// ImGui - standalone example application for DirectX 11
// If you are new to ImGui, see examples/README.txt and documentation at the top of imgui.cpp.

#include <assert.h>
#include <imgui.h>
#include "imgui_impl_dx12.h"
#include <d3d12.h>
#include <dxgi1_4.h>
#include <tchar.h>

struct FrameContext
{
    ID3D12CommandAllocator* CommandAllocator;
    UINT64                  FenceValue;
    bool                    FenceSignalled;
};

// Data
static int const                    NUM_FRAMES_IN_FLIGHT = 3;
static FrameContext                 g_frameContext[NUM_FRAMES_IN_FLIGHT] = {};
static UINT                         g_frameIndex = 0;

static int const                    NUM_BACK_BUFFERS = 3;
static IDXGIFactory4*               g_pdxgiFactory = NULL;
static ID3D12Device*                g_pd3dDevice = NULL;
static ID3D12DescriptorHeap*        g_pd3dRtvDescHeap = NULL;
static ID3D12DescriptorHeap*        g_pd3dSrvDescHeap = NULL;
static ID3D12CommandQueue*          g_pd3dCommandQueue = NULL;
static ID3D12GraphicsCommandList*   g_pd3dCommandList = NULL;
static ID3D12Fence*                 g_fence = NULL;
static HANDLE                       g_fenceEvent = NULL;
static UINT64                       g_fenceLastSignalledValue = 0;
static IDXGISwapChain3*             g_pSwapChain = NULL;
static HANDLE                       g_hSwapChainWaitableObject = NULL;
static ID3D12Resource*              g_mainRenderTargetResource[NUM_BACK_BUFFERS] = {};
static D3D12_CPU_DESCRIPTOR_HANDLE  g_mainRenderTargetDescriptor[NUM_BACK_BUFFERS] = {};

static void WaitForLastSubmittedFrame()
{
    FrameContext* frameCtxt = &g_frameContext[g_frameIndex % NUM_FRAMES_IN_FLIGHT];

    UINT64 fenceValue = frameCtxt->FenceValue;
    if (fenceValue == 0) { // means no fence was signalled
        return;
    }

    frameCtxt->FenceValue = 0;
    if (g_fence->GetCompletedValue() >= fenceValue) {
        return;
    }

    HRESULT hr = g_fence->SetEventOnCompletion(fenceValue, g_fenceEvent);
    assert(SUCCEEDED(hr));

    WaitForSingleObject(g_fenceEvent, INFINITE);
}

static FrameContext* WaitForNextFrameResources()
{
    UINT nextFrameIndex = g_frameIndex + 1;
    g_frameIndex = nextFrameIndex;

    HANDLE waitableObjects[] = {
        g_hSwapChainWaitableObject,
        NULL,
    };
    DWORD numWaitableObjects = 1;

    FrameContext* frameCtxt = &g_frameContext[nextFrameIndex % NUM_FRAMES_IN_FLIGHT];
    UINT64 fenceValue = frameCtxt->FenceValue;
    if (fenceValue != 0) { // means no fence was signalled
        frameCtxt->FenceValue = 0;

        HRESULT hr = g_fence->SetEventOnCompletion(fenceValue, g_fenceEvent);
        assert(SUCCEEDED(hr));

        waitableObjects[1] = g_fenceEvent;
        numWaitableObjects = 2;
    }

    HRESULT hr = WaitForMultipleObjects(numWaitableObjects, waitableObjects, TRUE, INFINITE);
    assert(SUCCEEDED(hr));

    return frameCtxt;
}

void CreateRenderTarget(HWND hWnd, int width, int height)
{
    DXGI_SWAP_CHAIN_DESC1 desc = {};
    desc.Width              = width;
    desc.Height             = height;
    desc.Format             = DXGI_FORMAT_B8G8R8A8_UNORM;
    desc.Stereo             = FALSE;
    desc.SampleDesc.Count   = 1;
    desc.SampleDesc.Quality = 0;
    desc.BufferUsage        = DXGI_USAGE_RENDER_TARGET_OUTPUT;
    desc.BufferCount        = NUM_BACK_BUFFERS;
    desc.Scaling            = DXGI_SCALING_STRETCH;
    desc.SwapEffect         = DXGI_SWAP_EFFECT_FLIP_DISCARD;
    desc.AlphaMode          = DXGI_ALPHA_MODE_UNSPECIFIED;
    desc.Flags              = DXGI_SWAP_CHAIN_FLAG_FRAME_LATENCY_WAITABLE_OBJECT;

    IDXGISwapChain1* swapChain1 = NULL;
    HRESULT hr = g_pdxgiFactory->CreateSwapChainForHwnd(g_pd3dCommandQueue, hWnd, &desc, NULL, NULL, &swapChain1);
    assert(SUCCEEDED(hr));

    hr = swapChain1->QueryInterface(IID_PPV_ARGS(&g_pSwapChain));
    assert(SUCCEEDED(hr));

    swapChain1->Release();

    hr = g_pSwapChain->SetMaximumFrameLatency(NUM_BACK_BUFFERS);
    assert(SUCCEEDED(hr));

    g_hSwapChainWaitableObject = g_pSwapChain->GetFrameLatencyWaitableObject();
    assert(g_hSwapChainWaitableObject != NULL);

    for (UINT i = 0; i < NUM_BACK_BUFFERS; ++i)
    {
        hr = g_pSwapChain->GetBuffer(i, IID_PPV_ARGS(&g_mainRenderTargetResource[i]));
        assert(SUCCEEDED(hr));

        g_pd3dDevice->CreateRenderTargetView(g_mainRenderTargetResource[i], NULL, g_mainRenderTargetDescriptor[i]);
    }
}

void CleanupRenderTarget()
{
    WaitForLastSubmittedFrame();

    if (g_pSwapChain) { g_pSwapChain->Release(); g_pSwapChain = NULL; }
    for (UINT i = 0; i < NUM_BACK_BUFFERS; ++i)
    {
        if (g_mainRenderTargetResource[i]) { g_mainRenderTargetResource[i]->Release(); g_mainRenderTargetResource[i] = NULL; }
    }
    if (g_hSwapChainWaitableObject != NULL) { CloseHandle(g_hSwapChainWaitableObject); }
}

HRESULT CreateDeviceD3D(HWND hWnd)
{
    (void) hWnd;

#ifdef _DEBUG
    {
        ID3D12Debug* debugController = NULL;
        if (SUCCEEDED(D3D12GetDebugInterface(IID_PPV_ARGS(&debugController))))
        {
            debugController->EnableDebugLayer();
            debugController->Release();
        }
    }
#endif

    if (CreateDXGIFactory1(IID_PPV_ARGS(&g_pdxgiFactory)) != S_OK)
        return E_FAIL;

    IDXGIAdapter1* adapter = NULL;
    for (UINT adapterIndex = 0; DXGI_ERROR_NOT_FOUND != g_pdxgiFactory->EnumAdapters1(adapterIndex, &adapter); ++adapterIndex)
    {
        DXGI_ADAPTER_DESC1 desc = {};
        adapter->GetDesc1(&desc);

        if (desc.Flags & DXGI_ADAPTER_FLAG_SOFTWARE)
        {
            adapter->Release();
            continue;
        }

        if (FAILED(D3D12CreateDevice(adapter, D3D_FEATURE_LEVEL_11_0, _uuidof(ID3D12Device), NULL)))
        {
            adapter->Release();
            continue;
        }

        break;
    }

    HRESULT hr = D3D12CreateDevice(adapter, D3D_FEATURE_LEVEL_11_0, IID_PPV_ARGS(&g_pd3dDevice));

    if (adapter != NULL)
    {
        adapter->Release();
    }

    if (FAILED(hr))
        return hr;

    {
        D3D12_DESCRIPTOR_HEAP_DESC desc = {};
        desc.Type           = D3D12_DESCRIPTOR_HEAP_TYPE_RTV;
        desc.NumDescriptors = NUM_BACK_BUFFERS;
        desc.Flags          = D3D12_DESCRIPTOR_HEAP_FLAG_NONE;
        desc.NodeMask       = 1;
        if (g_pd3dDevice->CreateDescriptorHeap(&desc, IID_PPV_ARGS(&g_pd3dRtvDescHeap)) != S_OK)
            return E_FAIL;

        SIZE_T rtvDescriptorSize = g_pd3dDevice->GetDescriptorHandleIncrementSize(D3D12_DESCRIPTOR_HEAP_TYPE_RTV);
        D3D12_CPU_DESCRIPTOR_HANDLE rtvHandle = g_pd3dRtvDescHeap->GetCPUDescriptorHandleForHeapStart();
        for (UINT i = 0; i < NUM_BACK_BUFFERS; ++i) {
            g_mainRenderTargetDescriptor[i] = rtvHandle;
            rtvHandle.ptr += rtvDescriptorSize;
        }
    }

    {
        D3D12_DESCRIPTOR_HEAP_DESC desc = {};
        desc.Type = D3D12_DESCRIPTOR_HEAP_TYPE_CBV_SRV_UAV;
        desc.NumDescriptors = 1;
        desc.Flags = D3D12_DESCRIPTOR_HEAP_FLAG_SHADER_VISIBLE;
        if (g_pd3dDevice->CreateDescriptorHeap(&desc, IID_PPV_ARGS(&g_pd3dSrvDescHeap)) != S_OK)
            return E_FAIL;
    }

    {
        D3D12_COMMAND_QUEUE_DESC desc = {};
        desc.Type     = D3D12_COMMAND_LIST_TYPE_DIRECT;
        desc.Flags    = D3D12_COMMAND_QUEUE_FLAG_NONE;
        desc.NodeMask = 1;
        if (g_pd3dDevice->CreateCommandQueue(&desc, IID_PPV_ARGS(&g_pd3dCommandQueue)) != S_OK)
            return E_FAIL;
    }

    for (UINT i = 0; i < NUM_FRAMES_IN_FLIGHT; ++i)
    {
        if (g_pd3dDevice->CreateCommandAllocator(D3D12_COMMAND_LIST_TYPE_DIRECT, IID_PPV_ARGS(&g_frameContext[i].CommandAllocator)) != S_OK)
            return E_FAIL;
    }

    if (g_pd3dDevice->CreateCommandList(0, D3D12_COMMAND_LIST_TYPE_DIRECT, g_frameContext[0].CommandAllocator, NULL, IID_PPV_ARGS(&g_pd3dCommandList)) != S_OK ||
        g_pd3dCommandList->Close() != S_OK)
        return E_FAIL;

    if (g_pd3dDevice->CreateFence(0, D3D12_FENCE_FLAG_NONE, IID_PPV_ARGS(&g_fence)) != S_OK)
        return E_FAIL;

    g_fenceEvent = CreateEvent(NULL, FALSE, FALSE, NULL);
    if (g_fenceEvent == NULL)
        return E_FAIL;

    return S_OK;
}

void CleanupDeviceD3D()
{
    CleanupRenderTarget();
    for (UINT i = 0; i < NUM_FRAMES_IN_FLIGHT; ++i)
    {
        if (g_frameContext[i].CommandAllocator) { g_frameContext[i].CommandAllocator->Release(); g_frameContext[i].CommandAllocator = NULL; }
    }
    if (g_pd3dCommandQueue) { g_pd3dCommandQueue->Release(); g_pd3dCommandQueue = NULL; }
    if (g_pd3dCommandList) { g_pd3dCommandList->Release(); g_pd3dCommandList = NULL; }
    if (g_pd3dRtvDescHeap) { g_pd3dRtvDescHeap->Release(); g_pd3dRtvDescHeap = NULL; }
    if (g_pd3dSrvDescHeap) { g_pd3dSrvDescHeap->Release(); g_pd3dSrvDescHeap = NULL; }
    if (g_fence) { g_fence->Release(); g_fence = NULL; }
    if (g_fenceEvent) { CloseHandle(g_fenceEvent); g_fenceEvent = NULL; }
    if (g_pd3dDevice) { g_pd3dDevice->Release(); g_pd3dDevice = NULL; }
    if (g_pdxgiFactory) { g_pdxgiFactory->Release(); g_pdxgiFactory = NULL; }
}

extern LRESULT ImGui_ImplDX12_WndProcHandler(HWND hWnd, UINT msg, WPARAM wParam, LPARAM lParam);
LRESULT WINAPI WndProc(HWND hWnd, UINT msg, WPARAM wParam, LPARAM lParam)
{
    if (ImGui_ImplDX12_WndProcHandler(hWnd, msg, wParam, lParam))
        return true;

    switch (msg)
    {
    case WM_SIZE:
        if (g_pd3dDevice != NULL && wParam != SIZE_MINIMIZED)
        {
            ImGui_ImplDX12_InvalidateDeviceObjects();
            CleanupRenderTarget();
            CreateRenderTarget(hWnd, (UINT)LOWORD(lParam), (UINT)HIWORD(lParam));
            ImGui_ImplDX12_CreateDeviceObjects();
        }
        return 0;
    case WM_SYSCOMMAND:
        if ((wParam & 0xfff0) == SC_KEYMENU) // Disable ALT application menu
            return 0;
        break;
    case WM_DESTROY:
        PostQuitMessage(0);
        return 0;
    }
    return DefWindowProc(hWnd, msg, wParam, lParam);
}

int main(int, char**)
{
    // Create application window
    WNDCLASSEX wc = { sizeof(WNDCLASSEX), CS_CLASSDC, WndProc, 0L, 0L, GetModuleHandle(NULL), NULL, LoadCursor(NULL, IDC_ARROW), NULL, NULL, _T("ImGui Example"), NULL };
    RegisterClassEx(&wc);
    HWND hwnd = CreateWindow(_T("ImGui Example"), _T("ImGui DirectX12 Example"), WS_OVERLAPPEDWINDOW, 100, 100, 1280, 800, NULL, NULL, wc.hInstance, NULL);

    // Initialize Direct3D
    if (CreateDeviceD3D(hwnd) < 0)
    {
        CleanupDeviceD3D();
        UnregisterClass(_T("ImGui Example"), wc.hInstance);
        return 1;
    }

    // Show the window
    ShowWindow(hwnd, SW_SHOWDEFAULT);
    UpdateWindow(hwnd);

    // Setup ImGui binding
    ImGui_ImplDX12_Init(hwnd, NUM_FRAMES_IN_FLIGHT, g_pd3dDevice, g_pd3dCommandList,
        g_pd3dSrvDescHeap->GetCPUDescriptorHandleForHeapStart(),
        g_pd3dSrvDescHeap->GetGPUDescriptorHandleForHeapStart());

    // Load Fonts
    // (there is a default font, this is only if you want to change it. see extra_fonts/README.txt for more details)
    //ImGuiIO& io = ImGui::GetIO();
    //io.Fonts->AddFontDefault();
    //io.Fonts->AddFontFromFileTTF("../../extra_fonts/Cousine-Regular.ttf", 15.0f);
    //io.Fonts->AddFontFromFileTTF("../../extra_fonts/DroidSans.ttf", 16.0f);
    //io.Fonts->AddFontFromFileTTF("../../extra_fonts/ProggyClean.ttf", 13.0f);
    //io.Fonts->AddFontFromFileTTF("../../extra_fonts/ProggyTiny.ttf", 10.0f);
    //io.Fonts->AddFontFromFileTTF("c:\\Windows\\Fonts\\ArialUni.ttf", 18.0f, NULL, io.Fonts->GetGlyphRangesJapanese());

    bool show_test_window = true;
    bool show_another_window = false;
    ImVec4 clear_col = ImColor(114, 144, 154);

    // Main loop
    MSG msg;
    ZeroMemory(&msg, sizeof(msg));
    while (msg.message != WM_QUIT)
    {
        if (PeekMessage(&msg, NULL, 0U, 0U, PM_REMOVE))
        {
            TranslateMessage(&msg);
            DispatchMessage(&msg);
            continue;
        }

        // Wait for frame resources to be available

        ImGui_ImplDX12_NewFrame();

        // 1. Show a simple window
        // Tip: if we don't call ImGui::Begin()/ImGui::End() the widgets appears in a window automatically called "Debug"
        {
            static float f = 0.0f;
            ImGui::Text("Hello, world!");
            ImGui::SliderFloat("float", &f, 0.0f, 1.0f);
            ImGui::ColorEdit3("clear color", (float*)&clear_col);
            if (ImGui::Button("Test Window")) show_test_window ^= 1;
            if (ImGui::Button("Another Window")) show_another_window ^= 1;
            ImGui::Text("Application average %.3f ms/frame (%.1f FPS)", 1000.0f / ImGui::GetIO().Framerate, ImGui::GetIO().Framerate);
        }

        // 2. Show another simple window, this time using an explicit Begin/End pair
        if (show_another_window)
        {
            ImGui::SetNextWindowSize(ImVec2(200,100), ImGuiSetCond_FirstUseEver);
            ImGui::Begin("Another Window", &show_another_window);
            ImGui::Text("Hello");
            ImGui::End();
        }

        // 3. Show the ImGui test window. Most of the sample code is in ImGui::ShowTestWindow()
        if (show_test_window)
        {
            ImGui::SetNextWindowPos(ImVec2(650, 20), ImGuiSetCond_FirstUseEver);     // Normally user code doesn't need/want to call it because positions are saved in .ini file anyway. Here we just want to make the demo initial state a bit more friendly!
            ImGui::ShowTestWindow(&show_test_window);
        }

        // Rendering
        FrameContext* frameCtxt = WaitForNextFrameResources();
        UINT backBufferIdx = g_pSwapChain->GetCurrentBackBufferIndex();

        HRESULT hr = frameCtxt->CommandAllocator->Reset();
        assert(SUCCEEDED(hr));

        hr = g_pd3dCommandList->Reset(frameCtxt->CommandAllocator, NULL);
        assert(SUCCEEDED(hr));

        D3D12_RESOURCE_BARRIER barrier = {};
        barrier.Type                   = D3D12_RESOURCE_BARRIER_TYPE_TRANSITION;
        barrier.Flags                  = D3D12_RESOURCE_BARRIER_FLAG_NONE;
        barrier.Transition.pResource   = g_mainRenderTargetResource[backBufferIdx];
        barrier.Transition.Subresource = D3D12_RESOURCE_BARRIER_ALL_SUBRESOURCES;
        barrier.Transition.StateBefore = D3D12_RESOURCE_STATE_PRESENT;
        barrier.Transition.StateAfter  = D3D12_RESOURCE_STATE_RENDER_TARGET;
        g_pd3dCommandList->ResourceBarrier(1, &barrier);

        g_pd3dCommandList->ClearRenderTargetView(g_mainRenderTargetDescriptor[backBufferIdx], (float*)&clear_col, 0, NULL);
        g_pd3dCommandList->OMSetRenderTargets(1, &g_mainRenderTargetDescriptor[backBufferIdx], FALSE, NULL);
        g_pd3dCommandList->SetDescriptorHeaps(1, &g_pd3dSrvDescHeap);
        ImGui::Render();

        barrier.Transition.StateBefore = D3D12_RESOURCE_STATE_RENDER_TARGET;
        barrier.Transition.StateAfter  = D3D12_RESOURCE_STATE_PRESENT;
        g_pd3dCommandList->ResourceBarrier(1, &barrier);

        hr = g_pd3dCommandList->Close();
        assert(SUCCEEDED(hr));

        g_pd3dCommandQueue->ExecuteCommandLists(1, (ID3D12CommandList* const*) &g_pd3dCommandList);

        hr = g_pSwapChain->Present(1, 0);
        assert(SUCCEEDED(hr));

        auto fenceValue = g_fenceLastSignalledValue + 1;
        hr = g_pd3dCommandQueue->Signal(g_fence, fenceValue);
        assert(SUCCEEDED(hr));
        g_fenceLastSignalledValue = fenceValue;
        frameCtxt->FenceValue = fenceValue;
    }

    ImGui_ImplDX12_Shutdown();
    CleanupDeviceD3D();
    UnregisterClass(_T("ImGui Example"), wc.hInstance);

    return 0;
}