/*
    * #%L
    * Bitrepository Common
    * %%
    * Copyright (C) 2010 - 2012 The State and University Library, The Royal Library and The State Archives, Denmark
    * %%
    * This program is free software: you can redistribute it and/or modify
    * it under the terms of the GNU Lesser General Public License as 
    * published by the Free Software Foundation, either version 2.1 of the 
   * License, or (at your option) any later version.
   * 
   * This program is distributed in the hope that it will be useful,
   * but WITHOUT ANY WARRANTY; without even the implied warranty of
   * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
   * GNU General Lesser Public License for more details.
   * 
   * You should have received a copy of the GNU General Lesser Public 
   * License along with this program.  If not, see
   * <http://www.gnu.org/licenses/lgpl-2.1.html>.
   * #L%
   */
  package org.bitrepository.service.database;
  
  import com.mchange.v2.c3p0.ComboPooledDataSource;
  import com.mchange.v2.c3p0.DataSources;
  import java.sql.Connection;
  import java.sql.SQLException;
  import java.util.Properties;
  import org.bitrepository.common.ArgumentValidator;
  import org.bitrepository.settings.referencesettings.DatabaseSpecifics;
  import org.slf4j.Logger;
  import org.slf4j.LoggerFactory;
  
  /**
   * The connector to a database.
   */
  public class DBConnector {
      /** The log.*/
      private Logger log = LoggerFactory.getLogger(getClass());
      /** The specifications for connection to the database.*/
      private final DatabaseSpecifics databaseSpecifics;
      /** The pool with data sources for the database connections.*/
      private ComboPooledDataSource connectionPool;
      
      /**
       * Constructor.
       * @param databaseSpecifics The specifics for the configuration of the database.
       */
      public DBConnector(DatabaseSpecifics databaseSpecifics) {
          ArgumentValidator.checkNotNull(databaseSpecifics, "DatabaseSpecifics specifics");
  
          silenceC3P0Logger();
          this.databaseSpecifics = databaseSpecifics;
          this.connectionPool = new ComboPooledDataSource();
          initialiseConnectionPool();
      }
      
      /**
       * @return The class for the driver for the database.
       */
      public String getDatabaseDriverClass() {
          return databaseSpecifics.getDriverClass();
      }
      
      /**
       * Initialises the ConnectionPool for the connections to the database.
       */
      private void initialiseConnectionPool() {
          try {
              log.info("Creating the connection to the database '" + databaseSpecifics + "'.");
              connectionPool.setDriverClass(databaseSpecifics.getDriverClass());
              connectionPool.setJdbcUrl(databaseSpecifics.getDatabaseURL());
              if(databaseSpecifics.isSetUsername()) {
                  connectionPool.setUser(databaseSpecifics.getUsername());
              }
              if(databaseSpecifics.isSetPassword()) {
                  connectionPool.setPassword(databaseSpecifics.getPassword());
              }
          } catch (Exception e) {
              throw new IllegalStateException("Could not connect to the database '" + databaseSpecifics + "'", e);
          }
      }
  
      /**
       * Hack to kill com.mchange.v2 log spamming.
       */
      private void silenceC3P0Logger() {
          Properties p = new Properties(System.getProperties());
          p.put("com.mchange.v2.log.MLog", "com.mchange.v2.log.FallbackMLog");
          p.put("com.mchange.v2.log.FallbackMLog.DEFAULT_CUTOFF_LEVEL", "OFF"); // or any other
          System.setProperties(p);
      }
      
      /**
       * Creates and connects to the database.
       * @return The connection to the database.
       */
      public Connection getConnection() {
          try {
             return connectionPool.getConnection();
         } catch (SQLException e) {
             throw new IllegalStateException("Could not establish connection to the database: '" + databaseSpecifics 
                     + "'", e);
         }
     }
     
     /**
      * Cleans up after use.
      */
     public void destroy() {
         try {
             DataSources.destroy(connectionPool);
         } catch (SQLException e) {
             log.error("Could not clean up the database '" + databaseSpecifics + "'.", e);
         }
     }
 }