//
// 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>


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）
        // SunTemple：FBX + DDS 压缩贴图（DdsLoader 验证场景）
        const auto model = GetAssets().LoadModel("assets/models/backpack/backpack.obj");
        const auto temple = GetAssets().LoadModel("assets/models/SunTemple/SunTemple.fbx");

        m_Spinners.push_back(scene.CreateEntity("backpack"));
        m_Spinners[0].AddComponent<MeshRendererComponent>(MeshRendererComponent{model});

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

        m_Ground = scene.CreateEntity("Ground");
        m_Ground.GetComponent<TransformComponent>()
                .SetPosition(glm::vec3(0.0f, -0.5f, 0.0f));   // dirty → 帧循环统一 Compose
        m_Ground.AddComponent<MeshRendererComponent>(MeshRendererComponent{ground});

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

        // 神庙实体 × 1（ FBX 单位较大，缩放到场景尺度）
        {
            auto e = scene.CreateEntity("SunTemple");
            e.GetComponent<TransformComponent>()
             .SetScale(glm::vec3(0.05f));
            e.AddComponent<MeshRendererComponent>(MeshRendererComponent{temple});
        }

        // 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
    {
        // 暂停时冻结动画时钟（帧历史验证：暂停后 Temporal Diff
        // 视图应在 2 帧内整屏变黑；相机移动同样会被 diff 捕捉到）
        if (!m_PauseAnim)
        {
            m_Time += deltaTime;
        }

        // 相机（WASD/Space/Shift 移动；位姿读写实体 Transform）
        m_Camera.GetComponent<CameraComponent>()
                .camera.Update(GetWindow(),
                               m_Camera.GetComponent<TransformComponent>(),
                               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.SetRotation(glm::vec3(0.0f, m_Time * 60.0f + static_cast<f32>(i) * 40.0f, 0.0f));
            t.SetScale(glm::vec3(0.5f));
        }
    }

    // ---- 事件 ----

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

    void OnRenderOverlay() override
    {
        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);
        }

        // 调试视图：帧历史差异（静止=黑，运动边缘发光=链路正确）
        bool temporalDiff = renderer.GetShowTemporalDiff();
        if (ImGui::Checkbox("Temporal Diff View", &temporalDiff))
        {
            renderer.SetShowTemporalDiff(temporalDiff);
        }
        ImGui::Checkbox("Pause Animation", &m_PauseAnim);

        // Pass 级 GPU 耗时（RG timestamp）
        ImGui::Separator();
        ImGui::Text("GPU Timings");
        ImGui::Text("instances: %u main / %u shadow",
                    renderer.GetMainInstanceCount(),
                    renderer.GetShadowInstanceCount());
        const auto& names = renderer.GetPassNames();
        const auto& times = renderer.GetPassGpuMs();
        for (size_t i = 0; i < names.size() && i < times.size(); ++i)
        {
            ImGui::Text("  %-12s %.3f ms", names[i].c_str(), times[i]);
        }

        // 帧率控制
        auto& app = *this;
        ImGui::Separator();
        ImGui::Text("Frame");
        bool vsync = app.GetVSync();
        if (ImGui::Checkbox("VSync", &vsync))
        {
            app.SetVSync(vsync);
            if (!vsync)
            {
                const f32 target = app.GetTargetFps();
                app.SetTargetFps(target);
            }
        }
        if (!vsync)
        {
            f32 target = app.GetTargetFps();
            if (ImGui::SliderFloat("target fps", &target, 24.0f, 360.0f, "%.0f"))
            {
                app.SetTargetFps(target);
            }
        }

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

        ImGui::End();


        // 自定义重载事件： 重载关闭事件模态框
        {
            if (m_ShowQuitConfirm)
            {
                ImGui::OpenPopup("Should quit?");
                m_ShowQuitConfirm = false;
            }

            ImGui::SetNextWindowPos(
                ImGui::GetMainViewport()->GetCenter(),
                ImGuiCond_Appearing, ImVec2(0.5f, 0.5f));

            if (ImGui::BeginPopupModal("Should quit?", nullptr,
                                       ImGuiWindowFlags_AlwaysAutoResize))
            {
                ImGui::TextUnformatted("Quit the application?");
                ImGui::Separator();
                if (ImGui::Button("Yes", ImVec2(120, 0)))
                {
                    m_QuitConfirmed = true;
                    ImGui::CloseCurrentPopup();
                }
                ImGui::SameLine();
                if (ImGui::Button("No", ImVec2(120, 0)))
                {
                    ImGui::CloseCurrentPopup();
                }
                ImGui::EndPopup();
            }

            if (m_QuitConfirmed)
            {
                m_QuitConfirmed = false;
                Close();
            }
        }
    }

    void OnWindowClose(const Event& event) override
    {
        m_ShowQuitConfirm = true;
    }

    void OnKeyPress(const Event& event) override
    {
        if (event.key == GLFW_KEY_GRAVE_ACCENT)
        {
            SetImGuiEnabled(!GetImGuiEnabled());
        }
        if (event.key == GLFW_KEY_F1)
        {
            STATS.PrintComparison();
        }
    }


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

private:
    bool m_ShowQuitConfirm = false;
    bool m_QuitConfirmed = false;
    EntityHandle m_Camera{}; // Scene::CreateEntity 之前为空
    EntityHandle m_Ground{};
    EntityHandle m_KeyLight{};
    std::vector<EntityHandle> m_Spinners;
    f32 m_Time = 0.0f;
    bool m_PauseAnim = false;   // 冻结动画时钟（帧历史 diff 验证用）
};

int main()
{
    SandboxApp app;

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

    return 0;
}