#region Copyright & License Information
/*
 * Copyright 2007-2010 The OpenRA Developers (see AUTHORS)
 * This file is part of OpenRA, which is free software. It is made 
 * available to you under the terms of the GNU General Public License
 * as published by the Free Software Foundation. For more information,
 * see LICENSE.
 */
#endregion

using System;
using System.Collections.Generic;
using System.Linq;
using OpenRA.FileFormats;
using OpenRA.Traits;

namespace OpenRA.GameRules
{
	public class ActorInfo
	{
		public readonly string Name;
		public readonly string Category;
		public readonly TypeDictionary Traits = new TypeDictionary();

		public ActorInfo( string name, MiniYaml node, Dictionary<string, MiniYaml> allUnits )
		{
			var mergedNode = MergeWithParent( node, allUnits ).Nodes;

			Name = name;
			MiniYaml categoryNode;
			if( mergedNode.TryGetValue( "Category", out categoryNode ) )
				Category = categoryNode.Value;

			foreach( var t in mergedNode )
				if( t.Key != "Inherits" && t.Key != "Category" && !t.Key.StartsWith("-") )
					Traits.Add( LoadTraitInfo( t.Key.Split('@')[0], t.Value ) );
		}

		static MiniYaml GetParent( MiniYaml node, Dictionary<string, MiniYaml> allUnits )
		{
			MiniYaml inherits;
			node.Nodes.TryGetValue( "Inherits", out inherits );
			if( inherits == null || string.IsNullOrEmpty( inherits.Value ) )
				return null;

			MiniYaml parent;
			allUnits.TryGetValue( inherits.Value, out parent );
			if( parent == null )
				return null;

			return parent;
		}

		static MiniYaml MergeWithParent( MiniYaml node, Dictionary<string, MiniYaml> allUnits )
		{
			var parent = GetParent( node, allUnits );
			if( parent != null )
				return MiniYaml.Merge( node, MergeWithParent( parent, allUnits ) );
			return node;
		}

		static ITraitInfo LoadTraitInfo(string traitName, MiniYaml my)
		{
			var info = Game.CreateObject<ITraitInfo>(traitName + "Info");
			FieldLoader.Load(info, my);
			return info;
		}

		public IEnumerable<ITraitInfo> TraitsInConstructOrder()
		{
			var ret = new List<ITraitInfo>();
			var t = Traits.WithInterface<ITraitInfo>().ToList();
			int index = 0;
			while( t.Count != 0 )
			{
				if( index >= t.Count )
					throw new InvalidOperationException( "Trait prerequisites not satisfied (or prerequisite loop) Actor={0} Unresolved={1}".F(
						Name, string.Join( ",", t.Select( x => x.GetType().Name ).ToArray())));

				var prereqs = PrerequisitesOf( t[ index ] );
				if( prereqs.Count == 0 || prereqs.All( n => ret.Any( x => x.GetType() == n || x.GetType().IsSubclassOf( n ) ) ) )
				{
					ret.Add( t[ index ] );
					t.RemoveAt( index );
					index = 0;
				}
				else
					++index;
			}

			return ret;
		}

		static List<Type> PrerequisitesOf( ITraitInfo info )
		{
			return info
				.GetType()
				.GetInterfaces()
				.Where( t => t.IsGenericType && t.GetGenericTypeDefinition() == typeof( ITraitPrerequisite<> ) )
				.Select( t => t.GetGenericArguments()[ 0 ] )
				.ToList();
		}
	}
}