//
// 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/Core/AsyncTask.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 <Engine/Renderer/IblGenerator.h>

#include <imgui.h>

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

#include <GLFW/glfw3.h>

#include <atomic>
#include <thread>

using namespace Engine;
using namespace Engine::ECS;

namespace
{
    // 可切换环境（IBL 动态切换演示）：路径 → AssetManager 缓存去重，
    // 重复选择同一环境零成本；首选路径触发一次 compute 预积分
    constexpr const char* kEnvPaths[] = {
        "assets/textures/venice_dawn_1_4k.hdr",
        "assets/textures/rooitou_park_4k.hdr",
        "assets/textures/pink_sunrise_4k.hdr",
        "assets/textures/birchwood_4k.hdr",
    };
    constexpr const char* kEnvNames[] = {
        "Venice Dawn", "Rooitou Park", "Pink Sunrise", "Birchwood",
    };
    constexpr int kEnvCount = 4;
    constexpr int kDefaultEnv = 0;
    constexpr const char* kTemplePath = "assets/models/SunTemple/SunTemple.fbx";

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

        ~SandboxApp() override
        {
            // worker 只做 CPU 解码（不碰 Vulkan），在任何 GPU 资源
            // 析构之前 join 即安全；派生析构先于基类成员析构执行
            if (m_EnvWorker.joinable()) {
                m_EnvWorker.join();
            }
        }

    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();

            // 默认环境（IBL 四件套）：经资产层加载（compute 预积分，毫秒级），
            // 其余环境在 ImGui 里按需 lazy 加载后切换
            const auto env = GetAssets().LoadEnvironment(
                kEnvPaths[kDefaultEnv]);
            if (env.Valid()) {
                GetRenderer().SetEnvironment(GetAssets().GetEnvironment(env));
            }

            // 模型资产（PBR 验证场景：backpack 为旧式贴图资产，
            // 退化为电介质因子路径——albedo+normal，metallic=0/roughness=0.5）
            const auto model = GetAssets().LoadModel("assets/models/backpack/backpack.obj");
            // const auto model = GetAssets().LoadModel("assets/models/pocket_watch_4k.gltf/pocket_watch_4k.gltf");

            // 大模型异步加载：assimp 解析在 worker 线程（SunTemple 约 3s），
            // 完成后 OnUpdate 收割 → GPU 构建 → 建实体（cm 尺度 → 0.001）
            m_TempleTask.Run([] { return Model::ParseFromDisk(kTemplePath); });
            m_TempleScale = 0.001f;


            int countSize = 0;
            for (int i = 0; i < countSize; i ++)
            {
                for (int j = 0; j < countSize; j ++)
                {
                    auto m = scene.CreateEntity();
                    m.AddComponent<MeshRendererComponent>(MeshRendererComponent{model});
                    m.GetComponent<TransformComponent>().SetPosition(glm::vec3{(i - countSize * 0.5) * 2, 0, (j - countSize * 0.5) * 2});
                    m_Spinners.push_back(m);
                }
            }

            // 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));

            // 灯光实体（第一个方向光 = 阴影光源）
            m_KeyLight = scene.CreateEntity("KeyLight");
            m_KeyLight.AddComponent<LightComponent>(
                LightComponent{
                    .type = LightComponent::Type::Directional,
                    .direction = glm::vec3(-0.5f, -0.6f, -0.35f),
                    .color = glm::vec4(1.0f, 0.95f, 0.9f, 5.0f),
                    .castShadow = true,
                });

            scene.CreateEntity("FillLight")
                 .AddComponent<LightComponent>(
                     LightComponent{
                         .type = LightComponent::Type::Directional,
                         .direction = glm::vec3(0.5f, -0.5f, 0.3f),
                         .color = glm::vec4(0.3f, 0.5f, 1.0f, 1.5f)
                     });

            // 点光源（位置 = 实体 Transform，出生即有；无阴影，距离衰减）
            auto fire = scene.CreateEntity("FirePitLight");
            fire.GetComponent<TransformComponent>().SetPosition(glm::vec3(2.0f, 1.5f, 1.0f));
            fire.AddComponent<LightComponent>(
                LightComponent{
                    .type = LightComponent::Type::Point,
                    .color = glm::vec4(1.0f, 0.6f, 0.3f, 1.0f),   // 暖橙
                    .radius = 8.0f,
                });

            auto cool = scene.CreateEntity("CoolFillLight");
            cool.GetComponent<TransformComponent>().SetPosition(glm::vec3(-2.5f, 2.0f, -2.0f));
            cool.AddComponent<LightComponent>(
                LightComponent{
                    .type = LightComponent::Type::Point,
                    .color = glm::vec4(0.3f, 0.5f, 1.0f, 1.2f),   // 冷蓝
                    .radius = 10.0f,
                });
        }

        void OnUpdate(f32 deltaTime) override
        {
            // 异步模型收割：解析完成 → GPU 构建 → 建实体
            if (m_TempleTask.Done()) {
                ParsedModel parsed = m_TempleTask.Take();
                const auto ref = GetAssets().LoadModel(kTemplePath,
                                                       std::move(parsed));
                if (ref.Valid()) {
                    auto temple = GetScene().CreateEntity("SunTemple");
                    temple.AddComponent<MeshRendererComponent>(
                        MeshRendererComponent{ref});
                    temple.GetComponent<TransformComponent>()
                           .SetScale(glm::vec3{m_TempleScale});
                    ENGINE_INFO("[ASYNC] SunTemple ready, entity created");
                }
            }

            // 异步环境加载：每帧收割完成的解码结果
            PollEnvironment();

            // 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));
            }
        }

        // ---- 事件 ----

        // ---- 异步环境加载（decode 后台线程 / GPU 生成主线程）----
        // decode 占切换耗时大头（4k ≈ 130ms）；worker 只产出纯 CPU
        // 像素数据，Vulkan 生成回主线程（设备非线程安全）。
        // 同一时刻最多一个 in-flight，忙碌期的新请求记为 pending 接力。
        void RequestEnvironment(int idx)
        {
            if (m_EnvLoadBusy)
            {
                m_EnvPending = idx;
                return;
            }
            StartEnvDecode(idx);
        }

        void StartEnvDecode(int idx)
        {
            m_EnvLoadBusy = true;
            m_EnvLoadDone.store(false);
            m_EnvLoadingPath = kEnvPaths[idx];
            m_EnvWorker = std::thread([this, idx]() {
                m_EnvDecoded = IblGenerator::DecodeHdr(kEnvPaths[idx]);
                m_EnvLoadDone.store(true);   // release：解码结果对主线程可见
            });
        }

        void PollEnvironment()
        {
            if (!m_EnvLoadBusy || !m_EnvLoadDone.load())
            {
                return;
            }

            m_EnvWorker.join();   // join = 同步点，解码结果此后归主线程
            m_EnvLoadBusy = false;

            if (m_EnvDecoded.Valid())
            {
                const auto ref = GetAssets().LoadEnvironment(
                    m_EnvLoadingPath, std::move(m_EnvDecoded));
                if (ref.Valid())
                {
                    GetRenderer().SetEnvironment(GetAssets().GetEnvironment(ref));
                }
            }
            m_EnvDecoded = {};

            // 忙碌期间的最新请求接力（rapid switch 只保留最终意图）
            if (m_EnvPending >= 0)
            {
                const int next = m_EnvPending;
                m_EnvPending = -1;
                StartEnvDecode(next);
            }
        }

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

        void OnRenderOverlay() override
        {
            ImGui::Begin("Scene Debug");
            auto& renderer = GetRenderer();

            // ---- Scene：场景内容（灯/动画） ----
            if (ImGui::CollapsingHeader("Scene", ImGuiTreeNodeFlags_DefaultOpen))
            {
                // 阴影光源（无开关，控件平铺聚拢）
                if (auto* light = m_KeyLight.TryGetComponent<LightComponent>())
                {
                    ImGui::Text("Key Light (shadow caster)");
                    ImGui::SliderFloat3("direction",
                                        &light->direction.x, -1.0f, 1.0f);
                    ImGui::SliderFloat("intensity", &light->color.a, 0.0f, 20.0f);
                    if (ImGui::Button("reset"))
                    {
                        light->direction = glm::vec3(-0.5f, -0.6f, -0.35f);
                        light->color.a = 2.0f;
                    }
                }
                ImGui::Checkbox("Pause Animation", &m_PauseAnim);
            }

            // ---- Rendering：渲染管线参数与开关 ----
            if (ImGui::CollapsingHeader("Rendering", ImGuiTreeNodeFlags_DefaultOpen))
            {
                // Tonemap（无开关，平铺）
                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);
                }

                // Bloom：开关即显隐——勾上才显示参数
                bool bloom = renderer.GetBloomEnabled();
                if (ImGui::Checkbox("Bloom", &bloom))
                {
                    renderer.SetBloomEnabled(bloom);
                }
                if (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);
                    }
                }

                // 无参数的纯开关：横排平铺
                bool shadows = renderer.GetShadowsEnabled();
                if (ImGui::Checkbox("Shadows", &shadows))
                {
                    renderer.SetShadowsEnabled(shadows);
                }
                ImGui::SameLine();
                bool taa = renderer.GetTAAEnabled();
                if (ImGui::Checkbox("TAA", &taa))
                {
                    renderer.SetTAAEnabled(taa);
                }
            }

            // ---- Environment：IBL 环境 + 调试视图（决定"看什么"） ----
            if (ImGui::CollapsingHeader("Environment", ImGuiTreeNodeFlags_DefaultOpen))
            {
                // 动态环境切换（Assets 层加载 → Renderer 换绑；缓存去重）
                ImGui::Text("Environment (IBL)");
                bool& DrawSkybox = GetScene().GetSettings().DrawSkybox;
                ImGui::Checkbox("DrawSkybox", &DrawSkybox);
                if (DrawSkybox)
                {
                    int envIdx = m_EnvIndex;
                    if (ImGui::Combo("env", &envIdx, kEnvNames, kEnvCount))
                    {
                        // 异步：解码后台线程，完成后 OnUpdate 里换绑
                        m_EnvIndex = envIdx;
                        RequestEnvironment(envIdx);
                    }
                    ImGui::Text(m_EnvLoadBusy ? "(decoding...)" :
                                "(switch = compute pre-integrate, ms-level)");

                    // 调试视图：单看某个 pass 的中间输出（类 UE pass debug）
                    const auto& viewNames = renderer.GetDebugViewNames();
                    int view = renderer.GetDebugView();
                    if (ImGui::Combo("Debug View", &view, viewNames.data(),
                                     static_cast<int>(viewNames.size())))
                    {
                        renderer.SetDebugView(view);
                    }
                }else
                {
                    ImGui::ColorEdit4("ClearColor", glm::value_ptr(GetScene().GetSettings().ClearColor));
                }
            }

            // ---- GPU Timings：只读遥测（默认折叠，不占面板高度） ----
            if (ImGui::CollapsingHeader("GPU Timings"))
            {
                // Pass 级 GPU 耗时（RG timestamp）
                ImGui::Text("instances: %u main / %u shadow",
                            renderer.GetMainInstanceCount(),
                            renderer.GetShadowInstanceCount());
                if (renderer.GetInstancesTruncated()) {
                    ImGui::TextColored(ImVec4(1.0f, 0.3f, 0.3f, 1.0f),
                        "TRUNCATED: instance buffer full!");
                }
                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]);
                }
            }

            // ---- Frame：帧率控制与显示 ----
            if (ImGui::CollapsingHeader("Frame", ImGuiTreeNodeFlags_DefaultOpen))
            {
                auto& app = *this;
                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::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
        {
            SetImGuiEnabled(true);
            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 = true;   // 冻结动画时钟（帧历史 diff 验证用）
        int m_EnvIndex = kDefaultEnv;

        // ---- 异步环境加载状态（单 in-flight + pending 接力）----
        std::thread m_EnvWorker;
        std::string m_EnvLoadingPath;
        DecodedEquirect m_EnvDecoded;          // worker 写 → join 后主线程读
        std::atomic<bool> m_EnvLoadDone{false};
        bool m_EnvLoadBusy = false;
        int m_EnvPending = -1;

        // ---- 异步模型加载（SunTemple）----
        AsyncTask<ParsedModel> m_TempleTask;
        f32 m_TempleScale = 1.0f;   // cm 尺度资产 → 米（解析后应用）
    };
}

int main()
{
    SandboxApp app;

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

    return 0;
}