/*
*
* CDDL HEADER START
*
* The contents of this file are subject to the terms of the
* Common Development and Distribution License, Version 1.0 only
* (the "License"). You may not use this file except in compliance
* with the License.
*
* You can obtain a copy of the license at license/ESCIDOC.LICENSE
* or http://www.escidoc.de/license.
* See the License for the specific language governing permissions
* and limitations under the License.
*
* When distributing Covered Code, include this CDDL HEADER in each
* file and include the License file at license/ESCIDOC.LICENSE.
* If applicable, add the following below this CDDL HEADER, with the
* fields enclosed by brackets "[]" replaced with your own identifying
* information: Portions Copyright [yyyy] [name of copyright owner]
*
* CDDL HEADER END
*/
/*
* Copyright 2006-2007 Fachinformationszentrum Karlsruhe Gesellschaft
* für wissenschaftlich-technische Information mbH and Max-Planck-
* Gesellschaft zur Förderung der Wissenschaft e.V.
* All rights reserved. Use is subject to license terms.
*/
/**
 * JavaCC file
 *
 * The following grammar is realized:
 *
 * searchString 	= ( expression )+
 * expression		= searchClause ( booleanClause )?
 * searchClause		= searchToken | "(" searchString ")"
 * booleanClause	= ( AND | OR | NOT ) expression
 * searchToken		= constant | phrase | escaped
 * escaped			= \ special
 * special			= "<"
 * phrase			= QUOT all characters except quot | masked quot QUOT
 * specialCharacters= "=", WHITESPACE , "<", ">", "/", "(", ")", NEWLINE, QUOT
 *
 * TODO NiH: Revise until 31.08.2007; comment this in when finished: Revised by NiH: DD.MM.YYYY
 */
options{
  JDK_VERSION = "1.5";
  STATIC = false;
  UNICODE_INPUT = true;
}
PARSER_BEGIN(QueryParser)
package de.mpg.escidoc.services.search.parser;
import java.util.*;
import java.io.*;
/**
 * This class is generated by JavaCC.  The most important method is
 * {@link #parse()}.
 *
 * Usage example:
 *  QueryParser parser = new QueryParser("my query to parse");
 *  String cqlQuery = parser.parse();
 *	
 * To enrich the cql query with indexes use {@link #addCQLIndex()} before parsing.
 * 
 * @author Miriam Doelle 
 *
 */
public class QueryParser{
  /**
   * Creates a new instance with the given string.
   */
public QueryParser(String query, String operator){
    this (new StringReader(query));
    this.booleanOperator = operator;
  }

  /** 
   *  Parses a query string, returning a CQL query string.
   *
   *  @param query  the query string to be parsed.
   *  @throws ParseException if the parsing fails
   */
   
public String parse(String query)throws ParseException{
    ReInit(new StringReader(query));
    try {
      matchQuery();
      return getCQLQuery();
    }
    catch (ParseException tme){
      // rethrow to include the original query:
throw new ParseException("Cannot parse '"+query+"': "+tme.getMessage());
    }
    catch (TokenMgrError tme){
      throw new ParseException("Cannot parse '"+query+"': "+tme.getMessage());
    }
  }
  /** 
   *  Parses a query, returning a CQL query string.
   *
   *  @param query  the query string to be parsed.
   *  @throws ParseException if the parsing fails
   */
public String parse()throws ParseException{
    try {
      matchQuery();
      return getCQLQuery();
    }
    catch (ParseException tme){
      // rethrow to include the original query:
throw new ParseException("Cannot parse query: "+tme.getMessage());
    }
    catch (TokenMgrError tme){
      throw new ParseException("Cannot parse query: "+tme.getMessage());
    }
  }
  /**
   * The resulting cql query.
   */
private String cqlQuery = "";

/**
* Boolean operator.
*/
private String booleanOperator = "";
  /**
   * The list of cql indexes.
   */
private List<String>cqlIndexList = new ArrayList<String>();
  /**
   * Returns the created cql query.
   */
public String getCQLQuery(){
    return cqlQuery;
  }
  /**
   * Adds a cql index to the list.
   */
public void addCQLIndex(String index){
    cqlIndexList.add(index);
  }
  /**
   * Returns the list of cql indexes.
   */
public List<String>getCQLIndexList(){
    return cqlIndexList;
  }
  
  /**
   * Escape the special characters in a string. Here you can decide whether a special character
   * will be used as a logical operator or not.
   */
  private String escapeSpecialCharacters( String escapeMe ) {
  	String result = escapeMe.replace( "<", "\\<" );
  	result = result.replace( ">", "\\>" );
  	result = result.replace( "+", "\\+" );
  	result = result.replace( "-", "\\-" );
  	result = result.replace( "&", "\\&" );
  	result = result.replace( "|", "\\|" );
  	result = result.replace( "(", "\\(" );
  	result = result.replace( ")", "\\)" );
  	result = result.replace( "[", "\\[" );
  	result = result.replace( "]", "\\]" );
  	result = result.replace( "^", "\\^" );
  	result = result.replace( "~", "\\~" );
  	result = result.replace( "!", "\\!" );
  	result = result.replace( "{", "\\{" );
  	result = result.replace( "}", "\\}" );
  	return result;
  }
  
  /**
   * Helper to add cql indexes to a searchToken.
   */
private String makeCQLIdexedSearchToken(String searchToken){
    
    searchToken = escapeSpecialCharacters( searchToken );  
    StringBuffer result = new StringBuffer();
    switch (cqlIndexList.size()){
      case 0:return searchToken;
      case 1:return result.append(cqlIndexList.get(0)).append(this.booleanOperator).append(searchToken).toString();
      default :// enclose in brackets
result.append("(");
      for (int i = 0;
      i<cqlIndexList.size();
      i++){
        String index = cqlIndexList.get(i);
        if (i>0){
          // add or operation between indexed searchTokens
result.append(" or ");
        }
        result.append(index).append(booleanOperator).append(searchToken);
      }
      result.append(")");
      return result.toString();
    }
  }
}
PARSER_END(QueryParser)
SKIP:{
  " "
  | "\r"
  | "\t"
}
TOKEN:{
  <AND:("AND")>
  | <OR:("OR")>
  | <NOT:("NOT")>
  | <QUOTED:"\""(~["\""] | "\\\"")+"\"">
  | <CONSTANT:(~["*", "?", "\n", "\"", " "])(~[ "\n", " " ])*>
}
void matchQuery():{
  String s;
}
{
  s = searchString(){
    cqlQuery = s;
  }
  <EOF>
}
String searchString():{
  String s;
  StringBuffer result = new StringBuffer();
}
{
  (s = expression(){
    if (result.length()>0){
      result.append(" and ").append(s);
    }
    else {
      result.append(s);
    }
  }
  )+{
    return result.toString();
  }
}
String expression():{
  String e1;
  String e2 = "";
  StringBuffer result = new StringBuffer();
}
{
  e1 = searchClause()[e2 = booleanClause()]{
    result.append(e1);
    if (!e2.equals("")){
      result.append(" ").append(e2);
    }
    return result.toString();
  }
}
String searchClause():{
  String s;
}
{
  (s = searchToken(){
    return s;
  }
  | ("("s = searchString()")"){
    return "("+s+")";
  }
  )
}
String searchToken():{
  Token t;
  String s;
}
{
  (t = phrase()){
    t.image = makeCQLIdexedSearchToken( t.image );
    return t.image;
  }
  |
  (t = <CONSTANT>){
    t.image = makeCQLIdexedSearchToken( "\"" + t.image + "\"");
    return t.image;
  }
}
Token phrase():{
  Token t;
}
{
  t = <QUOTED>{
    return t;
  }
}
String booleanClause():{
  String s;
  Token t;
}
{
  (t = <AND>
  | t = <OR>
  | t = <NOT>)s = expression(){
    return t.image.toLowerCase()+" "+s;
  }
}