// Copyright (c) ppy Pty Ltd <contact@ppy.sh>. Licensed under the MIT Licence.
// See the LICENCE file in the repository root for full licence text.

using System;
using System.Drawing;
using System.Runtime.InteropServices;
using osu.Framework.Platform.Windows.Native;
using SDL2;

namespace osu.Framework.Platform.Windows
{
    public class WindowsWindow : SDL2DesktopWindow
    {
        private const int seticon_message = 0x0080;
        private const int icon_big = 1;
        private const int icon_small = 0;

        private const int large_icon_size = 256;
        private const int small_icon_size = 16;

        private Icon smallIcon;
        private Icon largeIcon;

        public WindowsWindow()
        {
            try
            {
                // SDL doesn't handle DPI correctly on windows, but this brings things mostly in-line with expectations. (https://bugzilla.libsdl.org/show_bug.cgi?id=3281)
                SetProcessDpiAwareness(ProcessDpiAwareness.Process_System_DPI_Aware);
            }
            catch
            {
                // API doesn't exist on Windows 7 so it needs to be allowed to fail silently.
            }
        }

        protected override Size SetBorderless()
        {
            SDL.SDL_SetWindowBordered(SDLWindowHandle, SDL.SDL_bool.SDL_FALSE);

            Size positionOffsetHack = new Size(1, 1);

            var newSize = CurrentDisplay.Bounds.Size + positionOffsetHack;
            var newPosition = CurrentDisplay.Bounds.Location - positionOffsetHack;

            // for now let's use the same 1px hack that we've always used to force borderless.
            SDL.SDL_SetWindowSize(SDLWindowHandle, newSize.Width, newSize.Height);
            Position = newPosition;

            return newSize;
        }

        /// <summary>
        /// On Windows, SDL will use the same image for both large and small icons (scaled as necessary).
        /// This can look bad if scaling down a large image, so we use the Windows API directly so as
        /// to get a cleaner icon set than SDL can provide.
        /// If called before the window has been created, or we do not find two separate icon sizes, we fall back to the base method.
        /// </summary>
        internal override void SetIconFromGroup(IconGroup iconGroup)
        {
            smallIcon = iconGroup.CreateIcon(small_icon_size, small_icon_size);
            largeIcon = iconGroup.CreateIcon(large_icon_size, large_icon_size);

            var windowHandle = WindowHandle;

            if (windowHandle == IntPtr.Zero || largeIcon == null || smallIcon == null)
                base.SetIconFromGroup(iconGroup);
            else
            {
                SendMessage(windowHandle, seticon_message, (IntPtr)icon_small, smallIcon.Handle);
                SendMessage(windowHandle, seticon_message, (IntPtr)icon_big, largeIcon.Handle);
            }
        }

        public override Point PointToClient(Point point)
        {
            ScreenToClient(WindowHandle, ref point);
            return point;
        }

        public override Point PointToScreen(Point point)
        {
            ClientToScreen(WindowHandle, ref point);
            return point;
        }

        [DllImport("SHCore.dll", SetLastError = true)]
        internal static extern bool SetProcessDpiAwareness(ProcessDpiAwareness awareness);

        internal enum ProcessDpiAwareness
        {
            Process_DPI_Unaware = 0,
            Process_System_DPI_Aware = 1,
            Process_Per_Monitor_DPI_Aware = 2
        }

        [DllImport("user32.dll", SetLastError = true)]
        internal static extern bool ScreenToClient(IntPtr hWnd, ref Point point);

        [DllImport("user32.dll", SetLastError = true)]
        internal static extern bool ClientToScreen(IntPtr hWnd, ref Point point);

        [DllImport("user32.dll", CharSet = CharSet.Auto)]
        private static extern IntPtr SendMessage(IntPtr hWnd, int msg, IntPtr wParam, IntPtr lParam);
    }
}