/*========================================================================
        Copyright (C) 2006 by Geir-Tore Lindsve, Torbjørn Meistad 
        and Yngve Raudberget, hereby refered to as "the authors".
                        All rights reserved

    Permission is hereby granted, without written agreement and without
    license or royalty fees, to use, reproduce, prepare derivative
    works, distribute, and display this software and its documentation
    for NONCOMMERCIAL RESEARCH AND EDUCATIONAL PURPOSES, provided 
    that (1) the above copyright notice and the following two paragraphs 
    appear in all copies of the source code and (2) redistributions, 
    including without limitation binaries, reproduce these notices in 
    the supporting documentation. 

    IN NO EVENT SHALL THE AUTHORS, OR DISTRIBUTORS OF THIS SOFTWARE 
    BE LIABLE TO ANY PARTY FOR DIRECT, INDIRECT, SPECIAL, INCIDENTAL, 
    OR CONSEQUENTIAL DAMAGES ARISING OUT OF THE USE OF THIS SOFTWARE 
    AND ITS DOCUMENTATION, EVEN IF THE AUTHORS OR ANY OF THE ABOVE 
    PARTIES HAVE BEEN ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.

    THE AUTHORS SPECIFICALLY DISCLAIM ANY WARRANTIES, INCLUDING,
    BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND
    FITNESS FOR A PARTICULAR PURPOSE. THE SOFTWARE PROVIDED HEREUNDER IS
    ON AN "AS IS" BASIS, AND THE AUTHORS AND DISTRIBUTORS HAVE NO
    OBLIGATION TO PROVIDE MAINTENANCE, SUPPORT, UPDATES, ENHANCEMENTS, OR
    MODIFICATIONS.
========================================================================*/

using System;
using System.Collections;
using System.Collections.Generic;
using System.Text;
using System.Xml;
using System.Xml.Schema;

using CLab.Exceptions;
using System.IO;
using System.Reflection;

using CLab.Data;

namespace CLab.Parsers
{
    /// <summary>
    /// Parses and validates the input XML file.
    /// Inserts types, variables and rules to the set CP object
    /// </summary>
    public class ClabXmlParser
    {
        private CP cpObject;
        private XmlReader schemaReader;
        private XmlReader reader;
        private XmlReaderSettings settings;


        /// <summary>
        /// Initializes a new instance of the <see cref="T:ClabXmlParser"/> class.
        /// </summary>
        /// <param name="cpObject">The cp object which gets the data from the xml file.</param>
        public ClabXmlParser(CP cpObject)
        {
            this.cpObject = cpObject;
        }

        /// <summary>
        /// Initializes the parser.
        /// </summary>
        public void InitializeParser()
        {
            Assembly ase = Assembly.GetExecutingAssembly();
            Stream xmlSchema = ase.GetManifestResourceStream("CLab.Auxiliary.clabschema.xsd");
            schemaReader = XmlReader.Create(xmlSchema);
            XmlSchema schema = XmlSchema.Read(schemaReader, null);
            settings = new XmlReaderSettings();
            settings.Schemas.Add(schema);
            settings.ValidationType = ValidationType.Schema;
        }

        /// <summary>
        /// Parses the specified stream.
        /// </summary>
        /// <param name="stream">The stream.</param>
        /// <exception cref="CLab.Exceptions.ClabXMLParserException"/>
        public void Parse(Stream stream)
        {
            InitializeParser();
            try
            {
                reader = XmlTextReader.Create(stream, settings);
                RunParse();
            }
            catch (ArgumentNullException e)
            {
                throw new ClabXMLParserException(String.Format("Argument null {0]", stream.ToString(), e));
            }
            finally
            {
                stream.Close();
            }
        }

        /// <summary>
        /// Parses the specified XML file.
        /// </summary>
        /// <param name="xmlUrl">URL for the XML file.</param>
        /// <exception cref="CLab.Exceptions.ClabXMLParserException"/>
        public void Parse(String xmlUrl)
        {
            InitializeParser();
            try
            {
                reader = XmlTextReader.Create(xmlUrl, settings);
                RunParse();
            }
            catch (System.IO.FileNotFoundException e)
            {
                throw new ClabXMLParserException(String.Format("Could not load {0}", e.FileName), e);
            }
            catch (ClabXMLParserException e)
            {
                throw e;
            }
            finally
            {
                if(reader != null)
                reader.Close();
            }
        }


        /// <summary>
        /// Parses XML input and builds internal data structure for the problem definition
        /// </summary>
        /// <exception cref="CLab.Exceptions.ClabXMLParserException"/>
        private void RunParse()
        {
            Stack elementStack = new Stack();
            Stack typeStack = new Stack();
            Stack variableStack = new Stack();
            Stack rangeStack = new Stack();
            Stack leftExpressionStack = new Stack();
            Stack rightExpressionStack = new Stack();
            Stack operatorStack = new Stack();
            Stack leftOrRight = new Stack();
            int depth = -1;
            List<String> itemList = new List<String>();
            List<String> varList = new List<String>();
            String lastText = "";
            try
            {
                /*
                 * Start reading the xml-file.
                 */
                while (reader.Read())
                {
                    switch (reader.NodeType)
                    {

                        case XmlNodeType.Element:
                            String elementName = reader.Name;
                            elementStack.Push(elementName);
                            if (reader.HasAttributes)
                            {
                                bool isRange = false;
                                for (int i = 0; i < reader.AttributeCount; i++)
                                {
                                    //Move the attribute to the corresponding stack
                                    reader.MoveToAttribute(i);
                                    if (elementName.Equals("typeDecl"))
                                        typeStack.Push(reader.Value);
                                    else if (elementName.Equals("varDecl"))
                                        variableStack.Push(reader.Value);
                                    else if (elementName.Equals("range"))
                                    {
                                        isRange = true;
                                        rangeStack.Push(reader.Value);
                                    }
                                }
                                if (isRange)
                                {
                                    int endOfRange = Convert.ToInt32((String)rangeStack.Pop());
                                    int startOfRange = Convert.ToInt32((String)rangeStack.Pop());
                                    cpObject.AddType(new TypeRange((String)typeStack.Pop(), startOfRange, endOfRange));
                                }
                            }

                            /*
                             * The leftOrRight-stack is kept in order to keep track of which side of 
                             * an operator we are currently on
                             */
                            else if (elementName.Equals("left"))
                            {
                                depth++;
                                leftOrRight.Push("left");
                            }
                            else if (elementName.Equals("right"))
                            {
                                String dump = (String)leftOrRight.Pop();
                                leftOrRight.Push("right");
                            }
                            break;

                        /*
                         *All major processing is done when we reach an end tag 
                         */
                        case XmlNodeType.EndElement:
                            
                            String eName = (String)elementStack.Pop();
                            switch (eName)
                            {
                                case "description":
                                    cpObject.Description = lastText;
                                    break;

                                case "author":
                                    cpObject.Author = lastText;
                                    break;

                                case "date":
                                    cpObject.Date = lastText;
                                    break;

                                case "typeVar":
                                    if (lastText.Contains(" ")) lastText = "\"" + lastText + "\"";
                                    itemList.Add(lastText);
                                    break;

                                case "typeDecl":
                                    if (itemList.Count > 0)
                                        cpObject.AddType(new TypeEnum((String)typeStack.Pop(), itemList));
                                    itemList = new List<String>();
                                    break;

                                case "varName":
                                    varList.Add(lastText);
                                    //varName = lastText;
                                    break;

                                case "varDecl":
                                    String variableType = (String)variableStack.Pop();
                                    foreach (String s in varList)
                                    {
                                        cpObject.AddVariable(new Variable(variableType, s));
                                    }
                                    varList.Clear();
                                    //cpObject.AddVariable(new Variable((String)variableStack.Pop(), varName));
                                    itemList = new List<String>();
                                    break;

                                /*
                                 * If the id/integer element is part of a compound expression, insert it in the stack corresponding 
                                 * to the correct side of the operator.
                                 * Else default to the left side (only valid when used as the only expression in a rule)
                                 */
                                case "id":
                                case "integer":
                                    Expression exp;
                                    if (eName.Equals("id"))
                                    {
                                        if (lastText.Contains(" ")) lastText = "\"" + lastText + "\"";
                                        exp = new ExpressionId(lastText);
                                    }
                                    else
                                        exp = new ExpressionInt(Convert.ToInt32(lastText));

                                    if (leftOrRight.Count > 0)
                                    {
                                        if (leftOrRight.Peek().Equals("left"))
                                            leftExpressionStack.Push(exp);
                                        else if (leftOrRight.Peek().Equals("right"))
                                            rightExpressionStack.Push(exp);
                                        else
                                            throw new ClabInvalidExpressionException(1, lastText);
                                    }
                                    else
                                    {
                                        leftExpressionStack.Push(exp);
                                    }
                                    break;

                                case "operator":
                                    operatorStack.Push(Oper2type(lastText));
                                    break;

                                /*
                                 * We have a complete compound expression.
                                 * Build a new expression with the corresponding components from the stacks and insert the new expression
                                 * in the stack corresponding to the correct side of the outer expression.
                                 */
                                case "right":
                                    String dump = (String)leftOrRight.Pop();
                                    if (leftOrRight.Count > 0)
                                    {
                                        if (leftOrRight.Peek().Equals("left") & depth > 0)
                                            leftExpressionStack.Push(new ExpressionBinary((Expression)leftExpressionStack.Pop(), (Common.ExprType)operatorStack.Pop(), (Expression)rightExpressionStack.Pop()));
                                        else if (leftOrRight.Peek().Equals("right") & depth > 0)
                                            rightExpressionStack.Push(new ExpressionBinary((Expression)leftExpressionStack.Pop(), (Common.ExprType)operatorStack.Pop(), (Expression)rightExpressionStack.Pop()));
                                        else
                                            throw new ClabInvalidExpressionException(3, "");
                                    }
                                    depth--;
                                    break;

                                /*
                                 * If we have a negated expression, take the last expression in the stack and insert it in a new expression
                                 * of type et_neg (- operator) or et_not (! operator) and put it back in the stack
                                 */
                                case "neg":
                                case "not":
                                    Common.ExprType type;
                                    if (eName.Equals("neg"))
                                        type = Common.ExprType.et_neg;
                                    else
                                        type = Common.ExprType.et_not;
                                    if (leftOrRight.Count > 0)
                                    {
                                        if (leftOrRight.Peek().Equals("left"))
                                            leftExpressionStack.Push(new ExpressionNotNeg(type, (Expression)leftExpressionStack.Pop()));
                                        else if (leftOrRight.Peek().Equals("right"))
                                            rightExpressionStack.Push(new ExpressionNotNeg(type, (Expression)rightExpressionStack.Pop()));
                                    }
                                    else
                                    {
                                        if (rightExpressionStack.Count > 0)
                                            leftExpressionStack.Push(new ExpressionNotNeg(type, new ExpressionBinary((Expression)leftExpressionStack.Pop(), (Common.ExprType)operatorStack.Pop(), (Expression)rightExpressionStack.Pop())));
                                        else
                                            leftExpressionStack.Push(new ExpressionNotNeg(type, (Expression)leftExpressionStack.Pop()));
                                    }
                                    break;

                                /*
                                 * Build the final expression (a complete rule) and insert it in the cp object.
                                 */
                                case "ruleDecl":
                                    if (depth != -1)
                                        throw new ClabInvalidExpressionException(4, depth);
                                    if (rightExpressionStack.Count > 0)
                                        cpObject.AddRule(new ExpressionBinary((Expression)leftExpressionStack.Pop(), (Common.ExprType)operatorStack.Pop(), (Expression)rightExpressionStack.Pop()));
                                    else
                                        cpObject.AddRule((Expression)leftExpressionStack.Pop());
                                    break;

                                default:
                                    break;
                            }
                            break;

                        case XmlNodeType.Text:
                            lastText = reader.Value;
                            break;

                        default:
                            break;
                    }
                }
            }
            catch (XmlException e)
            {
                throw new ClabXMLParserException(String.Format("Failed reading XML file. {0}", e.Message), e);
            }
            catch (XmlSchemaValidationException e)
            {
                throw new ClabXMLParserException(String.Format("XML file failed validation. {0}", e.Message), e);
            }
            catch (InvalidOperationException e)
            {
                throw new ClabXMLParserException(String.Format("Something bad happened during parsing of rules from the XML file.\n{0}", e.ToString()), e);
            }
            catch (ClabInvalidExpressionException e)
            {
                throw new ClabXMLParserException(e.Message, e);
            }
        }


        /// <summary>
        /// Converts operators in string representation to their respective internal enum types
        /// </summary>
        /// <param name="oper">The operator.</param>
        /// <returns>Enum type from <see cref="F:CLab.Auxiliary.Common.ExprType"/></returns>
        /// <exception cref="CLab.Exceptions.ClabXMLParserException"/>
        Common.ExprType Oper2type(String oper)
        {
            Common.ExprType setType;
            switch (oper)
            {
                case ">>":
                    setType = Common.ExprType.et_impl;
                    break;
                case "|":
                    setType = Common.ExprType.et_or;
                    break;
                case "&":
                    setType = Common.ExprType.et_and;
                    break;
                case "<=":
                    setType = Common.ExprType.et_lte;
                    break;
                case ">=":
                    setType = Common.ExprType.et_gte;
                    break;
                case "<":
                    setType = Common.ExprType.et_lt;
                    break;
                case ">":
                    setType = Common.ExprType.et_gt;
                    break;
                case "!=":
                    setType = Common.ExprType.et_ne;
                    break;
                case "==":
                    setType = Common.ExprType.et_eq;
                    break;
                case "-":
                    setType = Common.ExprType.et_minus;
                    break;
                case "+":
                    setType = Common.ExprType.et_plus;
                    break;
                case "%":
                    setType = Common.ExprType.et_mod;
                    break;
                case "/":
                    setType = Common.ExprType.et_div;
                    break;
                case "*":
                    setType = Common.ExprType.et_times;
                    break;
                default:
                    throw new ClabXMLParserException("Invalid Expression type");
            }
            return setType;
        }
    }
}