using System;
using Microsoft.Maui.Graphics;
using Microsoft.UI.Xaml;
using Microsoft.UI.Xaml.Controls;
using WRect = Windows.Foundation.Rect;
using WSize = global::Windows.Foundation.Size;
 
namespace Microsoft.Maui.Controls.Platform
{
	public partial class ViewToHandlerConverter : Microsoft.UI.Xaml.Data.IValueConverter
	{
		public object? Convert(object value, Type targetType, object parameter, string language)
		{
			var view = value as View;
			if (view == null)
			{
				var page = value as Page;
				if (page != null)
				{
					return page.ToPlatform(page.FindMauiContext()!);
				}
			}
 
			if (view == null)
				return null;
 
			return new WrapperControl(view);
		}
 
		public object ConvertBack(object value, Type targetType, object parameter, string language)
		{
			throw new NotSupportedException();
		}
 
		internal partial class WrapperControl : Panel
		{
			readonly View _view;
			IView View => _view;
			IPlatformViewHandler? Handler => View.Handler as IPlatformViewHandler;
 
			FrameworkElement FrameworkElement { get; }
 
			internal void CleanUp()
			{
				_view?.Cleanup();
 
				if (_view != null)
					_view.MeasureInvalidated -= OnMeasureInvalidated;
			}
 
			public WrapperControl(View view)
			{
				_view = view;
				_view.MeasureInvalidated += OnMeasureInvalidated;
 
				FrameworkElement = view.ToPlatform(view.FindMauiContext()!);
 
#pragma warning disable RS0030 // Do not use banned APIs; Panel.Children is banned for performance reasons. Here we allow it as a part of initialization.
				Children.Add(FrameworkElement);
#pragma warning restore RS0030 // Do not use banned APIs
 
				// make sure we re-measure once the template is applied
 
				FrameworkElement.Loaded += (sender, args) =>
				{
					// If the view is a layout (stacklayout, grid, etc) we need to trigger a layout pass
					// with all the controls in a consistent native state (i.e., loaded) so they'll actually
					// have Bounds set
					Handler?.PlatformView?.InvalidateMeasure(View);
					InvalidateMeasure();
				};
			}
 
			void OnMeasureInvalidated(object? sender, EventArgs e)
			{
				InvalidateMeasure();
			}
 
			protected override WSize ArrangeOverride(WSize finalSize)
			{
				_view.IsInPlatformLayout = true;
				(_view.Handler as IPlatformViewHandler)?.LayoutVirtualView(finalSize);
 
				if (_view.Width <= 0 || _view.Height <= 0)
				{
					// Hide Panel when size _view is empty.
					// It is necessary that this element does not overlap other elements when it should be hidden.
					Opacity = 0;
				}
				else
				{
					Opacity = 1;
				}
 
				_view.IsInPlatformLayout = false;
 
				return finalSize;
			}
 
			protected override WSize MeasureOverride(WSize availableSize)
			{
				var request = (_view.Handler as IPlatformViewHandler)?.MeasureVirtualView(availableSize) ?? WSize.Empty;
 
				if (request.Height < 0)
				{
					request.Height = availableSize.Height;
				}
 
				WSize result;
				if (_view.HorizontalOptions.Alignment == LayoutAlignment.Fill && !double.IsInfinity(availableSize.Width) && availableSize.Width != 0)
				{
					result = new WSize(availableSize.Width, request.Height);
				}
				else
				{
					result = request;
				}
 
				return result;
			}
		}
	}
}