#########################################################################
##
##  myClient.pl by Jake Roberts.
##
##  A newbies attempt at TCP socket networking and Perl
##
##  This client plays ping pong with the server.  Its rather simple.
##
##  It does demonstrate the importance of defining a protocol for speaking
##  to the server.  The client must wait his turn to print to the $socket or
##  you can get locked up.
##
##  That idea was a real trip up for me as a newbie.
##
##  Most of the network/socket stuff was taken from examples from
##  www.perlmonks.org an excellent web site
##
##
#########################################################################

#!/perl/bin/perl -w

	use strict;
	use warnings;

	use IO::Socket::INET;


## Open a connection to the server
	my $socket = IO::Socket::INET->new(
							PeerAddr => 'localhost',
	      				  	PeerPort => '1776',
	      					Proto    => "tcp",
	      					Type     => SOCK_STREAM)
						or die "Socket::INET->new: $!\n\n";


## Modes
# 1 = Waiting for server connection
# 2 = Wait for Pong then Send Ping


## Play Ping ping with the server
	my $mode = 1;

	while (1) {
		my $response = <$socket>;   ## Read data from Server  ## It will wait here until it recieves a \n from the server
                                    ## Reading data from the server this way kind of sucks because you don't have any type of timeout


		if ($response) {  ## Important to check because if the connection is closed then $response will be undef
            chomp $response;  ## Remove the \n


			############
            ##  This is my ping Protocal.
            ##  The client and server MUST take turns talking or they will get stuck
            ##  So...first the client waits for a Connection Established signal....
            ##  then the client sends a ping to the server and waits his turn and listens
            ##  for a pong.  When a pong is recieved a ping is sent again...and so on.
            ##  They must play like good children and take turns talking and listening
            ############

            ## Mode 1 -- Waiting for connection signal
			if ($mode == 1) {
                if ($response eq "Connection Established") {
                    print $response,"\n";
					print $socket "ping\n";  ## The server send a Connect so now its our turn to say ping
					print "ping...";
                    $mode = 2;
				}
            } elsif ($mode == 2) {   ## We sent a ping and now we must wait for a pong before talking again.
                if ($response eq "pong") { ## We recieved a pong
                    print "pong\n";
		            sleep(3);    ## Wait just so things to fly by too fast
					print $socket "ping\n";  ## Now its our turn to talk...say ping
                	print "ping...";
                    $mode = 2;  ## Now that we said ping wait for a pong
				}
			} else {  ## Just in case some wierd thing happens
                close($socket);
                die "Entered invalid mode";
            }

		} else {  ## We got an undef and therefore?? the connection was closed.
            print "Lost connection\n";
            last;
        }
	}


	close($socket);

exit 0;