using System;
using System.Linq;
 
#nullable disable
 
namespace Microsoft.Maui.Controls.Xaml
{
	class SimplifyOnPlatformVisitor : IXamlNodeVisitor
	{
		public SimplifyOnPlatformVisitor(string targetFramework)
		{
 
			if (string.IsNullOrEmpty(targetFramework))
				return;
 
			if (targetFramework.IndexOf("-android", StringComparison.OrdinalIgnoreCase) != -1)
				Target = nameof(OnPlatformExtension.Android);
			if (targetFramework.IndexOf("-ios", StringComparison.OrdinalIgnoreCase) != -1)
				Target = nameof(OnPlatformExtension.iOS);
			if (targetFramework.IndexOf("-macos", StringComparison.OrdinalIgnoreCase) != -1)
				Target = nameof(OnPlatformExtension.macOS);
			if (targetFramework.IndexOf("-maccatalyst", StringComparison.OrdinalIgnoreCase) != -1)
				Target = nameof(OnPlatformExtension.MacCatalyst);
		}
 
		public string Target { get; }
 
		public TreeVisitingMode VisitingMode => TreeVisitingMode.BottomUp;
		public bool StopOnDataTemplate => false;
		public bool VisitNodeOnDataTemplate => true;
		public bool StopOnResourceDictionary => false;
		public bool IsResourceDictionary(ElementNode node) => false;
		public bool SkipChildren(INode node, INode parentNode) => false;
 
		public void Visit(ValueNode node, INode parentNode)
		{
		}
 
		public void Visit(MarkupNode node, INode parentNode)
		{
			//markup was already expanded to element
		}
 
		public void Visit(ElementNode node, INode parentNode)
		{
			if (Target is null)
				return;
 
			//`{OnPlatform}` markup extension
			if (node.XmlType.Name == nameof(OnPlatformExtension) && node.XmlType.NamespaceUri == XamlParser.MauiUri)
			{
				if (node.Properties.TryGetValue(new XmlName("", Target), out INode targetNode)
					|| node.Properties.TryGetValue(new XmlName("", nameof(OnPlatformExtension.Default)), out targetNode))
				{
					if (!node.TryGetPropertyName(parentNode, out XmlName name))
						return;
					if (parentNode is IElementNode parentEnode)
						parentEnode.Properties[name] = targetNode;
				}
				else if (node.CollectionItems.Count > 0) // syntax like {OnPlatform foo, iOS=bar}
				{
					if (!node.TryGetPropertyName(parentNode, out XmlName name))
						return;
					if (parentNode is IElementNode parentEnode)
						parentEnode.Properties[name] = node.CollectionItems[0];
				}
				else //no prop for target and no Default set
				{
					if (!node.TryGetPropertyName(parentNode, out XmlName name))
						return;
					//if there's no value for the targetPlatform, ignore the node.
					//this is slightly different than what OnPlatform does (return default(T))
					if (parentNode is IElementNode parentEnode)
						parentEnode.Properties.Remove(name);
				}
			}
 
			//`<OnPlatform>` elements
			//if (node.XmlType.Name == "OnPlatform" && node.XmlType.NamespaceUri == XamlParser.MauiUri)
			//{
			//	var onNode = GetOnNode(node, Target) ?? GetDefault(node);
 
			//	//Property node
			//	if (node.TryGetPropertyName(parentNode, out XmlName name)
			//		&& parentNode is IElementNode parentEnode)
			//	{
			//		if (onNode != null)
			//			parentEnode.Properties[name] = onNode;
			//		else
			//			parentEnode.Properties.Remove(name);
			//		return;
			//	}
 
			//	//Collection item
			//	if (onNode != null && parentNode is IElementNode parentEnode2)
			//		parentEnode2.CollectionItems[parentEnode2.CollectionItems.IndexOf(node)] = onNode;
 
			//}
 
			//INode GetOnNode(ElementNode onPlatform, string target)
			//{
			//	foreach (var onNode in onPlatform.CollectionItems)
			//	{
			//		if ((onNode as ElementNode).Properties.TryGetValue(new XmlName("", "Platform"), out var platform))
			//		{
			//			var splits = ((platform as ValueNode).Value as string).Split(',');
			//			foreach (var split in splits)
			//			{
			//				if (string.IsNullOrWhiteSpace(split))
			//					continue;
			//				if (split.Trim() == target)
			//				{
			//					if ((onNode as ElementNode).Properties.TryGetValue(new XmlName("", "Value"), out var node))
			//						return node;
 
			//					return (onNode as ElementNode).CollectionItems.FirstOrDefault();
			//				}
			//			}
			//		}
			//	}
			//	return null;
			//}
 
			//INode GetDefault(ElementNode onPlatform)
			//{
			//	if (node.Properties.TryGetValue(new XmlName("", "Default"), out INode defaultNode))
			//		return defaultNode;
			//	return null;
			//}
 
		}
 
		public void Visit(RootNode node, INode parentNode)
		{
		}
 
		public void Visit(ListNode node, INode parentNode)
		{
		}
	}
}