// Permission is hereby granted, free of charge, to any person obtaining
// a copy of this software and associated documentation files (the
// "Software"), to deal in the Software without restriction, including
// without limitation the rights to use, copy, modify, merge, publish,
// distribute, sublicense, and/or sell copies of the Software, and to
// permit persons to whom the Software is furnished to do so, subject to
// the following conditions:
// 
// The above copyright notice and this permission notice shall be
// included in all copies or substantial portions of the Software.
// 
// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
// EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
// MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
// NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE
// LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
// OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
// WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
//
// (C) 2005 Iain McCoy
//
// Copyright (c) 2007 Novell, Inc. (http://www.novell.com)
//
// Authors:
//   Iain McCoy (iain@mccoy.id.au)
//   Chris Toshok (toshok@ximian.com)
//

namespace System.Windows {
	public class PropertyMetadata {
		private object defaultValue;
		private bool isSealed;
		private PropertyChangedCallback propertyChangedCallback;
		private CoerceValueCallback coerceValueCallback;
		
		protected bool IsSealed {
			get { return isSealed; }
		}

		public object DefaultValue {
			get { return defaultValue; }
			set {
				if (IsSealed)
					throw new InvalidOperationException ("Cannot change metadata once it has been applied to a property");
				if (value == DependencyProperty.UnsetValue)
					throw new ArgumentException ("Cannot set property metadata's default value to 'Unset'");

				defaultValue = value;
			}
		}

		public PropertyChangedCallback PropertyChangedCallback {
			get { return propertyChangedCallback; }
			set {
				if (IsSealed)
					throw new InvalidOperationException ("Cannot change metadata once it has been applied to a property");
				propertyChangedCallback = value;
			}
		}

		public CoerceValueCallback CoerceValueCallback {
			get { return coerceValueCallback; }
			set {
				if (IsSealed)
					throw new InvalidOperationException ("Cannot change metadata once it has been applied to a property");
				coerceValueCallback = value;
			}
		}

		public PropertyMetadata()
			: this (null, null, null)
		{
		}

		public PropertyMetadata(object defaultValue)
			: this (defaultValue, null, null)
		{
		}

		public PropertyMetadata (PropertyChangedCallback propertyChangedCallback)
			: this (null, propertyChangedCallback, null)
		{
		}

		public PropertyMetadata (object defaultValue, PropertyChangedCallback propertyChangedCallback)
			: this (defaultValue, propertyChangedCallback, null)
		{
		}

		public PropertyMetadata (object defaultValue, PropertyChangedCallback propertyChangedCallback, CoerceValueCallback coerceValueCallback)
		{
			if (defaultValue == DependencyProperty.UnsetValue)
				throw new ArgumentException ("Cannot initialize property metadata's default value to 'Unset'");

			this.defaultValue = defaultValue;
			this.propertyChangedCallback = propertyChangedCallback;
			this.coerceValueCallback = coerceValueCallback;
		}
		
		protected virtual void Merge (PropertyMetadata baseMetadata, DependencyProperty dp)
		{
			if (defaultValue == null)
				defaultValue = baseMetadata.defaultValue;
			if (propertyChangedCallback == null)
				propertyChangedCallback = baseMetadata.propertyChangedCallback;
			if (coerceValueCallback == null)
				coerceValueCallback = baseMetadata.coerceValueCallback;
		}
		
		protected virtual void OnApply (DependencyProperty dp, Type targetType)
		{
		}

		internal void DoMerge (PropertyMetadata baseMetadata, DependencyProperty dp, Type targetType)
		{
			Merge (baseMetadata, dp);
			OnApply (dp, targetType);
			isSealed = true;
		}
	}
}