// render-d3d12.cpp
#include "render-d3d12.h"

#include "options.h"
#include "render.h"

// In order to use the Slang API, we need to include its header

#include <slang.h>

// We will be rendering with Direct3D 12, so we need to include
// the Windows and D3D12 headers

#define WIN32_LEAN_AND_MEAN
#define NOMINMAX
#include <Windows.h>
#undef WIN32_LEAN_AND_MEAN
#undef NOMINMAX

#include <dxgi1_4.h>
#include <d3d12.h>
#include <d3dcompiler.h>

// We will use the C standard library just for printing error messages.
#include <stdio.h>

#ifdef _MSC_VER
#include <stddef.h>
#if (_MSC_VER < 1900)
#define snprintf sprintf_s
#endif
#endif
//
using namespace Slang;

#define ENABLE_DEBUG_LAYER 1

namespace renderer_test {

// The Slang compiler currently generates HLSL source, so we'll need a utility
// routine (defined later) to translate that into D3D11 shader bytecode.
ID3DBlob* compileHLSLShader(
    char const* sourcePath,
    char const* source,
    char const* entryPointName,
    char const* dxProfileName);

static char const* vertexProfileName   = "vs_4_0";
static char const* fragmentProfileName = "ps_4_0";

//

class D3D12Renderer : public Renderer, public ShaderCompiler
{
public:
    IDXGISwapChain* dxSwapChain = NULL;

    ID3D12Device* dxDevice = NULL;

    virtual PROC loadProc(
        HMODULE module,
        char const* name)
    {
        PROC proc = GetProcAddress(module, name);
        if( !proc )
        {
            fprintf(stderr,
                "error: failed load symbol '%s'\n", name);
            exit(1);
        }
        return proc;
    }

    void checkResult(HRESULT result)
    {
        assert(SUCCEEDED(result));
    }

    virtual void initialize(void* inWindowHandle) override
    {
        auto windowHandle = (HWND) inWindowHandle;
        // Rather than statically link against D3D, we load it dynamically.

        HMODULE d3d12 = LoadLibraryA("d3d12.dll");
        if(!d3d12)
        {
            fprintf(stderr, "error: failed load 'd3d12.dll'\n");
            exit(1);
        }

#define LOAD_PROC(TYPE, NAME) \
        TYPE NAME##_ = (TYPE) loadProc(d3d12, #NAME)


        UINT dxgiFactoryFlags = 0;

#if ENABLE_DEBUG_LAYER
        LOAD_PROC(PFN_D3D12_GET_DEBUG_INTERFACE, D3D12GetDebugInterface);

        ID3D12Debug* debugController;
        if(SUCCEEDED(D3D12GetDebugInterface_(IID_PPV_ARGS(&debugController))))
        {
            debugController->EnableDebugLayer();
            dxgiFactoryFlags |= DXGI_CREATE_FACTORY_DEBUG;
        }
#endif
        
        typedef HRESULT (WINAPI *PFN_DXGI_CREATE_FACTORY_2)(UINT Flags, REFIID riid, _COM_Outptr_ void **ppFactory);


        LOAD_PROC(PFN_DXGI_CREATE_FACTORY_2, CreateDXGIFactory2);

        IDXGIFactory4* dxgiFactory;
        checkResult(CreateDXGIFactory2_(dxgiFactoryFlags, IID_PPV_ARGS(&dxgiFactory)));

        D3D_FEATURE_LEVEL featureLevel = D3D_FEATURE_LEVEL_11_0;

        // Search for an adapter that meets our requirements
        IDXGIAdapter* adapter = nullptr;

        LOAD_PROC(PFN_D3D12_CREATE_DEVICE, D3D12CreateDevice);

        UINT adapterCounter = 0;
        for(;;)
        {
            UINT adapterIndex = adapterCounter++;
            IDXGIAdapter1* candidateAdapter = nullptr;
            if(dxgiFactory->EnumAdapters1(adapterIndex, &candidateAdapter) == DXGI_ERROR_NOT_FOUND)
                break;

            DXGI_ADAPTER_DESC1 desc;
            candidateAdapter->GetDesc1(&desc);

            if( desc.Flags & DXGI_ADAPTER_FLAG_SOFTWARE )
            {
                // TODO: may want to allow software driver as fallback
            }
            else if( SUCCEEDED(D3D12CreateDevice_(
                candidateAdapter, featureLevel, IID_PPV_ARGS(&dxDevice))) )
            {
                // We found one!
                adapter = candidateAdapter;
                break;
            }

            candidateAdapter->Release();
        }

        if(!adapter)
        {
            return;
        }

        // Command Queue

        D3D12_COMMAND_QUEUE_DESC queueDesc = {};
        queueDesc.Type = D3D12_COMMAND_LIST_TYPE_DIRECT;

        ID3D12CommandQueue* commandQueue;
        checkResult(dxDevice->CreateCommandQueue(&queueDesc, IID_PPV_ARGS(&commandQueue)));

        // Swap Chain


        UINT frameCount = 2; // TODO: configure

        DXGI_SWAP_CHAIN_DESC1 swapChainDesc = {};
        swapChainDesc.BufferCount = frameCount;
        swapChainDesc.Width = gWindowWidth;
        swapChainDesc.Height = gWindowHeight;
        swapChainDesc.Format = DXGI_FORMAT_R8G8B8A8_UNORM;
        swapChainDesc.BufferUsage = DXGI_USAGE_RENDER_TARGET_OUTPUT;
        swapChainDesc.SwapEffect = DXGI_SWAP_EFFECT_DISCARD;
        swapChainDesc.SampleDesc.Count = 1;

        IDXGISwapChain1* swapChain;
        checkResult(dxgiFactory->CreateSwapChainForHwnd(
            commandQueue,
            windowHandle,
            &swapChainDesc,
            nullptr,
            nullptr,
            &swapChain));

        // Is this needed?
        dxgiFactory->MakeWindowAssociation(
            windowHandle, DXGI_MWA_NO_ALT_ENTER);

        IDXGISwapChain3* swapChainEx;
        swapChain->QueryInterface(IID_PPV_ARGS(&swapChainEx));

        UINT frameIndex = swapChainEx->GetCurrentBackBufferIndex();

        // Descriptor heaps

        D3D12_DESCRIPTOR_HEAP_DESC rtvHeapDesc = {};
        rtvHeapDesc.NumDescriptors = frameCount;
        rtvHeapDesc.Type = D3D12_DESCRIPTOR_HEAP_TYPE_RTV;

        ID3D12DescriptorHeap* rtvHeap;
        checkResult(dxDevice->CreateDescriptorHeap(&rtvHeapDesc, IID_PPV_ARGS(&rtvHeap)));

        UINT rtvDescriptorSize = dxDevice->GetDescriptorHandleIncrementSize(
            D3D12_DESCRIPTOR_HEAP_TYPE_RTV);

        D3D12_CPU_DESCRIPTOR_HANDLE rtvHandle = rtvHeap->GetCPUDescriptorHandleForHeapStart();

        // Create per-frame RTVs
        ID3D12Resource* backBufferResources[2];
        for( UINT ff = 0; ff < frameCount; ++ff )
        {
            checkResult(swapChainEx->GetBuffer(ff, IID_PPV_ARGS(&backBufferResources[ff])));
            dxDevice->CreateRenderTargetView(
                backBufferResources[ff],
                nullptr,
                rtvHandle);
            rtvHandle.ptr += rtvDescriptorSize;
        }

        ID3D12CommandAllocator* commandAllocator;
        checkResult(dxDevice->CreateCommandAllocator(
            D3D12_COMMAND_LIST_TYPE_DIRECT,
            IID_PPV_ARGS(&commandAllocator)));
    }

    float clearColor[4] = { 0, 0, 0, 0 };
    virtual void setClearColor(float const* color) override
    {
        memcpy(clearColor, color, sizeof(clearColor));
    }

    virtual void clearFrame() override
    {
    }

    virtual void presentFrame() override
    {
    }

    virtual void captureScreenShot(char const* outputPath) override
    {
    }

    virtual ShaderCompiler* getShaderCompiler() override
    {
        return this;
    }

    virtual Buffer* createBuffer(BufferDesc const& desc) override
    {
        return nullptr;
    }

    static DXGI_FORMAT mapFormat(Format format)
    {
        switch( format )
        {
        case Format::RGB_Float32:
            return DXGI_FORMAT_R32G32B32_FLOAT;
        case Format::RG_Float32:
            return DXGI_FORMAT_R32G32_FLOAT;
        default:
            return DXGI_FORMAT_UNKNOWN;
        }
    }

    virtual InputLayout* createInputLayout(InputElementDesc const* inputElements, UInt inputElementCount) override
    {
        return nullptr;
    }

    virtual void* map(Buffer* buffer, MapFlavor flavor) override
    {
        return nullptr;
    }

    virtual void unmap(Buffer* buffer) override
    {
    }

    virtual void setInputLayout(InputLayout* inputLayout) override
    {
    }

    virtual void setPrimitiveTopology(PrimitiveTopology topology) override
    {
    }

    virtual void setVertexBuffers(UInt startSlot, UInt slotCount, Buffer* const* buffers, UInt const* strides, UInt const* offsets) override
    {
    }

    virtual void setShaderProgram(ShaderProgram* inProgram) override
    {
    }

    virtual void setConstantBuffers(UInt startSlot, UInt slotCount, Buffer* const* buffers, UInt const* offsets) override
    {
    }

    virtual void draw(UInt vertexCount, UInt startVertex) override
    {
    }


    virtual void dispatchCompute(int x, int y, int z) override
    {
    }

    virtual BindingState * createBindingState(const ShaderInputLayout & layout)
    {
        return nullptr;
    }

    virtual void setBindingState(BindingState * state)
    {
    }

    virtual void serializeOutput(BindingState* state, const char * fileName)
    {
    }

    // ShaderCompiler interface

    virtual ShaderProgram* compileProgram(ShaderCompileRequest const& request) override
    {
        return nullptr;
    }

};

Renderer* createD3D12Renderer()
{
    return new D3D12Renderer();
}

} // renderer_test