import java.io.DataInputStream;
import java.io.DataOutputStream;
import java.io.FileInputStream;
import java.io.FileOutputStream;
import java.io.IOException;
import java.util.ArrayList;
import java.util.Scanner;

public class MainClass {

private Scanner input = new Scanner(System.in);
private Customer currentCustomer = null;
private ArrayList<Product> allProducts = null;
private String filterType;

/**
* this is the main function
* @param args
*/
public static void main(String[] args) {
   // create object of MainClass class to call MainClass functions
   // and access MainClass data members
   MainClass mainClass = new MainClass();
   // call login function to check if current customer is valid or not
   mainClass.login();
   // if currentCustomer is null this means this is invalid customer
   // so exit the program
   if (mainClass.currentCustomer == null) {
         System.exit(1);
   }
   // empty current customer Shopping Cart at the beginning of the system
   mainClass.currentCustomer.clearShoppingCart();
   // read all avilable products from products.bin file
   mainClass.readProducts();
   // print to the output console all prevoius customer purchases
   mainClass.currentCustomer.printPreviousCustomerPurchases(mainClass.allProducts);
   System.out.println("");
   // initialize filterType to ""
   mainClass.filterType = "";
   // show main menu to user
   mainClass.showMenu();
   // save all avilable products after changes stockCount to prducts.bin
   mainClass.updateProducts();

}

/**
* this function check if the current customer if valid or not
* if not it offer 3 options
* 1- re- login again
* 2- signUp
* 3- Exit
* if user choice option 1 it allow user to re-enter it's login data again
* if user choice option 2 it allow user to register as anew customer to our system
* , save it's data to customer.txt file and allow it to login again
* if user choice option 3 the system Exit
*/
public void login() {
   boolean validUser = false;
   String name = "";
   String pass = "";
   while (!validUser) {
         System.out.println("\nLogin To Shopping Application System");
         System.out.println("Please enter your name");
         name = input.nextLine().trim();
         System.out.println("Please enter your Password");
         pass = input.nextLine().trim();
         currentCustomer = Customer.login(name, pass);
         if (currentCustomer == null) {
            System.out.println("your Login Data is Invalid");
            System.out.println("1- re enter Login Data");
            System.out.println("2- Sign up for a new Customer");
            System.out.println("3- Exit");
            int choice = input.nextInt();
            input.nextLine();
            if (choice == 1) {
               continue;
            } else if (choice == 2) {
               signUp();
            } else {
               System.out.println("Thank you for your time");
               System.exit(1);
            }
         } else {
            validUser = true;
         }
   }

   System.out.println("Successfully Login to Shopping Application System As " + currentCustomer.getName());

}

/**
* this function allow user to register as anew customer to our system
* , save it's data to customer.txt file
*/
public void signUp() {
   System.out.println("\nSign Up to Shopping Application System");
   System.out.println("Please enter your name");
   String name = input.nextLine().trim();
   System.out.println("Please enter your Password");
   String pass = input.nextLine().trim();
   Customer customer = new Customer(name, pass);
   customer.saveCustomerInformation();
}

/**
* this function display the main menu to user to interact with our system
*/
public void showMenu() {
   int choice;
   while (true) {
         displayProducts();
         System.out.println("1- display All Product");
         System.out.println("2- Srarch by tybe");
         System.out.println("3- Select Product");
         System.out.println("4- Delete Product From shopping cart");
         System.out.println("5- Empty shopping cart");
         System.out.println("6- Purchases products");
         System.out.println("7- Logout");
         choice = input.nextInt();
         input.nextLine();
         switch (choice) {
            case 1:
               filterType = "";
               break;
            case 2:
               System.out.print("Enter Product Type To search (TV / Phone/DrawingTablet) ");
               filterType = input.nextLine();
               if (!(filterType.equalsIgnoreCase("TV")
                        || filterType.equalsIgnoreCase("Phone")
                        || filterType.equalsIgnoreCase("DrawingTablet"))) {
                     filterType = "";
               }
               break;
            case 3:
               selectProduct();
               break;
            case 4:
               deleteProductFromShoppingCart();
               break;
            case 5:
               currentCustomer.clearShoppingCart();
               System.out.println("Chopping Cart has been emptied");
               break;
            case 6:
               purchase();
               break;
            case 7:
               System.out.println("Thank you for your Time");
               return;
         }
         System.out.println("");
   }

}

/**
* this function display products names according to filterType
* if filterType = "" it display all products
* if filterType = "phone" it display all Phones only
* if filterType = "TV" it display all TV only
* if filterType = "DrawingTablet" it display all DrawingTablet only
*/
public void displayProducts() {
   for (Product p : allProducts) {
         if (p.getType().equalsIgnoreCase(filterType)) {
            System.out.println(p.getName());
         } else if (filterType.equals("")) {
            System.out.println(p.getName());
         }
   }
}

/**
* this function reads all products data from products.bin file and store it
* in arraylist if the file not exist yet or can not open the file
* this function call saveProducts functions to save all products
* to products.bin file first and then re read it again
*/

Read each problem carefully. 1.&nbsp; &nbsp; How many millisec...

Read each problem carefully. 1. How many millisec...