#pragma once

class GraphicsScene 
{
protected:

    // D2D Resources
    CComPtr<ID2D1Factory>           m_pFactory;
    CComPtr<ID2D1HwndRenderTarget>  m_pRenderTarget;

    float   m_fScaleX;
    float   m_fScaleY;

protected:

    // Derived class must implement these methods.
    virtual HRESULT CreateDeviceIndependentResources() = 0;
    virtual void    DiscardDeviceIndependentResources() = 0;
    virtual HRESULT CreateDeviceDependentResources() = 0;
    virtual void    DiscardDeviceDependentResources() = 0;
    virtual void    CalculateLayout() = 0;
    virtual void    RenderScene() = 0;

protected:

    HRESULT CreateGraphicsResources(HWND hwnd)
    {
        HRESULT hr = S_OK;
        if (m_pRenderTarget == NULL)
        {
            RECT rc;
            GetClientRect(hwnd, &rc);

            D2D1_SIZE_U size = D2D1::SizeU(rc.right, rc.bottom);

            hr = m_pFactory->CreateHwndRenderTarget(
                D2D1::RenderTargetProperties(),
                D2D1::HwndRenderTargetProperties(hwnd, size),
                &m_pRenderTarget
                );

            if (SUCCEEDED(hr))
            {
                hr = CreateDeviceDependentResources();
            }
            if (SUCCEEDED(hr))
            {
                CalculateLayout();
            }
        }
        return hr;
    }

    template <class T>
    T PixelToDipX(T pixels) const
    {
        return static_cast<T>(pixels / m_fScaleX);
    }

    template <class T>
    T PixelToDipY(T pixels) const
    {
        return static_cast<T>(pixels / m_fScaleY);
    }

public:
    GraphicsScene() : m_fScaleX(1.0f), m_fScaleY(1.0f) {}
    virtual ~GraphicsScene() {}

    HRESULT Initialize()
    {
        HRESULT hr = D2D1CreateFactory(D2D1_FACTORY_TYPE_SINGLE_THREADED, 
            &m_pFactory);

        if (SUCCEEDED(hr))
        {
            CreateDeviceIndependentResources();
        }
        return hr;
    }

    void Render(HWND hwnd)
    {
        HRESULT hr = CreateGraphicsResources(hwnd);
        if (FAILED(hr))
        {
            return;
        }

        assert(m_pRenderTarget != NULL);

        m_pRenderTarget->BeginDraw();

        RenderScene();

        hr = m_pRenderTarget->EndDraw();
        if (hr == D2DERR_RECREATE_TARGET)
        {
            DiscardDeviceDependentResources();
            m_pRenderTarget.Release();
        }
    }

    HRESULT Resize(int x, int y)
    {
        HRESULT hr = S_OK;
        if (m_pRenderTarget)
        {
            hr = m_pRenderTarget->Resize( D2D1::SizeU(x, y) );
            if (SUCCEEDED(hr))
            {
                CalculateLayout();
            }
        }
        return hr;
    }

    void CleanUp()
    {
        DiscardDeviceDependentResources();
        DiscardDeviceIndependentResources();
    }
};