package Class::MOP::Method::Wrapped;

use strict;
use warnings;

use Carp         'confess';
use Scalar::Util 'reftype', 'blessed';
use Sub::Name    'subname';

our $VERSION   = '0.02';
our $AUTHORITY = 'cpan:STEVAN';

use base 'Class::MOP::Method';

# NOTE:
# this ugly beast is the result of trying
# to micro optimize this as much as possible
# while not completely loosing maintainability.
# At this point it's "fast enough", after all
# you can't get something for nothing :)
my $_build_wrapped_method = sub {
    my $modifier_table = shift;
    my ($before, $after, $around) = (
        $modifier_table->{before},
        $modifier_table->{after},
        $modifier_table->{around},
    );
    if (@$before && @$after) {
        $modifier_table->{cache} = sub {
            $_->(@_) for @{$before};
            my @rval;
            ((defined wantarray) ?
                ((wantarray) ?
                    (@rval = $around->{cache}->(@_))
                    :
                    ($rval[0] = $around->{cache}->(@_)))
                :
                $around->{cache}->(@_));
            $_->(@_) for @{$after};
            return unless defined wantarray;
            return wantarray ? @rval : $rval[0];
        }
    }
    elsif (@$before && !@$after) {
        $modifier_table->{cache} = sub {
            $_->(@_) for @{$before};
            return $around->{cache}->(@_);
        }
    }
    elsif (@$after && !@$before) {
        $modifier_table->{cache} = sub {
            my @rval;
            ((defined wantarray) ?
                ((wantarray) ?
                    (@rval = $around->{cache}->(@_))
                    :
                    ($rval[0] = $around->{cache}->(@_)))
                :
                $around->{cache}->(@_));
            $_->(@_) for @{$after};
            return unless defined wantarray;
            return wantarray ? @rval : $rval[0];
        }
    }
    else {
        $modifier_table->{cache} = $around->{cache};
    }
};

sub wrap {
    my $class = shift;
    my $code  = shift;
    (blessed($code) && $code->isa('Class::MOP::Method'))
        || confess "Can only wrap blessed CODE";
    my $modifier_table = {
        cache  => undef,
        orig   => $code,
        before => [],
        after  => [],
        around => {
            cache   => $code->body,
            methods => [],
        },
    };
    $_build_wrapped_method->($modifier_table);
    my $method = $class->SUPER::wrap(sub { $modifier_table->{cache}->(@_) });
    $method->{'%!modifier_table'} = $modifier_table;
    $method;
}

sub get_original_method {
    my $code = shift;
    $code->{'%!modifier_table'}->{orig};
}

sub add_before_modifier {
    my $code     = shift;
    my $modifier = shift;
    unshift @{$code->{'%!modifier_table'}->{before}} => $modifier;
    $_build_wrapped_method->($code->{'%!modifier_table'});
}

sub add_after_modifier {
    my $code     = shift;
    my $modifier = shift;
    push @{$code->{'%!modifier_table'}->{after}} => $modifier;
    $_build_wrapped_method->($code->{'%!modifier_table'});
}

{
    # NOTE:
    # this is another possible candidate for
    # optimization as well. There is an overhead
    # associated with the currying that, if
    # eliminated might make around modifiers
    # more manageable.
    my $compile_around_method = sub {{
        my $f1 = pop;
        return $f1 unless @_;
        my $f2 = pop;
        push @_, sub { $f2->( $f1, @_ ) };
        redo;
    }};

    sub add_around_modifier {
        my $code     = shift;
        my $modifier = shift;
        unshift @{$code->{'%!modifier_table'}->{around}->{methods}} => $modifier;
        $code->{'%!modifier_table'}->{around}->{cache} = $compile_around_method->(
            @{$code->{'%!modifier_table'}->{around}->{methods}},
            $code->{'%!modifier_table'}->{orig}->body
        );
        $_build_wrapped_method->($code->{'%!modifier_table'});
    }
}

1;

__END__

=pod

=head1 NAME

Class::MOP::Method::Wrapped - Method Meta Object to handle before/around/after modifiers

=head1 DESCRIPTION

This is a L<Class::MOP::Method> subclass which provides the funtionality 
to wrap a given CODE reference with before, after and around method modifiers.

=head1 METHODS

=head2 Construction

=over 4

=item B<wrap ($code)>

This is the constructor, it will return a B<Class::MOP::Method::Wrapped>
instance that can be used to add before, after and around modifiers to.

=item B<get_original_method>

This returns the original CODE reference that was provided to the 
constructor.

=back

=head2 Modifiers

These three methods will add the method modifiers to the wrapped 
CODE reference. For more information on how method modifiers work, 
see the section in L<Class::MOP::Class>.

=over 4

=item B<add_before_modifier ($code)>

=item B<add_after_modifier ($code)>

=item B<add_around_modifier ($code)>

=back

=head1 AUTHORS

Stevan Little E<lt>stevan@iinteractive.comE<gt>

=head1 COPYRIGHT AND LICENSE

Copyright 2006-2008 by Infinity Interactive, Inc.

L<http://www.iinteractive.com>

This library is free software; you can redistribute it and/or modify
it under the same terms as Perl itself.

=cut