using System;
using System.Collections.Generic;
using System.Linq;
using System.Runtime.InteropServices;
using System.Text;
using System.Threading.Tasks;

namespace StgSharp.Graphics
{
    public abstract partial class glRenderStream:RenderStream
    {
        protected IntPtr glContextHandle
        {
            get { return ContextHandle; }
            set { ContextHandle = value; }
        }

        /// <summary>
        /// Init an OpenGl context if current form has not been binded to any context. and set the context binded to
        /// current form as current OpenGL context.
        /// </summary>
        /// <exception cref="Exception">
        /// Something goes wrong and StgSharp fails in creating a new OpenGL context.
        /// </exception>
        public unsafe void MakeAsCurrentContext()
        {
            if (CanvasHandle == default)
            {
                IntPtr windowPtr;
                byte[] tittleBytes = Encoding.UTF8.GetBytes(name);
                if (SharedCanvas == IntPtr.Zero)
                {
                    windowPtr = InternalIO.glfwCreateWindow(Width, Height, tittleBytes, monitor, IntPtr.Zero);
                }
                else
                {
                    windowPtr = InternalIO.glfwCreateWindow(Width, Height, tittleBytes, monitor, SharedCanvas.CanvasHandle);
                }
                if (((long)windowPtr == -1) || ((long)windowPtr == -2))
                {
                    throw new Exception("Cannot create window instance!");
                }
                else
                {
                    CanvasHandle = windowPtr;
                }

                ContextHandle = Marshal.AllocHGlobal(Marshal.SizeOf(typeof(GLcontext)));
                GLcontext* contextID = (GLcontext*)ContextHandle;
                *contextID = new GLcontext();
                contextID->glGetString = (delegate*<uint, IntPtr>)IntPtr.Zero;
            }
            GL.api = (GLcontext*)ContextHandle;
            InternalIO.glfwMakeContextCurrent(CanvasHandle);
        }

        internal sealed override void InternalInit()
        {
            Init();
        }

        internal sealed override void InternalDraw()
        {
            MakeAsCurrentContext();
            Main();
        }


        internal sealed override void InternalTerminate()
        {
            Deinit();
        }
    }
}