/***
    *  The contents of this file are subject to the Mozilla Public
    *  License Version 1.1 (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.mozilla.org/MPL/
    *
    *  Software distributed under the License is distributed on an "AS
    *  IS" basis, WITHOUT WARRANTY OF ANY KIND, either express or
    *  implied. See the License for the specific language governing
   *  rights and limitations under the License.
   *
   *  The Original Code is pow2toolkit library.
   *
   *  The Initial Owner of the Original Code is
   *  Claudio Fratarcangeli
   *
   *  Portions created by Power Of Two S.R.L. are
   *  Copyright (C) Power Of Two S.R.L.
   *  All Rights Reserved.
   *
   * Contributor(s):
   */
  
  package com.pow2.dao.datalist;
  
  import java.sql.Connection;
  import java.sql.Statement;
  import java.sql.ResultSet;
  import java.sql.SQLException;
  
  import com.pow2.dao.AbstractDAO;
  
  
  
  /***
   *  ResultSetDataListImpl class
   *
   * @author  Claudio Fratarcangeli
   * @created  5 dicembre 2002
   */
  public class ResultSetDataListImpl extends AbstractDAO implements ResultSetDataList
  {
    private ResultSetRowMapper rowMapper = null;
    private Connection conn = null;
    private Statement stmt = null;
    private ResultSet rs = null;
  
  
    /***
     *  Constructor
     *
     * @param  rowMapper the rowMapper instance
     * @param  conn the connection object
     * @param  stmt the statement object
     * @param  rs   the resultSet object
     */
    public ResultSetDataListImpl(ResultSetRowMapper rowMapper,
                                 Connection conn,
                                 Statement stmt,
                                 ResultSet rs)
    {
      this.rowMapper = rowMapper;
      this.conn = conn;
      this.stmt = stmt;
      this.rs = rs;
    }
  
  
    /***
     *  Get the iterator object for this data list.
     *
     * @return  the iterator object for this data list
     * @exception Exception if any error occurs
     */
    public DataListIterator iterator() throws Exception
    {
      return new ResultSetDataListIterator(this);
    }
  
  
    /***
     *  Put object state in item and return it.
     *  <br>
     *  Use rowMapper to map fields of ResultSet to instance variables of item.
     *  ResultSet index ranges from 1, while ResultSetDataList index
     *  ranges from 0.
     *
     * @param  index  the index value, starting from 0
     * @param  item   the item object to fill
     * @return  the item object filled with values retrieved from the resultSet
     * @exception Exception if any error occurs
     */
    public Object get(int index, Object item) throws Exception
    {
      try
      {
        // moves the cursor to the given row number in this ResultSet object;
        rs.absolute(index);
  
       // if the the current row number is not equal to the current index,
       // it means that there is no current row;
       if (rs.getRow() != index)
       {
         cat.error("::get - the row value is not equal to index [row: " + rs.getRow() + "; index: " + index + "]");
         throw new IndexOutOfBoundsException();
       }
 
       // uses the rowMapper to get map the recordSet data into the item object;
       item = rowMapper.mapRow(rs, item);
     }
     catch (SQLException e)
     {
       cat.error("::get - a SQL exception occurs at recordSet index [" + index + "]", e);
       throw e;
     }
 
     return item;
   }
 
 
   /***
    *  Check if the resultSet data list has got another record.
    *
    * @return  true  if the resultSet data list has got another record,
    *          false otherwise
    * @exception  Exception if any error occurs
    */
   public boolean hasNext() throws Exception
   {
     // cursor must must not be at the end of the resultSet;
     // current row must exist or cursor is before the first row;
     return (!rs.isLast() && ((rs.getRow() != 0) || rs.isBeforeFirst()));
   }
 
 
   /***
    *  Move the resultSetDataList cursor before the first row of the list.
    *
    * @exception Exception if any error occurs
    */
   public void beforeFirst() throws Exception
   {
      rs.beforeFirst();
   }
 
 
   /***
    *  Move the ResultSetDataList cursor to a specific row number.
    *  Rows are numbered starting from 0.
    *
    * @param  index the cursor index value, starting from 0
    * @exception Exception if any error occurs
    */
   public boolean absolute(int index) throws Exception
   {
     return rs.absolute(index + 1);
   }
 
 
   /***
    *  Check if the ResultSetDataList is empty.
    *
    * @return  The empty value
    * @exception Exception if any error occurs
    */
   public boolean isEmpty() throws Exception
   {
     boolean isEmpty = true;
 
     try
     {
       isEmpty =  (!rs.isBeforeFirst() &&
                   !rs.isAfterLast()   &&
                    rs.getRow() == 0);
     }
     catch (SQLException e)
     {
       throw e;
     }
 
     return isEmpty;
   }
 
 
   /***
    *  Check if any element exist at the <code>index</code> poition.
    *  <br>
    *  Preserve current location of cursor, find out if element exists and then
    *  put cursor back where it was to begin with.
    *
    * @param  index the index value, starting from 0
    * @return  true if any element exist at the <code>index</code> poition,
    *          false otherwise
    * @exception Exception if any error occurs
    */
   public boolean elementExists(int index) throws Exception
   {
     boolean beforeFirst = rs.isBeforeFirst();
     boolean afterLast   = rs.isAfterLast();
     int     currIndex   = rs.getRow();
     boolean exists      = rs.absolute(index + 1);
 
     // now move the cursor at its original position;
     if (beforeFirst)
       rs.beforeFirst();
 
     else if (afterLast)
       rs.afterLast();
 
     else if (currIndex != 0)
       rs.absolute(currIndex);
 
     return exists;
   }
 
 
   /***
    *  Close the data list resultSet, statement, and connection
    *  resources.
    *
    * @exception  Exception if any error occurs
    */
   public void close() throws Exception
   {
     closeResources(rs, stmt, conn, true);
 
     //if (rs   != null) rs.close();
     //if (stmt != null) stmt.close();
     //if (conn != null) conn.close();
   }
 }