// Author: Dwivedi, Ajay kumar
//            Adwiv@Yahoo.com
using System;
using System.Xml;
using System.ComponentModel;
using System.Xml.Serialization;

namespace System.Xml.Schema
{
	/// <summary>
	/// Summary description for XmlSchemaAttribute.
	/// </summary>
	public class XmlSchemaAttribute : XmlSchemaAnnotated
	{
		private object attributeType;
		private string defaultValue;
		private string fixedValue;
		private XmlSchemaForm form;
		private string name;
		private XmlQualifiedName qualifiedName;
		private XmlQualifiedName refName;
		private XmlSchemaSimpleType schemaType;
		private XmlQualifiedName schemaTypeName;
		private XmlSchemaUse use;
		//Compilation fields
		internal bool parentIsSchema = false;
		private static string xmlname = "attribute";

		public XmlSchemaAttribute()
		{
			//FIXME: Docs says the default is optional.
			//Whereas the MS implementation has default None.
			form	= XmlSchemaForm.None;
			use		= XmlSchemaUse.None;
			schemaTypeName	= XmlQualifiedName.Empty;
			qualifiedName	= XmlQualifiedName.Empty;
			refName			= XmlQualifiedName.Empty;
		}

		// Properties
		[XmlIgnore]
		public object AttributeType 
		{ //FIXME: This is not correct. Is it?
			get{ return attributeType; }
		}

		[DefaultValue(null)]
		[System.Xml.Serialization.XmlAttribute("default")]
		public string DefaultValue 
		{
			get{ return defaultValue;}
			set
			{ // Default Value and fixed Value are mutually exclusive
				fixedValue = null;
				defaultValue = value;
			}
		}

		[DefaultValue(null)]
		[System.Xml.Serialization.XmlAttribute("fixed")]
		public string FixedValue 
		{
			get{ return fixedValue;}
			set
			{ // Default Value and fixed Value are mutually exclusive
				defaultValue = null;
				fixedValue = value;
			}
		}

		[DefaultValue(XmlSchemaForm.None)]
		[System.Xml.Serialization.XmlAttribute("form")]
		public XmlSchemaForm Form 
		{
			get{ return form;}
			set{ form = value;}
		}

		[System.Xml.Serialization.XmlAttribute("name")]
		public string Name 
		{
			get{ return name;}
			set
			{
				name  = value;
			}
		}
		[XmlIgnore]
		public XmlQualifiedName QualifiedName 
		{
			get{ return qualifiedName;}
		}

		[System.Xml.Serialization.XmlAttribute("ref")]
		public XmlQualifiedName RefName 
		{
			get{ return refName;}
			set
			{
				refName = value; 
			}
		}

		[XmlElement("simpleType",Namespace="http://www.w3.org/2001/XMLSchema")]
		public XmlSchemaSimpleType SchemaType 
		{
			get{ return schemaType;}
			set{ schemaType = value;}
		}
		
		[System.Xml.Serialization.XmlAttribute("type")]
		public XmlQualifiedName SchemaTypeName 
		{
			get{ return schemaTypeName;}
			set{ schemaTypeName = value;}
		}

		[DefaultValue(XmlSchemaUse.None)]
		[System.Xml.Serialization.XmlAttribute("use")]
		public XmlSchemaUse Use 
		{
			get{ return use;}
			set{ use = value;}
		}
		/// <remarks>
		/// For an attribute:
		///  a) If the parent is schema 
		///		1-5		are from <xs:complexType name="topLevelAttribute"> in the Schema for Schema
		///		6-8		are from  "Constraints on XML Representations of Attribute Declarations"
		///		9-10	are from "Attribute Declaration Schema Component"
		///		11-16	are from "Constraints on Attribute Declaration Schema Components"
		///		1. ref	must be absent
		///		2. form must be absent
		///		3. use	must be absent
		///		4. name must be present and of type NCName
		///		5. *NO CHECK REQUIRED* Only simple types and annotation are allowed as content
		///		6. default and fixed must not both be present. 
		///		7. *NO CHECK REQUIRED* If default and use are both present... (Not possible since use is absent)
		///		8. type and <simpleType> must not both be present.
		///		9. Target Namespace should be schema's targetnamespace or absent
		///		10. Type Definiton coressponds to <simpletype> element, or type value, or absent
		///		11. *TO UNDERSTAND* Missing Sub-components
		///		12. value constraint must be of the same datatype as of type
		///		13. if the type definition is ID then there should be no value constraint.
		///		14. name must not be xmlns
		///		15. Targetnamespace must not be xsi. This implies the target namespace of schema can't be xsi if toplevel attributes are used.
		///		16. *Exception to rule 15* inbuilt attributes: xsi:nil, xsi:type, xsi:schemaLocation, xsi: noNamespaceSchemaLocation
		///	b) If the parent is complextype and ref is not set
		///		1. name must be present and of type NCName.
		///		2. type and <simpleType> must not both be present.
		///		3. default and fixed must not both be present. 
		///     4. If default and use are both present, use must have the ·actual value· optional.
		///		5. name must not be xmlns
		///		6. Targetnamespace must not be xsi.
		///		7. *Exception to rule 15* inbuilt attributes: xsi:nil, xsi:type, xsi:schemaLocation, xsi: noNamespaceSchemaLocation
		///		8. If form has actual value qualified or the schema's formdefault is qualified, targetnamespace
		///		   is same as schema's target namespace, otherwise absent.
		///	c) if the parent is not schema and ref is set
		///		1. name must not be present
		///		2. all of <simpleType>, form and type must be absent. 
		///		3. default and fixed must not both be present. 
		///     4. If default and use are both present, use must have the ·actual value· optional.
		/// </remarks>
		[MonoTODO]
		internal int Compile(ValidationEventHandler h, XmlSchemaInfo info)
		{
			errorCount = 0;
			
			if(parentIsSchema)//a
			{
				if(RefName!= null && !RefName.IsEmpty) // a.1
					error(h,"ref must be absent in the top level <attribute>");
				
				if(Form != XmlSchemaForm.None)	// a.2
					error(h,"form must be absent in the top level <attribute>");
				
				if(Use != XmlSchemaUse.None)		// a.3
					error(h,"use must be absent in the top level <attribute>");

				// TODO: a.10, a.11, a.12, a.13
				CompileCommon(h,info, true);
			}
			else // local
			{
				//FIXME: How to Use of AttributeFormDefault????
				if(RefName == null || RefName.IsEmpty)
				{
					//TODO: b.8
					CompileCommon(h,info, true);
				}
				else
				{
					if(this.name != null)
						error(h,"name must be absent if ref is present");
					if(this.form != XmlSchemaForm.None)
						error(h,"form must be absent if ref is present");
					if(this.schemaType != null)
						error(h,"simpletype must be absent if ref is present");
					if(this.schemaTypeName != null && !this.schemaTypeName.IsEmpty)
						error(h,"type must be absent if ref is present");
					CompileCommon(h,info,false);
				}
			}

			return errorCount;
		}
		
		private void CompileCommon(ValidationEventHandler h, XmlSchemaInfo info, bool refIsNotPresent)
		{
			if(refIsNotPresent)
			{
				if(Name == null)	//a.4, b.1, 
					error(h,"Required attribute name must be present");
				else if(!XmlSchemaUtil.CheckNCName(Name)) // a.4.2, b1.2
					error(h,"attribute name must be NCName");
				else if(Name == "xmlns") // a.14 , b5
					error(h,"attribute name must not be xmlns");
				else
					qualifiedName = new XmlQualifiedName(Name, info.TargetNamespace);	

				if(SchemaType != null)
				{
					if(SchemaTypeName != null && !SchemaTypeName.IsEmpty) // a.8
						error(h,"attribute can't have both a type and <simpleType> content");

					errorCount += SchemaType.Compile(h,info); 
				}

				if(SchemaTypeName != null && !XmlSchemaUtil.CheckQName(SchemaTypeName))
					error(h,SchemaTypeName+" is not a valid QName");
			}
			else
			{
				if(RefName == null || RefName.IsEmpty) 
					error(h,"Error: Should Never Happen. refname must be present");
				else
					qualifiedName = RefName;
			}

			if(info.TargetNamespace == XmlSchema.InstanceNamespace && Name != "nil" && Name != "type" 
				&& Name != "schemaLocation" && Name != "noNamespaceSchemaLocation") // a.15, a.16
				error(h,"targetNamespace can't be " + XmlSchema.InstanceNamespace);

			if(DefaultValue != null && FixedValue != null) // a.6, b.3, c.3
				error(h,"default and fixed must not both be present in an Attribute");

			if(DefaultValue != null && Use != XmlSchemaUse.None && Use != XmlSchemaUse.Optional)
				error(h,"if default is present, use must be optional");

			XmlSchemaUtil.CompileID(Id, this, info.IDCollection, h);
		}

		[MonoTODO]
		internal int Validate(ValidationEventHandler h)
		{
			return errorCount;
		}
		//<attribute
		//  default = string
		//  fixed = string
		//  form = (qualified | unqualified)
		//  id = ID
		//  name = NCName
		//  ref = QName
		//  type = QName
		//  use = (optional | prohibited | required) : optional
		//  {any attributes with non-schema namespace . . .}>
		//  Content: (annotation?, (simpleType?))
		//</attribute>
		internal static XmlSchemaAttribute Read(XmlSchemaReader reader, ValidationEventHandler h)
		{
			XmlSchemaAttribute attribute = new XmlSchemaAttribute();
			reader.MoveToElement();

			if(reader.NamespaceURI != XmlSchema.Namespace || reader.LocalName != xmlname)
			{
				error(h,"Should not happen :1: XmlSchemaAttribute.Read, name="+reader.Name,null);
				reader.SkipToEnd();
				return null;
			}

			attribute.LineNumber = reader.LineNumber;
			attribute.LinePosition = reader.LinePosition;
			attribute.SourceUri = reader.BaseURI;

			while(reader.MoveToNextAttribute())
			{
				if(reader.Name == "default")
				{
					attribute.defaultValue = reader.Value;
				}
				else if(reader.Name == "fixed")
				{
					attribute.fixedValue = reader.Value;
				}
				else if(reader.Name == "form")
				{
					Exception innerex;
					attribute.form = XmlSchemaUtil.ReadFormAttribute(reader,out innerex);
					if(innerex != null)
						error(h, reader.Value + " is not a valid value for form attribute", innerex);
				}
				else if(reader.Name == "id")
				{
					attribute.Id = reader.Value;
				}
				else if(reader.Name == "name")
				{
					attribute.name = reader.Value;
				}
				else if(reader.Name == "ref")
				{
					Exception innerex;
					attribute.refName = XmlSchemaUtil.ReadQNameAttribute(reader,out innerex);
					if(innerex != null)
						error(h, reader.Value + " is not a valid value for ref attribute",innerex);
				}
				else if(reader.Name == "type")
				{
					Exception innerex;
					attribute.schemaTypeName = XmlSchemaUtil.ReadQNameAttribute(reader,out innerex);
					if(innerex != null)
						error(h, reader.Value + " is not a valid value for type attribute",innerex);
				}
				else if(reader.Name == "use")
				{
					Exception innerex;
					attribute.use = XmlSchemaUtil.ReadUseAttribute(reader,out innerex);
					if(innerex != null)
						error(h, reader.Value + " is not a valid value for use attribute", innerex);
				}
				else if(reader.NamespaceURI == "" || reader.NamespaceURI == XmlSchema.Namespace)
				{
					error(h,reader.Name + " is not a valid attribute for attribute",null);
				}
				else
				{
					if(reader.Prefix == "xmlns")
						attribute.Namespaces.Add(reader.LocalName, reader.Value);
					else if(reader.Name == "xmlns")
						attribute.Namespaces.Add("",reader.Value);
					//TODO: Add to Unhandled attributes
				}
			}
			
			reader.MoveToElement();
			if(reader.IsEmptyElement)
				return attribute;

			//  Content: (annotation?, (simpleType?))
			int level = 1;
			while(reader.ReadNextElement())
			{
				if(reader.NodeType == XmlNodeType.EndElement)
				{
					if(reader.LocalName != xmlname)
						error(h,"Should not happen :2: XmlSchemaAttribute.Read, name="+reader.Name,null);
					break;
				}
				if(level <= 1 && reader.LocalName == "annotation")
				{
					level = 2; //Only one annotation
					XmlSchemaAnnotation annotation = XmlSchemaAnnotation.Read(reader,h);
					if(annotation != null)
						attribute.Annotation = annotation;
					continue;
				}
				if(level <=2 && reader.LocalName == "simpleType")
				{
					level = 3;
					XmlSchemaSimpleType stype = XmlSchemaSimpleType.Read(reader,h);
					if(stype != null)
						attribute.schemaType = stype;
					continue;
				}
				reader.RaiseInvalidElementError();
			}
			return attribute;
		}
		
	}
}