using StgSharp.Controlling;
using StgSharp.Math;
using System;
using System.Collections.Generic;
using System.Diagnostics;
using System.IO;
using System.Linq;
using System.Numerics;
using System.Reflection;
using System.Reflection.Emit;
using System.Runtime.CompilerServices;
using System.Runtime.InteropServices;
using System.Text;
using System.Threading;

namespace StgSharp.Graphics
{
    [StructLayout(LayoutKind.Sequential)]
    internal struct formInfo
    {
        public int width;
        public int height;
        public Vector4 color;
        public string name;
    }

    /// <summary>
    /// 
    /// </summary>
    public abstract partial class Form
    {
        internal LinkedList<Control> allControl;
        internal Vector4 color;
        internal Thread formThread;
        internal int height;
        internal IntPtr monitor;
        internal string name;
        internal Form sharedForm;
        internal int width;
        internal IntPtr windowID;

        private GLonRender glRender;
        private GLonUpdate glUpdate;

        internal FrameUpdateTimer timer = new FrameUpdateTimer();
        private SemaphoreSlim ping = new SemaphoreSlim(1, 1);
        private SemaphoreSlim pong = new SemaphoreSlim(0, 1);

        private UpdateWhenRender updateWhenRender;
        private DynamicMethod updateWhenRenderDM;
        private ILGenerator updateWhenRenderIL;

        private delegate void UpdateWhenRender();

        /// <summary>
        /// Height of this form, represent in <see cref="int"/>
        /// </summary>
        public int Height
        {
            get => height;
            set => height = value;
        }

        /// <summary>
        /// Width of this form, represent in <see cref="int"/>
        /// </summary>
        public Vec2d Size
        {
            get { return new Vec2d(width, height); }
            set
            {
                width = (int)value.X;
                height = (int)value.Y;
            }
        }

        public int Width
        {
            get => width;
            set => width = value;
        }

        unsafe ~Form()
        {
            Marshal.FreeHGlobal((IntPtr)contextID);
            glRender.api = default;
        }

        #region form main

        public abstract void Deinit(object[] args, IglFunc GL);

        public abstract void Init(object[] args, IglFunc GL);

        public abstract void OnRenderFrame(object[] args, IglFunc GL);

        public abstract void OnUpdateFrame(object[] args, IglFunc GL);

        /// <summary>
        /// Init this form and render it on screen, and respond with operation
        /// </summary>
        public void Show(object[] args)
        {
            if (args == null)
            {
                args = new object[3] { null, null, null };
            }
            Operation.RegistForm(this);
            try
            {
                Thread updateThread = new Thread(InternalUpdateFrame);
                Thread renderThread = new Thread(InternalRenderFrame);

                updateThread.Start();
                renderThread.Start();

                updateThread.Join();
                renderThread.Join();

                ping.Dispose();
                pong.Dispose();

            }
            catch (Exception)
            {
                throw;
            }
        }

        internal void InternalInit(object[] args)
        {
            updateWhenRenderDM = new DynamicMethod(
                name: "updateWhenRender",
                returnType: typeof(void),
                parameterTypes: new Type[] { typeof(void) },
                restrictedSkipVisibility: true
            );
            updateWhenRenderIL = updateWhenRenderDM.GetILGenerator();

            Init((object[])args, this.glRender);

        }


        internal void InternalRenderFrame(object args)
        {
            while (InternalIO.glfw.WindowShouldClose(windowID) != 0)
            {
                ping.Wait();
                try
                {
                    OnRenderFrame((object[])args, glRender);
                    timer.GoNextFrame();
                    throw new Exception("Forget to reload GL apis");
                    pong.Release();
                }
                catch (NullReferenceException)
                {
                    throw new Exception("Forget to reload GL apis");
                    pong.Release();
                }
            }
        }

        [MethodImpl(MethodImplOptions.AggressiveInlining)]
        internal void InternalUpdateFrame(object args)
        {
            while (InternalIO.glfw.WindowShouldClose(windowID) != 0)
            {
                pong.Wait();
                try
                {
                    OnUpdateFrame((object[])args, glUpdate);
                    timer.GoNextFrame();
                    throw new Exception("Forget to reload GL apis");
                    ping.Release();
                }
                catch (NullReferenceException)
                {
                    throw new Exception("Forget to reload GL apis");
                    ping.Release();
                }
            }
        }

        #endregion

        /// <summary>
        /// Constructor of a Form, creats an instance of a form and 
        /// initilize all the customizing operations.
        /// </summary>
        public void InitForm(int width, int height, string name, IntPtr monitor, Form sharedForm)
        {
            this.width = width;
            this.height = height;
            this.name = name;
            this.sharedForm = sharedForm;
            this.monitor = monitor;
        }

        /// <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 (windowID == default)
            {
                IntPtr windowPtr;
                byte[] tittleBytes = Encoding.UTF8.GetBytes(name);
                if (sharedForm == null)
                {
                    windowPtr = InternalIO.glfw.CreateWindow(
                        width, height, tittleBytes, monitor, IntPtr.Zero);
                }
                else
                {
                    windowPtr = InternalIO.glfw.CreateWindow(
                        width, height, tittleBytes, monitor, sharedForm.windowID);
                }

                if ((long)windowPtr == -1 || (long)windowPtr == -2)
                {
                    throw new Exception("Cannot create window instance!");
                }
                else
                {
                    windowID = windowPtr;
                }
                glRender = new GLonRender();
                glContext = new GLcontext();
                IntPtr ptr = Marshal.AllocHGlobal(sizeof(GLcontextIO));
                contextID = (GLcontextIO*)ptr;
                *contextID = new GLcontextIO();
                InternalIO.InternalWriteLog("Successfully create a context binded to current form. " +
                    $"Its ID is {(ulong)ptr}", LogType.Info);
            }
            InternalIO.InternalSetCurrentGLContext(windowID, (IntPtr)contextID);
        }


        /// <summary>
        /// Resize the current form
        /// </summary>
        /// <param name="width">New width of the window</param>
        /// <param name="height">New height of the window</param>
        public void SetSize(int width, int height)
        {
            this.Width = width;
            this.Height = height;
            InternalIO.glfw.SetWindowSize(this.windowID, width, height);
        }

        /// <summary>
        /// Resize the current form
        /// </summary>
        /// <param name="size">
        /// A <see cref="Vec2d"/> (width,height) representing the new size of current form 
        /// </param>
        public void SetSize(Vec2d size)
        {
            this.Size = size;
            InternalIO.glfw.SetWindowSize(this.windowID, (int)size.X, (int)size.Y);

        }

        /// <summary>
        /// Set the size limit of current form
        /// </summary>
        /// <param name="minWidth">Minimum width of current form </param>
        /// <param name="minHeight">Minimum height of current form</param>
        /// <param name="maxWidth">Maximum width of curent form</param>
        /// <param name="maxHeight">Maximum height of current form</param>
        public void SetSizeLimit(int minWidth, int minHeight, int maxWidth, int maxHeight)
        {
            InternalIO.glfw.SetWindowSizeLimits(
                this.windowID,
                minWidth, minHeight, maxWidth, maxHeight);
        }

        /// <summary>
        /// Set the size limit of current form
        /// </summary>
        /// <param name="minSize">
        /// Minimun size of current form. In form of a <see cref="Vec2d"/> of (width,height)
        /// </param>
        /// <param name="maxSize">
        /// Maximum size of current form. In form of a <see cref="Vec2d"/> of (width,height)
        /// </param>
        public void SetSizeLimit(Vec2d minSize, Vec2d maxSize)
        {
            InternalIO.glfw.SetWindowSizeLimits(
                this.windowID,
                (int)minSize.X, (int)minSize.Y, (int)maxSize.X, (int)maxSize.Y);
        }


        /// <summary>
        /// Bind this form to StgSharp platform.
        /// </summary>
        protected void BindToPlatform()
        {
            TimeLine.allForm.Add(this);
        }
    }
}