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#pod items and no circular dependencies. BUT you can at least rely on
#pod this class to do the job properly regardless of the particulars of
#pod the situation, which is probably more important.
#pod
#pod =head2 METHODS
#pod
#pod =cut

use 5.005;
use strict;
use List::Util            ();
use Algorithm::Dependency ();
use Params::Util qw{_INSTANCE _STRING};

our $VERSION = '1.112';


#####################################################################
# Constructor and Accessors

#pod =pod
#pod
#pod =head2 new @params
#pod
#pod The C<new> constructor creates a new C<Algorithm::Dependency::Weight>
#pod object. It takes a number of key/value pairs as parameters (although
#pod at the present time only one).
#pod
#pod =over 4
#pod
#pod =item source => $Source
#pod
#pod The C<source> param is mostly the same as for L<Algorithm::Dependency>.
#pod The one addition is that as a source you can provide an
#pod L<Algorithm::Dependency> object, and the L<Algorithm::Dependency::Source>
#pod for that will be used.
#pod
#pod =back
#pod
#pod Returns a new C<Algorithm::Dependency::Weight> object, or C<undef> on error.
#pod
#pod =cut

sub new {
	my $class = shift;
	my %args  = @_;

	# Get the source object, or derive it from an existing alg-dep
	my $source = _INSTANCE($args{source}, 'Algorithm::Dependency')
		? $args{source}->source
		: _INSTANCE($args{source}, 'Algorithm::Dependency::Source')
		or return undef;

	# Build the alg-dep object we use
	my $algdep = Algorithm::Dependency->new(
		source         => $source,
		ignore_orphans => 1,
		) or return undef;

	# Create the basic object
	my $self = bless {
		source => $source,
		algdep => $algdep,
		weight => {},
		}, $class;

	$self;
}

#pod =pod
#pod
#pod =head2 source
#pod
#pod The C<source> accessor returns the source used for the weight calculations.
#pod
#pod This will be either the one passed to the constructor, or the source from
#pod inside the C<Algorithm::Dependency> object passed as the C<source> param
#pod (B<not> the object itself, B<its> source).
#pod
#pod =cut

sub source {
	$_[0]->{source}
}





#####################################################################
# Algorithm::Dependency::Weight Methods

#pod =pod
#pod
#pod =head2 weight $name
#pod
#pod The C<weight> method takes the name of a single item and calculates its
#pod weight based on the configuration of the C<Algorithm::Dependency::Weight>
#pod object.
#pod
#pod Returns the weight as a scalar (which in the naive case will be an
#pod integer, but in more complex uses may be any real number), or C<undef>
#pod on error.
#pod
#pod =cut

sub weight {
	my $self = shift;
	my $id   = defined(_STRING($_[0])) ? shift : return undef;
	$self->{weight}->{$id} or
	$self->{weight}->{$id} = $self->_weight($id);
}

sub _weight {
	my $self  = shift;
	my $items = $self->{algdep}->schedule($_[0]) or return undef;
	scalar(@$items);
}

#pod =pod
#pod