/**
 * Represents a simple bank. This class illustrates one way in which
 * two classes can interact with one another:
 *  1. Methods can take objects as input arguments
 *  2. Methods can return objects as return values
 */
public class SimpleBank{

    // Instance variables
    private int numAccountsOpened;
    private int nextAccountNumber;  // A 9-digit number
    
    /**
     * Constructs a new Bank
     */
    public SimpleBank(){
        numAccountsOpened = 0;
        nextAccountNumber = 100000000;
    }

    /**
     * This method opens a new bank account with the given information
     * Notice that the return type of this method is SimpleBankAccount
     */
    public SimpleBankAccount openAccount(String theName, double theInitialBalance){
        
        // Create a new SimpleBankAccount
        SimpleBankAccount account = new SimpleBankAccount(theName, theInitialBalance, ""+nextAccountNumber);
                
        // Update the state of the Bank object
        nextAccountNumber++;
        numAccountsOpened++;        
        
        // Return newly opened account
        return account;                                                          
    }
    
    /**
     * Transfers the specified amount from one account to the other
     * Notice that this method takes objects of type SimpleBankAccount as input arguments
     */
    public void transfer(double amount, SimpleBankAccount from, SimpleBankAccount to){
        from.withdrawal(amount);
        to.deposit(amount);
    }
    
    /**
     * Returns the number of accounts the bank has opened
     */
    public int getNumAccountsOpen(){
        return numAccountsOpened;
    }
}