package org.apache.ojb.broker.util;

 /* Copyright 2002-2005 The Apache Software Foundation

  *

  * Licensed under the Apache License, Version 2.0 (the "License");

  * you may not use this file except in compliance with the License.

  * You may obtain a copy of the License at

  *

  *     http://www.apache.org/licenses/LICENSE-2.0

  *

  * Unless required by applicable law or agreed to in writing, software

  * distributed under the License is distributed on an "AS IS" BASIS,

  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.

  * See the License for the specific language governing permissions and

  * limitations under the License.

  */

 import java.sql.ResultSet;

 import java.sql.SQLException;

 import org.apache.commons.lang.StringUtils;

 /**

  * Helper class for all SQL related stuff.

  * 

  * @author <a href="mailto:armin@codeAuLait.de">Armin Waibel </a>

  * @version $Id: SqlHelper.java,v 1.1 2007-08-24 22:17:36 ewestfal Exp $

  */

 public class SqlHelper

 {

     /** define the name of the pseudo column holding the class to be instantiated. */

     public static final String OJB_CLASS_COLUMN = "OJB_CLAZZ"; 

     /**

          * Helper Class for a split column <br>

          * ie: sum (distinct amount) as theAmount

          * 

          * <pre>

          *  prefix = 'sum (distinct '

          *  column = 'amount'

          *  suffix = ') as theAmount'

          * </pre>

          */

         public static final class PathInfo

         {

                 public String column;

                 public String prefix;

                 public String suffix;

         public final String path;  //original Path

                 PathInfo(String aPath, String aPrefix, String aColumn, String aSuffix)

         {

             path = aPath;

                         column = aColumn;

                         prefix = aPrefix;

                         suffix = aSuffix;

                 }

         }

         /**

          * remove functions and () from path <br>

          * ie: avg(amount) -> amount <br>

          * ie: sum (accounts.amount) -> accounts.amount <br>

          * ie: count(distinct id) as theCount-> id <br>

          * 

          * @param aPath

          *            the path to the attribute

          */

         public static String cleanPath(String aPath)

         {

                 return splitPath(aPath).column;

         }

     /**

      * Split a path into column , prefix and suffix, the prefix contains all

      * info up to the column <br>

      * ie: avg(amount) -> amount , avg( , )<br>

      * ie: sum (accounts.amount) as theSum -> accounts.amount , sum( , ) as

      * theSum <br>

      * ie: count( distinct id ) as bla -> id , count(distinct , ) as bla <br>

      * Supports simple expressions ie: price * 1.05

      * 

      * TODO: cannot resolve multiple attributes in expression 

      * ie: price - bonus

      * 

      * @param aPath

      * @return PathInfo

      */

     public static PathInfo splitPath(String aPath)

     {

         String prefix = null;

         String suffix = null;

         String colName = aPath;

         if (aPath == null)

         {

             return new PathInfo(null, null, null, null);

         }

         // ignore leading ( and trailing ) ie: sum(avg(col1))

         int braceBegin = aPath.lastIndexOf("(");

         int braceEnd = aPath.indexOf(")");

         int opPos = StringUtils.indexOfAny(aPath, "+-/*");

         if (braceBegin >= 0 && braceEnd >= 0 && braceEnd > braceBegin)

         {

             int colBegin;

             int colEnd;

             String betweenBraces;

             betweenBraces = aPath.substring(braceBegin + 1, braceEnd).trim();

             // look for ie 'distinct name'

             colBegin = betweenBraces.indexOf(" ");

             // look for multiarg function like to_char(col,'format_mask')

             colEnd = betweenBraces.indexOf(",");

             colEnd = colEnd > 0 ? colEnd : betweenBraces.length();

             prefix = aPath.substring(0, braceBegin + 1) + betweenBraces.substring(0, colBegin + 1);

             colName = betweenBraces.substring(colBegin + 1, colEnd);

             suffix = betweenBraces.substring(colEnd) + aPath.substring(braceEnd);

         }

         else if (opPos >= 0)

         {

             colName = aPath.substring(0, opPos).trim();

             suffix = aPath.substring(opPos);

         }

         return new PathInfo(aPath, prefix, colName.trim(), suffix);

     }

     /**

      * Returns the name of the class to be instantiated.

      * @param rs the Resultset

      * @return null if the column is not available

      */

     public static String getOjbClassName(ResultSet rs)

     {

         try

         {

             return rs.getString(OJB_CLASS_COLUMN);

         }

         catch (SQLException e)

         {

             return null;

         }

     }

 }