using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using SharpGL.Version;

namespace SharpGL.RenderContextProviders
{
    public class NativeWindowRenderContextProvider : RenderContextProvider
    {
        /// <summary>
        /// Initializes a new instance of the <see cref="NativeWindowRenderContextProvider"/> class.
        /// </summary>
        public NativeWindowRenderContextProvider()
        {
            //  We cannot layer GDI drawing on top of open gl drawing.
            GDIDrawingEnabled = false;
        }

        /// <summary>
        /// Creates the render context provider. Must also create the OpenGL extensions.
        /// </summary>
        /// <param name="openGLVersion">The desired OpenGL version.</param>
        /// <param name="gl">The OpenGL context.</param>
        /// <param name="width">The width.</param>
        /// <param name="height">The height.</param>
        /// <param name="bitDepth">The bit depth.</param>
        /// <param name="parameter">The parameter.</param>
        /// <returns></returns>
        /// <exception cref="System.Exception">A valid Window Handle must be provided for the NativeWindowRenderContextProvider</exception>
        public override bool Create(OpenGLVersion openGLVersion, OpenGL gl, int width, int height, int bitDepth, object parameter)
        {
            //  Call the base.
            base.Create(openGLVersion, gl, width, height, bitDepth, parameter);

            //  Cast the parameter to the device context.
            try
            {
                windowHandle = (IntPtr)parameter;
            }
            catch
            {
                throw new Exception("A valid Window Handle must be provided for the NativeWindowRenderContextProvider");
            }

		    //	Get the window device context.
		    deviceContextHandle = Win32.GetDC(windowHandle);

		    //	Setup a pixel format.
		    Win32.PIXELFORMATDESCRIPTOR pfd = new Win32.PIXELFORMATDESCRIPTOR();
            pfd.Init();
		    pfd.nVersion = 1;
		    pfd.dwFlags = Win32.PFD_DRAW_TO_WINDOW | Win32.PFD_SUPPORT_OPENGL | Win32.PFD_DOUBLEBUFFER;
		    pfd.iPixelType = Win32.PFD_TYPE_RGBA;
		    pfd.cColorBits = (byte)bitDepth;
		    pfd.cDepthBits = 16;
		    pfd.cStencilBits = 8;
		    pfd.iLayerType = Win32.PFD_MAIN_PLANE;
		
		    //	Match an appropriate pixel format 
		    int iPixelformat;
		    if((iPixelformat = Win32.ChoosePixelFormat(deviceContextHandle, pfd)) == 0 )
			    return false;

		    //	Sets the pixel format
            if (Win32.SetPixelFormat(deviceContextHandle, iPixelformat, pfd) == 0)
		    {
			    return false;
		    }

		    //	Create the render context.
            renderContextHandle = Win32.wglCreateContext(deviceContextHandle);
            
            //  Make the context current.
            MakeCurrent();

            //  Update the render context if required.
            UpdateContextVersion(gl);

            //  Return success.
            return true;
        }

        /// <summary>
        /// Destroys the render context provider instance.
        /// </summary>
	    public override void Destroy()
	    {
		    //	Release the device context.
		    Win32.ReleaseDC(windowHandle, deviceContextHandle);
            
		    //	Call the base, which will delete the render context handle.
            base.Destroy();
	    }

        /// <summary>
        /// Sets the dimensions of the render context provider.
        /// </summary>
        /// <param name="width">Width.</param>
        /// <param name="height">Height.</param>
	    public override void SetDimensions(int width, int height)
	    {
            //  Call the base.
            base.SetDimensions(width, height);
	    }

        /// <summary>
        /// Blit the rendered data to the supplied device context.
        /// </summary>
        /// <param name="hdc">The HDC.</param>
	    public override void Blit(IntPtr hdc)
	    {
		    if(deviceContextHandle != IntPtr.Zero || windowHandle != IntPtr.Zero)
		    {
			    //	Swap the buffers.
                Win32.SwapBuffers(deviceContextHandle);
		    }
	    }

        /// <summary>
        /// Makes the render context current.
        /// </summary>
	    public override void MakeCurrent()
	    {
		    if(renderContextHandle != IntPtr.Zero)
			    Win32.wglMakeCurrent(deviceContextHandle, renderContextHandle);
	    }

        /// <summary>
        /// The window handle.
        /// </summary>
        protected IntPtr windowHandle = IntPtr.Zero;
    }
}