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use strict;
use warnings;

=head1 NAME

Algorithm::Evolutionary::Op::Generation_Skeleton - Even more customizable single generation for an evolutionary algorithm.
                 
=head1 SYNOPSIS

    use Algorithm::Evolutionary qw( Individual::BitString 
				Op::Mutation Op::Crossover
				Op::RouletteWheel
				Fitness::ONEMAX Op::Generation_Skeleton
				Op::Replace_Worst);

    use Algorithm::Evolutionary::Utils qw(average);

    my $onemax = new Algorithm::Evolutionary::Fitness::ONEMAX;

    my @pop;
    my $number_of_bits = 20;
    my $population_size = 20;
    my $replacement_rate = 0.5;
    for ( 1..$population_size ) {
      my $indi = new Algorithm::Evolutionary::Individual::BitString $number_of_bits ; #Creates random individual
      $indi->evaluate( $onemax );
      push( @pop, $indi );
    }

    my $m =  new Algorithm::Evolutionary::Op::Mutation 0.5;
    my $c = new Algorithm::Evolutionary::Op::Crossover; #Classical 2-point crossover

    my $selector = new Algorithm::Evolutionary::Op::RouletteWheel $population_size; #One of the possible selectors

    my $generation = 
      new Algorithm::Evolutionary::Op::Generation_Skeleton( $onemax, $selector, [$m, $c], $replacement_rate );

    my @sortPop = sort { $b->Fitness() <=> $a->Fitness() } @pop;
    my $bestIndi = $sortPop[0];
    my $previous_average = average( \@sortPop );
    $generation->apply( \@sortPop );

=head1 Base Class

L<Algorithm::Evolutionary::Op::Base>

=head1 DESCRIPTION

Skeleton class for a general single-generation (or single step) in an
evolutionary algorithm; its instantiation requires a
L<fitness|Algorithm::Evolutionary::Fitness::Base> function, a
L<Selector|Algorithm::Evolutionary::Op::Selector>, a reference to an
array of operators and a replacement operator

=head1 METHODS

=cut

package Algorithm::Evolutionary::Op::Generation_Skeleton;

use lib qw(../../..);

our $VERSION = '3.3';

use Carp;

use base 'Algorithm::Evolutionary::Op::Base';

use Algorithm::Evolutionary qw(Wheel Op::Replace_Worst);
use Sort::Key qw( rnkeysort);

# Class-wide constants
our $APPLIESTO =  'ARRAY';
our $ARITY = 1;

=head2 new( $evaluation_function, $selector, $ref_to_operator_array, $replacement_operator )

Creates an algorithm, with no defaults except for the default
replacement operator (defaults to L<Algorithm::Evolutionary::Op::ReplaceWorst>)

=cut

sub new {
  my $class = shift;
  my $self = {};
  $self->{_eval} = shift || croak "No eval function found";
  $self->{_selector} = shift || croak "No selector found";
  $self->{_ops} = shift || croak "No operators found";
  $self->{_replacementRate} = shift || 1; #Default to all  replaced
  $self->{_replacement_op} = shift || new Algorithm::Evolutionary::Op::Replace_Worst;
  bless $self, $class;
  return $self;
}


=head2 set( $ref_to_params_hash, $ref_to_code_hash, $ref_to_operators_hash )

Sets the instance variables. Takes a ref-to-hash as
input. Not intended to be used from outside the class