ProhibitConditionComplexity.pm

package Perl::Critic::Policy::Mardem::ProhibitConditionComplexity;

use utf8;

use 5.010;

use strict;
use warnings;

our $VERSION = '0.06';

use Readonly;

use Perl::Critic::Utils         qw{ :severities :data_conversion :classification };
use Perl::Critic::Utils::McCabe qw{ calculate_mccabe_of_main };

use Perl::Critic::Mardem::Util qw( search_for_block_keyword);

use base 'Perl::Critic::Policy';

Readonly::Scalar my $EXPL => q{Consider refactoring};

# see lib\PPI\Lexer.pm
Readonly::Array my @BLOCK_SEARCH_KEYWORD => qw(
    IF ELSIF UNLESS
    WHILE UNTIL
    FOR FOREACH );

sub default_severity
{
    return $SEVERITY_MEDIUM;
}

sub default_themes
{
    return qw(complexity maintenance);
}

sub applies_to
{
    return ( 'PPI::Structure::Condition', 'PPI::Structure::For' );
}

sub supported_parameters
{
    return (
        {   'name'            => 'max_mccabe',
            'description'     => 'The maximum complexity score allowed.',
            'default_string'  => '2',
            'behavior'        => 'integer',
            'integer_minimum' => 1,
        },
    );
}

sub violates
{
    my ( $self, $elem, undef ) = @_;

    my $score = calculate_mccabe_of_main( $elem );
    if ( $score <= $self->{ '_max_mccabe' } ) {
        return;
    }

    my $block_keyword = search_for_block_keyword( $elem );
    if ( !$block_keyword ) {
        $block_keyword = 'no-keyword-found';
    }
    else {
        my @found = grep { $block_keyword eq $_ } @BLOCK_SEARCH_KEYWORD;
        if ( !@found ) {
            return;    # if a keyword is found, but not for an conditional block - than ignore
        }
    }

    my $desc = qq<"${block_keyword}" condition has a high complexity score ($score)>;
    return $self->violation( $desc, $EXPL, $elem );
}

1;

__END__

#-----------------------------------------------------------------------------

=pod

=encoding utf8

=head1 NAME

Perl::Critic::Policy::Mardem::ProhibitConditionComplexity - condition complexity "if/while/for/... (...){}"

=head1 DESCRIPTION

This Policy approximates the McCabe score within a coditional block "eg if(...)".

See L<http://en.wikipedia.org/wiki/Cyclomatic_complexity>

It should help to find complex conditions, which should be extracted
into subs, to be more testable.

eg. from

  if( $a && $b || $c > 20 ) { ... }

to

  if( _some_test ($a, $b, $c) ) { .. }

  sub _some_test {
    my ($a, $b, $c ) = @_;

    return  $a && $b || $c > 20;
  }

=head1 CONFIGURATION

The maximum acceptable McCabe can be set with the C<max_mccabe>
configuration item. Any block with a McCabe score higher than
this number will generate a policy violation. The default is 2.

An example section for a F<.perlcriticrc>:

  [Mardem::ProhibitConditionComplexity]
  max_mccabe = 1

=head1 AFFILIATION

This policy is part of L<Perl::Critic::Mardem>.

=head1 AUTHOR

Markus Demml, mardem@cpan.com

=head1 LICENSE AND COPYRIGHT

Copyright (c) 2024, Markus Demml

This library is free software; you can redistribute it and/or modify it
under the same terms as the Perl 5 programming language system itself.
The full text of this license can be found in the LICENSE file included
with this module.

=cut