** Given the following definitions, your goal is to write an API program to
 *  buy the correct number of shares of IBM stock needed to bring the total
 *  position of IBM stock in your account up to 1000.
 *  - The order should be submitted at the current Ask price of IBM as per
 *    the available market data.
 *  - You can assume that there are currently less than 1000 shares of IBM
 *    in the account, therefore you will always submit a Buy order.
 *  - When the order is filled, print out the word "Success."
 *
 *  To accomplish this, do the following:
 *
 *  Review the IServer and ApiMessageHandler interfaces and ServerFactory class
 *  below. These interfaces and class should not be modified in any way.
 *
 *  Create a main() method in ApiTest as a starting point for your application.
 *
 *  Implement ApiMessageHandler to handle events from the server.
 *
 *  Instantiate an IServer object by calling ServerFactory.createServer().
 *
 *  Connect to the server and register your message handler. Connect to host
 *  "localhost" on port 4444.
 *
 *  Request market data for IBM.
 *
 *  Request the current account positions.
 *
 *  When you have received the current position of IBM and the current Ask price,
 *  calculate the number of shares needed and submit the order at the correct price.
 *
 *  Wait for the order status and print "Success" when the order is filled.
 *
 *  Guiding principle: write the minimum amount of code necessary to accomplish the goal.
 *
 */

class ConnectionException extends Exception {}

enum Side {
    Buy, Sell
};

enum OrderStatus {
    Open, Filled, Canceled
}

/** Calling these methods is how you send messages to the server. */
interface IServer {
    /** Connects you to the server and also registers your message handler
     *  with the server object. The message handler passed in here will receive all
     *  future events that are generated from request to server. */
    void connect( String host, int port, ApiMessageHandler handler) throws ConnectionException;

    /** Requests market data for the specified symbol and exchange.
     *  Valid values for exchange are NYSE and NASDAQ. After the request is made,
     *  market data for the specified contract will flow back into the application
     *  through the ApiMessageHandler.marketDataReceived() method. */
    void requestMarketData( String symbol, String exchange);

    /** Requests the current positions in the account. After this request
     *  is made, the position data flows back into the app through the
     *  ApiMessageHandler.positionReceived() method. */
    void requestPortfolio();

    /** Places an order. The orderId should be a unique number generated by the client. */
    void placeOrder( int orderId, Side side, int quantity, String symbol, String exchange, double price);
}

/** Implementing this interface is how you receive messages from the server. */
interface ApiMessageHandler {
    /** Receives market data for symbols requested via the IServer.requestMarketData method. */
    void marketDataReceived( String symbol, double bid, double ask, double last);

    /** Receives account positions in response to a request via the IServer.requestPortfolio() method. */
    void positionReceived( String symbol, int position);

    /** Receives the status of an order that was placed via the IServer.placeOrder() method. */
    void orderStatusReceived( int orderId, OrderStatus status);
}

/** This class allows you to instantiate an object that implements the IServer
 *  interface. The actual implementation of createServer() is hidden from view;
 *  you can assume that the method is actually there (you don't need to implement it. */
class ServerFactory {
    public static final ServerFactory INSTANCE = new ServerFactory();

    /** Private constructor to enforce singleton. */
    private ServerFactory() {
    }

    /** This method returns an object that implements the IServer interface. */
    public IServer createServer() { ... }
}

class ApiTest {
}