#include <d3d9.h>

#define PRIMITIVE_TRIANGLE_STRIP    1
#define PRIMITIVE_TRIANGLE_LIST        2
#define PRIMITIVE_LINE_STRIP        3
#define PRIMITIVE_LINE_LIST            4
#define PRIMITIVE_POINT_LIST        5
#define PRIMITIVE_TRIANGLE_FAN        6

#define CLASS_NAME    "GameApp"

#define release_com(p)    do { if(p) { (p)->Release(); (p) = NULL; } } while(0)

IDirect3D9*                g_d3d;
IDirect3DDevice9*        g_device;
IDirect3DVertexBuffer9* g_vertex_buffer;

DWORD                    g_primitive_type = PRIMITIVE_TRIANGLE_STRIP;
DWORD                    g_fill_mode = D3DFILL_WIREFRAME;

struct sCustomVertex
{
    float x, y, z, rhw;
    DWORD color;
};

#define D3DFVF_CUSTOM_VERTEX (D3DFVF_XYZRHW | D3DFVF_DIFFUSE) 

void init_vb()
{
    sCustomVertex vertices[] =
    {
        {  50.0f, 250.0f, 0.5f, 1.0f, 0xffff0000, },
        { 150.0f,  50.0f, 0.5f, 1.0f, 0xffff0000, }, 
        { 250.0f, 250.0f, 0.5f, 1.0f, 0xffff0000, },
        
        { 350.0f,  50.0f, 0.5f, 1.0f, 0xffff0000, }, 
        { 450.0f, 250.0f, 0.5f, 1.0f, 0xffff0000, },
        { 550.0f, 50.0f,  0.5f, 1.0f, 0xffff0000, }
    };

    g_device->CreateVertexBuffer(sizeof(vertices), 0, D3DFVF_CUSTOM_VERTEX, D3DPOOL_DEFAULT, &g_vertex_buffer, NULL);

    void* ptr;

    g_vertex_buffer->Lock(0, sizeof(vertices), (void**)&ptr, 0);
    memcpy(ptr, vertices, sizeof(vertices));
    g_vertex_buffer->Unlock();
}

bool init_d3d(HWND hwnd)
{
    g_d3d = Direct3DCreate9(D3D_SDK_VERSION);

    if(g_d3d == NULL)
        return false;

    D3DPRESENT_PARAMETERS d3dpp;
    ZeroMemory(&d3dpp, sizeof(d3dpp));

    d3dpp.Windowed            = TRUE;
    d3dpp.SwapEffect        = D3DSWAPEFFECT_DISCARD;
    d3dpp.BackBufferFormat    = D3DFMT_UNKNOWN;

    if(FAILED(g_d3d->CreateDevice(D3DADAPTER_DEFAULT, D3DDEVTYPE_HAL, hwnd, D3DCREATE_SOFTWARE_VERTEXPROCESSING,
                                  &d3dpp, &g_device)))
    {
        return false;
    }

    init_vb();

    g_device->SetRenderState(D3DRS_CULLMODE, D3DCULL_NONE);    // do not cull any face
    g_device->SetRenderState(D3DRS_FILLMODE, g_fill_mode);

    return true;
}

void cleanup()
{
    release_com(g_vertex_buffer);
    release_com(g_device);
    release_com(g_d3d);
}

void render()
{
    g_device->Clear(0, NULL, D3DCLEAR_TARGET, D3DCOLOR_XRGB(5, 5, 5), 1.0f, 0);

    g_device->BeginScene();

    g_device->SetRenderState(D3DRS_FILLMODE, g_fill_mode);
    g_device->SetStreamSource(0, g_vertex_buffer, 0, sizeof(sCustomVertex));
    g_device->SetFVF(D3DFVF_CUSTOM_VERTEX);
    
    switch(g_primitive_type)
    {
    case PRIMITIVE_TRIANGLE_STRIP:
        g_device->DrawPrimitive(D3DPT_TRIANGLESTRIP, 0, 4);
        break;

    case PRIMITIVE_TRIANGLE_LIST:  
        g_device->DrawPrimitive(D3DPT_TRIANGLELIST, 0, 2);
        break;

    case PRIMITIVE_LINE_STRIP:  
        g_device->DrawPrimitive(D3DPT_LINESTRIP, 0, 5);
        break;

    case PRIMITIVE_LINE_LIST: 
        g_device->DrawPrimitive(D3DPT_LINELIST, 0, 3);
        break;

    case PRIMITIVE_POINT_LIST:
        g_device->DrawPrimitive(D3DPT_POINTLIST, 0, 6);
        break;

    case PRIMITIVE_TRIANGLE_FAN:
        g_device->DrawPrimitive(D3DPT_TRIANGLEFAN, 0, 4);
        break;
    }

    g_device->EndScene();

    g_device->Present(NULL, NULL, NULL, NULL);
}

LRESULT WINAPI WinProc(HWND hwnd, UINT msg, WPARAM wParam, LPARAM lParam)
{
    switch(msg)
    {
    case WM_KEYDOWN:
        switch(wParam)
        {
        case 49:    // key "1"
        case 50:    // key "2"
        case 51:    // key "3"
        case 52:    // key "4"
        case 53:    // key "5"
        case 54:    // key "6"
            g_primitive_type = (DWORD)wParam - 48;
            break;

        case VK_SPACE:
            g_fill_mode = (g_fill_mode == D3DFILL_WIREFRAME) ? D3DFILL_SOLID : D3DFILL_WIREFRAME;
            break;

        case VK_ESCAPE:
            DestroyWindow(hwnd);
            break;
        }    
        break;

    case WM_DESTROY:        
        PostQuitMessage(0);
        return 0;
    }

    return DefWindowProc(hwnd, msg, wParam, lParam);
}

int WINAPI WinMain(HINSTANCE inst, HINSTANCE, LPSTR, INT)
{
    WNDCLASSEX wc;

    wc.cbSize            = sizeof(WNDCLASSEX);
    wc.style            = CS_CLASSDC;
    wc.lpfnWndProc        = WinProc;
    wc.cbClsExtra        = 0;
    wc.cbWndExtra        = 0;
    wc.hInstance        = inst;
    wc.hIcon            = NULL;
    wc.hCursor            = NULL;
    wc.hbrBackground    = NULL;
    wc.lpszMenuName        = NULL;
    wc.lpszClassName    = CLASS_NAME;
    wc.hIconSm            = NULL;

    if(! RegisterClassEx(&wc))
        return -1;

    HWND hwnd = CreateWindow(CLASS_NAME, "Direct3D App", WS_OVERLAPPEDWINDOW, 200, 100, 600, 300,
                             NULL, NULL, wc.hInstance, NULL);

    if(hwnd == NULL)
        return -1;

    if(init_d3d(hwnd))
    {
        ShowWindow(hwnd, SW_SHOWDEFAULT);
        UpdateWindow(hwnd);

        MSG msg;
        ZeroMemory(&msg, sizeof(msg));

        while(msg.message != WM_QUIT)
        {
            if(PeekMessage(&msg, NULL, 0, 0, PM_REMOVE))
            {
                TranslateMessage(&msg);
                DispatchMessage(&msg);
            }
                
            render();
        }
    }

    cleanup();

    UnregisterClass(CLASS_NAME, wc.hInstance);    

    return 0;
}