#!/usr/bin/perl
use utf8;
use strict;
use warnings;
use IO::Select;
use Data::Dumper;
use IO::Socket::INET; # Non-blocking I/O concept.
use constant TRUE      => scalar 1;
use constant ARGUMENTS => scalar 1;
use constant NICKNAME  => scalar 12;
use constant MAXBYTES  => scalar 15;

# flush memory after every initialization
$| = 1;

my $info = $ARGV[0]; # User message IP:PORT;
my $error = "ERROR";
my $newline = "\n";
my %hash = (); # global variable
my @clients = ();
my ( $client_data , $server_sock , $sock , $new_sock , $trans , $readable_handles , $port , $kidpid , $data , $msg , $string);

if (@ARGV > ARGUMENTS) {
    print "\nPlease no more than ".ARGUMENTS." argument input!\n";
    print "\nCorrect Syntax: perl $0 IP:PORT (e.g. 127.0.0.1:5000)\n";
    exit();
}
elsif (@ARGV < ARGUMENTS) {
    print "\nPlease no less than ".ARGUMENTS." argument input!\n";
    print "\nCorrect Syntax: perl $0 IP:PORT (e.g. 127.0.0.1:5000)\n";
    exit();
}
else {
    
    my $string = index($info, ':');

    if ($string == '-1') {
	die "Please include ':' in your input - ".$info."\n";
    }

    my @input = split( ':' , $info );

    $server_sock = new IO::Socket::INET( LocalAddr => $input[0],
					 LocalPort => $input[1],
					 Proto     => 'tcp',
					 Listen    => SOMAXCONN,
					 Reuse     => 1 ) or die "Could not connect: $!";

    print "\n[Server $0 accepting clients at PORT: ".$input[1]." and IP: ".$input[0]."]\n";

    $readable_handles = new IO::Select();
    $readable_handles->add($server_sock);

    while (TRUE) {

	(my $new_readable) = IO::Select->select($readable_handles, undef, undef, 0);
	# conver string to array @$new_readable
	foreach $sock (@$new_readable) {	    
	    # Check if sock is the same with server (e.g. 5000)
	    # if same (new client) accept client socket
	    # else read from socket input
	    if ($sock == $server_sock) {
		$new_sock = $sock->accept()
		    or die sprintf "ERROR (%d)(%s)(%d)(%s)", $!,$!,$^E,$^E;
		$readable_handles->add($new_sock);
		$trans = "Hello version";
		$client_data = &send($trans,$new_sock);
		print "First send: ".$client_data."\n";
	    }
	    else {
		$port = $sock->peerport();
		print "This is \$sock: ".$sock."\n";
		print "This is \$port: ".$port."\n";
		$msg = receive($sock);
		print "First receive: ".$msg."\n";
		my @text = split(/ / , $msg , 2); # LIMIT = 2 Only the first two gaps split
		print Dumper(\@text);
		if ($text[0] eq "NICK") {
		    if (length($text[1]) > NICKNAME) {
			$trans = "".$error." Please no more than ".NICKNAME." characters as nickname!";
			$client_data = &send($trans,$sock);
			$readable_handles->remove($sock);
			close($sock);		    
		    }
		    elsif ($text[1] =~ s/\W//g) {
			$trans = "".$error." Special characters detected in the nickname, please remove them!";
			$client_data = &send($trans,$sock);		    
			$readable_handles->remove($sock);
			close($sock);
		    }
		    else {
			$hash{$port}=$text[1];
			$trans = "OK";
			$client_data = &send($trans,$sock);
			print "Second send: ".$client_data."\n";
		    }
		} # End of if ($text[0] eq "NICK")
		elsif ($text[0] eq "MSG") {
		    if (length($text[1]) > MAXBYTES) {
			$trans = "".$error." Please remember that message limit is ".MAXBYTES." bytes, this is the rest of the segmented message: ".$text[1]."";
			$client_data = &send($trans,$sock);
			print "In case of message over ".MAXBYTES." send: ".$client_data."\n";
		    }
		    else {
			# Get all client(s) socket(s)
			my @sockets = $readable_handles->can_write();
			# Send the same message to client(s)
			print Dumper(\%hash);
			foreach my $sck (@sockets) {
                            my $final = "".$text[0]." ".$hash{$port}." '".$text[1]."'";
			    &send($final,$sck);
			    #print STDOUT "The following data send to Client(s): (\ ".$final." \)\n";
			} # End of foreach
		    }
		} # End of elsif ($text[0] eq "MSG")
		else {
		    print "Closing client '".$hash{$port}."'!\n";
		    # when the client disconnects
		    delete $hash{$port};
		    $readable_handles->remove($sock);
		    close($sock);
		} # End of else condition
	    } # End of else condition ($sock == $server_sock)
	} # End of foreach new sock
    } # End of While (1)

    print "Terminating Server\n";
    close $server_sock;
    getc();
} # End of else @ARGV

sub send {
    chomp($_[0]);
    $_[0] = "".$_[0]."".$newline."";
    utf8::encode($_[0]);
    $_[1]->send($_[0]);
    chomp ($_[0]);
    #print "The following data send to Cliets: (\ ".$_[0]." \)\n";
    return $_[0];
}

sub receive {
    my @array = ();
    $_[0]->recv($data , MAXBYTES);
    print "Length of received: ".length($data)."\n";
    utf8::decode($data);
    chomp ($data);
    # In case of terminating message Client will send Client request MSG (exit or quit) but we can use only the Client part
    if ($data !~ /^MSG|NICK|Client/i) {
	$data = "MSG " . "Segmended message: " . "".$data."";
    }
    if($data =~ /^$/) {
	print "Data packet received empty!\n";
	print "From host: ".$_[0]->peerhost()." and port: ".$_[0]->peerport()."\n";
	$data = "MSG Server received empty packet from ".$_[0]->peerhost."!";
	return $data;
    }
    elsif ($data !~ /^$/) {
	#print STDOUT "The following data received from Client: (\ ".$data." \)\n";
	#print "From host: ".$sock->peerhost()." and port: ".$sock->peerport()."\n";
	return $data;
    }
    else {
	$error = "".$error."".$newline."";
	utf8::encode ($error);
	$server_sock->send($error);
	print "Invalid client: ".$new_sock->peerhost()." terminating!\n";
	$readable_handles->remove($sock);
	close($sock);
    }
}

##</code><code>##

#!/usr/bin/perl
use utf8;
use strict;
use warnings;
use Data::Dumper;
use IO::Socket::INET;
use constant ARGUMENTS => scalar 2;
use constant NICKNAME  => scalar 12;
use constant MAXBYTES  => scalar 255;
use constant MAX_PORT  => scalar 65536;
use constant MIN_PORT  => scalar 1;

# flush memory after every initialization
$| = 1;

my $info = $ARGV[0]; # User message argv[0]
my $Nickname = $ARGV[1]; # User nickname argv[1]
my ( $kidpid, $line , $client_sock , $data , $send );
my $error = 'ERROR';
my $newline = "\n";

if (@ARGV > ARGUMENTS) {
    print "\nPlease no more than ".ARGUMENTS." arguments (ARGV[])!\n";
    print "\nCorrect Syntax: perl $0 'IP:PORT  NICKNAME' (e.g. 127.0.0.1:5000 Thanos)\n\n";
    exit();
}
elsif (@ARGV < ARGUMENTS) {
    print "\nPlease no less than ".ARGUMENTS." arguments (ARGV[])\n";
    print "\nCorrect Syntax: perl $0 'IP:PORT  NICKNAME' (e.g. 127.0.0.1:5000 Thanos)\n\n";
    exit();
}
else {
    
    my $string = index($info, ':');

    if ($string == '-1') {
	die "Please add ':' in your input - ".$info."\n";
    }

    my @input = split( ':' , $info );

    if ( ($input[1] > MAX_PORT) || ($input[1] < MIN_PORT) ) {
	print "\nPlease use port number between ".MIN_PORT." - ".MAX_PORT."\n\n";
	exit();
    }

    # create a tcp connection to the specified host and port 
    $client_sock = IO::Socket::INET->new( Proto    => "tcp",
					  PeerAddr => $input[0],
					  PeerPort => $input[1] 
	) or die "Can't connect to port ".$input[1]." at ".$input[0].": $!\n";

    $client_sock->autoflush(1);    # so output gets there right away 
    print STDERR "[Connected to ".$input[0].":".$input[1]."]\n";
    
    #$line = <$client_sock>;
    my $receive_msg = receive();
    if ($receive_msg eq "Hello version") {
	$Nickname = "NICK ".$Nickname."";
	$send = &send($Nickname);
	$receive_msg = receive();
	if ($receive_msg eq "OK") {
	    # split the program into two processes, identical twins
	    die "can't fork: $!" unless defined( $kidpid = fork() );
	    # the if{} block runs only in the parent process 
	    if ($kidpid) {
		# copy the socket to standard output 
		while ( defined( $receive_msg = receive() ) ) {
		    print "Third receive: ".$receive_msg."\n";
		    print "Client '".$ARGV[1]."' enter your text here:\n";
		} # End of While reading (parent)
	    } # End of if (parent)
	    # the else{} block runs only in the child process 
	    else {
		  print "Please note that maximum characters are ".MAXBYTES."\n";
		  print "Client '".$ARGV[1]."' enter your text here:\n";
		  # copy standard input to the socket 
		  while ( defined( chomp($line = <STDIN>) ) ) {
		      my $line = "MSG ".$line."";
		      if ($line =~ /quit|exit/i) {
			  $line = "Client request ".$line."";
			  print "".$line."\n";
			  my $send = &send($line);
			  kill( "TERM", $kidpid );    # send SIGTERM to child 
		      }
		      $send = &send($line);
		  } # End of read and send
	    } # End of else child
	} # End of if (OK)
	else {
	    print "Did not Receive OK!\n";
	    exit();
	}
    } # End of if (Hello version)
    else {
	print "Did not receive Hello version!\n";
	exit();
    }
} # End of else @ARGV

sub send {
    chomp($_[0]);
    $_[0] = "".$_[0]."".$newline."";
    utf8::encode($_[0]);
    $client_sock->send($_[0]);
    chomp($_[0]);
    #print "The following data send to Server: (\ ".$_[0]." \)\n";
    return $_[0];
}

sub receive {    
    # we can read from socket through recv()  in IO::Socket::INET
    $client_sock->recv($data , MAXBYTES);
    utf8::decode($data);
    chomp($data);
    #print STDOUT "The following data received form Server: (\ ".$_[0]." \)\n";
    return $data;
}