using System;
using System.Collections.Generic;
using System.Xml.Linq;
using System.Reflection;

namespace srl.Xml;

// --- INPUT ADAPTER ---
public class XmlAdapter : IInput
{
	private XElement _e;
	private XAttribute _a;

	public XmlAdapter( XElement e ) => _e = e;
	public XmlAdapter( XAttribute a ) => _a = a;

	public string? Value => _e?.Value ?? _a?.Value;
	public bool IsLeaf => _a != null || ( _e != null && !_e.HasElements );

	public IInput? GetAttr( string name )
	{
		if( _e == null )
			return null;
		// Case-Insensitive search
		var a = _e.Attribute( name ) ?? _e.Attribute( name.ToLower() );
		return a != null ? new XmlAdapter( a ) : null;
	}

	public IInput? GetChild( string name )
	{
		if( _e == null )
			return null;

		var c = _e.Element( name ) ?? _e.Element( name.ToLower() );

		return c != null ? new XmlAdapter( c ) : null;
	}

	// Extra helper for Dot Notation scanning
	public IEnumerable<(string, string)> GetAllAttrs()
	{
		if( _e == null )
			yield break;
		foreach( var a in _e.Attributes() )
			yield return (a.Name.LocalName, a.Value);
	}
}

// --- OUTPUT DRIVER ---
public class XmlDriver : Driver
{
	private Stack<XElement> _stack = new();
	private XDocument _doc;

	public XDocument Document => _doc;

	public XmlDriver()
	{
		_doc = new XDocument();
	}

	public void BeginScope( string name, Type type, int id )
	{
		var el = new XElement( name );

		// Polymorphism Metadata (if needed, e.g. <Item type="Sword">)
		// el.Add(new XAttribute("_type", type.Name));

		if( id > 0 )
			el.Add( new XAttribute( "_id", id ) ); // DAG ID

		if( _stack.Count > 0 )
			_stack.Peek().Add( el );
		else
			_doc.Add( el );

		_stack.Push( el );
	}

	public void EndScope() => _stack.Pop();

	public void BeginCollection( string name, int count )
	{
		// XML doesn't strictly need array wrappers, but it helps structure
		// We use the same BeginScope logic effectively
		var el = new XElement( name, new XAttribute( "_count", count ) );
		if( _stack.Count > 0 )
			_stack.Peek().Add( el );
		_stack.Push( el );
	}

	public void EndCollection() => _stack.Pop();

	public void WriteAttr( string name, string value )
	{
		if( _stack.Count == 0 )
			return;
		_stack.Peek().Add( new XAttribute( name, value ) );
	}

	public void WriteRef( string name, int id )
	{
		var el = new XElement( name, new XAttribute( "_ref", id ) );
		_stack.Peek().Add( el );
	}

	public void OnProp( MemberInfo m, string name ) { /* Optional: Write tooltips/comments */ }
}

// --- FACADE ---
public static class XmlSerializer
{
	public static string Serialize( object obj )
	{
		var driver = new XmlDriver();
		srl.Walker.Serialize( obj, driver );
		return driver.Document.ToString();
	}

	public static void Deserialize( object root, string xml )
	{
		var doc = XDocument.Parse( xml );
		var adapter = new XmlAdapter( doc.Root );

		// 1. Standard Load
		srl.Loader.Load( root, adapter );

		// 2. Dot Notation Pass (MyBag Cool.Rare="Changed")
		srl.Loader.LoadDotNotations( root, adapter.GetAllAttrs() );
	}
}