//ATM.java
//represents an ATM

public class ATM
{
    private boolean userAuthenticated;
    private int currentAccountNumber;
    private Screen screen;
    private Keypad keypad;
    private CashDispenser cashDispenser;
    private DepositSlot depositSlot;
    private BankDatabase bankDatabase;

    //constant coresponding to main menu options
    private static final int BALANCE_INQUIRY=1;
    private static final int WITHDRAWAL=2;
    private static final int DEPOSIT=3;
    private static final int EXIT=4;

    //no argument ATM constructor intitializes instancevariables
    public ATM()
    {
        userAuthenticated = false;
        currentAccountNumber = 0;
        screen = new Screen();
        keypad = new Keypad();
        cashDispenser = new CashDispenser();
        depositSlot = new DepositSlot();
        bankDatabase = new BankDatabase();
    }// end of no argument construct

    //start ATM
    public void run()
    {
        // welcome authenticated user
        while(true)
        {
            //loop while user is not yet authenthicated
            while(!userAuthenticated)
            {
                screen.displayMessageLine("\nwelcome!!");
                authenticateUser();
            }//end while

            performTransactions();
            userAuthenticated = false;
            currentAccountNumber = 0;
            screen.displayMessageLine("\nThank you Goodbye!");
        }//endwhile
    }//endmethodrun

    //attemp to authentiate against database
    private void authenticateUser()
    {
        screen.displayMessage("\n please enter your account number: ");
        int accountNumber = keypad.getInput();
        screen.displayMessage( "\nEnter your PIN: " );
        int pin = keypad.getInput();

        // set userAuthenticated to boolean value returned by database
        userAuthenticated =
            bankDatabase.authenticateUser(accountNumber,pin);

        // check wether authentication succeeded
        if( userAuthenticated )
        {
            currentAccountNumber = accountNumber;
        }//end if
        else
            screen.displayMessageLine(
            "Invalid account number, or PIN,Please try again");
    }

    //display Main menu and perform transaction;
    private void performTransactions()
    {
        //local variable to store transaction;
        Transaction currentTransaction = null;

        boolean userExited = false;

        //loop wile user still not exit
        while(!userExited)
        {
            //show main menu anfd get user selection
            int mainMenuSelection = displayMainMenu();

            //decidevhow to proceed based on user selection
            switch ( mainMenuSelection )
            {
                //user choose one transaction type
                case BALANCE_INQUIRY:
                case WITHDRAWAL:
                case DEPOSIT:

                //initialize as new object of chosen type;
                currentTransaction =
                    createTransaction( mainMenuSelection );

                    currentTransaction.execute(); //execute transaction
                    break;
                    case EXIT:// user choose exit
                    screen.displayMessageLine("\nExiting the system....");
                    userExited = true;
                    break;
                    default: // user input integer other than 1-4
                    screen.displayMessageLine(
                        "\nYou did not enter a valid selection, try again");
                    break;
            }//end switch
        }//end while
    }//end method performTransaction

    //dislay main menu and return input selection
    private int displayMainMenu()
    {
        screen.displayMessageLine( "\nMain menu:" );
        screen.displayMessageLine( "1 - View my balance" );
        screen.displayMessageLine( "2 - Withdraw cash" );
        screen.displayMessageLine( "3 - Deposit funds" );
        screen.displayMessageLine( "4 - Exit\n" );
        screen.displayMessage( "Enter a choice: " );
        return keypad.getInput(); // return user's selection
    }//end method displayMainMenu

    //return object  of specified transaction subcalss
    private Transaction createTransaction( int type )
    {
        Transaction temp = null;

        //determine wich type to create
        switch ( type )
        {
            case BALANCE_INQUIRY:
                temp = new BalanceInquiry(
                    currentAccountNumber, screen, bankDatabase);
                break;
            case WITHDRAWAL: // create new Withdrawal transaction
                temp = new Withdrawal( currentAccountNumber, screen,
                    bankDatabase, keypad, cashDispenser );
                break;
            case DEPOSIT: // create new Deposit transaction
                temp = new Deposit( currentAccountNumber, screen,
                    bankDatabase, keypad, depositSlot );
                break;
        } // end switch

        return temp;// return newly created object
    }//end method createTransaction
}//end ATM