using System;
using System.Collections.Generic;
using System.Linq;
using System.Reflection;
using System.Text;
using System.Threading;
using System.Threading.Tasks;

namespace StgSharp.Graphics
{
    public abstract partial class Form
    {
        #region form thread setting

        private List<FrameAsyncThread> frameAsyncThreadList;

        #endregion form thread setting

        /// <summary>
        /// Init this form and render it on screen, and respond with operation
        /// </summary>
        public unsafe void Show()
        {
            if (gl == null)
            {
                InternalIO.InternalWriteLog($"Attempt to show form {name} before init", LogType.Error);
            }
            else
            {
                frameTimeProvider = new TimeSpanProvider(1 / 60.0, TimeSpanProvider.DefaultProvider);
                MethodInfo[] methods = this.GetType().GetMethods(
                    BindingFlags.Public |
                    BindingFlags.Instance |
                    BindingFlags.DeclaredOnly);
                if (methods.Length != 0)
                {
                    foreach (MethodInfo m in methods)       //find all methods decorated by RenderActivityAttribute
                    {
                        RenderActivityAttribute attr = m.GetCustomAttribute<RenderActivityAttribute>(false);
                        if (attr == null)
                        {
                            continue;
                        }
                        if (!m.IsStatic && (m.GetParameters().Length != 0) && (m.ReturnType != typeof(void)))
                        {
                            throw new NotSupportedException("A render activity cannot have parameters, returning value or be static.");
                        }
                        if (m.Name != "Main")
                        {
                            ThreadStart s = (ThreadStart)Delegate.CreateDelegate(typeof(ThreadStart), this, m);
                            FrameAsyncThread t = new(s,attr._priority);
                            frameAsyncThreadList.Add(t);
                        }
                    }
                }
                List<IGrouping<int,FrameAsyncThread>> threadGroup = frameAsyncThreadList.GroupBy<FrameAsyncThread, int>((t) => t.Priority).ToList();
                int priority = 0;
                foreach (var group in threadGroup)
                {
                    foreach (var t in group)
                    {
                        t.Priority = priority;
                    }
                    priority++;
                }
                
                
                (Barrier, Barrier) b = FrameAsyncThread.CombineAsync(true, frameAsyncThreadList);
                FrameAsyncThread.AsyncStartAll(frameAsyncThreadList);
                if (b.Item1 == null)
                {
                    while (!ShouldClose)
                    {
                        Main();
                        SwapBuffers();
                        PollEvents();
                        frameTimeProvider.WaitNextSpan();
                        Interlocked.Add(ref _frameCount, 1);
                    }
                }
                else
                {
                    while (!ShouldClose)
                    {
                        b.Item1.SignalAndWait();
                        Main();
                        b.Item2.SignalAndWait();
                        SwapBuffers();
                        PollEvents();
                        frameTimeProvider.WaitNextSpan();
                        Interlocked.Add(ref _frameCount, 1);
                    }
                    FrameAsyncThread.TerminateAll(frameAsyncThreadList);
                    b.Item1.SignalAndWait();
                    FrameAsyncThread.WaitAll(frameAsyncThreadList);
                }
                //InternalDeinit();
            }
        }
    }
}