Withdrawal.java

// Withdrawal.java
// Represents a withdrawal ATM transaction

public class Withdrawal extends Transaction {
    private int amount; // amount to withdraw
    private Keypad keypad; // reference to keypad
    private CashDispenser cashDispenser; // reference to cash dispenser

    // constant corresponding to menu option to cancel
    private final static int CANCELED = 6;

    // Withdrawal constructor
    public Withdrawal(int userAccountNumber, Screen atmScreen, 
                      BankDatabase atmBankDatabase, Keypad atmKeypad, 
                      CashDispenser atmCashDispenser) {
        // initialize superclass variables
        super(userAccountNumber, atmScreen, atmBankDatabase);
        
        // initialize references to keypad and cash dispenser
        keypad = atmKeypad;
        cashDispenser = atmCashDispenser;
    } // end Withdrawal constructor

    // Execute withdrawal for GUI
    public boolean executeGUI(int selectedAmount) {
        BankDatabase bankDatabase = getBankDatabase();
        Screen screen = getScreen();
    
        // Check if the selected amount is valid
        if (selectedAmount != CANCELED) {
            double availableBalance = bankDatabase.getAvailableBalance(getAccountNumber());
    
            if (selectedAmount <= availableBalance) {   
                if (cashDispenser.isSufficientCashAvailable(selectedAmount)) {
                    bankDatabase.debit(getAccountNumber(), selectedAmount);
                    cashDispenser.dispenseCash(selectedAmount);
    
                    screen.displayMessageLine("\nPlease take your cash now.");
                    return true; // Withdrawal successful
                } else {
                    screen.displayMessageLine("\nInsufficient cash available in the ATM.");
                    return false; // Insufficient cash in ATM
                }
            } else {
                screen.displayMessageLine("\nInsufficient funds in your account.");
                return false; // Insufficient funds in account
            }
        } else {
            screen.displayMessageLine("\nTransaction canceled.");
            return false; // Transaction canceled
        }
    }
    // perform transaction
    public void execute() {
        boolean cashDispensed = false; // cash was not dispensed yet
        double availableBalance; // amount available for withdrawal

        // get references to bank database and screen
        BankDatabase bankDatabase = getBankDatabase(); 
        Screen screen = getScreen();

        // loop until cash is dispensed or the user cancels
        do {
            // obtain a chosen withdrawal amount from the user 
            amount = displayMenuOfAmounts();
            
            // check whether user chose a withdrawal amount or canceled
            if (amount != CANCELED) {
                // get available balance of account involved
                availableBalance = bankDatabase.getAvailableBalance(getAccountNumber());
        
                // check whether the user has enough money in the account 
                if (amount <= availableBalance) {   
                    // check whether the cash dispenser has enough money
                    if (cashDispenser.isSufficientCashAvailable(amount)) {
                        // update the account involved to reflect withdrawal
                        bankDatabase.debit(getAccountNumber(), amount);
                        
                        cashDispenser.dispenseCash(amount); // dispense cash
                        cashDispensed = true; // cash was dispensed

                        // instruct user to take cash
                        screen.displayMessageLine("\nPlease take your cash now.");
                    } // end if
                    else // cash dispenser does not have enough cash
                        screen.displayMessageLine("\nInsufficient cash available in the ATM." +
                                                   "\n\nPlease choose a smaller amount.");
                } // end if
                else // not enough money available in user's account
                {
                    screen.displayMessageLine("\nInsufficient funds in your account." +
                                               "\n\nPlease choose a smaller amount.");
                } // end else
            } // end if
            else // user chose cancel menu option 
            {
                screen.displayMessageLine("\nCanceling transaction...");
                return; // return to main menu because user canceled
            } // end else
        } while (!cashDispensed);

    } // end method execute

    // display a menu of withdrawal amounts and the option to cancel;
    // return the chosen amount or CANCELED if the user chooses to cancel
    private int displayMenuOfAmounts() {
        int userChoice = 0; // local variable to store return value

        Screen screen = getScreen(); // get screen reference
        
        // array of amounts to correspond to menu numbers
        int amounts[] = { 0, 100, 500, 1000 };

        // loop while no valid choice has been made
        while (userChoice == 0) {
            // display the menu
            screen.displayMessageLine("\nWithdrawal Menu:");
            screen.displayMessageLine("1 - HK$ 100");
            screen.displayMessageLine("2 - HK$ 500");
            screen.displayMessageLine("3 - HK$ 1000");
            screen.displayMessageLine("4 - Enter your amount");
            screen.displayMessageLine("5 - Cancel transaction");
            screen.displayMessage("\nChoose a withdrawal amount: ");

            int input = keypad.getInput(); // get user input through keypad

            // determine how to proceed based on the input value
            switch (input) {
                case 1: // if the user chose a withdrawal amount 
                case 2: // (i.e., chose option 1, 2, or 3), return the
                case 3: // corresponding amount from amounts array 
                    userChoice = amounts[input]; // save user's choice
                    break;       
                case 4: // Allow user to enter a custom amount
                screen.displayMessage("\nEnter your amount (must be a multiple of HK$100 or HK$1000): ");
                int customAmount = keypad.getInput(); // get custom amount from keypad
                if (customAmount >= 100 && (customAmount % 100 == 0 || customAmount % 1000 == 0)) {
                    userChoice = customAmount; // save custom amount
                } else {
                    screen.displayMessageLine("\nInvalid amount. Please enter a valid amount.");
                }
                break;
            case 5:      
                userChoice = CANCELED; // save user's choice to cancel
                break;
            default: // the user did not enter a valid value
                screen.displayMessageLine("\nInvalid selection. Try again.");
        } // end switch
    } // end while

        return userChoice; // return withdrawal amount or CANCELED
    } // end method displayMenuOfAmounts
} // end class Withdrawal