package NeuralNet;

use Strict;
use Carp;

require "Neuron.pm";

#######################################################################
#
#   Class; Neural Net
#
#   Representation of a neural network.  This class directly
#   manages layers (LAYERS) of nodes (i.e. Neurons).
#
#######################################################################

   # constructor
   
   sub new 
   {
      my $proto = shift;
      my $class = ref( $proto ) || $proto;
      my $self  = {};
      
      $self->{LAYERS}  = [];
      
      #
      #  Allow methods to be called on this object.
      #
      bless( $self, $class );
      return $self;
   }

   #
   #   layers: read-only method that returns a list of all layers.
   #
   sub layers
   {
      my $self = shift;
      return $self->{LAYERS};
   }
   
   #
   #   numLayers: read-only method that returns the number of layers.
   #
   sub numLayers
   {
      my $self = shift;
      return scalar @{$self->{LAYERS}};
   }
   
   #
   #   layer: returns the n-th layer requested.
   #
   sub layer
   {
      my $self   = shift;
      my $num    = shift;
      my @layers = $self->layers;
      
      return @{$layers[$num]};
   }
   
   #
   #   lastLayer: returns the output layer.
   #
   sub lastLayer
   {
      my $self   = shift;
      my @layers = $self->layers;

      return @{$layers[$#layers]};
   }
   
   #
   #   addLayer: Adds a reference to a layer of nodes.
   #
   #   addLayer( number of nodes in layer )
   #
   sub addLayer
   {
      my $self      = shift;
      my $nodeCount = shift;
      my @lastlayer = $self->lastLayer;
      my @newlayer  = ( 0..$nodeCount );
      
      #
      #  create children
      #
      foreach (@newlayer)
      {
         $_ = Neuron->new();
      }
      
      #
      #  hook them up with the previous layer
      #  (if there is one)
      #
      foreach $parent (@lastlayer)
      {
         foreach $child (@newlayer)
         {
            $parent->addChild( $child );
         }
      }
      
      #
      #  add them to the network
      #
      push( @{$self->{LAYERS}}, \@newlayer );
   }
   
1;