//==============================================================================
// SqlObjectResultSet.java
//==============================================================================

package tribble.sql;

import java.lang.IllegalAccessException;
import java.lang.InstantiationException;
import java.lang.Object;
import java.lang.String;

import java.lang.reflect.Constructor;
import java.lang.reflect.InvocationTargetException;

import java.sql.ResultSet;
import java.sql.SQLException;
import java.sql.Statement;

import java.util.List;


/*******************************************************************************
* SQL query result set.
* See {@link SqlObjectQuery} for details.
*
* <!-- ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ -->
* <dl>
* <dt> <b>Source code:</b> </dt>
*  <dd> Available at:
*   <a href="http://david.tribble.com/src/java/tribble/sql/SqlObjectResultSet.java"
*    >http://david.tribble.com/src/java/tribble/sql/SqlObjectResultSet.java</a>
*  </dd>
* <dt> <b>Documentation:</b> </dt>
*  <dd> Available at:
*   <a href="http://david.tribble.com/docs/tribble/sql/SqlObjectResultSet.html"
*    >http://david.tribble.com/docs/tribble/sql/SqlObjectResultSet.html</a>
*  </dd>
* </dl>
*
* @version	@(#)$Revision: 1.7 $ $Date: 2008/09/13 21:24:37 $
* @since	2008-02-14
* @author	David R. Tribble (david&#64;tribble.com)
*	<p>
*	Copyright ©2008 by David R. Tribble, all rights reserved.<br/>
*	Permission is granted to any person or entity except those designated by
*	by the United States Department of State as a terrorist, or terrorist
*	government or agency, to use and distribute this source code provided
*	that the original copyright notice remains present and unaltered.
*
* @see	SqlObjectQuery
*/

public class SqlObjectResultSet
{
    static final String		REV =
        "@(#)tribble/sql/SqlObjectResultSet.java $Revision: 1.7 $ $Date: 2008/09/13 21:24:37 $\n";


// ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~
// Variables

    /** Query result object type. */
    private Class			m_type;

    /** Constructor (default, no-arg) for the result object type. */
    private Constructor			m_ctor;

    /** List of mappings from the selected fields to result class members. */
    private List/*<FieldTypeMap>*/	m_mappings;

    /** Parent SQL query that produced this result set. */
    private SqlObjectQuery		m_query;

    /** JDBC query statement for this result set. */
    private Statement			m_stmt;

    /** JDBC query result set. */
    private ResultSet			m_results;

    /** Has a result row. */
    private boolean			m_hasRow;


// ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~
// Constructors

    /***************************************************************************
    * Constructor.
    *
    * @since	1.1, 2008-02-14
    */

    SqlObjectResultSet(SqlObjectQuery query, Class type, Constructor ctor,
        List mappings, ResultSet results, Statement stmt)
    {
        // Initialize
        m_query =    query;
        m_type =     type;
        m_ctor =     ctor;
        m_mappings = mappings;
        m_results =  results;
        m_stmt =     stmt;
    }


// ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~
// Methods

    /***************************************************************************
    * Close this result set, releasing all object storage associated with it.
    *
    * <p>
    * Note that this method never throws <tt>SQLException</tt>, even if such an
    * exception results during the closing of the result set.
    *
    * @since	1.1, 2008-02-24
    */

    public void close()
    {
        // Close the result set
        if (m_results != null)
        {
            try
            {
                m_results.close();
            }
            catch (SQLException ex)
            { }

            m_results = null;
        }

        // Close the query statement
        if (m_stmt != null)
        {
            try
            {
                m_stmt.close();
            }
            catch (SQLException ex)
            { }

            m_stmt = null;
        }
    }


    /***************************************************************************
    * Determines if there is a next row in the results of the SQL query, and
    * advances to that row.
    *
    * @throws	SQLException
    * Thrown if an error occurs when the SQL result set is advanced to the next
    * result row.
    *
    * @since	1.1, 2008-02-24
    */

    public boolean next()
        throws SQLException
    {
        SQLException	err = null;

        // Sanity check
        if (m_results == null)
            throw new SQLException("Result set is no longer active");

        // Advance the result set pointer to the next result row
        try
        {
            m_hasRow = m_results.next();
        }
        catch (SQLException ex)
        {
            err = ex;
            m_hasRow = false;
        }

        if (!m_hasRow)
        {
            // No more result rows in the result set, clean up
            close();
        }

        if (err != null)
            throw err;
        return m_hasRow;
    }


    /***************************************************************************
    * Retrieve the next row from the results of the SQL query.
    *
    * @return
    * An object of the result class type, populated with the selected columns of
    * the current row of the query result set.
    *
    * @throws	SQLException
    * Thrown if an error occurs while retrieving field (column) values from the
    * SQL query result set.
    *
    * @throws	InstantiationException (unchecked)
    * Thrown if an object of the result type could not be created.
    *
    * @since	1.1, 2008-02-14
    */

    public Object getResult()
        throws SQLException
    {
        Object		res;
        Exception	err = null;

        // Sanity check
        if (m_results == null)
            throw new SQLException("Result set is no longer active");

        try
        {
            // Create a new object for the current result row
            res = m_ctor.newInstance(new Class[0]);

            // Retrieve the selected fields from the result row,
            //  and populate the return object with them
            for (int i = 0;  i < m_mappings.size();  i++)
            {
                FieldTypeMap	map;

                map = (FieldTypeMap) m_mappings.get(i);
                if (map != null)
                    map.mapResultField(res, i+1, m_results);
            }

            return res;
        }
        catch (IllegalAccessException ex)
        {
            err = ex;
        }
        catch (InvocationTargetException ex)
        {
            err = ex;
        }
        catch (Exception ex)
        {
            err = ex;
        }

        // Handle failures
        if (err != null)
        {
            SQLException	ex;

            ex = new SQLException("Cannot create result object: "
                + m_type.getName());
            ex.initCause(err);
            throw ex;
        }
        return null;		// Should never occur
    }
}

// End SqlObjectResultSet.java