package org.ultramine.mods.hawkeye.database;

/****************************************************************
 * Licensed to the Apache Software Foundation (ASF) under one   *
 * or more contributor license agreements.  See the NOTICE file *
 * distributed with this work for additional information        *
 * regarding copyright ownership.  The ASF licenses this file   *
 * to you 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.DatabaseMetaData;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.util.Locale;

import org.ultramine.mods.hawkeye.util.HawkUtil;

/**
 * <p>
 * Helper class for managing common JDBC tasks.
 * </p>
 *
 * <p>
 * This class is abstract to allow implementations to take advantage of
 * different logging capabilities/interfaces in different parts of the code.
 * </p>
 *
 * @version CVS $Revision: 494012 $ $Date: 2007-01-08 11:23:58 +0100 (Mo, 08 Jan
 *          2007) $
 */
abstract public class JDBCUtil
{
	/**
	 * An abstract method which child classes override to handle logging of
	 * errors in their particular environments.
	 *
	 * @param errorString
	 *            the error message generated
	 */
	abstract protected void delegatedLog(String errorString);

	/**
	 * Checks database metadata to see if a table exists. Try UPPER, lower, and
	 * MixedCase, to see if the table is there.
	 *
	 * @param dbMetaData
	 *            the database metadata to be used to look up this table
	 * @param tableName
	 *            the table name
	 *
	 * @throws SQLException
	 *             if an exception is encountered while accessing the database
	 */
	public static boolean tableExists(DatabaseMetaData dbMetaData, String tableName) throws SQLException
	{
		return (tableExistsCaseSensitive(dbMetaData, tableName) || tableExistsCaseSensitive(dbMetaData, tableName.toUpperCase(Locale.US)) || tableExistsCaseSensitive(dbMetaData,
				tableName.toLowerCase(Locale.US)));
	}

	/**
	 * Checks database metadata to see if a table exists. This method is
	 * sensitive to the case of the provided table name.
	 *
	 * @param dbMetaData
	 *            the database metadata to be used to look up this table
	 * @param tableName
	 *            the case sensitive table name
	 *
	 * @throws SQLException
	 *             if an exception is encountered while accessing the database
	 */
	public static boolean tableExistsCaseSensitive(DatabaseMetaData dbMetaData, String tableName) throws SQLException
	{
		ResultSet rsTables = dbMetaData.getTables(null, null, tableName, null);
		try
		{
			boolean found = rsTables.next();
			return found;
		}
		finally
		{
			closeJDBCResultSet(rsTables);
		}
	}

	/**
	 * Checks database metadata to see if a column exists in a table Try UPPER,
	 * lower, and MixedCase, both on the table name and the column name, to see
	 * if the column is there.
	 *
	 * @param dbMetaData
	 *            the database metadata to be used to look up this column
	 * @param tableName
	 *            the table name
	 * @param columnName
	 *            the column name
	 *
	 * @throws SQLException
	 *             if an exception is encountered while accessing the database
	 */
	public static boolean columnExists(DatabaseMetaData dbMetaData, String tableName, String columnName) throws SQLException
	{
		return (columnExistsCaseSensitive(dbMetaData, tableName, columnName) || columnExistsCaseSensitive(dbMetaData, tableName, columnName.toUpperCase(Locale.US))
				|| columnExistsCaseSensitive(dbMetaData, tableName, columnName.toLowerCase(Locale.US))
				|| columnExistsCaseSensitive(dbMetaData, tableName.toUpperCase(Locale.US), columnName)
				|| columnExistsCaseSensitive(dbMetaData, tableName.toUpperCase(Locale.US), columnName.toUpperCase(Locale.US))
				|| columnExistsCaseSensitive(dbMetaData, tableName.toUpperCase(Locale.US), columnName.toLowerCase(Locale.US))
				|| columnExistsCaseSensitive(dbMetaData, tableName.toLowerCase(Locale.US), columnName)
				|| columnExistsCaseSensitive(dbMetaData, tableName.toLowerCase(Locale.US), columnName.toUpperCase(Locale.US)) || columnExistsCaseSensitive(dbMetaData,
					tableName.toLowerCase(Locale.US), columnName.toLowerCase(Locale.US)));
	}

	/**
	 * Checks database metadata to see if a column exists in a table. This
	 * method is sensitive to the case of both the provided table name and
	 * column name.
	 *
	 * @param dbMetaData
	 *            the database metadata to be used to look up this column
	 * @param tableName
	 *            the case sensitive table name
	 * @param columnName
	 *            the case sensitive column name
	 *
	 * @throws SQLException
	 *             if an exception is encountered while accessing the database
	 */
	public static boolean columnExistsCaseSensitive(DatabaseMetaData dbMetaData, String tableName, String columnName) throws SQLException
	{
		ResultSet rsTables = dbMetaData.getColumns(null, null, tableName, columnName);
		try
		{
			boolean found = rsTables.next();
			return found;
		}
		finally
		{
			closeJDBCResultSet(rsTables);
		}
	}

	/**
	 * Closes database result set and logs if an error is encountered
	 *
	 * @param aResultSet
	 *            the result set to be closed
	 */
	public static void closeJDBCResultSet(ResultSet aResultSet)
	{
		try
		{
			if(aResultSet != null)
			{
				aResultSet.close();
			}
		}
		catch(SQLException ex)
		{
			HawkUtil.error("Unable to close JDBCResulset: " + ex);
		}
	}

}