using System;
using System.Collections;
using System.Collections.Generic;
using System.Collections.Immutable;
using System.Linq;
using System.Reflection;
using System.Runtime.Serialization;
using System.Xml;

namespace ser;


// --- Primitive Handler ---
public partial class PrimitiveHandler : ser.ITypeHandler
{
	public void WriteXml( XmlSer xml, XmlWriter writer, object? obj, string name, Type memberType, bool forceType )
	{
		if( obj == null )
		{
			writer.WriteStartElement( name );
			writer.WriteAttributeString( "v", "null" );
			writer.WriteEndElement();
			return;
		}

		bool writeElements = xml._cfg.POD == POD.Elements || forceType || !( writer is XmlTextWriter );
		if( !writeElements && writer is XmlTextWriter tw )
			writeElements = tw.WriteState != WriteState.Element;

		if( writeElements )
			writer.WriteStartElement( name );

		if( forceType || xml._cfg.POD == POD.Elements )
		{
			if( forceType )
				writer.WriteAttributeString( "_.t", obj.GetType().FullName );

			writer.WriteAttributeString( "v", obj.ToString() );
		}
		else
		{
			writer.WriteAttributeString( name, obj.ToString() );
		}

		if( writeElements )
			writer.WriteEndElement();
	}
}

// --- Proxy Handler ---
public partial class ProxyHandler : ITypeHandler
{
	public void WriteXml( XmlSer xml, XmlWriter writer, object? obj, string name, Type memberType, bool forceType )
	{
		if( obj == null )
		{ xml.GetHandler( typeof( object ) ).WriteXml( xml, writer, null, name, memberType, forceType ); return; }

		var ti = xml._meta.Get( obj.GetType() );
		if( !ti.ProxyDef.HasValue )
		{ log.error( "Proxy write called without proxy def!" ); return; }

		writer.WriteStartElement( name );
		var proxyStr = ti.ProxyDef.Value.fnSer( obj );

		// TODO: Allow arbitrary writing here
		writer.WriteAttributeString( "proxy", proxyStr );
		writer.WriteEndElement();
	}
}

// --- ISerializable Handler ---
public partial class ISerializableHandler : ITypeHandler
{
	public void WriteXml( XmlSer xml, XmlWriter writer, object? obj, string name, Type memberType, bool forceType )
	{
		if( obj == null )
		{ /* Write null */ return; }
		if( !( obj is ISerializable serObj ) )
		{ /* Error */ return; }

		writer.WriteStartElement( name );
		xml.WriteTypeAttr( writer, memberType, obj.GetType() );

		if( xml.HandleGraphWrite( writer, obj, out bool first ) )
		{
			if( first )
			{
				var serInfo = new SerializationInfo( obj.GetType(), new FormatterConverter() );
				var context = new StreamingContext( StreamingContextStates.All );
				serObj.GetObjectData( serInfo, context );

				foreach( var member in serInfo )
				{
					xml.WriteNode( writer, member.Value, refl.TypeToIdentifier( member.Name ), member.ObjectType, true ); // Force type for ISer
				}
			}
		}
		writer.WriteEndElement();
	}
}

// --- Collection Handler ---
public partial class CollectionHandler : ITypeHandler
{
	public void WriteXml( XmlSer xml, XmlWriter writer, object? obj, string name, Type memberType, bool forceType )
	{
		if( obj == null )
		{ /* Write null */ return; }
		if( !( obj is IEnumerable collection ) )
		{ /* Error */ return; }

		writer.WriteStartElement( name );
		xml.WriteTypeAttr( writer, memberType, obj.GetType() );

		if( xml.HandleGraphWrite( writer, obj, out bool first ) )
		{
			if( first )
			{
				Type elemType = GetElementType( obj.GetType() );
				int i = 0;
				foreach( var item in collection )
				{
					xml.WriteNode( writer, item, $"i{i++}", elemType, false );
				}
			}
		}
		writer.WriteEndElement();
	}
}


// --- Object Handler (Default/Complex) ---
public partial class ObjectHandler : ITypeHandler
{
	public void WriteXml( XmlSer xml, XmlWriter writer, object? obj, string name, Type memberType, bool forceType )
	{
		if( obj == null )
		{ /* Write null */ return; }

		writer.WriteStartElement( name );
		xml.WriteTypeAttr( writer, memberType, obj.GetType() );
		var ti = xml._meta.Get( obj.GetType() );

		if( xml.HandleGraphWrite( writer, obj, out bool first ) )
		{
			if( first )
			{
				foreach( var memberMeta in ti.Members )
				{
					var value = memberMeta.GetValue( obj );
					if( value != null )
					{
						// If POD-Attribute, write attribute
						if( memberMeta.IsPodAttribute )
						{
							try
							{
								writer.WriteAttributeString( memberMeta.XmlName, value.ToString() );
							}
							catch( Exception ex )
							{
								log.error( $"Writing Att {memberMeta.XmlName} = [{value}]" );
							}
						}
						else
						{
							try
							{
								xml.WriteNode( writer, value, memberMeta.XmlName, memberMeta.Type, false );
							}
							catch( Exception ex )
							{
								log.error( $"Writing Node {memberMeta.XmlName} = [{value}]" );
							}
						}
					}


				}




			}
		}

		writer.WriteEndElement();
	}
}