using System;
using System.Reflection;
using System.Runtime.InteropServices;
using Intromat.DXExt;
using SharpDX;

namespace Intromat.Graphics
{
    internal static class DebugInterface
    {
        [Flags]
        public enum LoadLibraryFlags : uint
        {
            LoadLibrarySearchSystem32 = 0x00000800
        }

        private static readonly GetDebugInterface? getDebugInterface;

        static DebugInterface()
        {
            var moduleHandle = LoadLibraryEx("dxgi.dll", IntPtr.Zero, LoadLibraryFlags.LoadLibrarySearchSystem32);
            if (moduleHandle != IntPtr.Zero)
            {
                var procedureHandle = GetProcAddress(moduleHandle, "DXGIGetDebugInterface1");
                if (procedureHandle != IntPtr.Zero)
                    getDebugInterface = (GetDebugInterface)Marshal.GetDelegateForFunctionPointer(procedureHandle, typeof(GetDebugInterface));
            }
        }

        public static GraphicsAnalysis? TryCreateGraphicsAnalysis()
        {
            if (getDebugInterface == null)
                return null;

            var guid = typeof(GraphicsAnalysis).GetTypeInfo().GUID;
            var result = getDebugInterface(0, ref guid, out var comPtr);
            if (result.Failure)
                return null;

            return comPtr != IntPtr.Zero ? (GraphicsAnalysis)comPtr : null;
        }

        [DllImport("kernel32.dll", SetLastError = true)]
        public static extern IntPtr LoadLibraryEx(string lpFileName, IntPtr hReservedNull, LoadLibraryFlags dwFlags);

        [DllImport("kernel32.dll")]
        public static extern IntPtr GetProcAddress(IntPtr hModule, string procName);

        [UnmanagedFunctionPointer(CallingConvention.Winapi)]
        private delegate Result GetDebugInterface(uint flags, ref Guid guid, out IntPtr result);
    }
}