/*
    * Copyright 2006-2007 the original author or authors.
    *
    * 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.
   */
  
  package org.springframework.batch.support;
  
  import java.util.HashMap;
  import java.util.Map;
  
  import javax.sql.DataSource;
  
  import org.springframework.jdbc.support.JdbcUtils;
  import org.springframework.jdbc.support.MetaDataAccessException;
  
  
  /**
   * Enum representing a database type, such as DB2 or oracle.  The type also
   * contains a product name, which is expected to be the same as the product name
   * provided by the database driver's metadata.
   * 
   * @author Lucas Ward
   * @since 2.0
   */
  public enum DatabaseType {
  
  	DERBY("Apache Derby"), 
  	DB2("DB2"), 
  	DB2ZOS("DB2ZOS"), 
  	HSQL("HSQL Database Engine"),
  	SQLSERVER("Microsoft SQL Server"),
  	MYSQL("MySQL"),
  	ORACLE("Oracle"),
  	POSTGRES("PostgreSQL"),
  	SYBASE("Sybase"), H2("H2");
  	
  	private static final Map<String, DatabaseType> nameMap;
  	
  	static{
  		nameMap = new HashMap<String, DatabaseType>();
  		for(DatabaseType type: values()){
  			nameMap.put(type.getProductName(), type);
  		}
  	}
  	//A description is necessary due to the nature of database descriptions
  	//in metadata.
  	private final String productName;
  	
  	private DatabaseType(String productName) {
  		this.productName = productName;
  	}
  	
  	public String getProductName() {
  		return productName;
  	}
  	
  	/**
  	 * Static method to obtain a DatabaseType from the provided product name.
  	 * 
  	 * @param productName
  	 * @return DatabaseType for given product name.
  	 * @throws IllegalArgumentException if none is found.
  	 */
  	public static DatabaseType fromProductName(String productName){
  		if(!nameMap.containsKey(productName)){
  			throw new IllegalArgumentException("DatabaseType not found for product name: [" + 
  					productName + "]");
  		}
  		else{
  			return nameMap.get(productName);
  		}
  	}
  	
  	/**
  	 * Convenience method that pulls a database product name from the DataSource's metadata.
  	 * 
  	 * @param dataSource
  	 * @return DatabaseType
  	 * @throws MetaDataAccessException
  	 */
  	public static DatabaseType fromMetaData(DataSource dataSource) throws MetaDataAccessException {
  		String databaseProductName =
  				JdbcUtils.extractDatabaseMetaData(dataSource, "getDatabaseProductName").toString();
  		if ("DB2".equals(databaseProductName)) {
  			String databaseProductVersion =
  					JdbcUtils.extractDatabaseMetaData(dataSource, "getDatabaseProductVersion").toString();
  			if (!databaseProductVersion.startsWith("SQL")) {
  				databaseProductName = "DB2ZOS";
 			}
 			else {
 				databaseProductName = JdbcUtils.commonDatabaseName(databaseProductName);
 			}
 		}
 		else {
 			databaseProductName = JdbcUtils.commonDatabaseName(databaseProductName);
 		}
 		return fromProductName(databaseProductName);
 	}
 }