#!/usr/bin/perl
use strict;
use warnings;

sub main {
    print "Simple OS Simulator\n";
    print "Type 'help' for available commands.\n";

    while (1) {
        print "> ";
        chomp(my $input = <STDIN>);
        
        if ($input eq 'exit') {
            last;
        } elsif ($input eq 'help') {
            print "Available commands:\n";
            print "  help - show this help message\n";
            print "  date - show the current date and time\n";
           print "  echo <message> - print the given message\n";
            print "  exit - exit the simulator\n";
        } elsif ($input =~ /^echo (.*)$/) {
            print "$1\n";
        } elsif ($input eq 'date') {
            my ($sec, $min, $hour, $mday, $mon, $year, $wday, $yday, $isdst) = localtime();
            $year += 1900; $mon += 1;
            print "$mon/$mday/$year $hour:$min:$sec\n";
        } else {
            print "Unknown command. Type 'help' for available commands.\n";
        }
    }
}

main();