using System;

using System.Reflection;

using System.Collections;

using System.Collections.Generic;

using System.Text;



namespace Server.Commands.Generic

{

	public sealed class DistinctExtension : BaseExtension

	{

		public static ExtensionInfo ExtInfo = new ExtensionInfo( 30, "Distinct", -1, delegate() { return new DistinctExtension(); } );



		public static void Initialize()

		{

			ExtensionInfo.Register( ExtInfo );

		}



		public override ExtensionInfo Info

		{

			get { return ExtInfo; }

		}



		private List<Property> m_Properties;



		private IComparer m_Comparer;



		public DistinctExtension()

		{

			m_Properties = new List<Property>();

		}



		public override void Optimize( Mobile from, Type baseType, ref AssemblyEmitter assembly )

		{

			if ( baseType == null )

				throw new Exception( "Distinct extension may only be used in combination with an object conditional." );



			foreach ( Property prop in m_Properties )

			{

				prop.BindTo( baseType, PropertyAccess.Read );

				prop.CheckAccess( from );

			}



			if ( assembly == null )

				assembly = new AssemblyEmitter( "__dynamic", false );



			m_Comparer = DistinctCompiler.Compile( assembly, baseType, m_Properties.ToArray() );

		}



		public override void Parse( Mobile from, string[] arguments, int offset, int size )

		{

			if ( size < 1 )

				throw new Exception( "Invalid distinction syntax." );



			int end = offset + size;



			while ( offset < end )

			{

				string binding = arguments[offset++];



				m_Properties.Add( new Property( binding ) );

			}

		}



		public override void Filter( ArrayList list )

		{

			if ( m_Comparer == null )

				throw new InvalidOperationException( "The extension must first be optimized." );



			ArrayList copy = new ArrayList( list );



			copy.Sort( m_Comparer );



			list.Clear();



			object last = null;



			for ( int i = 0; i < copy.Count; ++i )

			{

				object obj = copy[i];



				if ( last == null || m_Comparer.Compare( obj, last ) != 0 )

				{

					list.Add( obj );

					last = obj;

				}

			}

		}

	}

}