// Copyright (c) The Avalonia Project. All rights reserved.
// Licensed under the MIT license. See licence.md file in the project root for full license information.

using System;
using Avalonia;
using Avalonia.Controls;
using Avalonia.Markup.Xaml;
using RenderDemo.ViewModels;
using ReactiveUI;
using System.Runtime.InteropServices;

namespace RenderDemo
{
    public class MainWindow : Window
    {
        internal enum AccentState
        {
            ACCENT_DISABLED = 1,
            ACCENT_ENABLE_GRADIENT = 0,
            ACCENT_ENABLE_TRANSPARENTGRADIENT = 2,
            ACCENT_ENABLE_BLURBEHIND = 3,
            ACCENT_INVALID_STATE = 4
        }

        [StructLayout(LayoutKind.Sequential)]
        internal struct AccentPolicy
        {
            public AccentState AccentState;
            public int AccentFlags;
            public int GradientColor;
            public int AnimationId;
        }

        [StructLayout(LayoutKind.Sequential)]
        internal struct WindowCompositionAttributeData
        {
            public WindowCompositionAttribute Attribute;
            public IntPtr Data;
            public int SizeOfData;
        }

        internal enum WindowCompositionAttribute
        {
            // ...
            WCA_ACCENT_POLICY = 19
            // ...
        }

        [DllImport("user32.dll")]
        internal static extern int SetWindowCompositionAttribute(IntPtr hwnd, ref WindowCompositionAttributeData data);

        internal void EnableBlur()
        {
            var hndl = this.PlatformImpl.Handle.Handle;

            var accent = new AccentPolicy();
            accent.AccentState = AccentState.ACCENT_ENABLE_BLURBEHIND;

            var accentStructSize = Marshal.SizeOf(accent);

            var accentPtr = Marshal.AllocHGlobal(accentStructSize);
            Marshal.StructureToPtr(accent, accentPtr, false);

            var data = new WindowCompositionAttributeData();
            data.Attribute = WindowCompositionAttribute.WCA_ACCENT_POLICY;
            data.SizeOfData = accentStructSize;
            data.Data = accentPtr;


            SetWindowCompositionAttribute(hndl, ref data);

            Marshal.FreeHGlobal(accentPtr);
        }

        public MainWindow()
        {
            this.InitializeComponent();
            this.AttachDevTools();

            var vm = new MainWindowViewModel();
            vm.WhenAnyValue(x => x.DrawDirtyRects).Subscribe(x => Renderer.DrawDirtyRects = x);
            vm.WhenAnyValue(x => x.DrawFps).Subscribe(x => Renderer.DrawFps = x);
            this.DataContext = vm;

            EnableBlur();
        }

        private void InitializeComponent()
        {
            AvaloniaXamlLoader.Load(this);
        }
    }
}