// Copyright (c) AlphaSierraPapa for the SharpDevelop Team (for details please see \doc\copyright.txt)
// This code is distributed under the GNU LGPL (for details please see \doc\license.txt)

using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Diagnostics;
using System.Windows.Markup;
using System.Xml;
using System.Windows.Data;
using System.Windows;

namespace ICSharpCode.WpfDesign.XamlDom
{
	/// <summary>
	/// Represents a xaml object element.
	/// </summary>
	[DebuggerDisplay("XamlObject: {Instance}")]
	public sealed class XamlObject : XamlPropertyValue
	{
		XamlDocument document;
		XmlElement element;
		Type elementType;
		object instance;
		List<XamlProperty> properties = new List<XamlProperty>();
		
		/// <summary>For use by XamlParser only.</summary>
		internal XamlObject(XamlDocument document, XmlElement element, Type elementType, object instance)
		{
			this.document = document;
			this.element = element;
			this.elementType = elementType;
			this.instance = instance;

			var contentAttrs = elementType.GetCustomAttributes(typeof(ContentPropertyAttribute), true) as ContentPropertyAttribute[];
			if (contentAttrs != null && contentAttrs.Length > 0) {
				this.contentPropertyName = contentAttrs[0].Name;
			}

			ServiceProvider = new XamlObjectServiceProvider(this);
			CreateWrapper();
		}
		
		/// <summary>For use by XamlParser only.</summary>
		internal void AddProperty(XamlProperty property)
		{
			#if DEBUG
			if (property.IsAttached == false) {
				foreach (XamlProperty p in properties) {
					if (p.IsAttached == false && p.PropertyName == property.PropertyName)
						Debug.Fail("duplicate property");
				}
			}
			#endif
			properties.Add(property);
		}
		
		#region XamlPropertyValue implementation
		internal override object GetValueFor(XamlPropertyInfo targetProperty)
		{
			if (IsMarkupExtension) {
				var value = ProvideValue();
				if (value is string && targetProperty != null && targetProperty.ReturnType != typeof(string)) {
					return XamlParser.CreateObjectFromAttributeText((string)value, targetProperty, this);
				}
				return value;
			} else {
				return instance;
			}
		}
		
		internal override XmlNode GetNodeForCollection()
		{
			return element;
		}
		#endregion
		
		XamlObject parentObject;
		
		/// <summary>
		/// Gets the parent object.
		/// </summary>
		public XamlObject ParentObject {
			get {
				return parentObject;
			}
			internal set { parentObject = value; }
		}
		
		internal override void OnParentPropertyChanged()
		{
			parentObject = (ParentProperty != null) ? ParentProperty.ParentObject : null;
			base.OnParentPropertyChanged();
		}
		
		internal XmlElement XmlElement {
			get { return element; }
		}

		XmlAttribute xmlAttribute;

		internal XmlAttribute XmlAttribute { 
			get { return xmlAttribute; }
			set {
				xmlAttribute = value;
				element = VirualAttachTo(XmlElement, value.OwnerElement);
			}
		}

		static XmlElement VirualAttachTo(XmlElement e, XmlElement target) 
		{
			var prefix = target.GetPrefixOfNamespace(e.NamespaceURI);
			XmlElement newElement = e.OwnerDocument.CreateElement(prefix, e.LocalName, e.NamespaceURI);

			foreach (XmlAttribute a in target.Attributes) {
				if (a.Prefix == "xmlns" || a.Name == "xmlns") {
					newElement.Attributes.Append(a.Clone() as XmlAttribute);
				}
			}

			while (e.HasChildNodes) {
				newElement.AppendChild(e.FirstChild);
			}

			XmlAttributeCollection ac = e.Attributes;
			while (ac.Count > 0) {
				newElement.Attributes.Append(ac[0]);
			}
			
			return newElement;
		}
		
		internal override void AddNodeTo(XamlProperty property)
		{	
			if (!UpdateXmlAttribute(true)) {
				property.AddChildNodeToProperty(element);
			}
			UpdateMarkupExtensionChain();
		}
		
		internal override void RemoveNodeFromParent()
		{			
			if (XmlAttribute != null) {
				XmlAttribute.OwnerElement.RemoveAttribute(XmlAttribute.Name);
				xmlAttribute = null;
			} else {
				if (!UpdateXmlAttribute(false)) {
					element.ParentNode.RemoveChild(element);
				}
			}			
			//TODO: PropertyValue still there
			//UpdateMarkupExtensionChain();
		}

		//TODO: reseting path property for binding doesn't work in XamlProperty
		//use CanResetValue()
		internal void OnPropertyChanged(XamlProperty property)
		{			
			UpdateXmlAttribute(false);
			UpdateMarkupExtensionChain();
		}

		void UpdateMarkupExtensionChain()
		{
			var obj = this;
			while (obj != null && obj.IsMarkupExtension) {
				obj.ParentProperty.UpdateValueOnInstance();
				obj = obj.ParentObject;
			}			
		}

		bool UpdateXmlAttribute(bool force)
		{
			var holder = FindXmlAttributeHolder();
			if (holder == null && force && IsMarkupExtension) {
				holder = this;
			}
			if (holder != null && MarkupExtensionPrinter.CanPrint(holder)) {
				var s = MarkupExtensionPrinter.Print(holder);
				holder.XmlAttribute = holder.ParentProperty.SetAttribute(s);
				return true;
			}
			return false;
		}

		XamlObject FindXmlAttributeHolder()
		{
			var obj = this;
			while (obj != null && obj.IsMarkupExtension) {
				if (obj.XmlAttribute != null) {
					return obj;
				}
				obj = obj.ParentObject;
			}
			return null;
		}
		
		/// <summary>
		/// Gets the XamlDocument where this XamlObject is declared in.
		/// </summary>
		public XamlDocument OwnerDocument {
			get { return document; }
		}
		
		/// <summary>
		/// Gets the instance created by this object element.
		/// </summary>
		public object Instance {
			get { return instance; }
		}

		/// <summary>
		/// Gets whether this instance represents a MarkupExtension.
		/// </summary>
		public bool IsMarkupExtension {
			get { return instance is MarkupExtension; }
		}

		/// <summary>
		/// Gets whether there were load errors for this object.
		/// </summary>
		public bool HasErrors { get; internal set; }

		/// <summary>
		/// Gets the type of this object element.
		/// </summary>
		public Type ElementType {
			get { return elementType; }
		}
		
		/// <summary>
		/// Gets a read-only collection of properties set on this XamlObject.
		/// This includes both attribute and element properties.
		/// </summary>
		public IList<XamlProperty> Properties {
			get {
				return properties.AsReadOnly();
			}
		}

		string contentPropertyName;

		/// <summary>
		/// Gets the name of the content property.
		/// </summary>
		public string ContentPropertyName {
			get {
				return contentPropertyName; 
			}
		}
		
		/// <summary>
		/// Finds the specified property, or creates it if it doesn't exist.
		/// </summary>
		public XamlProperty FindOrCreateProperty(string propertyName)
		{
			if (propertyName == null)
				throw new ArgumentNullException("propertyName");
			
//			if (propertyName == ContentPropertyName)
//				return 
			
			foreach (XamlProperty p in properties) {
				if (!p.IsAttached && p.PropertyName == propertyName)
					return p;
			}
			PropertyDescriptorCollection propertyDescriptors = TypeDescriptor.GetProperties(instance);
			PropertyDescriptor propertyInfo = propertyDescriptors[propertyName];
			XamlProperty newProperty;
			if (propertyInfo != null) {
				newProperty = new XamlProperty(this, new XamlNormalPropertyInfo(propertyInfo));
			} else {
				EventDescriptorCollection events = TypeDescriptor.GetEvents(instance);
				EventDescriptor eventInfo = events[propertyName];
				if (eventInfo != null) {
					newProperty = new XamlProperty(this, new XamlEventPropertyInfo(eventInfo));
				} else {
					throw new ArgumentException("The property '" + propertyName + "' doesn't exist on " + elementType.FullName, "propertyName");
				}
			}
			properties.Add(newProperty);
			return newProperty;
		}
		
		/// <summary>
		/// Finds the specified property, or creates it if it doesn't exist.
		/// </summary>
		public XamlProperty FindOrCreateAttachedProperty(Type ownerType, string propertyName)
		{
			if (ownerType == null)
				throw new ArgumentNullException("ownerType");
			if (propertyName == null)
				throw new ArgumentNullException("propertyName");
			
			foreach (XamlProperty p in properties) {
				if (p.IsAttached && p.PropertyTargetType == ownerType && p.PropertyName == propertyName)
					return p;
			}
			XamlPropertyInfo info = XamlParser.TryFindAttachedProperty(ownerType, propertyName);
			if (info == null) {
				throw new ArgumentException("The attached property '" + propertyName + "' doesn't exist on " + ownerType.FullName, "propertyName");
			}
			XamlProperty newProperty = new XamlProperty(this, info);
			properties.Add(newProperty);
			return newProperty;
		}
		
		/// <summary>
		/// Gets an attribute in the x:-namespace.
		/// </summary>
		public string GetXamlAttribute(string name)
		{
			return element.GetAttribute(name, XamlConstants.XamlNamespace);
		}
		
		/// <summary>
		/// Sets an attribute in the x:-namespace.
		/// </summary>
		public void SetXamlAttribute(string name, string value)
		{
			if (value == null)
				element.RemoveAttribute(name, XamlConstants.XamlNamespace);
			else
				element.SetAttribute(name, XamlConstants.XamlNamespace, value);
		}

		/// <summary>
		/// Gets/Sets the <see cref="XamlObjectServiceProvider"/> associated with this XamlObject.
		/// </summary>
		public XamlObjectServiceProvider ServiceProvider { get; set; }

		MarkupExtensionWrapper wrapper;

		void CreateWrapper()
		{
			if (Instance is Binding) {
				wrapper = new BindingWrapper();
			} else if (Instance is StaticResourceExtension) {
				wrapper = new StaticResourceWrapper();
			}
			if (wrapper != null) {
				wrapper.XamlObject = this;
			}
		}

		object ProvideValue()
		{			
			if (wrapper != null) {
				return wrapper.ProvideValue();
			}
			return (Instance as MarkupExtension).ProvideValue(ServiceProvider);
		}

		internal string GetNameForMarkupExtension()
		{
			string markupExtensionName = XmlElement.Name;
			
			// By convention a markup extension class name typically includes an "Extension" suffix.
			// When you reference the markup extension in XAML the "Extension" suffix is optional.
			// If present remove it to avoid bloating the XAML.
			if (markupExtensionName.EndsWith("Extension", StringComparison.Ordinal)) {
				markupExtensionName = markupExtensionName.Substring(0, markupExtensionName.Length - 9);
			}
			
			return markupExtensionName;
		}
	}

	abstract class MarkupExtensionWrapper
	{
		public XamlObject XamlObject { get; set; }
		public abstract object ProvideValue();
	}

	class BindingWrapper : MarkupExtensionWrapper
	{
		public override object ProvideValue()
		{
			var target = XamlObject.Instance as Binding;
			//TODO: XamlObject.Clone()
			var b = new Binding();
			foreach (PropertyDescriptor pd in TypeDescriptor.GetProperties(target)) {
				if (pd.IsReadOnly) continue;
				try {
					var val1 = pd.GetValue(b);
					var val2 = pd.GetValue(target);
					if (object.Equals(val1, val2)) continue;
					pd.SetValue(b, val2);
				} catch {}
			}
			return b.ProvideValue(XamlObject.ServiceProvider);
		}
	}

	class StaticResourceWrapper : MarkupExtensionWrapper
	{
		public override object ProvideValue()
		{
			var target = XamlObject.Instance as StaticResourceExtension;
			return XamlObject.ServiceProvider.Resolver.FindResource(target.ResourceKey);
		}
	}
}