//------------------------------------------------------------------------------
// <copyright file="NodeFunctions.cs" company="Microsoft">
//     Copyright (c) Microsoft Corporation.  All rights reserved.
// </copyright>                                                                
// <owner current="true" primary="true">[....]</owner>
//------------------------------------------------------------------------------

namespace MS.Internal.Xml.XPath {
    using System;
    using System.Xml;
    using System.Xml.XPath;
    using System.Diagnostics;
    using System.Globalization;
    using System.Xml.Xsl;
    using FT = MS.Internal.Xml.XPath.Function.FunctionType;

    internal sealed class NodeFunctions : ValueQuery {
        Query arg = null;
        FT funcType;
        XsltContext xsltContext;

        public NodeFunctions(FT funcType, Query arg) {
            this.funcType = funcType;
            this.arg = arg; 
        }

        public override void SetXsltContext(XsltContext context){
            this.xsltContext = context.Whitespace ? context : null;
            if (arg != null) {
                arg.SetXsltContext(context);
            }
        }
        
        private XPathNavigator EvaluateArg(XPathNodeIterator context) {
            if (arg == null) {
                return context.Current;
            }
            arg.Evaluate(context);
            return arg.Advance();
        }

        public override object Evaluate(XPathNodeIterator context)  {
            XPathNavigator argVal;

            switch (funcType) {
            case FT.FuncPosition:
                return (double)context.CurrentPosition;
            case FT.FuncLast:
                return (double)context.Count;
            case FT.FuncNameSpaceUri:
                argVal = EvaluateArg(context);
                if (argVal != null) {
                    return argVal.NamespaceURI;
                }
                break;
            case FT.FuncLocalName:
                argVal = EvaluateArg(context);
                if (argVal != null) {
                    return argVal.LocalName;
                }
                break;
            case FT.FuncName :
                argVal = EvaluateArg(context);
                if (argVal != null) {
                    return argVal.Name;
                }
                break;
            case FT.FuncCount:
                arg.Evaluate(context);
                int count = 0;
                if (xsltContext != null) {
                    XPathNavigator nav;
                    while ((nav = arg.Advance()) != null) {
                        if (nav.NodeType != XPathNodeType.Whitespace || xsltContext.PreserveWhitespace(nav)) {
                            count++;
                        }
                    }
                } else {
                    while (arg.Advance() != null) {
                        count++;
                    }
                }
                return (double) count;
            }
            return string.Empty;
        }

        public override XPathResultType StaticType { get { return Function.ReturnTypes[(int)funcType]; } }

        public override XPathNodeIterator Clone() {
            NodeFunctions method = new NodeFunctions(funcType, Clone(arg));
            method.xsltContext = this.xsltContext;
            return method;
       }

        public override void PrintQuery(XmlWriter w) {
            w.WriteStartElement(this.GetType().Name);
            w.WriteAttributeString("name", funcType.ToString());
            if (arg != null) {
                arg.PrintQuery(w);
            }
            w.WriteEndElement();
        }
    }
}