using System;
using System.Collections.Generic;
using System.Linq;
using System.Runtime.CompilerServices;
using System.Runtime.InteropServices;
using System.Runtime.Versioning;
using System.Security.AccessControl;
using System.Text;
using System.Threading.Tasks;



namespace System
{
    /// <summary>
    /// A handle to an OpenGL object.
    /// </summary>
    public unsafe class glHandle
    {
        private readonly uint[] _value;
        internal int length;
        internal uint* handle;

        public uint this[int index]
        {
            get
            {
                if (index > length)
                {
                    throw new IndexOutOfRangeException();
                }
                return *(handle + index);
            }
            set
            {
                if (index > length)
                {
                    throw new IndexOutOfRangeException();
                }
                *(handle + index) = value;
            }
        }

        public glHandle(int count)
        {
            _value = new uint[count];
            length = count;
            handle = (uint*)GCHandle.Alloc(_value, GCHandleType.Pinned).AddrOfPinnedObject();
        }

        internal glHandle(uint[] val)
        {
            _value = val;
            length = val.Length;
            handle = (uint*)GCHandle.Alloc(_value, GCHandleType.Pinned).AddrOfPinnedObject();
        }

        internal glHandle(uint val)
        {
            _value = [val];
            length = 1;
            handle = (uint*)GCHandle.Alloc(_value, GCHandleType.Pinned).AddrOfPinnedObject();
        }

        public void Free()
        {
            if (_value == null)
            {
                return;
            }
            GCHandle h = GCHandle.FromIntPtr((IntPtr)handle);
            h.Free();
        }

        /// <summary>
        /// Realse all resource in this handle. 
        /// This will release all resource in this <see cref="glHandle"/>.
        /// This <see langword="glHandle"/> will be not usable.
        /// </summary>
        public void Release()
        {
            if (_value == null)
            {
                return;
            }
            else
            {
                GCHandle.FromIntPtr((IntPtr)handle).Free();
                handle = (uint*)IntPtr.Zero;
            }
        }

    }
}