/*
 * 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.
 */

package org.apache.log4j.db.dialect;

import org.apache.log4j.db.ConnectionSource;
import org.apache.log4j.spi.ComponentBase;

import java.sql.DatabaseMetaData;
import java.sql.SQLException;


/**
 * 
 * @author Ceki Gulcu
 *
 */
public class Util extends ComponentBase {
  private static final String POSTGRES_PART = "postgresql";
  private static final String MYSQL_PART = "mysql";
  private static final String ORACLE_PART = "oracle";
  //private static final String MSSQL_PART = "mssqlserver4";
  private static final String MSSQL_PART = "microsoft";
  private static final String HSQL_PART = "hsql";
  
  public static int discoverSQLDialect(DatabaseMetaData meta) {
    int dialectCode = 0;

    try {

      String dbName = meta.getDatabaseProductName().toLowerCase();

      if (dbName.indexOf(POSTGRES_PART) != -1) {
        return ConnectionSource.POSTGRES_DIALECT;
      } else if (dbName.indexOf(MYSQL_PART) != -1) {
        return ConnectionSource.MYSQL_DIALECT;
      } else if (dbName.indexOf(ORACLE_PART) != -1) {
        return ConnectionSource.ORACLE_DIALECT;
      } else if (dbName.indexOf(MSSQL_PART) != -1) {
        return ConnectionSource.MSSQL_DIALECT;
      } else if (dbName.indexOf(HSQL_PART) != -1) {
        return ConnectionSource.HSQL_DIALECT;
      } else {
        return ConnectionSource.UNKNOWN_DIALECT;
      }
    } catch (SQLException sqle) {
      // we can't do much here
    }

    return dialectCode;
  }

  public static SQLDialect getDialectFromCode(int dialectCode) {
    SQLDialect sqlDialect = null;

    switch (dialectCode) {
    case ConnectionSource.POSTGRES_DIALECT:
      sqlDialect = new PostgreSQLDialect();

      break;
    case ConnectionSource.MYSQL_DIALECT:
      sqlDialect = new MySQLDialect();

      break;
    case ConnectionSource.ORACLE_DIALECT:
      sqlDialect = new OracleDialect();

      break;
    case ConnectionSource.MSSQL_DIALECT:
      sqlDialect = new MsSQLDialect();

      break;
    case ConnectionSource.HSQL_DIALECT:
      sqlDialect = new HSQLDBDialect();

      break;
    }
    return sqlDialect;
  }
  
  /**
   * This method handles cases where the 
   * {@link DatabaseMetaData#supportsGetGeneratedKeys} method is missing in the
   * JDBC driver implementation.
   */
  public boolean supportsGetGeneratedKeys(DatabaseMetaData meta) {
    try {
      //
      //   invoking JDK 1.4 method by reflection
      //
      return ((Boolean) DatabaseMetaData.class.getMethod("supportsGetGeneratedKeys", null).invoke(meta, null)).booleanValue();
    } catch(Throwable e) {
      getLogger().info("Could not call supportsGetGeneratedKeys method. This may be recoverable");
      return false;
    }
  }
  
/** 
  * This method handles cases where the 
  * {@link DatabaseMetaData#supportsBatchUpdates} method is missing in the
  * JDBC driver implementation.
  */
  public boolean supportsBatchUpdates(DatabaseMetaData meta) {
    try {
      return meta.supportsBatchUpdates();
    } catch(Throwable e) {
      getLogger().info("Missing DatabaseMetaData.supportsBatchUpdates method.");
      return false;
    }
  }
}