#include <gtest/gtest.h>

#include "XCUIBackend/XCUIRHIRenderBackend.h"

#include <XCEngine/Rendering/RenderContext.h>
#include <XCEngine/Rendering/RenderSurface.h>
#include <XCEngine/RHI/RHIBuffer.h>
#include <XCEngine/RHI/RHICapabilities.h>
#include <XCEngine/RHI/RHICommandList.h>
#include <XCEngine/RHI/RHICommandQueue.h>
#include <XCEngine/RHI/RHIDevice.h>
#include <XCEngine/RHI/RHIDescriptorPool.h>
#include <XCEngine/RHI/RHIDescriptorSet.h>
#include <XCEngine/RHI/RHIPipelineLayout.h>
#include <XCEngine/RHI/RHIPipelineState.h>
#include <XCEngine/RHI/RHIResourceView.h>
#include <XCEngine/RHI/RHISampler.h>
#include <XCEngine/UI/DrawData.h>

#include <array>
#include <cstdint>
#include <cstring>
#include <type_traits>
#include <vector>

namespace {

using XCEngine::Editor::XCUIBackend::IXCUITextAtlasProvider;
using XCEngine::Editor::XCUIBackend::XCUIRHIRenderBackend;
using XCEngine::Rendering::RenderContext;
using XCEngine::Rendering::RenderSurface;
using XCEngine::RHI::BlendDesc;
using XCEngine::RHI::BufferDesc;
using XCEngine::RHI::BufferType;
using XCEngine::RHI::CommandQueueType;
using XCEngine::RHI::ComparisonFunc;
using XCEngine::RHI::DepthStencilStateDesc;
using XCEngine::RHI::DescriptorHeapType;
using XCEngine::RHI::DescriptorPoolDesc;
using XCEngine::RHI::DescriptorSetLayoutBinding;
using XCEngine::RHI::DescriptorSetLayoutDesc;
using XCEngine::RHI::Format;
using XCEngine::RHI::GraphicsPipelineDesc;
using XCEngine::RHI::InputLayoutDesc;
using XCEngine::RHI::PipelineStateHash;
using XCEngine::RHI::PipelineType;
using XCEngine::RHI::PrimitiveTopology;
using XCEngine::RHI::RasterizerDesc;
using XCEngine::RHI::Rect;
using XCEngine::RHI::ResourceStates;
using XCEngine::RHI::ResourceViewDesc;
using XCEngine::RHI::ResourceViewDimension;
using XCEngine::RHI::ResourceViewType;
using XCEngine::RHI::RHICommandList;
using XCEngine::RHI::RHICommandQueue;
using XCEngine::RHI::RHIDescriptorPool;
using XCEngine::RHI::RHIDescriptorSet;
using XCEngine::RHI::RHIDevice;
using XCEngine::RHI::RHIPipelineLayout;
using XCEngine::RHI::RHIPipelineState;
using XCEngine::RHI::RHIResourceView;
using XCEngine::RHI::RHISampler;
using XCEngine::RHI::RHIBuffer;
using XCEngine::RHI::RHIShader;
using XCEngine::RHI::RHIType;
using XCEngine::RHI::SamplerDesc;
using XCEngine::RHI::Viewport;
using XCEngine::UI::UIColor;
using XCEngine::UI::UIDrawData;
using XCEngine::UI::UIDrawList;
using XCEngine::UI::UIRect;
using XCEngine::UI::UITextureHandle;
using XCEngine::UI::UITextureHandleKind;

class FakeResourceViewBase {
public:
    explicit FakeResourceViewBase(
        ResourceViewType viewType,
        ResourceViewDimension dimension = ResourceViewDimension::Texture2D,
        Format format = Format::R8G8B8A8_UNorm)
        : m_viewType(viewType)
        , m_dimension(dimension)
        , m_format(format) {
    }

    void ShutdownBase() {
        m_valid = false;
    }

    void* GetNativeHandleBase() {
        return this;
    }

    bool IsValidBase() const {
        return m_valid;
    }

    ResourceViewType GetViewTypeBase() const {
        return m_viewType;
    }

    ResourceViewDimension GetDimensionBase() const {
        return m_dimension;
    }

    Format GetFormatBase() const {
        return m_format;
    }

    void SetValid(bool valid) {
        m_valid = valid;
    }

private:
    ResourceViewType m_viewType = ResourceViewType::ShaderResource;
    ResourceViewDimension m_dimension = ResourceViewDimension::Texture2D;
    Format m_format = Format::R8G8B8A8_UNorm;
    bool m_valid = true;
};

class FakeShaderResourceView final : public XCEngine::RHI::RHIShaderResourceView {
public:
    explicit FakeShaderResourceView(bool valid = true)
        : m_base(ResourceViewType::ShaderResource) {
        m_base.SetValid(valid);
    }

    void Shutdown() override { m_base.ShutdownBase(); }
    void* GetNativeHandle() override { return m_base.GetNativeHandleBase(); }
    bool IsValid() const override { return m_base.IsValidBase(); }
    ResourceViewType GetViewType() const override { return m_base.GetViewTypeBase(); }
    ResourceViewDimension GetDimension() const override { return m_base.GetDimensionBase(); }
    Format GetFormat() const override { return m_base.GetFormatBase(); }

private:
    FakeResourceViewBase m_base;
};

class FakeRenderTargetView final : public XCEngine::RHI::RHIRenderTargetView {
public:
    FakeRenderTargetView()
        : m_base(ResourceViewType::RenderTarget) {
    }

    void Shutdown() override { m_base.ShutdownBase(); }
    void* GetNativeHandle() override { return m_base.GetNativeHandleBase(); }
    bool IsValid() const override { return m_base.IsValidBase(); }
    ResourceViewType GetViewType() const override { return m_base.GetViewTypeBase(); }
    ResourceViewDimension GetDimension() const override { return m_base.GetDimensionBase(); }
    Format GetFormat() const override { return m_base.GetFormatBase(); }

private:
    FakeResourceViewBase m_base;
};

class FakeVertexBufferView final : public XCEngine::RHI::RHIVertexBufferView {
public:
    explicit FakeVertexBufferView(std::uint32_t size, std::uint32_t stride)
        : m_size(size)
        , m_stride(stride)
        , m_base(ResourceViewType::VertexBuffer, ResourceViewDimension::Buffer, Format::Unknown) {
    }

    void Shutdown() override { m_base.ShutdownBase(); }
    void* GetNativeHandle() override { return m_base.GetNativeHandleBase(); }
    bool IsValid() const override { return m_base.IsValidBase(); }
    ResourceViewType GetViewType() const override { return m_base.GetViewTypeBase(); }
    ResourceViewDimension GetDimension() const override { return m_base.GetDimensionBase(); }
    Format GetFormat() const override { return m_base.GetFormatBase(); }
    std::uint64_t GetBufferAddress() const override { return 0u; }
    std::uint32_t GetSize() const override { return m_size; }
    std::uint32_t GetStride() const override { return m_stride; }

private:
    std::uint32_t m_size = 0;
    std::uint32_t m_stride = 0;
    FakeResourceViewBase m_base;
};

class FakeBuffer final : public RHIBuffer {
public:
    explicit FakeBuffer(const BufferDesc& desc)
        : m_size(desc.size)
        , m_stride(desc.stride)
        , m_type(static_cast<BufferType>(desc.bufferType))
        , m_storage(static_cast<std::size_t>(desc.size), 0u) {
    }

    void* Map() override { return m_storage.data(); }
    void Unmap() override {}

    void SetData(const void* data, size_t size, size_t offset = 0) override {
        if (data == nullptr || offset + size > m_storage.size()) {
            return;
        }
        std::memcpy(m_storage.data() + offset, data, size);
    }

    std::uint64_t GetSize() const override { return m_size; }
    BufferType GetBufferType() const override { return m_type; }
    void SetBufferType(BufferType type) override { m_type = type; }
    std::uint32_t GetStride() const override { return m_stride; }
    void SetStride(std::uint32_t stride) override { m_stride = stride; }
    void* GetNativeHandle() override { return this; }
    ResourceStates GetState() const override { return m_state; }
    void SetState(ResourceStates state) override { m_state = state; }
    const std::string& GetName() const override { return m_name; }
    void SetName(const std::string& name) override { m_name = name; }
    void Shutdown() override { m_storage.clear(); }

private:
    std::uint64_t m_size = 0;
    std::uint32_t m_stride = 0;
    BufferType m_type = BufferType::Vertex;
    ResourceStates m_state = ResourceStates::Common;
    std::string m_name = {};
    std::vector<std::uint8_t> m_storage = {};
};

class FakeDescriptorSet final : public RHIDescriptorSet {
public:
    explicit FakeDescriptorSet(const DescriptorSetLayoutDesc& layout) {
        if (layout.bindings != nullptr && layout.bindingCount > 0u) {
            m_bindings.assign(layout.bindings, layout.bindings + layout.bindingCount);
            m_views.resize(layout.bindingCount, nullptr);
            m_samplers.resize(layout.bindingCount, nullptr);
        }
    }

    void Shutdown() override {
        m_views.clear();
        m_samplers.clear();
        m_constantBuffer.clear();
        m_constantDirty = false;
    }

    void Bind() override {}
    void Unbind() override {}

    void Update(std::uint32_t offset, RHIResourceView* view) override {
        if (offset >= m_views.size()) {
            m_views.resize(offset + 1u, nullptr);
        }
        m_views[offset] = view;
    }

    void UpdateSampler(std::uint32_t offset, RHISampler* sampler) override {
        if (offset >= m_samplers.size()) {
            m_samplers.resize(offset + 1u, nullptr);
        }
        m_samplers[offset] = sampler;
    }

    void WriteConstant(std::uint32_t, const void* data, size_t size, size_t offset = 0) override {
        if (data == nullptr) {
            return;
        }
        if (m_constantBuffer.size() < offset + size) {
            m_constantBuffer.resize(offset + size, 0u);
        }
        std::memcpy(m_constantBuffer.data() + offset, data, size);
        m_constantDirty = true;
    }

    std::uint32_t GetBindingCount() const override {
        return static_cast<std::uint32_t>(m_bindings.size());
    }

    const DescriptorSetLayoutBinding* GetBindings() const override {
        return m_bindings.empty() ? nullptr : m_bindings.data();
    }

    void* GetConstantBufferData() override {
        return m_constantBuffer.empty() ? nullptr : m_constantBuffer.data();
    }

    size_t GetConstantBufferSize() const override {
        return m_constantBuffer.size();
    }

    bool IsConstantDirty() const override {
        return m_constantDirty;
    }

    void MarkConstantClean() override {
        m_constantDirty = false;
    }

private:
    std::vector<DescriptorSetLayoutBinding> m_bindings = {};
    std::vector<RHIResourceView*> m_views = {};
    std::vector<RHISampler*> m_samplers = {};
    std::vector<std::uint8_t> m_constantBuffer = {};
    bool m_constantDirty = false;
};

class FakeDescriptorPool final : public RHIDescriptorPool {
public:
    explicit FakeDescriptorPool(const DescriptorPoolDesc& desc)
        : m_desc(desc) {
    }

    bool Initialize(const DescriptorPoolDesc& desc) override {
        m_desc = desc;
        return true;
    }

    void Shutdown() override {}
    void* GetNativeHandle() override { return this; }
    std::uint32_t GetDescriptorCount() const override { return m_desc.descriptorCount; }
    DescriptorHeapType GetType() const override { return m_desc.type; }

    RHIDescriptorSet* AllocateSet(const DescriptorSetLayoutDesc& layout) override {
        ++m_allocationCount;
        return new FakeDescriptorSet(layout);
    }

    void FreeSet(RHIDescriptorSet* set) override {
        delete set;
    }

    std::uint32_t GetAllocationCount() const {
        return m_allocationCount;
    }

private:
    DescriptorPoolDesc m_desc = {};
    std::uint32_t m_allocationCount = 0;
};

class FakePipelineLayout final : public RHIPipelineLayout {
public:
    bool Initialize(const XCEngine::RHI::RHIPipelineLayoutDesc& desc) override {
        m_desc = desc;
        return true;
    }

    void Shutdown() override {}
    void* GetNativeHandle() override { return this; }

private:
    XCEngine::RHI::RHIPipelineLayoutDesc m_desc = {};
};

class FakePipelineState final : public RHIPipelineState {
public:
    explicit FakePipelineState(const GraphicsPipelineDesc& desc)
        : m_inputLayout(desc.inputLayout)
        , m_rasterizer(desc.rasterizerState)
        , m_blend(desc.blendState)
        , m_depthStencil(desc.depthStencilState) {
    }

    void SetInputLayout(const InputLayoutDesc& layout) override { m_inputLayout = layout; }
    void SetRasterizerState(const RasterizerDesc& state) override { m_rasterizer = state; }
    void SetBlendState(const BlendDesc& state) override { m_blend = state; }
    void SetDepthStencilState(const DepthStencilStateDesc& state) override { m_depthStencil = state; }
    void SetTopology(std::uint32_t topologyType) override { m_topologyType = topologyType; }
    void SetRenderTargetFormats(std::uint32_t, const std::uint32_t*, std::uint32_t) override {}
    void SetSampleCount(std::uint32_t count) override { m_sampleCount = count; }
    void SetComputeShader(RHIShader* shader) override { m_computeShader = shader; }
    const RasterizerDesc& GetRasterizerState() const override { return m_rasterizer; }
    const BlendDesc& GetBlendState() const override { return m_blend; }
    const DepthStencilStateDesc& GetDepthStencilState() const override { return m_depthStencil; }
    const InputLayoutDesc& GetInputLayout() const override { return m_inputLayout; }
    PipelineStateHash GetHash() const override { return {}; }
    RHIShader* GetComputeShader() const override { return m_computeShader; }
    bool HasComputeShader() const override { return m_computeShader != nullptr; }
    bool IsValid() const override { return true; }
    void EnsureValid() override {}
    void Shutdown() override {}
    void Bind() override {}
    void Unbind() override {}
    void* GetNativeHandle() override { return this; }
    PipelineType GetType() const override { return PipelineType::Graphics; }

private:
    InputLayoutDesc m_inputLayout = {};
    RasterizerDesc m_rasterizer = {};
    BlendDesc m_blend = {};
    DepthStencilStateDesc m_depthStencil = {};
    std::uint32_t m_topologyType = 0u;
    std::uint32_t m_sampleCount = 1u;
    RHIShader* m_computeShader = nullptr;
};

class FakeSampler final : public RHISampler {
public:
    void Shutdown() override {}
    void Bind(unsigned int) override {}
    void Unbind(unsigned int) override {}
    void* GetNativeHandle() override { return this; }
    unsigned int GetID() override { return 1u; }
};

class FakeCommandQueue final : public RHICommandQueue {
public:
    void Shutdown() override {}
    void ExecuteCommandLists(std::uint32_t, void**) override {}
    void Signal(XCEngine::RHI::RHIFence*, std::uint64_t) override {}
    void Wait(XCEngine::RHI::RHIFence*, std::uint64_t) override {}
    std::uint64_t GetCompletedValue() override { return 0u; }
    void WaitForIdle() override {}
    CommandQueueType GetType() const override { return CommandQueueType::Direct; }
    std::uint64_t GetTimestampFrequency() const override { return 0u; }
    void* GetNativeHandle() override { return this; }
    void WaitForPreviousFrame() override {}
    std::uint64_t GetCurrentFrame() const override { return 0u; }
};

class FakeCommandList final : public RHICommandList {
public:
    void Shutdown() override {}
    void Reset() override {}
    void Close() override {}
    void TransitionBarrier(RHIResourceView*, ResourceStates, ResourceStates) override {}
    void BeginRenderPass(XCEngine::RHI::RHIRenderPass*, XCEngine::RHI::RHIFramebuffer*, const Rect&, std::uint32_t, const XCEngine::RHI::ClearValue*) override {}
    void EndRenderPass() override {}
    void SetShader(RHIShader*) override {}

    void SetPipelineState(RHIPipelineState* pso) override {
        pipelineStateHistory.push_back(pso);
    }

    void SetGraphicsDescriptorSets(
        std::uint32_t,
        std::uint32_t count,
        RHIDescriptorSet** descriptorSets,
        RHIPipelineLayout*) override {
        if (count >= 2u && descriptorSets != nullptr) {
            textureDescriptorSetHistory.push_back(descriptorSets[1]);
        }
    }

    void SetComputeDescriptorSets(std::uint32_t, std::uint32_t, RHIDescriptorSet**, RHIPipelineLayout*) override {}
    void SetPrimitiveTopology(PrimitiveTopology topology) override { primitiveTopologyHistory.push_back(topology); }
    void SetViewport(const Viewport& viewport) override { viewportHistory.push_back(viewport); }
    void SetViewports(std::uint32_t count, const Viewport* viewports) override {
        for (std::uint32_t index = 0; index < count; ++index) {
            viewportHistory.push_back(viewports[index]);
        }
    }
    void SetScissorRect(const Rect& rect) override { scissorHistory.push_back(rect); }
    void SetScissorRects(std::uint32_t count, const Rect* rects) override {
        for (std::uint32_t index = 0; index < count; ++index) {
            scissorHistory.push_back(rects[index]);
        }
    }
    void SetRenderTargets(std::uint32_t count, RHIResourceView**, RHIResourceView* = nullptr) override {
        renderTargetBindHistory.push_back(count);
    }
    void SetStencilRef(std::uint8_t) override {}
    void SetBlendFactor(const float[4]) override {}
    void SetVertexBuffers(std::uint32_t, std::uint32_t, RHIResourceView**, const std::uint64_t*, const std::uint32_t*) override {}
    void SetIndexBuffer(RHIResourceView*, std::uint64_t) override {}

    void Draw(std::uint32_t vertexCount, std::uint32_t, std::uint32_t startVertex, std::uint32_t) override {
        drawVertexCounts.push_back(vertexCount);
        drawStartVertices.push_back(startVertex);
    }

    void DrawIndexed(std::uint32_t, std::uint32_t, std::uint32_t, std::int32_t, std::uint32_t) override {}
    void Clear(float, float, float, float, std::uint32_t) override {}
    void ClearRenderTarget(RHIResourceView*, const float[4], std::uint32_t = 0, const Rect* = nullptr) override {}
    void ClearDepthStencil(RHIResourceView*, float, std::uint8_t, std::uint32_t = 0, const Rect* = nullptr) override {}
    void CopyResource(RHIResourceView*, RHIResourceView*) override {}
    void Dispatch(std::uint32_t, std::uint32_t, std::uint32_t) override {}
    void* GetNativeHandle() override { return this; }

    std::vector<RHIPipelineState*> pipelineStateHistory = {};
    std::vector<PrimitiveTopology> primitiveTopologyHistory = {};
    std::vector<Viewport> viewportHistory = {};
    std::vector<Rect> scissorHistory = {};
    std::vector<std::uint32_t> renderTargetBindHistory = {};
    std::vector<RHIDescriptorSet*> textureDescriptorSetHistory = {};
    std::vector<std::uint32_t> drawVertexCounts = {};
    std::vector<std::uint32_t> drawStartVertices = {};
};

class FakeDevice final : public RHIDevice {
public:
    bool Initialize(const XCEngine::RHI::RHIDeviceDesc&) override { return true; }
    void Shutdown() override {}
    RHIBuffer* CreateBuffer(const BufferDesc& desc) override { return new FakeBuffer(desc); }
    XCEngine::RHI::RHITexture* CreateTexture(const XCEngine::RHI::TextureDesc&) override { return nullptr; }
    XCEngine::RHI::RHITexture* CreateTexture(const XCEngine::RHI::TextureDesc&, const void*, size_t, std::uint32_t = 0) override { return nullptr; }
    XCEngine::RHI::RHISwapChain* CreateSwapChain(const XCEngine::RHI::SwapChainDesc&, RHICommandQueue*) override { return nullptr; }
    RHICommandList* CreateCommandList(const XCEngine::RHI::CommandListDesc&) override { return nullptr; }
    RHICommandQueue* CreateCommandQueue(const XCEngine::RHI::CommandQueueDesc&) override { return nullptr; }
    RHIShader* CreateShader(const XCEngine::RHI::ShaderCompileDesc&) override { return nullptr; }
    RHIPipelineState* CreatePipelineState(const GraphicsPipelineDesc& desc) override { return new FakePipelineState(desc); }
    RHIPipelineLayout* CreatePipelineLayout(const XCEngine::RHI::RHIPipelineLayoutDesc&) override { return new FakePipelineLayout(); }
    XCEngine::RHI::RHIFence* CreateFence(const XCEngine::RHI::FenceDesc&) override { return nullptr; }
    RHISampler* CreateSampler(const SamplerDesc&) override { return new FakeSampler(); }
    XCEngine::RHI::RHIRenderPass* CreateRenderPass(std::uint32_t, const XCEngine::RHI::AttachmentDesc*, const XCEngine::RHI::AttachmentDesc*) override { return nullptr; }
    XCEngine::RHI::RHIFramebuffer* CreateFramebuffer(XCEngine::RHI::RHIRenderPass*, std::uint32_t, std::uint32_t, std::uint32_t, RHIResourceView**, RHIResourceView*) override { return nullptr; }
    RHIDescriptorPool* CreateDescriptorPool(const DescriptorPoolDesc& desc) override { return new FakeDescriptorPool(desc); }
    RHIDescriptorSet* CreateDescriptorSet(RHIDescriptorPool*, const DescriptorSetLayoutDesc&) override { return nullptr; }
    RHIResourceView* CreateVertexBufferView(RHIBuffer* buffer, const ResourceViewDesc& desc) override {
        return new FakeVertexBufferView(static_cast<std::uint32_t>(buffer != nullptr ? buffer->GetSize() : 0u), desc.structureByteStride);
    }
    RHIResourceView* CreateIndexBufferView(RHIBuffer*, const ResourceViewDesc&) override { return nullptr; }
    RHIResourceView* CreateRenderTargetView(XCEngine::RHI::RHITexture*, const ResourceViewDesc&) override { return nullptr; }
    RHIResourceView* CreateDepthStencilView(XCEngine::RHI::RHITexture*, const ResourceViewDesc&) override { return nullptr; }
    RHIResourceView* CreateShaderResourceView(XCEngine::RHI::RHITexture*, const ResourceViewDesc&) override { return nullptr; }
    RHIResourceView* CreateUnorderedAccessView(XCEngine::RHI::RHITexture*, const ResourceViewDesc&) override { return nullptr; }
    const XCEngine::RHI::RHICapabilities& GetCapabilities() const override { return m_capabilities; }
    const XCEngine::RHI::RHIDeviceInfo& GetDeviceInfo() const override { return m_deviceInfo; }
    void* GetNativeDevice() override { return this; }

private:
    XCEngine::RHI::RHICapabilities m_capabilities = {};
    XCEngine::RHI::RHIDeviceInfo m_deviceInfo = {};
};

UITextureHandle MakeExternalTextureHandle(FakeShaderResourceView& shaderView, std::uint32_t width = 32u, std::uint32_t height = 32u) {
    UITextureHandle texture = {};
    texture.nativeHandle = reinterpret_cast<std::uintptr_t>(&shaderView);
    texture.width = width;
    texture.height = height;
    texture.kind = UITextureHandleKind::ShaderResourceView;
    return texture;
}

} // namespace

TEST(XCUIRHIRenderBackendTest, ExposesNativeOverlayEntryAndAtlasInjection) {
    static_assert(std::is_same_v<
                  decltype(std::declval<XCUIRHIRenderBackend&>().Render(
                      std::declval<const RenderContext&>(),
                      std::declval<const RenderSurface&>(),
                      std::declval<const UIDrawData&>())),
                  bool>);
    static_assert(std::is_same_v<
                  decltype(std::declval<XCUIRHIRenderBackend&>().SetTextAtlasProvider(
                      std::declval<const IXCUITextAtlasProvider*>())) ,
                  void>);
    static_assert(std::is_same_v<
                  decltype(std::declval<const XCUIRHIRenderBackend&>().GetLastOverlayStats().drawListCount),
                  std::size_t>);

    SUCCEED();
}

TEST(XCUIRHIRenderBackendTest, RenderRejectsInvalidContextAndLeavesStatsClear) {
    XCUIRHIRenderBackend backend = {};
    RenderSurface surface(128, 72);
    UIDrawData drawData = {};

    EXPECT_FALSE(backend.Render(RenderContext(), surface, drawData));
    EXPECT_EQ(backend.GetLastOverlayStats().commandCount, 0u);
    EXPECT_EQ(backend.GetLastOverlayStats().renderedCommandCount, 0u);
}

TEST(XCUIRHIRenderBackendTest, SetTextAtlasProviderStoresPointerAndResetStatsClearsCounters) {
    XCUIRHIRenderBackend backend = {};

    class StubAtlasProvider final : public IXCUITextAtlasProvider {
    public:
        bool GetAtlasTextureView(PixelFormat, AtlasTextureView& outView) const override {
            outView = {};
            return false;
        }
        std::size_t GetFontCount() const override { return 0u; }
        FontHandle GetFont(std::size_t) const override { return {}; }
        FontHandle GetDefaultFont() const override { return {}; }
        bool GetFontInfo(FontHandle, FontInfo& outInfo) const override {
            outInfo = {};
            return false;
        }
        bool GetBakedFontInfo(FontHandle, float, BakedFontInfo& outInfo) const override {
            outInfo = {};
            return false;
        }
        bool FindGlyph(FontHandle, float, std::uint32_t, GlyphInfo& outInfo) const override {
            outInfo = {};
            return false;
        }
    } atlasProvider;

    backend.SetTextAtlasProvider(&atlasProvider);
    EXPECT_EQ(backend.GetTextAtlasProvider(), &atlasProvider);

    backend.SetTextAtlasProvider(nullptr);
    EXPECT_EQ(backend.GetTextAtlasProvider(), nullptr);

    backend.ResetStats();
    EXPECT_EQ(backend.GetLastStats().drawListCount, 0u);
    EXPECT_EQ(backend.GetLastStats().commandCount, 0u);
    EXPECT_EQ(backend.GetLastStats().batchCount, 0u);
    EXPECT_EQ(backend.GetLastStats().renderedCommandCount, 0u);
    EXPECT_EQ(backend.GetLastStats().skippedCommandCount, 0u);
    EXPECT_EQ(backend.GetLastStats().textureResolveCount, 0u);
    EXPECT_EQ(backend.GetLastStats().textureCacheHitCount, 0u);
}

TEST(XCUIRHIRenderBackendTest, RenderReusesExternalTextureBindingsAcrossTexturedBatches) {
    FakeDevice device = {};
    FakeCommandList commandList = {};
    FakeCommandQueue commandQueue = {};
    FakeRenderTargetView renderTarget = {};
    FakeShaderResourceView externalTextureView(true);

    RenderContext context = {};
    context.device = &device;
    context.commandList = &commandList;
    context.commandQueue = &commandQueue;
    context.backendType = RHIType::D3D12;

    RenderSurface surface(64, 48);
    surface.SetColorAttachment(&renderTarget);

    UIDrawData drawData = {};
    UIDrawList& firstDrawList = drawData.EmplaceDrawList("FirstTexturedBatch");
    firstDrawList.PushClipRect(UIRect(4.0f, 6.0f, 12.0f, 10.0f));
    firstDrawList.AddImage(
        UIRect(0.0f, 0.0f, 18.0f, 18.0f),
        MakeExternalTextureHandle(externalTextureView),
        UIColor(1.0f, 0.8f, 0.6f, 1.0f));
    firstDrawList.PopClipRect();

    UIDrawList& secondDrawList = drawData.EmplaceDrawList("SecondTexturedBatch");
    secondDrawList.PushClipRect(UIRect(20.0f, 8.0f, 10.0f, 12.0f));
    secondDrawList.AddImage(
        UIRect(18.0f, 4.0f, 16.0f, 16.0f),
        MakeExternalTextureHandle(externalTextureView),
        UIColor(0.7f, 0.9f, 1.0f, 1.0f));
    secondDrawList.PopClipRect();

    XCUIRHIRenderBackend backend = {};
    ASSERT_TRUE(backend.Render(context, surface, drawData));

    const XCUIRHIRenderBackend::OverlayStats& stats = backend.GetLastOverlayStats();
    EXPECT_EQ(stats.drawListCount, 2u);
    EXPECT_EQ(stats.commandCount, 6u);
    EXPECT_EQ(stats.batchCount, 2u);
    EXPECT_EQ(stats.colorBatchCount, 0u);
    EXPECT_EQ(stats.texturedBatchCount, 2u);
    EXPECT_EQ(stats.scissoredBatchCount, 2u);
    EXPECT_EQ(stats.renderedCommandCount, 2u);
    EXPECT_EQ(stats.skippedCommandCount, 0u);
    EXPECT_EQ(stats.textureResolveCount, 2u);
    EXPECT_EQ(stats.textureCacheHitCount, 1u);
    EXPECT_EQ(stats.vertexCount, 12u);
    EXPECT_EQ(stats.triangleCount, 4u);

    ASSERT_EQ(commandList.renderTargetBindHistory.size(), 1u);
    ASSERT_EQ(commandList.viewportHistory.size(), 1u);
    ASSERT_EQ(commandList.drawVertexCounts.size(), 2u);
    EXPECT_EQ(commandList.drawVertexCounts[0], 6u);
    EXPECT_EQ(commandList.drawVertexCounts[1], 6u);
    ASSERT_EQ(commandList.textureDescriptorSetHistory.size(), 2u);
    EXPECT_EQ(commandList.textureDescriptorSetHistory[0], commandList.textureDescriptorSetHistory[1]);

    ASSERT_EQ(commandList.scissorHistory.size(), 4u);
    EXPECT_EQ(commandList.scissorHistory[0].left, 0);
    EXPECT_EQ(commandList.scissorHistory[0].top, 0);
    EXPECT_EQ(commandList.scissorHistory[0].right, 64);
    EXPECT_EQ(commandList.scissorHistory[0].bottom, 48);
    EXPECT_EQ(commandList.scissorHistory[1].left, 4);
    EXPECT_EQ(commandList.scissorHistory[1].top, 6);
    EXPECT_EQ(commandList.scissorHistory[1].right, 16);
    EXPECT_EQ(commandList.scissorHistory[1].bottom, 16);
    EXPECT_EQ(commandList.scissorHistory[2].left, 20);
    EXPECT_EQ(commandList.scissorHistory[2].top, 8);
    EXPECT_EQ(commandList.scissorHistory[2].right, 30);
    EXPECT_EQ(commandList.scissorHistory[2].bottom, 20);
    EXPECT_EQ(commandList.scissorHistory[3].left, 0);
    EXPECT_EQ(commandList.scissorHistory[3].top, 0);
    EXPECT_EQ(commandList.scissorHistory[3].right, 64);
    EXPECT_EQ(commandList.scissorHistory[3].bottom, 48);
}

TEST(XCUIRHIRenderBackendTest, RenderSkipsTexturedBatchWhenExternalTextureViewIsInvalid) {
    FakeDevice device = {};
    FakeCommandList commandList = {};
    FakeCommandQueue commandQueue = {};
    FakeRenderTargetView renderTarget = {};
    FakeShaderResourceView invalidTextureView(false);

    RenderContext context = {};
    context.device = &device;
    context.commandList = &commandList;
    context.commandQueue = &commandQueue;
    context.backendType = RHIType::D3D12;

    RenderSurface surface(32, 32);
    surface.SetColorAttachment(&renderTarget);

    UIDrawData drawData = {};
    UIDrawList& drawList = drawData.EmplaceDrawList("InvalidExternalTexture");
    drawList.AddImage(
        UIRect(2.0f, 4.0f, 12.0f, 8.0f),
        MakeExternalTextureHandle(invalidTextureView),
        UIColor(1.0f, 1.0f, 1.0f, 1.0f));

    XCUIRHIRenderBackend backend = {};
    ASSERT_TRUE(backend.Render(context, surface, drawData));

    const XCUIRHIRenderBackend::OverlayStats& stats = backend.GetLastOverlayStats();
    EXPECT_EQ(stats.commandCount, 1u);
    EXPECT_EQ(stats.batchCount, 1u);
    EXPECT_EQ(stats.texturedBatchCount, 1u);
    EXPECT_EQ(stats.renderedCommandCount, 0u);
    EXPECT_EQ(stats.skippedCommandCount, 1u);
    EXPECT_EQ(stats.textureResolveCount, 1u);
    EXPECT_EQ(stats.textureCacheHitCount, 0u);
    EXPECT_EQ(commandList.drawVertexCounts.size(), 0u);
    EXPECT_EQ(commandList.textureDescriptorSetHistory.size(), 0u);
}