package de.fhdw.wtf.persistence.facade;
   
   import java.io.IOException;
   import java.sql.Connection;
   import java.sql.DriverManager;
   import java.sql.SQLException;
   
   import de.fhdw.wtf.persistence.exception.ClassFacadeUninitializedException;
   import de.fhdw.wtf.persistence.exception.NotConnectableException;
  import de.fhdw.wtf.persistence.exception.NotConnectedException;
  import de.fhdw.wtf.persistence.exception.OracleJDBCDriverMissing;
  import de.fhdw.wtf.persistence.exception.OtherSQLException;
  import de.fhdw.wtf.persistence.exception.PersistenceException;
  import de.fhdw.wtf.persistence.utils.PropertiesReader;
  
  /**
   * A Class to access an oracle database with a JDBC Driver.
   * 
   */
  public final class OracleDatabaseManager extends DatabaseManager {
  	
  	private static final String JDBC_SEPERATOR = ":";
  	
  	private static final String CONNECTION_PREFIX_ORACLE = "jdbc:oracle:thin:@";
  	
  	private static final String JDBC_ORACLE_DRIVER_NAME = "oracle.jdbc.OracleDriver";
  	
  	private ClassFacade classFacade;
  	
  	/**
  	 * The Oracle Database Manager is a singleton, therefore one single instance is stored in this static field.
  	 */
  	private static OracleDatabaseManager instance;
  	
  	/**
  	 * A boolean flag indicating whether a connection to the database is established or not.
  	 */
  	private boolean isConnected;
  	
  	/**
  	 * The Name of the Oracle Schema, which the Manager will connect to. Usually its the same as the user name.
  	 */
  	private String schemaName;
  	
  	/**
  	 * The Username of an valid oracle user account, which has resource privilegies and has full access to packages in
  	 * the given Schema.
  	 */
  	private String userName;
  	
  	/**
  	 * The password of the given user. Password will be stored in plain text.
  	 */
  	private String userPassword;
  	
  	/**
  	 * The SID of the Oracle Database.
  	 */
  	private String oracleSID;
  	
  	/**
  	 * The name of the host where the oracle database is running.
  	 */
  	private String hostname;
  	
  	/**
  	 * The port on which the Oracle Net Listener listens.
  	 */
  	private String port;
  	
  	/**
  	 * The Oracle Database Manager will establish a single connection.
  	 */
  	private Connection defaultConnection;
  	
  	/**
  	 * Creates a new unconnected Database Manager.
  	 */
  	private OracleDatabaseManager() {
  		this.isConnected = false;
  	}
  	
  	@Override
  	public void setConnectionConstantsFromFile(final PropertiesReader reader) throws IOException {
  		this.schemaName = reader.getProperty("schema");
  		this.userName = reader.getProperty("username");
  		this.userPassword = reader.getProperty("password");
  		this.oracleSID = reader.getProperty("sid");
  		this.hostname = reader.getProperty("hostname");
  		this.port = reader.getProperty("port");
  	}
  	
  	/**
  	 * @see de.fhdw.wtf.persistence.facade.DatabaseManager#connect()
  	 * @throws OracleJDBCDriverMissing
  	 *             if JDBC driver is missing
  	 * @throws NotConnectableException
  	 *             if an SQL error occurs
  	 */
 	@Override
 	public void connect() throws PersistenceException {
 		try {
 			Class.forName(JDBC_ORACLE_DRIVER_NAME);
 			this.isConnected = true;
 			this.defaultConnection =
 					DriverManager.getConnection(
 							CONNECTION_PREFIX_ORACLE + this.getHostname() + JDBC_SEPERATOR + this.getPort()
 									+ JDBC_SEPERATOR + this.getOracleSID(),
 							this.getUserName(),
 							this.getUserPassword());
 		} catch (final ClassNotFoundException e) {
 			throw new OracleJDBCDriverMissing();
 		} catch (final SQLException e) {
 			throw new NotConnectableException(this, e);
 		}
 	}
 	
 	/**
 	 * This Method provides the default connection object to the Database. This Method will only works if connect has
 	 * been successfully executed before otherwise an exception will be thrown.
 	 * 
 	 * @return Provides the default database connection.
 	 * @throws PersistenceException
 	 *             This Exception will be thrown if the Manager has not been connected to Orcle before.
 	 */
 	public Connection getConnection() throws PersistenceException {
 		if (this.isConnected) {
 			return this.defaultConnection;
 		}
 		throw new NotConnectedException();
 	}
 	
 	@Override
 	public ClassFacade getClassFacade() {
 		if (this.classFacade == null) {
 			this.classFacade = new OracleClassFacadeImplementation(this);
 		}
 		return this.classFacade;
 	}
 	
 	@Override
 	public ObjectFacade getObjectFacade() throws ClassFacadeUninitializedException {
 		return new OracleObjectFacadeImplementation(this, this.getClassFacade().getTypeManager());
 	}
 	
 	@Override
 	public void resetDatabase() throws PersistenceException, IOException {
 		final OracleDataBasePreparator prep = new OracleDataBasePreparator();
 		final boolean tableStructureValid = prep.isTableStructureValid();
 		if (tableStructureValid) {
 			this.clearTables();
 		} else {
 			prep.dropWholeSchema();
 			prep.createWholeSchema();
 		}
 		final boolean areProceduresCreated = prep.areProceduresCreated();
 		if (!areProceduresCreated) {
 			prep.createProcedures();
 		}
 	}
 	
 	@Override
 	public void clearTables() throws PersistenceException {
 		new OracleObjectFacadeImplementation(this, null).clear();
 		this.getClassFacade().clear();
 	}
 	
 	/**
 	 * Provides the singleton instance of the Oracle Database Manager.
 	 * 
 	 * @return The Oracle Database manager.
 	 */
 	public static synchronized OracleDatabaseManager getInstance() {
 		if (instance == null) {
 			instance = new OracleDatabaseManager();
 		}
 		return instance;
 	}
 	
 	@Override
 	public void disconnect() throws PersistenceException {
 		try {
 			this.getConnection().close();
 		} catch (final SQLException e) {
 			throw new OtherSQLException(e);
 		}
 		this.isConnected = false;
 		
 	}
 	
 	@Override
 	public boolean isConnected() {
 		return this.isConnected;
 	}
 	
 	/**
 	 * 
 	 * @return Provides the set Schema Name.
 	 */
 	public String getSchemaName() {
 		return this.schemaName;
 	}
 	
 	/**
 	 * 
 	 * @return Provides the set Username.
 	 */
 	public String getUserName() {
 		return this.userName;
 	}
 	
 	/**
 	 * 
 	 * @return Provides the set Password.
 	 */
 	public String getUserPassword() {
 		return this.userPassword;
 	}
 	
 	/**
 	 * 
 	 * @return Provides the Set Oracle SID.
 	 */
 	public String getOracleSID() {
 		return this.oracleSID;
 	}
 	
 	/**
 	 * 
 	 * @return Provides the set Hostname.
 	 */
 	public String getHostname() {
 		return this.hostname;
 	}
 	
 	/**
 	 * 
 	 * @return Provides the set port.
 	 */
 	public String getPort() {
 		return this.port;
 	}
 	
 }