//
// Created by atdunbg on 2026/9/20.
//
// SandboxApp：第一个基于 Application 框架的程序。
//
// main 的全部职责：定义一个 Application 派生类并运行它。
// 窗口、渲染器、事件泵、帧计时、场景容器全部由框架管理；
// 这里只写"程序逻辑"：创建实体、逐帧更新组件、事件响应。
//

#include <Engine/Core/Application.h>
#include <Engine/Core/Log.h>
#include <Engine/Core/Stats.h>
#include <Engine/ECS/Scene.h>
#include <Engine/ECS/EntityHandle.h>
#include <Engine/ECS/Components.h>
#include <Engine/Assets/AssetManager.h>
#include <Engine/Renderer/Renderer.h>

#include <imgui.h>

#include <glm/glm.hpp>
#include <glm/gtc/matrix_transform.hpp>

#include <GLFW/glfw3.h>

#include "Engine/ImGui/ImGuiLayer.h"

using namespace Engine;
using namespace Engine::ECS;

class SandboxApp final : public Application
{
public:
    SandboxApp()
        : Application("HelloVulkan", 800, 600)
    {
    }

protected:
    // ---- 生命周期 ----

    void OnInit() override
    {
        Scene& scene = GetScene();

        // ImGui 叠加层（框架只做管线桥接，UI 内容全部在这里定义）
        EnableImGui();

        // 模型资产（AssetManager 负责加载/缓存/生命周期，返回句柄）
        auto backpack = GetAssets().LoadModel("assets/models/backpack/backpack.obj");

        // 地面：程序化纯色平面（半边长 15，中心 y=-2）
        auto ground = GetAssets().CreatePlane(15.0f, 140, 140, 145);

        m_Ground = scene.CreateEntity("Ground");
        m_Ground.AddComponent<TransformComponent>()
            .SetPosition(glm::vec3(0.0f, -0.5f, 0.0f))
            .Compose();
        m_Ground.AddComponent<MeshRendererComponent>(MeshRendererComponent{ground});

        // 相机实体（primary = 当前渲染视角）
        m_Camera = scene.CreateEntity("MainCamera");
        auto& camera = m_Camera.AddComponent<CameraComponent>();
        camera.primary = true;
        camera.camera.SetPosition(glm::vec3(0.0f, 0.0f, 7.0f));

        // 背包实体 × 3（悬浮在地面上方）
        for (int i = 0; i < 3; ++i) {
            auto e = scene.CreateEntity("Backpack" + std::to_string(i));

            e.AddComponent<TransformComponent>()
                .SetPosition(glm::vec3((i - 1) * 1.5f, 0.0f, 0.0f))
                .SetScale(glm::vec3(0.5f))
                .Compose();

            e.AddComponent<MeshRendererComponent>(MeshRendererComponent{backpack});

            m_Spinners.push_back(e);
        }

        // 灯光实体（第一个灯 = 阴影光源）
        m_KeyLight = scene.CreateEntity("KeyLight");
        m_KeyLight.AddComponent<LightComponent>(
            LightComponent{glm::vec3(-0.5f, -0.6f, -0.35f),
                           glm::vec4(1.0f, 0.95f, 0.9f, 1.0f)});

        scene.CreateEntity("FillLight")
            .AddComponent<LightComponent>(
                LightComponent{glm::vec3(0.5f, -0.5f, 0.3f),
                               glm::vec4(0.3f, 0.5f, 1.0f, 0.8f)});
    }

    void OnUpdate(f32 deltaTime) override
    {
        m_Time += deltaTime;

        // 相机（WASD/Space/Shift 移动）
        m_Camera.GetComponent<CameraComponent>()
            .camera.Update(GetWindow(), deltaTime);

        // 旋转动画：编辑 Transform 分量后 Compose 重算 world
        for (size_t i = 0; i < m_Spinners.size(); ++i) {
            auto& t = m_Spinners[i].GetComponent<TransformComponent>();
            t.position = glm::vec3((static_cast<f32>(i) - 1.0f) * 1.5f, 0.0f, 0.0f);
            t.rotation.y = m_Time * 60.0f + static_cast<f32>(i) * 40.0f;
            t.scale = glm::vec3(0.5f);
            t.Compose();
        }
    }

    // ---- 事件 ----

    // ---- 叠加层 UI（唯一允许出现 ImGui 控件的地方）----

    void OnRenderOverlay() override
    {
        if (!m_OverlayVisible) return;

        ImGui::ShowDemoWindow();

        ImGui::Begin("Scene Debug");

        // 阴影光源方向：拖动滑条实时看影子变化
        if (auto* light = m_KeyLight.TryGetComponent<LightComponent>()) {
            ImGui::Text("Key Light (shadow caster)");
            ImGui::SliderFloat3("direction",
                                &light->direction.x, -1.0f, 1.0f);
            if (ImGui::Button("reset")) {
                light->direction = glm::vec3(-0.5f, -0.6f, -0.35f);
            }
        }

        // Tonemap + Bloom 参数（HDR 后处理输出端）
        auto& renderer = GetRenderer();
        ImGui::Separator();
        ImGui::Text("Tonemap");
        f32 exposure = renderer.GetExposure();
        if (ImGui::SliderFloat("exposure", &exposure, 0.1f, 4.0f)) {
            renderer.SetExposure(exposure);
        }
        bool aces = renderer.GetUseACES();
        if (ImGui::Checkbox("ACES", &aces)) {
            renderer.SetUseACES(aces);
        }

        ImGui::Text("Bloom");
        f32 threshold = renderer.GetBloomThreshold();
        if (ImGui::SliderFloat("threshold", &threshold, 0.0f, 2.0f)) {
            renderer.SetBloomThreshold(threshold);
        }
        f32 strength = renderer.GetBloomStrength();
        if (ImGui::SliderFloat("strength", &strength, 0.0f, 2.0f)) {
            renderer.SetBloomStrength(strength);
        }

        ImGui::Separator();
        ImGui::Text("fps: %.1f  frame: %llu",
                    1.0f / GetDeltaTime(),
                    static_cast<unsigned long long>(GetFrameCount()));

        ImGui::End();
    }

    void OnKeyPress(const Event& event) override
    {
        if (event.key == GLFW_KEY_GRAVE_ACCENT) {
            m_OverlayVisible = !m_OverlayVisible;   // ` 反折叠加层
        }
        if (event.key == GLFW_KEY_F1) {
            STATS.PrintComparison();
        }
        if (event.key == GLFW_KEY_ESCAPE) {
            Close();
        }
    }

    void OnWindowResize(const Event& event) override
    {
        ENGINE_INFO("App: window resized to {}x{}", event.width, event.height);
    }

private:
    EntityHandle m_Camera{};                 // Scene::CreateEntity 之前为空
    EntityHandle m_Ground{};
    EntityHandle m_KeyLight{};
    std::vector<EntityHandle> m_Spinners;
    bool m_OverlayVisible = true;
    f32 m_Time = 0.0f;
};

int main()
{
    SandboxApp app;

    try {
        app.Run();
    }
    catch (const std::exception& e) {
        ENGINE_FATAL("Exception: {}", e.what());
        return -1;
    }

    return 0;
}