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

    internal sealed class VariableQuery : ExtensionQuery {
        private IXsltContextVariable variable;

        public VariableQuery(string name, string prefix) : base(prefix, name) {}
        private VariableQuery(VariableQuery other) : base(other) {
            this.variable = other.variable;
        }

        public override void SetXsltContext(XsltContext context) {
            if (context == null) {
                throw XPathException.Create(Res.Xp_NoContext);
            }

			if (this.xsltContext != context) {
                xsltContext = context;
				variable = xsltContext.ResolveVariable(prefix, name);
                // Since null is allowed for ResolveFunction, allow it for ResolveVariable as well
                if (variable == null) {
                    throw XPathException.Create(Res.Xp_UndefVar, QName);
                }
            }
        }

        public override object Evaluate(XPathNodeIterator nodeIterator) {
			if (xsltContext == null) {
				throw XPathException.Create(Res.Xp_NoContext);
			}

            return ProcessResult(variable.Evaluate(xsltContext));
        }

        public override XPathResultType StaticType { get {
            if (variable != null) {  // Temp. fix to overcome dependency on static type
                return GetXPathType(Evaluate(null));
            }
            XPathResultType result = variable != null ? variable.VariableType : XPathResultType.Any;
			if (result == XPathResultType.Error) {
				// In v.1 we confused Error & Any so now for backward compatibility we should allow users to return any of them.
				result = XPathResultType.Any;
			}
            return result;
        } }

        public override XPathNodeIterator Clone() { return new VariableQuery(this); }

        public override void PrintQuery(XmlWriter w) {
            w.WriteStartElement(this.GetType().Name);
            w.WriteAttributeString("name", prefix.Length != 0 ? prefix + ':' + name : name);
            w.WriteEndElement();
        }
    }
}