//------------------------------------------------------------------------------
// <copyright file="NumericExpr.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;

    internal sealed class NumericExpr : ValueQuery {
        private Operator.Op op;
        private Query opnd1;
        private Query opnd2;

        public NumericExpr(Operator.Op op, Query opnd1, Query  opnd2) {
            Debug.Assert(
                op == Operator.Op.PLUS || op == Operator.Op.MINUS || 
                op == Operator.Op.MUL  || op == Operator.Op.DIV ||
                op == Operator.Op.MOD
            );
            Debug.Assert(opnd1 != null && opnd2 != null);
            if (opnd1.StaticType != XPathResultType.Number) {
                opnd1 = new NumberFunctions(Function.FunctionType.FuncNumber, opnd1);
            }
            if (opnd2.StaticType != XPathResultType.Number) {
                opnd2 = new NumberFunctions(Function.FunctionType.FuncNumber, opnd2);
            }
            this.op = op;
            this.opnd1 = opnd1;
            this.opnd2 = opnd2;
        }
        private NumericExpr(NumericExpr other) : base(other) {
            this.op    = other.op;
            this.opnd1 = Clone(other.opnd1);
            this.opnd2 = Clone(other.opnd2);
        }

        public override void SetXsltContext(XsltContext context){
            opnd1.SetXsltContext(context);
            opnd2.SetXsltContext(context);
        }

        public override object Evaluate(XPathNodeIterator nodeIterator) {
            return GetValue(this.op,
                XmlConvert.ToXPathDouble(opnd1.Evaluate(nodeIterator)),
                XmlConvert.ToXPathDouble(opnd2.Evaluate(nodeIterator))
            );
        }
        private static double GetValue(Operator.Op op, double n1, double n2) {
            Debug.Assert(op == Operator.Op.PLUS || op == Operator.Op.MINUS || op == Operator.Op.MOD || op == Operator.Op.DIV || op == Operator.Op.MUL);
            switch (op) {
            case Operator.Op.PLUS   : return  n1 + n2;
            case Operator.Op.MINUS  : return  n1 - n2;
            case Operator.Op.MOD    : return  n1 % n2;
            case Operator.Op.DIV    : return  n1 / n2;
            case Operator.Op.MUL    : return  n1 * n2;               
            }
            return 0;
        }

        public override XPathResultType StaticType { get { return XPathResultType.Number; } }

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

        public override void PrintQuery(XmlWriter w) {
            w.WriteStartElement(this.GetType().Name);
            w.WriteAttributeString("op", op.ToString());
            opnd1.PrintQuery(w);
            opnd2.PrintQuery(w);
            w.WriteEndElement();
        }
    }
}