScopedPointer<Server_GameLifecycleStrategy> lifecycleStrategy;
+
     void createGameStateChangedEvent(Event_GameStateChanged *event,
                                      Server_AbstractParticipant *recipient,
                                      bool omniscient,
@@ -220,6 +223,12 @@ public:
     }
     /** @brief Replace the deck validation strategy; takes ownership of @p strategy. */
     void setDeckValidationStrategy(Server_DeckValidationStrategy *strategy);
+
+    /** @brief Get the current game lifecycle strategy (non-owning). */
+    Server_GameLifecycleStrategy *getLifecycleStrategy() const
+    {
+        return lifecycleStrategy.data();
+    }
 };
 
 #endif

libcockatrice_network/libcockatrice/network/server/remote/game/server_game_lifecycle_strategy.h

@@ -0,0 +1,43 @@
+#ifndef SERVER_GAME_LIFECYCLE_STRATEGY_H
+#define SERVER_GAME_LIFECYCLE_STRATEGY_H
+
+class Server_Game;
+
+/**
+ * @brief Strategy hook invoked around a game's lifecycle transitions.
+ *
+ * Subclasses can intercept the game start to perform custom setup (e.g. draft or
+ * tournament initialization); the default implementation never intercepts.
+ */
+class Server_GameLifecycleStrategy
+{
+public:
+    virtual ~Server_GameLifecycleStrategy() = default;
+
+    /** @brief How the game start should proceed after this hook returns. */
+    enum class StartAction
+    {
+        ProceedNormal, ///< Continue with the normal game start flow.
+        Handled,       ///< The strategy handled the start; abort the normal flow.
+    };
+
+    /**
+     * @brief Called when a game is about to start.
+     * @return How the start flow should proceed.
+     */
+    virtual StartAction onGameStarting(Server_Game *game) = 0;
+};
+
+/**
+ * @brief Default lifecycle strategy that never intercepts the game start.
+ */
+class Server_DefaultLifecycleStrategy : public Server_GameLifecycleStrategy
+{
+public:
+    StartAction onGameStarting(Server_Game *) override
+    {
+        return StartAction::ProceedNormal;
+    }
+};
+
+#endif