ServerLoop.hpp

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/*
** EPITECH PROJECT, 2025
** rtype
** File description:
** ServerLoop.hpp - Fixed timestep game loop for deterministic gameplay
*/
 
#pragma once
 
#include <atomic>
#include <memory>
#include <mutex>
#include <thread>
#include "common/ECSWrapper/ECSWorld.hpp"
#include "server/Core/Clock/FrameTimer.hpp"
#include "server/Core/ServerLoop/IServerLoop.hpp"
#include "server/Game/Logic/IGameLogic.hpp"
 
namespace server {
 
    class EventBus;
 
    class ServerLoop : public IServerLoop {
       public:
        explicit ServerLoop(std::unique_ptr<IGameLogic> gameLogic, std::shared_ptr<EventBus> eventBus,
                            float gameSpeedMultiplier = 1.0f);
 
        ~ServerLoop() override;
 
        bool initialize();
 
        void start() override;
 
        void stop() override;
 
        bool isRunning() const override { return _loopThread.joinable(); }
 
        uint32_t getCurrentTick() const;
 
        IGameLogic &getGameLogic() { return *_gameLogic; }
 
        std::shared_ptr<ecs::wrapper::ECSWorld> getECSWorld();
 
        float getGameSpeedMultiplier() const { return _gameSpeedMultiplier; }
 
       private:
        void _gameLoopThread(std::stop_token stopToken);
 
        void _fixedUpdate();
 
        // Game logic
        std::unique_ptr<IGameLogic> _gameLogic;
        std::shared_ptr<EventBus> _eventBus;
        FrameTimer _frameTimer;
 
        // Threading
        std::jthread _loopThread;
        std::atomic<bool> _initialized{false};
 
        // Timing
        static constexpr float BASE_FIXED_TIMESTEP = 1.0f / 60.0f;  // 60 Hz base rate
        static constexpr float MAX_FRAME_ACCUMULATOR = 0.2f;        // Skip frames if lag > 200ms
 
        float _gameSpeedMultiplier{1.0f};  // Game speed multiplier (0.25 to 1.0)
        float _scaledTimestep{
            BASE_FIXED_TIMESTEP};  // Scaled timestep = base * multiplier (passed to systems)
        double _timeAccumulator{0.0};
        uint32_t _frameCount{0};
        uint32_t _skippedFrames{0};
 
        // Synchronization
        mutable std::mutex _stateMutex;
    };
 
}  // namespace server