#! /usr/bin/perl -W
use strict;
use 5.010;
sub heading;
# A script that allows a user to perform system administration tasks 
# Programmer name:          Michael A. Gregor
# Course:                   COSC 146
# Lab#:                     7
# Due Date:                 3/10/16
# lab7.pl

my %accounts = (tom => "BigApple");
my %types = (tom => "admin");
my $choice;
my ($userID, $passwd, $type);
my @userID = $userID;

# call the function named 'heading' to display the output heading
heading;

my $menu = <<MENU;

         System Administration Tasks

1- Create a new account
2- Delete an account
3- Change an account password
4- List users in alphabetical order 
5- Exit the system

MENU

while (1) {
 # display the menu
  print $menu, "\n";

 # get the user choice and fullfil the request
  print "Make your choice: ";
  chomp($choice = <STDIN>);

  if ($choice == 1){
   #print "a\n";  # replace the print-statements with your own code !!!!!!!!!!!!!!!!!
    # get user id and password
    print "Enter your userID: ";
    chomp ($userID = <STDIN>);
    print "Enter your password: ";
    chomp ($passwd = <STDIN>);
      
    # is there an account by that name already? if so, display a message and then start the next loop iteration
    if (exists $accounts{$userID}) {
        print "Duplicate user id, try again later"
    }
      
    
    # no account by that name, ask the user for the account type
    else {
        print "Enter the account type, admin (or regular): ";
        chomp ($type = <STDIN>);
    
    # create the account and then print a message
       $accounts{$userID} = $passwd;
       $types{$userID} = $type;
       print "Account was successfully created \n";
    }
    } elsif ($choice == 2){
          
        # get user id and password
        print "Enter your userID: ";
        chomp ($userID = <STDIN>);
        print "Enter your password: ";
        chomp ($passwd = <STDIN>);
        
        
        
        # authenticate the user account. If it is a valid account with admin privileges, go ahead and delete the
        # account. If the account is invalid or has no admin privieges, display an appropriate message in each case
        if (authenticate($userID, $passwd, %accounts) == 1) {
            if ($type eq 'admin') {
                delete $accounts{$userID};
                print "Account was deleted successfully";
            } else {
                print "Can't delete, Contact the system administrator";
            }
        }
        
            
    } elsif ($choice == 3){
        
        
        # get user id and password
        print "Enter your userID: ";
        chomp ($userID = <STDIN>);
        print "Enter your password: ";
        chomp ($passwd = <STDIN>);
        
        # authenticate the user account. If it is a valid account, ask the user for the new password.
        # have the user re-enter the new password again and confirm that they are the same. If so, change
        # the password. In any case, print a appropriate message
        if (authenticate($userID, $passwd, %accounts) == 1) {
            print "Enter a new password: ";
            chomp (my $passwd = <STDIN>);
            print "re-enter the password again: ";
            chomp (my $npass1 = <STDIN>);
            if ($passwd eq $npass1) {
                $passwd = $npass1;          
                $accounts{$userID} = $passwd;
                print "password was changed successfully";
            } else {
                print "password was not changed!";
            }
        }
        
        
    } elsif ($choice == 4){
        
        # sort the users in descending order
        foreach $userID (reverse sort keys %accounts) {
            
        # print out login names 3 per line
            @keys = keys %accounts;
            for (my $counter = 1; $counter <= @keys; $counter++)
    {
        print "$userID\t";
        print "\n" if $counter % 3 == 0;
    }
    }
    } elsif ($choice == 5){
        
        # print a message and terminate the script
        print "Good bye! \n\n";
        exit;
    } else {
        print "Invalid choice, TRY AGAIN!\n";
    }
}


# write a function definition for the function named 'heading'. This function prints out the output heading

sub heading {
    print "\n";
    print "Programmer name:          Michael A. Gregor \n";
    print "Course:                   COSC 146 \n";
    print "Lab#:                     7 \n";
    print "Due Date:                 3/10/16 \n";
}
# authenticate a user. return 1 if the user id and password combination is good. Otherwise return 0;
sub authenticate {
   my $id = shift;
   my $passwd = shift;
   my %accounts = @_;
   if (exists $accounts{$id} && $accounts{$id} eq $passwd){
      return 1;
   } else {
      return 0;
   } 
}