//------------------------------------------------------------------------------
// <copyright file="FunctionQuery.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.Xsl;
    using System.Xml.XPath;
    using System.Diagnostics;
    using System.Globalization;
    using System.Collections.Generic;

    internal sealed class FunctionQuery : ExtensionQuery {
        private IList<Query> args;
        private IXsltContextFunction function;

        public FunctionQuery(string prefix, string name, List<Query> args) : base(prefix, name) {
            this.args = args;
        }
        private FunctionQuery(FunctionQuery other) : base(other) {
            this.function = other.function;
            Query[] tmp = new Query[other.args.Count]; {                
                for (int i = 0; i < tmp.Length; i ++) {
                    tmp[i] = Clone(other.args[i]);
                }
                args = tmp;
            }
            this.args = tmp;
        }

        public override void SetXsltContext(XsltContext context) {
            if (context == null) {
                throw XPathException.Create(Res.Xp_NoContext);
            }
			if (this.xsltContext != context) {
                xsltContext = context;
                foreach (Query argument in args) {
                    argument.SetXsltContext(context);
                }
                XPathResultType[] argTypes = new XPathResultType[args.Count];
                for(int i = 0; i < args.Count; i ++) {
                    argTypes[i] = args[i].StaticType;
                }
                function = xsltContext.ResolveFunction(prefix, name, argTypes);
                // KB article allows to return null, see http://support.microsoft.com/?kbid=324462#6
                if (function == null) {
                    throw XPathException.Create(Res.Xp_UndefFunc, QName);
                }
            }
        }

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

            // calculate arguments:
            object[] argVals = new object[args.Count];
            for (int i = 0; i < args.Count; i ++) {
                argVals[i] = args[i].Evaluate(nodeIterator);
                if (argVals[i] is XPathNodeIterator) {// ForBack Compat. To protect our queries from users. bug#372077 & 20006123 
                    argVals[i] = new XPathSelectionIterator(nodeIterator.Current, args[i]);
                }
            }
            try {
                return ProcessResult(function.Invoke(xsltContext, argVals, nodeIterator.Current));
            } catch(Exception ex) {
                throw XPathException.Create(Res.Xp_FunctionFailed, QName, ex);
            }
        }

        public override XPathNavigator MatchNode(XPathNavigator navigator) {
            if (name != "key" && prefix.Length != 0) {
                throw XPathException.Create(Res.Xp_InvalidPattern);
            }
            this.Evaluate(new XPathSingletonIterator(navigator, /*moved:*/true));
            XPathNavigator nav = null;
            while ((nav = this.Advance()) != null) {
                if (nav.IsSamePosition(navigator)) {
                    return nav;
                }
            }
            return nav;
        }

        public override XPathResultType StaticType { get {
            XPathResultType result = function != null ? function.ReturnType : 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 FunctionQuery(this); }

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