import java.util.LinkedList;
import java.util.Queue;
/**
 * implements the running of the bank
 * The principle thing that happens in the bank
 * is in the run method 
 */
public class Bank implements BankInterface, Runnable {

    /** The queue of customers  */
    Queue<Customer> customerQueue;
    /** Allows stopping the separate running thread. */
    private volatile boolean exit = false;
    /** Just record when the bank opened so you can say 
     * how long it was open when it closed.
     */
    private long openingTime;

    /** A customer came in.  Add it to the queue */
    @Override
    public void enteringCustomer(Customer customer) {
        customerQueue.add(customer);
    }

    /** Initialize the bank */
    public Bank()
    {
        customerQueue = new LinkedList<Customer>();
    }

    /** Close the back.  That is stop accepting new customers */
    public void closeBank()
    {
        exit=true;
    }

    /** Open the doors. */
    public void openBank()
    {
        openingTime = System.nanoTime();
        (new Thread(this)).start();
    }

    /**
     * All that happens in the bank is that the "teller" checks the 
     * customer queue. If q not empty the teller deals with the 
     * customer.
     */
    @Override
    public void run()
    {
        while(true)
        {
            System.out.println(String.format("%.1f Teller tooking at queue of length %d", (System.nanoTime()-openingTime) / 1000000000.0, customerQueue.size()));
            if (customerQueue.isEmpty())
            {
                // if no customers wait before checking is there are customers
                try { Thread.sleep(100); } catch (Exception e) {}
                if (exit) break;
            }
            else
            {
                // have a customer so remover from customer q
                Customer customer = customerQueue.poll();
                // Work with the customer for some amount of time
                // sleep can throw an exception
                try { Thread.sleep(customer.transactionLength()*100); } catch (Exception e) {}
                // Now completed with the customer, so tell the customer that
                customer.completed();

                double tt = (System.nanoTime()-openingTime) / 1000000000.0;
                System.out.println(String.format("     %.1f Processed customer which took time 0.%d", tt, customer.transactionLength()));
            }
        }
    }
}