using System;
using System.Xml;
using System.Collections;
using Mono.Xml;
using Mono.Xml.Schema;
using System.Xml.Serialization;

namespace System.Xml.Schema
{
	/// <summary>
	///  All Methods in this class should use XmlConvert. Some Methods are not present in the
	///  MS Implementation. We should provide them.
	/// </summary>
	internal class XmlSchemaUtil
	{
		static XmlSchemaUtil()
		{
			FinalAllowed = XmlSchemaDerivationMethod.Restriction | 
				XmlSchemaDerivationMethod.Extension;
			ComplexTypeBlockAllowed = FinalAllowed;
			ElementBlockAllowed = XmlSchemaDerivationMethod.Substitution | 
				FinalAllowed;
		}

		internal static XmlSchemaDerivationMethod FinalAllowed;
		internal static XmlSchemaDerivationMethod ElementBlockAllowed;
		internal static XmlSchemaDerivationMethod ComplexTypeBlockAllowed;

		public static void AddToTable (XmlSchemaObjectTable table, XmlSchemaObject obj,
			XmlQualifiedName qname, ValidationEventHandler h)
		{
			if (table.Contains (qname)) {
				// FIXME: This logic unexpectedly allows 
				// one redefining item and two or more redefining items.
				// FIXME: redefining item is not simple replacement,
				// but much more complex stuff.
				if (obj.isRedefineChild) {	// take precedence.
					if (obj.redefinedObject != null)
						obj.error (h, "Named item " + qname + " was already contained in the schema object table.");
					else
						obj.redefinedObject = table [qname];
					table.Set (qname, obj);
				}
				else if (table [qname].isRedefineChild) {
					if (table [qname].redefinedObject != null)
						obj.error (h, "Named item " + qname + " was already contained in the schema object table.");
					else
						table [qname].redefinedObject = obj;
					return;	// never add to the table.
				}
				else
					obj.error (h, "Named item " + qname + " was already contained in the schema object table.");
			}
			else
				table.Set (qname, obj);
		}

		public static void CompileID(string id,  XmlSchemaObject xso, Hashtable idCollection, ValidationEventHandler h)
		{
			//check if the string conforms to http://www.w3.org/TR/2001/REC-xmlschema-2-20010502/datatypes.html#ID
			// 1. ID must be a NCName
			// 2. ID must be unique in the schema
			if(id == null)
				return;
			if(!CheckNCName(id)) 
				xso.error(h,id+" is not a valid id attribute");
			else if(idCollection.ContainsKey(id))
				xso.error(h,"Duplicate id attribute "+id);
			else
				idCollection.Add(id,xso);
		}

		[MonoTODO]
		public static bool CheckAnyUri(string uri)
		{
			if (uri.StartsWith ("##"))
				return false;
			return true;
		}

		public static bool CheckToken(string token)
		{
			//check if the string conforms to http://www.w3.org/TR/2001/REC-xmlschema-2-20010502/datatypes.html#token
			return true;
		}

		public static bool CheckNormalizedString(string token)
		{
			return true;
		}

		public static bool CheckLanguage(string lang)
		{
			//check if the string conforms to http://www.w3.org/TR/2001/REC-xmlschema-2-20010502/datatypes.html#language
			return true;
		}
		public static bool CheckNCName(string name)
		{
			//check if the string conforms to http://www.w3.org/TR/2001/REC-xmlschema-2-20010502/datatypes.html#NCName
			try
			{
				XmlConvert.VerifyNCName(name);
				return true;
			}
			catch(Exception ex)
			{
				return false;
			}
		}

		public static bool CheckQName(XmlQualifiedName qname)
		{
			// What is this doing?
			return true;
		}

		public static XmlParserContext GetParserContext (XmlReader reader)
		{
			XmlTextReader xtr = reader as XmlTextReader;
			if (xtr != null)
				return xtr.GetInternalParserContext ();
			XmlNodeReader xnr = reader as XmlNodeReader;
			if (xnr != null)
				return xnr.GetInternalParserContext ();
			XmlValidatingReader xvr = reader as XmlValidatingReader;
			if (xvr != null)
				return xvr.GetInternalParserContext ();
			IHasXmlParserContext xctx = reader as IHasXmlParserContext;
			if (xctx != null)
				return xctx.ParserContext;

			throw new NotSupportedException ("XmlParserContext cannot be acquired from this XmlReader.");
		}

		public static bool IsSchemaDatatypeEquals (XsdAnySimpleType st1, object v1,
			XsdAnySimpleType st2, object v2)
		{
			if (v1 == null || v2 == null)
				return false;

			if (st1 == null)
				st1 = XmlSchemaSimpleType.AnySimpleType;
			if (st2 == null)
				st2 = XmlSchemaSimpleType.AnySimpleType;

			Type t = st2.GetType ();
			if (st1 is XsdFloat) {
				return st2 is XsdFloat && Convert.ToSingle (v1) == Convert.ToSingle (v2);
			} else if (st1 is XsdDouble) {
				return st2 is XsdDouble && Convert.ToDouble (v1) == Convert.ToDouble (v2);
			} else if (st1 is XsdDecimal) {
				if (!(st2 is XsdDecimal) || Convert.ToDecimal (v1) != Convert.ToDecimal (v2))
					return false;
				if (st1 is XsdNonPositiveInteger)
					return st2 is XsdNonPositiveInteger || t == typeof (XsdDecimal) || t == typeof (XsdInteger);
				else if (st1 is XsdPositiveInteger)
					return st2 is XsdPositiveInteger || t == typeof (XsdDecimal) || 
						t == typeof (XsdInteger) || t == typeof (XsdNonNegativeInteger);
				else if (st1 is XsdUnsignedLong)
					return st2 is XsdUnsignedLong || t == typeof (XsdDecimal) || 
						t == typeof (XsdInteger) || t == typeof (XsdNonNegativeInteger);
				else if (st1 is XsdNonNegativeInteger)
					return st2 is XsdNonNegativeInteger || t == typeof (XsdDecimal) || t == typeof (XsdInteger);
				else if (st1 is XsdLong)
					return st2 is XsdLong || t == typeof (XsdDecimal) || t == typeof (XsdInteger);
				return true;
			}
			else if (!v1.Equals (v2))
				return false;
			if (st1 is XsdString) {
				if (!(st2 is XsdString))
					return false;
				if (st1 is XsdNMToken && (st2 is XsdLanguage || st2 is XsdName))
					return false;
				if (st2 is XsdNMToken && (st1 is XsdLanguage || st1 is XsdName))
					return false;
				if (st1 is XsdName && (st2 is XsdLanguage || st2 is XsdNMToken))
					return false;
				if (st2 is XsdName && (st1 is XsdLanguage || st1 is XsdNMToken))
					return false;
			}
			else if (st1 != st2)
				return false;
			return true;
		}

		public static bool IsValidQName(string qname)
		{
			foreach(string part in qname.Split(new char[]{':'},2))
			{
				if(!CheckNCName(part))
					return false;
			}
			return true;
		}

		//FIXME: First remove all the multiple instances of whitespace and then return the strings.
		//The current method returns empty strings if there are two or more consecutive whitespaces.
		public static string[] SplitList(string list)
		{
			if(list == null || list == string.Empty)
				return new string [0];

			string[] listarr = list.Split(new char[]{' ','\t','\n'});
			int pos=0;
			int i = 0;
			for(i=0;i<listarr.Length;i++)
			{
				if(listarr[i] != null && listarr[i] != String.Empty)
				{
					listarr[pos++] = listarr[i];
				}
			}
			if(pos == i)
				return listarr;
			string[] retarr = new String[pos];
			if(pos!=0)
				Array.Copy(listarr, retarr, pos);
			return retarr;
		}

		public static void ReadUnhandledAttribute(XmlReader reader, XmlSchemaObject xso)
		{
			if(reader.Prefix == "xmlns")
				xso.Namespaces.Add(reader.LocalName, reader.Value);
			else if(reader.Name == "xmlns")
				xso.Namespaces.Add("",reader.Value);
			else
			{
				if(xso.unhandledAttributeList == null)
					xso.unhandledAttributeList = new System.Collections.ArrayList();
				XmlAttribute attr = new XmlDocument().CreateAttribute(reader.LocalName,reader.NamespaceURI);
				attr.Value = reader.Value;
				ParseWsdlArrayType (reader, attr);
				xso.unhandledAttributeList.Add(attr);
			}
		}
		
		static void ParseWsdlArrayType (XmlReader reader, XmlAttribute attr)
		{
			if (attr.NamespaceURI == XmlSerializer.WsdlNamespace && attr.LocalName == "arrayType")
			{
				string ns = "", type, dimensions;
				TypeTranslator.ParseArrayType (attr.Value, out type, out ns, out dimensions);
				if (ns != "") ns = reader.LookupNamespace (ns) + ":";
				attr.Value = ns + type + dimensions;
			}
		}

		public static bool ReadBoolAttribute(XmlReader reader, out Exception innerExcpetion)
		{
			innerExcpetion = null;
			try
			{
				bool val = XmlConvert.ToBoolean(reader.Value);
				return val;
			}
			catch(Exception ex)
			{
				innerExcpetion = ex;
				return false;
			}
		}
		public static decimal ReadDecimalAttribute(XmlReader reader,  out Exception innerExcpetion)
		{
			innerExcpetion = null;
			try
			{
				decimal val = XmlConvert.ToDecimal(reader.Value);
				return val;
			}
			catch(Exception ex)
			{
				innerExcpetion = ex;
				return decimal.Zero;
			}
		}

		// Is some value is read, return it.
		// If no values return empty.
		// If exception, return none
		public static XmlSchemaDerivationMethod ReadDerivationAttribute(XmlReader reader, out Exception innerExcpetion, string name, XmlSchemaDerivationMethod allowed)
		{
			innerExcpetion = null;
			try
			{
				string list = reader.Value;
				string warn = "";
				XmlSchemaDerivationMethod val = 0;
				
				if(list.IndexOf("#all") != -1 && list.Trim() != "#all")
				{
					innerExcpetion = new Exception(list+" is not a valid value for "+ name +". #all if present must be the only value");
					return XmlSchemaDerivationMethod.All;
				}
				foreach(string xsdm in XmlSchemaUtil.SplitList(list))
				{
					switch(xsdm)
					{
						case "":
							val = AddFlag (val, XmlSchemaDerivationMethod.Empty, allowed); break;
						case "#all":
							val = AddFlag (val,XmlSchemaDerivationMethod.All, allowed); break;
						case "substitution":
							val = AddFlag (val,XmlSchemaDerivationMethod.Substitution, allowed); break;
						case "extension":
							val = AddFlag (val,XmlSchemaDerivationMethod.Extension, allowed); break;
						case "restriction":
							val = AddFlag (val,XmlSchemaDerivationMethod.Restriction, allowed); break;
						case "list":
							val = AddFlag (val,XmlSchemaDerivationMethod.List, allowed); break;
						case "union":
							val = AddFlag (val,XmlSchemaDerivationMethod.Union, allowed); break;
						default:
							warn += xsdm + " "; break;
					}
				}
				if(warn != "")
						innerExcpetion = new Exception(warn + "is/are not valid values for " + name);
				return val;
			}
			catch(Exception ex)
			{
				innerExcpetion = ex;
				return XmlSchemaDerivationMethod.None;
			}
		}

		private static XmlSchemaDerivationMethod AddFlag (XmlSchemaDerivationMethod dst,
			XmlSchemaDerivationMethod add, XmlSchemaDerivationMethod allowed)
		{
			if ((add & allowed) == 0 && allowed != XmlSchemaDerivationMethod.All)
				throw new ArgumentException (add + " is not allowed in this attribute.");
			if ((dst & add) != 0)
				throw new ArgumentException (add + " is already specified in this attribute.");
			return dst | add;
		}

		public static XmlSchemaForm ReadFormAttribute(XmlReader reader, out Exception innerExcpetion)
		{
			innerExcpetion = null;
			XmlSchemaForm val = XmlSchemaForm.None;
			switch(reader.Value)
			{
				case "qualified":
					val = XmlSchemaForm.Qualified; break;
				case "unqualified":
					val = XmlSchemaForm.Unqualified; break;
				default:
					innerExcpetion = new Exception("only qualified or unqulified is a valid value"); break;
			}
			return val;
		}

		public static XmlSchemaContentProcessing ReadProcessingAttribute(XmlReader reader, out Exception innerExcpetion)
		{
			innerExcpetion = null;
			XmlSchemaContentProcessing val = XmlSchemaContentProcessing.None;
			switch(reader.Value)
			{
				case "lax":
					val = XmlSchemaContentProcessing.Lax; break;
				case "strict":
					val = XmlSchemaContentProcessing.Strict; break;
				case "skip":
					val = XmlSchemaContentProcessing.Skip; break;
				default:
					innerExcpetion = new Exception("only lax , strict or skip are valid values for processContents");
					break;
			}
			return val;
		}

		public static XmlSchemaUse ReadUseAttribute(XmlReader reader, out Exception innerExcpetion)
		{
			innerExcpetion = null;
			XmlSchemaUse val = XmlSchemaUse.None;
			switch(reader.Value)
			{
				case "optional":
					val = XmlSchemaUse.Optional; break;
				case "prohibited":
					val = XmlSchemaUse.Prohibited; break;
				case "required":
					val = XmlSchemaUse.Required; break;
				default:
					innerExcpetion = new Exception("only optional , prohibited or required are valid values for use");
					break;
			}
			return val;
		}
		public static XmlQualifiedName ReadQNameAttribute(XmlReader reader, out Exception innerEx)
		{
			return ToQName(reader, reader.Value, out innerEx);
		}

		//While Creating a XmlQualifedName, we should check:
		// 1. If a prefix is present, its namespace should be resolvable.
		// 2. If a prefix is not present, and if the defaultNamespace is set, 
		public static XmlQualifiedName ToQName(XmlReader reader, string qnamestr, out Exception innerEx)
		{

			string ns;
			string name;
			XmlQualifiedName qname;
			innerEx = null;
			
			if(!IsValidQName(qnamestr))
			{
				innerEx = new Exception(qnamestr + " is an invalid QName. Either name or namespace is not a NCName");
				return XmlQualifiedName.Empty;
			}

			string[] values = qnamestr.Split(new char[]{':'},2);

			if(values.Length == 2)
			{
				ns = reader.LookupNamespace(values[0]);
				if(ns == null)
				{
					innerEx = new Exception("Namespace Prefix '"+values[0]+"could not be resolved");
					return XmlQualifiedName.Empty;
				}
				name = values[1];
			}
			else
			{
				//Default Namespace
				ns = reader.LookupNamespace("");
				name = values[0];
			}

			qname = new XmlQualifiedName(name,ns);
			return qname;
		}

		public static int ValidateAttributesResolved (
			XmlSchemaObjectTable attributesResolved,
			ValidationEventHandler h,
			XmlSchema schema,
			XmlSchemaObjectCollection attributes,
			XmlSchemaAnyAttribute anyAttribute,
			ref XmlSchemaAnyAttribute anyAttributeUse,
			XmlSchemaAttributeGroup redefined)
		{
			int errorCount = 0;
			if (anyAttribute != null && anyAttributeUse == null)
				anyAttributeUse = anyAttribute;

			foreach (XmlSchemaObject xsobj in attributes) {
				XmlSchemaAttributeGroupRef grpRef = xsobj as XmlSchemaAttributeGroupRef;
				if (grpRef != null) {
					// Resolve attributeGroup redefinition.
					XmlSchemaAttributeGroup grp = null;
					if (redefined != null && grpRef.RefName == redefined.QualifiedName)
						grp = redefined;
					else
						grp = schema.AttributeGroups [grpRef.RefName] as XmlSchemaAttributeGroup;
					// otherwise, it might be missing sub components.
					if (grp == null) {
						if (!schema.missedSubComponents)// && schema.Schemas [grpRef.RefName.Namespace] != null)
							grpRef.error (h, "Referenced attribute group " + grpRef.RefName + " was not found in the corresponding schema.");
						continue;
					}
					if (grp.AttributeGroupRecursionCheck) {
						grp.error (h, "Attribute group recursion was found: " + grpRef.RefName);
						continue;
					}
					try {
						grp.AttributeGroupRecursionCheck = true;
						errorCount += grp.Validate (h, schema);
					} finally {
						grp.AttributeGroupRecursionCheck = false;
					}
					if (grp.AnyAttributeUse != null) {
						// FIXME: should validate wildcard subset validity. See spec 3.10.6
						if (anyAttribute == null)
							anyAttributeUse = grp.AnyAttributeUse;
					}
					foreach (XmlSchemaAttribute attr in grp.AttributeUses) {
						if (attr.RefName != null && attr.RefName != XmlQualifiedName.Empty)
							AddToTable (attributesResolved, attr, attr.RefName, h);
						else
							AddToTable (attributesResolved, attr, attr.QualifiedName, h);
					}
				} else {
					XmlSchemaAttribute attr = xsobj as XmlSchemaAttribute;
					if (attr != null) {
						errorCount += attr.Validate (h, schema);
						if (attr.RefName != null && attr.RefName != XmlQualifiedName.Empty)
							AddToTable (attributesResolved, attr, attr.RefName, h);
						else
							AddToTable (attributesResolved, attr, attr.QualifiedName, h);
					} else {
						if (anyAttribute == null) {
							anyAttributeUse = (XmlSchemaAnyAttribute) xsobj;
							anyAttribute.Validate (h, schema);
						}
					}
				}
			}
			return errorCount;
		}

	}
}