cs381/as6/SceneManager.hpp

#pragma once

#include "Draw.hpp"
#include "Entities.hpp"
#include "Systems.hpp"

#include "raylib.h"

#include <memory>
#include <utility>
#include <vector>

class SceneManager;

class Scene {
  public:
    explicit Scene(SceneManager &owner) : manager(owner) {}
    virtual ~Scene() = default;

    virtual void Enter() {}
    virtual void Exit() {}
    virtual void Update(float dt) = 0;
    virtual void Draw() = 0;

  protected:
    SceneManager &manager;
};

/**
 * Manages the current active scene, using an object oriented state machine approach.
 */
class SceneManager {
  public:
    /**
     * @brief Changes the current scene, invoking `Exit` on the old scene and `Enter`
     * on the new scene. The new scene is constructed in-place with the provided arguments.
     *
     * @tparam T The type of the new scene, must derive from `Scene`.
     * @param args Arguments forwarded to the constructor of the new scene.
     */
    template <typename T, typename... Args> void ChangeScene(Args &&...args);

    /**
     * @brief Changes to the provided next scene, invoking `Exit` on the old scene and
     * `Enter` on the new scene.
     *
     * @param nextScene The new scene to switch to.
     */
    void ChangeScene(std::unique_ptr<Scene> nextScene);
    void Update(float dt);
    void Draw();

  private:
    // use unique_ptr to enforce single ownership and ensure proper cleanup on
    // scene change
    std::unique_ptr<Scene> current;
};

class StartMenuScene;
class GameplayScene;
class DeathScene;

class StartMenuScene : public Scene {
  public:
    explicit StartMenuScene(SceneManager &owner) : Scene(owner) {}
    void Update(float dt) override;
    void Draw() override;
};

class GameplayScene : public Scene {
  public:
    explicit GameplayScene(SceneManager &owner) : Scene(owner) {}
    void Enter() override;
    void Update(float dt) override;
    void Draw() override;

  private:
    std::vector<std::shared_ptr<Entity>> entities;
    GameContext context;
    bool wantsDeathScene = false;
    int collectedCount = 0;
    float meterValue = 60.0f;
};

class DeathScene : public Scene {
  public:
    explicit DeathScene(SceneManager &owner) : Scene(owner) {}
    void Update(float dt) override;
    void Draw() override;
};

inline void SceneManager::ChangeScene(std::unique_ptr<Scene> nextScene) {
    if (current) {
        current->Exit();
    }

    current = std::move(nextScene);
    if (current) {
        current->Enter();
    }
}

inline void SceneManager::Update(float dt) {
    if (current) {
        current->Update(dt);
    }
}

inline void SceneManager::Draw() {
    if (current) {
        current->Draw();
    }
}

inline void StartMenuScene::Update(float) {
    if (IsKeyPressed(KEY_ENTER) || IsMouseButtonPressed(MOUSE_BUTTON_LEFT)) {
        manager.ChangeScene<GameplayScene>();
    }
}

inline void StartMenuScene::Draw() {
    DrawSceneOutline();
    DrawText("Gravity Surfing", 24, 28, 36, Color{230, 238, 255, 255});
    DrawText("Click or press Enter to start", 24, 78, 22, Color{140, 198, 220, 255});
    DrawText("Left mouse controls gravity well", 24, 130, 18, Color{170, 185, 205, 255});
    DrawText("Collect stars and dodge hazards", 24, 156, 18, Color{170, 185, 205, 255});
}

inline void GameplayScene::Enter() {
    entities.clear();
    entities.reserve(20);
    context = {};
    wantsDeathScene = false;
    collectedCount = 0;
    meterValue = 60.0f;

    context.onPlayerDeath = [this]() { wantsDeathScene = true; };
    context.AddCollectiblePickedListener([this](Entity &) { ++collectedCount; });
    context.AddMeterChangedListener([this](float, float newValue) { meterValue = newValue; });

    entities.push_back(CreateWorld());
    entities.push_back(CreateGravityWell());
    entities.push_back(CreateProbe());
    entities.push_back(CreateStar(900.0f, 120.0f));
    entities.push_back(CreateAsteroid(1100.0f, 330.0f));
    entities.push_back(CreateNullZone(1280.0f, 70.0f));
    entities.push_back(CreateHUD());

    if (auto meter = entities.back()->GetComponent<MeterComponent>()) {
        meterValue = meter->get().value;
    }
}

inline void GameplayScene::Update(float dt) {
    UpdateAllSystems(entities, context, dt);
    if (wantsDeathScene) {
        manager.ChangeScene<DeathScene>();
    }
}

inline void GameplayScene::Draw() {
    DrawSceneOutline();
    DrawText("Gravity Surfing", 14, 12, 20, Color{230, 238, 255, 255});

    auto worldScroll = entities[0]->GetComponent<ScrollComponent>();
    auto probeTransform = entities[2]->GetComponent<TransformComponent>();

    if (worldScroll) {
        DrawText(TextFormat("scrollX: %.2f", worldScroll->get().scrollX), 14, 40, 16,
                 Color{125, 225, 205, 255});
    }

    if (probeTransform) {
        const auto &probe = probeTransform->get();
        DrawText(TextFormat("probe: (%.1f, %.1f)", probe.x, probe.y), 14, 60, 16,
                 Color{235, 215, 125, 255});
    }

    DrawText(TextFormat("meter: %.1f", meterValue), 14, 80, 16, Color{120, 210, 190, 255});
    DrawText(TextFormat("stars: %i", collectedCount), 14, 100, 16, Color{255, 223, 86, 255});

    for (auto &entity : entities) {
        if (!entity) {
            continue;
        }

        auto collectible = entity->GetComponent<CollectibleComponent>();
        if (collectible && collectible->get().collected) {
            continue;
        }

        auto render = entity->GetComponent<RenderComponent>();
        if (render) {
            render->get().Draw();
        }
    }
}

inline void DeathScene::Update(float) {
    if (IsKeyPressed(KEY_ENTER) || IsMouseButtonPressed(MOUSE_BUTTON_LEFT)) {
        manager.ChangeScene<GameplayScene>();
        return;
    }

    if (IsKeyPressed(KEY_ESCAPE)) {
        manager.ChangeScene<StartMenuScene>();
    }
}

inline void DeathScene::Draw() {
    DrawSceneOutline();
    DrawText("PROBE LOST", 24, 28, 36, Color{255, 208, 208, 255});
    DrawText("Press Enter or click to restart", 24, 84, 22, Color{255, 170, 170, 255});
    DrawText("Press Esc for menu", 24, 116, 20, Color{200, 188, 188, 255});
}

template <typename T, typename... Args> inline void SceneManager::ChangeScene(Args &&...args) {
    ChangeScene(std::make_unique<T>(*this, std::forward<Args>(args)...));
}