#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.Drawing;
using System.Linq;
using System.Reflection;

namespace OpenRA.FileFormats
{
	public static class FieldLoader
	{
		public static Func<string,Type,string,object> InvalidValueAction = (s,t,f) =>
		{
			throw new InvalidOperationException("FieldLoader: Cannot parse `{0}` into `{1}.{2}` ".F(s,f,t) );
		};
		
		public static Action<string,Type> UnknownFieldAction = (s,f) =>
		{
			throw new NotImplementedException( "FieldLoader: Missing field `{0}` on `{1}`".F( s, f.Name ) );
		};

		public static void Load( object self, MiniYaml my )
		{
			var loadDict = typeLoadInfo[ self.GetType() ];

			foreach( var kv in loadDict )
			{
				object val;
				if( kv.Value != null )
					val = kv.Value( kv.Key.Name, kv.Key.FieldType, my );
				else if( !TryGetValueFromYaml( kv.Key.Name, kv.Key.FieldType, my, out val ) )
					continue;

				kv.Key.SetValue( self, val );
			}
		}

		static bool TryGetValueFromYaml( string fieldName, Type fieldType, MiniYaml yaml, out object ret )
		{
			ret = null;
			var n = yaml.Nodes.Where( x=>x.Key == fieldName ).ToList();
			if( n.Count == 0 )
				return false;
			if( n.Count == 1 && n[ 0 ].Value.Nodes.Count == 0 )
			{
				ret = GetValue( fieldName, fieldType, n[ 0 ].Value.Value );
				return true;
			}
			throw new InvalidOperationException( "TryGetValueFromYaml: unable to load field {0} (of type {1})".F( fieldName, fieldType ) );
		}

		public static T Load<T>(MiniYaml y) where T : new()
		{
			var t = new T();
			Load(t, y);
			return t;
		}
		
		public static void LoadFields( object self, Dictionary<string,MiniYaml> my, IEnumerable<string> fields )
		{
			foreach (var field in fields)
			{
				if (!my.ContainsKey(field)) continue;
				LoadField(self,field,my[field].Value);
			}
		}

		public static void LoadField( object self, string key, string value )
		{
			var field = self.GetType().GetField( key.Trim() );

			if( field == null )
				UnknownFieldAction( key.Trim(), self.GetType() );
			else if( field.HasAttribute<FieldFromYamlKeyAttribute>() )
				return;
			else
				field.SetValue( self, GetValue( field.Name, field.FieldType, value ) );
		}
				
		public static object GetValue( string field, Type fieldType, string x )
		{
			if (x != null) x = x.Trim();
			if( fieldType == typeof( int ) )
			{
				int res;
				if (int.TryParse(x,out res))
					return res;
				return InvalidValueAction(x,fieldType, field);
			}
			
			else if( fieldType == typeof( ushort ) )
			{
				ushort res;
				if (ushort.TryParse(x,out res))
					return res;
				return InvalidValueAction(x,fieldType, field);
			}

			else if (fieldType == typeof(float))
			{
				float res;
				if (float.TryParse(x.Replace("%",""), out res))
					return res * (x.Contains( '%' ) ? 0.01f : 1f);
				return InvalidValueAction(x,fieldType, field);
			}

			else if (fieldType == typeof(string))
				return x;
			
			else if (fieldType == typeof(Color))
			{
				var parts = x.Split(',');
				if (parts.Length == 3)
					return Color.FromArgb(int.Parse(parts[0]), int.Parse(parts[1]), int.Parse(parts[2]));
				if (parts.Length == 4)
					return Color.FromArgb(int.Parse(parts[0]), int.Parse(parts[1]), int.Parse(parts[2]), int.Parse(parts[3]));
				return InvalidValueAction(x,fieldType, field);
			}
			
			else if (fieldType.IsEnum)
			{
				if (!Enum.GetNames(fieldType).Select(a => a.ToLower()).Contains(x.ToLower()))
					return InvalidValueAction(x,fieldType, field);
				return Enum.Parse(fieldType, x, true);
			}
			
			else if (fieldType == typeof(bool))
				return ParseYesNo(x, fieldType, field);

			else if (fieldType.IsArray)
			{
				if (x == null)
					return Array.CreateInstance(fieldType.GetElementType(), 0);

				var parts = x.Split(new char[] { ',' }, StringSplitOptions.RemoveEmptyEntries);

				var ret = Array.CreateInstance(fieldType.GetElementType(), parts.Length);
				for (int i = 0; i < parts.Length; i++)
					ret.SetValue(GetValue(field, fieldType.GetElementType(), parts[i].Trim()), i);
				return ret;
			}
			else if (fieldType == typeof(int2))
			{
				var parts = x.Split(new char[] { ',' }, StringSplitOptions.RemoveEmptyEntries);
				return new int2(int.Parse(parts[0]), int.Parse(parts[1]));
			}
			
			UnknownFieldAction("[Type] {0}".F(x),fieldType);
			return null;
		}

		static object ParseYesNo( string p, System.Type fieldType, string field )
		{
			p = p.ToLowerInvariant();
			if( p == "yes" ) return true;
			if( p == "true" ) return true;
			if( p == "no" ) return false;
			if( p == "false" ) return false;
			return InvalidValueAction(p,fieldType, field);
		}

		static Cache<Type, Dictionary<FieldInfo, Func<string, Type, MiniYaml, object>>> typeLoadInfo = new Cache<Type, Dictionary<FieldInfo, Func<string, Type, MiniYaml, object>>>( GetTypeLoadInfo );

		static Dictionary<FieldInfo, Func<string, Type, MiniYaml, object>> GetTypeLoadInfo( Type type )
		{
			var ret = new Dictionary<FieldInfo, Func<string, Type, MiniYaml, object>>();

			var fieldsToLoad = new List<FieldInfo>();
			var attr = (CustomLoadAttribute[])type.GetCustomAttributes( typeof( CustomLoadAttribute ), false );
			if( attr.Length == 0 )
			{
				var defCtor = type.GetConstructor( new Type[ 0 ] );
				if( defCtor == null || ( defCtor.GetMethodImplementationFlags() | MethodImplAttributes.Runtime ) == 0 )
					throw new InvalidOperationException( "FieldLoader: refusing to load type {0}; has non-default ctor".F( type ) );
				fieldsToLoad.AddRange( type.GetFields() );
			}
			else if( attr[ 0 ].Fields != null )
				fieldsToLoad.AddRange( attr[ 0 ].Fields.Select( x => type.GetField( x ) ) );
			else
				fieldsToLoad.AddRange( type.GetFields() );

			foreach( var field in fieldsToLoad )
				ret.Add( field, null );

			foreach( var field in type.GetFields() )
			{
				var use = (LoadUsingAttribute[])field.GetCustomAttributes( typeof( LoadUsingAttribute ), false );
				if( use.Length != 0 )
					ret[ field ] = ( _1, _2, yaml ) => use[ 0 ].Loader( yaml );
				else
				{
					var attr2 = (FieldFromYamlKeyAttribute[])field.GetCustomAttributes( typeof( FieldFromYamlKeyAttribute ), false );
					if( attr2.Length != 0 )
						ret[ field ] = ( f, ft, yaml ) => GetValue( f, ft, yaml.Value );
				}
			}

			return ret;
		}

		public class CustomLoadAttribute : Attribute
		{
			public string[] Fields;
		}

		public class LoadUsingAttribute : Attribute
		{
			public readonly Func<MiniYaml, object> Loader;

			public LoadUsingAttribute( Func<MiniYaml, object> loader )
			{
				Loader = loader;
			}
		}
	}

	public static class FieldSaver
	{
		public static MiniYaml Save(object o)
		{
			var nodes = new List<MiniYamlNode>();
			string root = null;

			foreach( var f in o.GetType().GetFields( BindingFlags.Public | BindingFlags.Instance ) )
			{
				if( f.HasAttribute<FieldFromYamlKeyAttribute>() )
					root = FormatValue( o, f );
				else
					nodes.Add( new MiniYamlNode( f.Name, FormatValue( o, f ) ) );
			}

			return new MiniYaml( root, nodes );
		}
		
		public static MiniYaml SaveDifferences(object o, object from)
		{
			if (o.GetType() != from.GetType())
				throw new InvalidOperationException("FieldLoader: can't diff objects of different types");

			var fields = o.GetType().GetFields(BindingFlags.Public | BindingFlags.Instance)
				.Where(f => FormatValue(o,f) != FormatValue(from,f));

			return new MiniYaml( null, fields.Select( f => new MiniYamlNode(
					f.Name,
					FormatValue( o, f ) ) ).ToList() );
		}

		public static string FormatValue(object o, FieldInfo f)
		{
			var v = f.GetValue(o);
			if (v == null)
				return "";

			// Color.ToString() does the wrong thing; force it to format as an array
			if (f.FieldType == typeof(Color))
			{
				var c = (Color)v;
				return "{0},{1},{2},{3}".F(c.A,c.R,c.G,c.B);
			}
			
			return f.FieldType.IsArray
				? string.Join(",", ((Array)v).OfType<object>().Select(a => a.ToString()).ToArray())
				: v.ToString();
		}
	}

	public class FieldFromYamlKeyAttribute : Attribute { }
}