state.h

// SPDX-License-Identifier: MIT
// SPDX-FileCopyrightText: 2025-2026 Manuel Osorio
#pragma once
#include "flint/graphics/renderer.h"
#include "flint/window/IWindow.h"
 
#include <deque>
#include <memory>
#include <vector>
 
namespace Flint {
 
  class State {
    public:
      virtual ~State() = default;
      virtual void handleInput(IWindow &window) = 0;
 
      virtual void update(float deltaTime) = 0;
 
      virtual void render(GPURenderer &gpuRenderer, IWindow &window) = 0;
 
      virtual void onEnter() {
      }
 
      virtual void onExit() {
      }
 
    protected:
      std::string m_contextName;
  };
 
  class StateManager {
    public:
      StateManager() = default;
      virtual ~StateManager() = default;
      enum class TransitionType {
        PUSH,    
        POP,     
        REPLACE, 
        CLEAR    
      };
 
      struct PendingTransition {
          TransitionType         type;  
          std::unique_ptr<State> state; 
      };
 
      void pushState(std::unique_ptr<State> state);
 
      void popState();
 
      void replaceState(std::unique_ptr<State> state);
 
      [[nodiscard]] State *currentState() const;
 
      [[nodiscard]] bool empty() const;
 
      void queueTransition(TransitionType type, std::unique_ptr<State> newState);
 
      void applyTransitions();
 
      void clearStates();
 
      const std::vector<std::unique_ptr<State>> &getStates() const;
 
      void renderAllBelow(GPURenderer &gpuRenderer, IWindow &window, State *topState) const;
 
      State *peekBelow(const State *top) const;
 
    private:
      std::vector<std::unique_ptr<State>> m_states;
      std::deque<PendingTransition>       m_transitionQueue;
  };
}