#define NOMINMAX
#include <windows.h>

#include <gtest/gtest.h>

#include "../RenderingIntegrationMain.h"
#include "../RenderingIntegrationImageAssert.h"

#include <XCEngine/Components/CameraComponent.h>
#include <XCEngine/Components/GameObject.h>
#include <XCEngine/Components/GaussianSplatRendererComponent.h>
#include <XCEngine/Core/Asset/IResource.h>
#include <XCEngine/Core/Asset/ResourceManager.h>
#include <XCEngine/Core/Math/Color.h>
#include <XCEngine/Core/Math/Vector3.h>
#include <XCEngine/Rendering/Execution/SceneRenderer.h>
#include <XCEngine/Rendering/RenderContext.h>
#include <XCEngine/Rendering/RenderSurface.h>
#include <XCEngine/Resources/GaussianSplat/GaussianSplat.h>
#include <XCEngine/Resources/Material/Material.h>
#include <XCEngine/Resources/BuiltinResources.h>
#include <XCEngine/Resources/Shader/Shader.h>
#include <XCEngine/RHI/RHITexture.h>
#include <XCEngine/Scene/Scene.h>

#include "../../../RHI/integration/fixtures/RHIIntegrationFixture.h"

#include <algorithm>
#include <cstring>
#include <filesystem>
#include <limits>
#include <memory>
#include <system_error>
#include <vector>

using namespace XCEngine::Components;
using namespace XCEngine::Math;
using namespace XCEngine::Rendering;
using namespace XCEngine::Resources;
using namespace XCEngine::RHI;
using namespace XCEngine::RHI::Integration;
using namespace RenderingIntegrationTestUtils;

namespace {

constexpr const char* kD3D12Screenshot = "gaussian_splat_scene_d3d12.ppm";
constexpr const char* kOpenGLScreenshot = "gaussian_splat_scene_opengl.ppm";
constexpr const char* kVulkanScreenshot = "gaussian_splat_scene_vulkan.ppm";
constexpr uint32_t kFrameWidth = 1280;
constexpr uint32_t kFrameHeight = 720;
constexpr uint32_t kBaselineSubsetSplatCount = 65536u;

std::filesystem::path GetRoomPlyPath() {
    return std::filesystem::path(XCENGINE_TEST_ROOM_PLY_PATH);
}

std::filesystem::path CreateRuntimeProjectRoot() {
    return GetExecutableDirectory() /
           ("__xc_gaussian_splat_scene_runtime_" + std::to_string(static_cast<unsigned long>(::GetCurrentProcessId())));
}

void LinkOrCopyFixture(const std::filesystem::path& sourcePath, const std::filesystem::path& destinationPath) {
    std::error_code ec;
    std::filesystem::create_directories(destinationPath.parent_path(), ec);
    ec.clear();
    std::filesystem::create_hard_link(sourcePath, destinationPath, ec);
    if (ec) {
        ec.clear();
        std::filesystem::copy_file(
            sourcePath,
            destinationPath,
            std::filesystem::copy_options::overwrite_existing,
            ec);
    }

    ASSERT_FALSE(ec) << ec.message();
}

const char* GetScreenshotFilename(RHIType backendType) {
    switch (backendType) {
        case RHIType::D3D12:
            return kD3D12Screenshot;
        case RHIType::Vulkan:
            return kVulkanScreenshot;
        case RHIType::OpenGL:
        default:
            return kOpenGLScreenshot;
    }
}

GaussianSplat* CreateGaussianSplatSubset(
    const GaussianSplat& source,
    uint32_t maxSplatCount,
    const char* path) {
    const uint32_t sourceSplatCount = source.GetSplatCount();
    const uint32_t subsetSplatCount = std::min(sourceSplatCount, maxSplatCount);
    if (subsetSplatCount == 0u) {
        return nullptr;
    }

    const GaussianSplatPositionRecord* positions = source.GetPositionRecords();
    const GaussianSplatOtherRecord* other = source.GetOtherRecords();
    const GaussianSplatColorRecord* colors = source.GetColorRecords();
    const GaussianSplatSHRecord* sh = source.GetSHRecords();
    const GaussianSplatSection* positionsSection = source.FindSection(GaussianSplatSectionType::Positions);
    const GaussianSplatSection* otherSection = source.FindSection(GaussianSplatSectionType::Other);
    const GaussianSplatSection* colorSection = source.FindSection(GaussianSplatSectionType::Color);
    const GaussianSplatSection* shSection = source.FindSection(GaussianSplatSectionType::SH);
    if (positions == nullptr ||
        other == nullptr ||
        colors == nullptr ||
        positionsSection == nullptr ||
        otherSection == nullptr ||
        colorSection == nullptr) {
        return nullptr;
    }

    std::vector<uint32_t> selectedIndices(subsetSplatCount, 0u);
    for (uint32_t subsetIndex = 0u; subsetIndex < subsetSplatCount; ++subsetIndex) {
        const uint64_t scaledIndex =
            (static_cast<uint64_t>(subsetIndex) * static_cast<uint64_t>(sourceSplatCount)) /
            static_cast<uint64_t>(subsetSplatCount);
        selectedIndices[subsetIndex] =
            static_cast<uint32_t>(std::min<uint64_t>(scaledIndex, static_cast<uint64_t>(sourceSplatCount - 1u)));
    }

    std::vector<GaussianSplatPositionRecord> subsetPositions(subsetSplatCount);
    std::vector<GaussianSplatOtherRecord> subsetOther(subsetSplatCount);
    std::vector<GaussianSplatColorRecord> subsetColors(subsetSplatCount);
    std::vector<GaussianSplatSHRecord> subsetSh(shSection != nullptr && sh != nullptr ? subsetSplatCount : 0u);
    for (uint32_t subsetIndex = 0u; subsetIndex < subsetSplatCount; ++subsetIndex) {
        const uint32_t sourceIndex = selectedIndices[subsetIndex];
        subsetPositions[subsetIndex] = positions[sourceIndex];
        subsetOther[subsetIndex] = other[sourceIndex];
        subsetColors[subsetIndex] = colors[sourceIndex];
        if (!subsetSh.empty()) {
            subsetSh[subsetIndex] = sh[sourceIndex];
        }
    }

    const uint32_t subsetChunkCount =
        (subsetSplatCount + (kGaussianSplatChunkSize - 1u)) / kGaussianSplatChunkSize;
    std::vector<GaussianSplatChunkRecord> subsetChunks(subsetChunkCount);
    for (uint32_t chunkIndex = 0u; chunkIndex < subsetChunkCount; ++chunkIndex) {
        const uint32_t startIndex = chunkIndex * kGaussianSplatChunkSize;
        const uint32_t endIndex = std::min(startIndex + kGaussianSplatChunkSize, subsetSplatCount);

        Vector3 minPosition(
            std::numeric_limits<float>::max(),
            std::numeric_limits<float>::max(),
            std::numeric_limits<float>::max());
        Vector3 maxPosition(
            -std::numeric_limits<float>::max(),
            -std::numeric_limits<float>::max(),
            -std::numeric_limits<float>::max());

        for (uint32_t subsetIndex = startIndex; subsetIndex < endIndex; ++subsetIndex) {
            const Vector3& position = subsetPositions[subsetIndex].position;
            minPosition.x = std::min(minPosition.x, position.x);
            minPosition.y = std::min(minPosition.y, position.y);
            minPosition.z = std::min(minPosition.z, position.z);
            maxPosition.x = std::max(maxPosition.x, position.x);
            maxPosition.y = std::max(maxPosition.y, position.y);
            maxPosition.z = std::max(maxPosition.z, position.z);
        }

        GaussianSplatChunkRecord chunk = {};
        chunk.posX = Vector2(minPosition.x, maxPosition.x);
        chunk.posY = Vector2(minPosition.y, maxPosition.y);
        chunk.posZ = Vector2(minPosition.z, maxPosition.z);
        subsetChunks[chunkIndex] = chunk;
    }

    XCEngine::Containers::Array<GaussianSplatSection> sections;
    XCEngine::Containers::Array<XCEngine::Core::uint8> payload;
    sections.Reserve(shSection != nullptr && sh != nullptr ? 5u : 4u);

    size_t payloadOffset = 0u;
    auto appendSection = [&](const GaussianSplatSection& sourceSection,
                             const void* sourceData,
                             uint32_t elementCount,
                             uint32_t elementStride) {
        GaussianSplatSection section = sourceSection;
        section.dataOffset = payloadOffset;
        section.elementCount = elementCount;
        section.elementStride = elementStride;
        section.dataSize = static_cast<XCEngine::Core::uint64>(elementCount) * elementStride;
        sections.PushBack(section);

        const size_t newPayloadSize = payload.Size() + static_cast<size_t>(section.dataSize);
        payload.Resize(newPayloadSize);
        std::memcpy(payload.Data() + payloadOffset, sourceData, static_cast<size_t>(section.dataSize));
        payloadOffset = newPayloadSize;
    };

    appendSection(
        *positionsSection,
        subsetPositions.data(),
        subsetSplatCount,
        sizeof(GaussianSplatPositionRecord));
    appendSection(
        *otherSection,
        subsetOther.data(),
        subsetSplatCount,
        sizeof(GaussianSplatOtherRecord));
    appendSection(
        *colorSection,
        subsetColors.data(),
        subsetSplatCount,
        sizeof(GaussianSplatColorRecord));
    if (shSection != nullptr && sh != nullptr) {
        appendSection(
            *shSection,
            subsetSh.data(),
            subsetSplatCount,
            sizeof(GaussianSplatSHRecord));
    }
    GaussianSplatSection chunksSection = {};
    chunksSection.type = GaussianSplatSectionType::Chunks;
    chunksSection.format = GaussianSplatSectionFormat::ChunkFloat32;
    appendSection(
        chunksSection,
        subsetChunks.data(),
        subsetChunkCount,
        sizeof(GaussianSplatChunkRecord));

    GaussianSplatMetadata metadata = source.GetMetadata();
    metadata.splatCount = subsetSplatCount;
    metadata.bounds = source.GetBounds();
    metadata.chunkCount = subsetChunkCount;
    metadata.cameraCount = 0u;
    metadata.chunkFormat = GaussianSplatSectionFormat::ChunkFloat32;
    metadata.cameraFormat = GaussianSplatSectionFormat::Unknown;

    auto* gaussianSplat = new GaussianSplat();
    IResource::ConstructParams params = {};
    params.name = "GaussianSplatSceneSubset";
    params.path = path;
    params.guid = ResourceGUID::Generate(params.path);
    gaussianSplat->Initialize(params);
    if (!gaussianSplat->CreateOwned(metadata, std::move(sections), std::move(payload))) {
        delete gaussianSplat;
        return nullptr;
    }

    return gaussianSplat;
}

class GaussianSplatSceneTest : public RHIIntegrationFixture {
protected:
    void SetUp() override;
    void TearDown() override;
    void RenderFrame() override;

private:
    void PrepareRuntimeProject();
    void BuildScene();
    RHIResourceView* GetCurrentBackBufferView();

    std::filesystem::path m_projectRoot;
    std::unique_ptr<Scene> m_scene;
    std::unique_ptr<SceneRenderer> m_sceneRenderer;
    std::vector<RHIResourceView*> m_backBufferViews;
    RHITexture* m_depthTexture = nullptr;
    RHIResourceView* m_depthView = nullptr;
    ResourceHandle<GaussianSplat> m_gaussianSplat;
    GaussianSplat* m_subsetGaussianSplat = nullptr;
    Material* m_material = nullptr;
};

void GaussianSplatSceneTest::SetUp() {
    RHIIntegrationFixture::SetUp();
    PrepareRuntimeProject();

    m_sceneRenderer = std::make_unique<SceneRenderer>();
    m_scene = std::make_unique<Scene>("GaussianSplatScene");

    BuildScene();

    TextureDesc depthDesc = {};
    depthDesc.width = kFrameWidth;
    depthDesc.height = kFrameHeight;
    depthDesc.depth = 1;
    depthDesc.mipLevels = 1;
    depthDesc.arraySize = 1;
    depthDesc.format = static_cast<uint32_t>(Format::D24_UNorm_S8_UInt);
    depthDesc.textureType = static_cast<uint32_t>(XCEngine::RHI::TextureType::Texture2D);
    depthDesc.sampleCount = 1;
    depthDesc.sampleQuality = 0;
    depthDesc.flags = 0;
    m_depthTexture = GetDevice()->CreateTexture(depthDesc);
    ASSERT_NE(m_depthTexture, nullptr);

    ResourceViewDesc depthViewDesc = {};
    depthViewDesc.format = static_cast<uint32_t>(Format::D24_UNorm_S8_UInt);
    depthViewDesc.dimension = ResourceViewDimension::Texture2D;
    depthViewDesc.mipLevel = 0;
    m_depthView = GetDevice()->CreateDepthStencilView(m_depthTexture, depthViewDesc);
    ASSERT_NE(m_depthView, nullptr);

    m_backBufferViews.resize(2, nullptr);
}

void GaussianSplatSceneTest::TearDown() {
    m_sceneRenderer.reset();

    if (m_depthView != nullptr) {
        m_depthView->Shutdown();
        delete m_depthView;
        m_depthView = nullptr;
    }

    if (m_depthTexture != nullptr) {
        m_depthTexture->Shutdown();
        delete m_depthTexture;
        m_depthTexture = nullptr;
    }

    for (RHIResourceView*& backBufferView : m_backBufferViews) {
        if (backBufferView != nullptr) {
            backBufferView->Shutdown();
            delete backBufferView;
            backBufferView = nullptr;
        }
    }
    m_backBufferViews.clear();

    m_scene.reset();

    delete m_material;
    m_material = nullptr;
    delete m_subsetGaussianSplat;
    m_subsetGaussianSplat = nullptr;
    m_gaussianSplat.Reset();

    ResourceManager& manager = ResourceManager::Get();
    manager.UnloadAll();
    manager.SetResourceRoot("");
    manager.Shutdown();

    if (!m_projectRoot.empty()) {
        std::error_code ec;
        std::filesystem::remove_all(m_projectRoot, ec);
    }

    RHIIntegrationFixture::TearDown();
}

void GaussianSplatSceneTest::PrepareRuntimeProject() {
    const std::filesystem::path roomPlyPath = GetRoomPlyPath();
    ASSERT_TRUE(std::filesystem::exists(roomPlyPath)) << roomPlyPath.string();

    m_projectRoot = CreateRuntimeProjectRoot();
    const std::filesystem::path assetsDir = m_projectRoot / "Assets";
    const std::filesystem::path runtimeRoomPath = assetsDir / "room.ply";

    std::error_code ec;
    std::filesystem::remove_all(m_projectRoot, ec);
    std::filesystem::create_directories(assetsDir, ec);
    ASSERT_FALSE(ec) << ec.message();

    LinkOrCopyFixture(roomPlyPath, runtimeRoomPath);

    ResourceManager& manager = ResourceManager::Get();
    manager.Initialize();
    manager.SetResourceRoot(m_projectRoot.string().c_str());

    m_gaussianSplat = manager.Load<GaussianSplat>("Assets/room.ply");
    ASSERT_TRUE(m_gaussianSplat.IsValid());
    ASSERT_NE(m_gaussianSplat.Get(), nullptr);
    ASSERT_TRUE(m_gaussianSplat->IsValid());
    ASSERT_GT(m_gaussianSplat->GetSplatCount(), 0u);
    ASSERT_EQ(m_gaussianSplat->GetSHOrder(), 3u);
    m_subsetGaussianSplat = CreateGaussianSplatSubset(
        *m_gaussianSplat.Get(),
        kBaselineSubsetSplatCount,
        "Tests/Rendering/GaussianSplatScene/RoomSubset.xcgsplat");
    ASSERT_NE(m_subsetGaussianSplat, nullptr);
    ASSERT_TRUE(m_subsetGaussianSplat->IsValid());
    ASSERT_GT(m_subsetGaussianSplat->GetSplatCount(), 0u);
    ASSERT_EQ(m_subsetGaussianSplat->GetSHOrder(), 3u);
}

void GaussianSplatSceneTest::BuildScene() {
    ASSERT_NE(m_scene, nullptr);
    ASSERT_NE(m_subsetGaussianSplat, nullptr);

    m_material = new Material();
    IResource::ConstructParams params = {};
    params.name = "GaussianSplatSceneMaterial";
    params.path = "Tests/Rendering/GaussianSplatScene/Room.material";
    params.guid = ResourceGUID::Generate(params.path);
    m_material->Initialize(params);
    m_material->SetShader(ResourceManager::Get().Load<Shader>(GetBuiltinGaussianSplatShaderPath()));
    m_material->SetRenderQueue(MaterialRenderQueue::Transparent);
    m_material->SetFloat("_PointScale", 1.0f);
    m_material->SetFloat("_OpacityScale", 1.0f);

    GameObject* cameraObject = m_scene->CreateGameObject("MainCamera");
    auto* camera = cameraObject->AddComponent<CameraComponent>();
    camera->SetPrimary(true);
    camera->SetFieldOfView(45.0f);
    camera->SetNearClipPlane(0.1f);
    camera->SetFarClipPlane(500.0f);
    camera->SetClearColor(XCEngine::Math::Color(0.02f, 0.025f, 0.035f, 1.0f));

    const Bounds& bounds = m_subsetGaussianSplat->GetBounds();
    const Vector3 boundsMin = bounds.GetMin();
    const Vector3 boundsMax = bounds.GetMax();
    const Vector3 center(
        (boundsMin.x + boundsMax.x) * 0.5f,
        (boundsMin.y + boundsMax.y) * 0.5f,
        (boundsMin.z + boundsMax.z) * 0.5f);
    const float sizeX = std::max(boundsMax.x - boundsMin.x, 0.001f);
    const float sizeY = std::max(boundsMax.y - boundsMin.y, 0.001f);
    const float sizeZ = std::max(boundsMax.z - boundsMin.z, 0.001f);
    const float maxExtent = std::max(sizeX, std::max(sizeY, sizeZ));
    const float uniformScale = 3.0f / maxExtent;

    GameObject* root = m_scene->CreateGameObject("GaussianSplatRoot");
    root->GetTransform()->SetLocalPosition(Vector3(0.0f, -0.35f, 3.2f));
    root->GetTransform()->SetLocalScale(Vector3(uniformScale, uniformScale, uniformScale));

    GameObject* splatObject = m_scene->CreateGameObject("RoomGaussianSplat");
    splatObject->SetParent(root, false);
    splatObject->GetTransform()->SetLocalPosition(Vector3(-center.x, -center.y, -center.z));

    auto* splatRenderer = splatObject->AddComponent<GaussianSplatRendererComponent>();
    splatRenderer->SetGaussianSplat(m_subsetGaussianSplat);
    splatRenderer->SetMaterial(m_material);
    splatRenderer->SetCastShadows(false);
    splatRenderer->SetReceiveShadows(false);
}

RHIResourceView* GaussianSplatSceneTest::GetCurrentBackBufferView() {
    const int backBufferIndex = GetCurrentBackBufferIndex();
    if (backBufferIndex < 0) {
        return nullptr;
    }

    if (static_cast<size_t>(backBufferIndex) >= m_backBufferViews.size()) {
        m_backBufferViews.resize(static_cast<size_t>(backBufferIndex) + 1, nullptr);
    }

    if (m_backBufferViews[backBufferIndex] == nullptr) {
        ResourceViewDesc viewDesc = {};
        viewDesc.format = static_cast<uint32_t>(Format::R8G8B8A8_UNorm);
        viewDesc.dimension = ResourceViewDimension::Texture2D;
        viewDesc.mipLevel = 0;
        m_backBufferViews[backBufferIndex] =
            GetDevice()->CreateRenderTargetView(GetCurrentBackBuffer(), viewDesc);
    }

    return m_backBufferViews[backBufferIndex];
}

void GaussianSplatSceneTest::RenderFrame() {
    ASSERT_NE(m_scene, nullptr);
    ASSERT_NE(m_sceneRenderer, nullptr);

    RHICommandList* commandList = GetCommandList();
    ASSERT_NE(commandList, nullptr);

    commandList->Reset();

    RenderSurface surface(kFrameWidth, kFrameHeight);
    surface.SetColorAttachment(GetCurrentBackBufferView());
    surface.SetDepthAttachment(m_depthView);

    RenderContext renderContext = {};
    renderContext.device = GetDevice();
    renderContext.commandList = commandList;
    renderContext.commandQueue = GetCommandQueue();
    renderContext.backendType = GetBackendType();

    ASSERT_TRUE(m_sceneRenderer->Render(*m_scene, nullptr, renderContext, surface));

    commandList->Close();
    void* commandLists[] = { commandList };
    GetCommandQueue()->ExecuteCommandLists(1, commandLists);
}

TEST_P(GaussianSplatSceneTest, RenderRoomGaussianSplatScene) {
    RHICommandQueue* commandQueue = GetCommandQueue();
    RHISwapChain* swapChain = GetSwapChain();
    ASSERT_NE(commandQueue, nullptr);
    ASSERT_NE(swapChain, nullptr);

    constexpr int kTargetFrameCount = 1;
    const char* screenshotFilename = GetScreenshotFilename(GetBackendType());

    for (int frameCount = 0; frameCount <= kTargetFrameCount; ++frameCount) {
        if (frameCount > 0) {
            commandQueue->WaitForPreviousFrame();
        }

        BeginRender();
        RenderFrame();

        if (frameCount >= kTargetFrameCount) {
            commandQueue->WaitForIdle();
            ASSERT_TRUE(TakeScreenshot(screenshotFilename));

            const std::filesystem::path gtPath = ResolveRuntimePath("GT.ppm");
            if (!std::filesystem::exists(gtPath)) {
                GTEST_SKIP() << "GT.ppm missing, screenshot captured for baseline generation: " << screenshotFilename;
            }

            ASSERT_TRUE(CompareWithGoldenTemplate(screenshotFilename, "GT.ppm", 8.0f));
            break;
        }

        swapChain->Present(0, 0);
    }
}

} // namespace

INSTANTIATE_TEST_SUITE_P(D3D12, GaussianSplatSceneTest, ::testing::Values(RHIType::D3D12));
#if defined(XCENGINE_SUPPORT_OPENGL)
INSTANTIATE_TEST_SUITE_P(OpenGL, GaussianSplatSceneTest, ::testing::Values(RHIType::OpenGL));
#endif
#if defined(XCENGINE_SUPPORT_VULKAN)
INSTANTIATE_TEST_SUITE_P(Vulkan, GaussianSplatSceneTest, ::testing::Values(RHIType::Vulkan));
#endif

GTEST_API_ int main(int argc, char** argv) {
    return RunRenderingIntegrationTestMain(argc, argv);
}