package examples.jms.messageformat;

import javax.ejb.CreateException;
import javax.ejb.SessionBean;
import javax.ejb.SessionContext;
import javax.naming.Context;
import javax.naming.InitialContext;
import javax.naming.NamingException;
import weblogic.ejbgen.*;
import weblogic.ejb.GenericSessionBean;

/**
 * TraderBean is a stateful SessionBean. This EJBean illustrates:
 * <ul>
 * <li> Automatic persistence of state between calls to the SessionBean
 * <li> The ability to look up values from the beans environment
 * <li> The use of Application-defined exceptions
 * </ul>
 *
 * @author Copyright (c) 1998-2005 by BEA Systems, Inc. All Rights Reserved.
 */
@EnvEntries({
    @EnvEntry(name = "BEAS",
              type = "java.lang.Double",
              value = "100.0"),
    @EnvEntry(name = "MSFT",
              type = "java.lang.Double",
              value = "150.0")
})
@FileGeneration(remoteClass = Constants.Bool.TRUE,
                localHome = Constants.Bool.FALSE,
                remoteHome = Constants.Bool.TRUE,
                remoteClassName = "Trader",
                remoteHomeName = "TraderHome",
                localClass = Constants.Bool.FALSE)
@JarSettings(ejbClientJar = "jms_statefulSession_client.jar")
@JndiName(remote = "jms-statefulSession-TraderHome")
@Session(idleTimeoutSeconds = "600",
         maxBeansInCache = "1000",
         transTimeoutSeconds = "600",
         type = Session.SessionType.STATEFUL,
         defaultTransaction = Constants.TransactionAttribute.REQUIRED,
         ejbName = "jmsStatefulSession",
         enableCallByReference = Constants.Bool.TRUE,
         allowRemoveDuringTransaction = Constants.Bool.TRUE)
public class TraderBean extends GenericSessionBean {

  static final boolean VERBOSE = false;

  private Context environment;
  private double tradingBalance;

  /**
   * This method corresponds to the create method in the home interface
   * "TraderHome.java".
   * The parameter sets of the two methods are identical. When the client calls
   * <code>TraderHome.create()</code>, the container allocates an instance of 
   * the EJBean and calls <code>ejbCreate()</code>.
   *
   * @exception               javax.ejb.CreateException
   *                          if there is a problem creating the bean
   * @see                     examples.jms.messageformat.Trader
   */
  public void ejbCreate() throws CreateException {
    log("ejbCreate called");
    try {
      InitialContext ic = new InitialContext();
      environment = (Context) ic.lookup("java:comp/env");
    } catch (NamingException ne) {
      throw new CreateException("Could not look up context");
    }
    this.tradingBalance = 0.0;
  }

  /**
   * Buys shares of a stock for a named customer.
   *
   * @param customerName      String Customer name
   * @param stockSymbol       String Stock symbol
   * @param shares            int Number of shares to buy
   * @return                  TradeResult Trade Result
   * @exception               examples.jms.messageformat.ProcessingErrorException
   *                          if there is an error while buying the shares
   */
  @RemoteMethod()
  public TradeResult buy(String customerName, String stockSymbol, int shares)
    throws ProcessingErrorException
  {
    log("buy ("+customerName+", "+stockSymbol+", "+shares+")");

    double price = getStockPrice(stockSymbol);
    tradingBalance -= (shares * price); // subtract purchases from cash account

    return new TradeResult(shares, price, TradeResult.BUY);
  }

  /**
   * Sells shares of a stock for a named customer.
   *
   * @param customerName      String Customer name
   * @param stockSymbol       String Stock symbol
   * @param shares            int Number of shares to buy
   * @return                  TradeResult Trade Result
   * @exception               examples.jms.messageformat.ProcessingErrorException
   *                          if there is an error while selling the shares
   */
  @RemoteMethod()
  public TradeResult sell(String customerName, String stockSymbol, int shares)
    throws ProcessingErrorException
  {
    log("sell ("+customerName+", "+stockSymbol+", "+shares+")");

    double price = getStockPrice(stockSymbol);
    tradingBalance += (shares * price);

    return new TradeResult(shares, price, TradeResult.SELL);
  }

  /**
   * Returns the current balance of a trading session.
   *
   * @return                  double Balance
   */
  @RemoteMethod()
  public double getBalance() {
    return tradingBalance;
  }

  /**
   * Returns the stock price for a given stock.
   *
   * @param stockSymbol       String Stock symbol
   * @return                  double Stock price
   * @exception               examples.jms.messageformat.ProcessingErrorException
   *                          if there is an error while checking the price
   */
  public double getStockPrice(String stockSymbol) 
    throws ProcessingErrorException 
  {
    try {
      return ((Double) environment.lookup(stockSymbol)).doubleValue();
    } catch (NamingException ne) {
      throw new ProcessingErrorException ("Stock symbol "+stockSymbol+
                                          " does not exist");
    } catch (NumberFormatException nfe) {
      throw new ProcessingErrorException("Invalid price for stock "+stockSymbol);
    }
  }

  private void log(String s) {
    if(VERBOSE) {
      System.out.println(s);
    }
  }
}