package Foo::Inbox;

use strict;
use warnings;

our $VERSION = '0.003';

# $inbox = Foo::Inbox->new();

sub new {
    bless [ {}, [] ], shift;
}

# $scalar = $inbox->size( [ $key ] );
# %pairs  = $inbox->size();

sub size {
    my ( $self, $key ) = @_;

    if ( defined $key ) {
        exists $self->[0]{$key} ? scalar @{ $self->[0]{$key} } : 0;
    }
    elsif ( wantarray ) {
        local $_;
        map { $_ => scalar @{ $self->[0]{$_} } } keys %{ $self->[0] };
    }
    else {
        my $size = 0;
        foreach my $key ( keys %{ $self->[0] } ) {
            $size += scalar @{ $self->[0]{$key} };
        }
        $size;
    }
}

# $inbox->send( $from, $to, $arg1, ... );
# $inbox->send( $from, \@list, $arg1, ... );

sub send {
    my ( $self, $from, $to ) = ( shift, shift, shift );
    my $mesg = [ $from, [ @_ ] ];

    if ( ref $to eq 'ARRAY' ) {
        push @{ $self->[0]{$_ } }, $mesg for @{ $to };
    } else {
        push @{ $self->[0]{$to} }, $mesg;
    }

    return;
}

# $inbox->recv( $from );

sub recv {
    my ( $self, $from ) = @_;
    return @{ $self->[1] } unless exists $self->[0]{ $from };

    @{ shift @{ $self->[0]{ $from } } // $self->[1] };
}

# $inbox->end();

sub end {
    $_[0]->[1] = [ 'manager', [ 'END' ] ];

    return;
}

1;


##</code><code>##

use strict;
use warnings;

use Foo::Inbox;
use MCE::Hobo;
use MCE::Shared;

use List::Util 'shuffle';
use Time::HiRes 'sleep';

my $inbox = MCE::Shared->share( Foo::Inbox->new() );
my @names = shuffle qw/ Barny Betty Fred Wilma /;
my $index = 0;

$| = 1;

sub foo {
  my $name  = shift;
  my $count = 0;

  # remove my name from the list
  @names = grep { $_ ne $name } shuffle @names;

  # send greeting to names on the list
  $inbox->send($name, \@names, 'Hello');

  while ( 1 ) {
    if ( my ($from, $data) = $inbox->recv($name) ) {

      # so soon, alrighty then ;-)
      last if $data->[0] eq 'END';

      # display the message received
      printf "%-5s received %s from %s\n", $name, $data->[0], $from;

      # forward the message to another worker
      $inbox->send($name, $names[ ++$index % @names ], $data->[0])
        if ( $from eq 'manager' );

      next;
    }

    sleep 0.01;
  }
}

MCE::Hobo->create(\&foo, $_) for @names;

# Enter message or type quit to terminate the script.

while ( my $msg = <STDIN> ) {
  chomp $msg; next unless ( length $msg );
  $inbox->end(), last() if ( $msg eq 'quit' );
  $inbox->send('manager', $names[ ++$index % @names ], $msg);
}

MCE::Hobo->waitall;


##</code><code>##

Betty received Hello from Barny
Wilma received Hello from Barny
Fred  received Hello from Barny
Wilma received Hello from Betty
Barny received Hello from Betty
Betty received Hello from Wilma
Fred  received Hello from Betty
Betty received Hello from Fred
Fred  received Hello from Wilma
Wilma received Hello from Fred
Barny received Hello from Wilma
Barny received Hello from Fred
Hello, it's me
Betty received Hello, it's me from manager
Barny received Hello, it's me from Betty
Hello, can you hear me?
Wilma received Hello, can you hear me? from manager
Fred  received Hello, can you hear me? from Wilma
quit