package Perl::Critic::Policy;

use 5.006001;
use strict;
use warnings;

use English qw< -no_match_vars >;
use Readonly;

use File::Spec ();
use ActiveState::Handy qw< stringf >;

use overload ( q<""> => 'to_string', cmp => '_compare' );

use Perl::Critic::Utils qw<
    :characters
    :booleans
    :severities
    :data_conversion
    interpolate
    is_integer
    policy_long_name
    policy_short_name
    severity_to_number
>;
use Perl::Critic::Utils::DataConversion qw< dor >;
use Perl::Critic::Utils::POD qw<
    get_module_abstract_for_module
    get_raw_module_abstract_for_module
>;
use Perl::Critic::Exception::AggregateConfiguration;
use Perl::Critic::Exception::Configuration;
use Perl::Critic::Exception::Configuration::Option::Policy::ExtraParameter;
use Perl::Critic::Exception::Configuration::Option::Policy::ParameterValue;
use Perl::Critic::Exception::Fatal::PolicyDefinition
    qw< throw_policy_definition >;
use Perl::Critic::PolicyConfig qw<>;
use Perl::Critic::PolicyParameter qw<>;
use Perl::Critic::Violation qw<>;

use Exception::Class;   # this must come after "use P::C::Exception::*"

our $VERSION = '1.125';

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

Readonly::Scalar my $NO_LIMIT => 'no_limit';

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

my $format = "%p\n"; #Default stringy format

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

sub new {
    my ($class, %config) = @_;

    my $self = bless {}, $class;

    my $config_object;
    if ($config{_config_object}) {
        $config_object = $config{_config_object};
    }
    else {
        $config_object =
            Perl::Critic::PolicyConfig->new(
                $self->get_short_name(),
                \%config,
            );
    }

    $self->__set_config( $config_object );

    my @parameters;
    my $parameter_metadata_available = 0;

    if ( $class->can('supported_parameters') ) {
        $parameter_metadata_available = 1;
        @parameters =
            map
                { Perl::Critic::PolicyParameter->new($_) }
                $class->supported_parameters();
    }
    $self->{_parameter_metadata_available} = $parameter_metadata_available;
    $self->{_parameters} = \@parameters;

    my $errors = Perl::Critic::Exception::AggregateConfiguration->new();
    foreach my $parameter ( @parameters ) {
        eval {
            $parameter->parse_and_validate_config_value( $self, $config_object );
        }
            or do {
                $errors->add_exception_or_rethrow($EVAL_ERROR);
            };

        $config_object->remove( $parameter->get_name() );
    }

    if ($parameter_metadata_available) {
        $config_object->handle_extra_parameters( $self, $errors );
    }

    if ( $errors->has_exceptions() ) {
        $errors->rethrow();
    }

    return $self;
}

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

sub is_safe {
    return $TRUE;
}

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

sub initialize_if_enabled {
    return $TRUE;
}

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

sub prepare_to_scan_document {
    return $TRUE;
}

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

sub __get_parameter_name {
    my ( $self, $parameter ) = @_;

    return '_' . $parameter->get_name();
}

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

sub __set_parameter_value {
    my ( $self, $parameter, $value ) = @_;

    $self->{ $self->__get_parameter_name($parameter) } = $value;

    return;
}

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

sub __set_base_parameters {
    my ($self) = @_;

    my $config = $self->__get_config();
    my $errors = Perl::Critic::Exception::AggregateConfiguration->new();

    $self->_set_maximum_violations_per_document($errors);

    my $user_severity = $config->get_severity();
    if ( defined $user_severity ) {
        my $normalized_severity = severity_to_number( $user_severity );
        $self->set_severity( $normalized_severity );
    }

    my $user_set_themes = $config->get_set_themes();
    if ( defined $user_set_themes ) {
        my @set_themes = words_from_string( $user_set_themes );
        $self->set_themes( @set_themes );
    }

    my $user_add_themes = $config->get_add_themes();
    if ( defined $user_add_themes ) {
        my @add_themes = words_from_string( $user_add_themes );
        $self->add_themes( @add_themes );
    }

    if ( $errors->has_exceptions() ) {
        $errors->rethrow();
    }

    return;
}

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

sub _set_maximum_violations_per_document {
    my ($self, $errors) = @_;

    my $config = $self->__get_config();

    if ( $config->is_maximum_violations_per_document_unlimited() ) {
        return;
    }

    my $user_maximum_violations =
        $config->get_maximum_violations_per_document();

    if ( not is_integer($user_maximum_violations) ) {
        $errors->add_exception(
            new_parameter_value_exception(
                'maximum_violations_per_document',
                $user_maximum_violations,
                undef,
                "does not look like an integer.\n"
            )
        );

        return;
    }
    elsif ( $user_maximum_violations < 0 ) {
        $errors->add_exception(
            new_parameter_value_exception(
                'maximum_violations_per_document',
                $user_maximum_violations,
                undef,
                "is not greater than or equal to zero.\n"
            )
        );

        return;
    }

    $self->set_maximum_violations_per_document(
        $user_maximum_violations
    );

    return;
}

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

# Unparsed configuration, P::C::PolicyConfig.  Compare with get_parameters().
sub __get_config {
    my ($self) = @_;

    return $self->{_config};
}

sub __set_config {
    my ($self, $config) = @_;

    $self->{_config} = $config;

    return;
}

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

sub get_long_name {
    my ($self) = @_;

    return policy_long_name(ref $self);
}

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

sub get_short_name {
    my ($self) = @_;

    return policy_short_name(ref $self);
}

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

sub is_enabled {
    my ($self) = @_;

    return $self->{_enabled};
}

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

sub __set_enabled {
    my ($self, $new_value) = @_;

    $self->{_enabled} = $new_value;

    return;
}

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

sub applies_to {
    return qw(PPI::Element);
}

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

sub set_maximum_violations_per_document {
    my ($self, $maximum_violations_per_document) = @_;

    $self->{_maximum_violations_per_document} =
        $maximum_violations_per_document;

    return $self;
}

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

sub get_maximum_violations_per_document {
    my ($self) = @_;

    return
        exists $self->{_maximum_violations_per_document}
            ? $self->{_maximum_violations_per_document}
            : $self->default_maximum_violations_per_document();
}

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

sub default_maximum_violations_per_document {
    return;
}

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

sub set_severity {
    my ($self, $severity) = @_;
    $self->{_severity} = $severity;
    return $self;
}

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

sub get_severity {
    my ($self) = @_;
    return $self->{_severity} || $self->default_severity();
}

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

sub default_severity {
    return $SEVERITY_LOWEST;
}

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

sub set_themes {
    my ($self, @themes) = @_;
    $self->{_themes} = [ sort @themes ];
    return $self;
}

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

sub get_themes {
    my ($self) = @_;
    my @themes = defined $self->{_themes} ? @{ $self->{_themes} } : $self->default_themes();
    my @sorted_themes = sort @themes;
    return @sorted_themes;
}

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

sub add_themes {
    my ($self, @additional_themes) = @_;
    #By hashifying the themes, we squish duplicates
    my %merged = hashify( $self->get_themes(), @additional_themes);
    $self->{_themes} = [ keys %merged];
    return $self;
}

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

sub default_themes {
    return ();
}

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

sub get_abstract {
    my ($self) = @_;

    return get_module_abstract_for_module( ref $self );
}

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

sub get_raw_abstract {
    my ($self) = @_;

    return get_raw_module_abstract_for_module( ref $self );
}

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

sub parameter_metadata_available {
    my ($self) = @_;

    return $self->{_parameter_metadata_available};
}

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

sub get_parameters {
    my ($self) = @_;

    return $self->{_parameters};
}

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

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

    return throw_policy_definition
        $self->get_short_name() . q/ does not implement violates()./;
}

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

sub violation {  ## no critic (ArgUnpacking)
    my ( $self, $desc, $expl, $elem ) = @_;
    # HACK!! Use goto instead of an explicit call because P::C::V::new() uses caller()
    my $sev = $self->get_severity();
    @_ = ('Perl::Critic::Violation', $desc, $expl, $elem, $sev );
    goto &Perl::Critic::Violation::new;
}

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

sub new_parameter_value_exception {
    my ( $self, $option_name, $option_value, $source, $message_suffix ) = @_;

    return Perl::Critic::Exception::Configuration::Option::Policy::ParameterValue->new(
        policy          => $self->get_short_name(),
        option_name     => $option_name,
        option_value    => $option_value,
        source          => $source,
        message_suffix  => $message_suffix
    );
}

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

## no critic (Subroutines::RequireFinalReturn)
sub throw_parameter_value_exception {
    my ( $self, $option_name, $option_value, $source, $message_suffix ) = @_;

    $self->new_parameter_value_exception(
        $option_name, $option_value, $source, $message_suffix
    )
        ->throw();
}
## use critic


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

# Static methods.

sub set_format { return $format = $_[0] }  ## no critic(ArgUnpacking)
sub get_format { return $format         }

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

sub to_string {
    my ($self, @args) = @_;

    # Wrap the more expensive ones in sub{} to postpone evaluation
    my %fspec = (
         'P' => sub { $self->get_long_name() },
         'p' => sub { $self->get_short_name() },
         'a' => sub { dor($self->get_abstract(), $EMPTY) },
         'O' => sub { $self->_format_parameters(@_) },
         'U' => sub { $self->_format_lack_of_parameter_metadata(@_) },
         'S' => sub { $self->default_severity() },
         's' => sub { $self->get_severity() },
         'T' => sub { join $SPACE, $self->default_themes() },
         't' => sub { join $SPACE, $self->get_themes() },
         'V' => sub { dor( $self->default_maximum_violations_per_document(), $NO_LIMIT ) },
         'v' => sub { dor( $self->get_maximum_violations_per_document(), $NO_LIMIT ) },
    );
    return stringf(get_format(), %fspec);
}

sub _format_parameters {
    my ($self, $parameter_format) = @_;

    return $EMPTY if not $self->parameter_metadata_available();

    my $separator;
    if ($parameter_format) {
        $separator = $EMPTY;
    } else {
        $separator = $SPACE;
        $parameter_format = '%n';
    }

    return
        join
            $separator,
            map { $_->to_formatted_string($parameter_format) } @{ $self->get_parameters() };
}

sub _format_lack_of_parameter_metadata {
    my ($self, $message) = @_;

    return $EMPTY if $self->parameter_metadata_available();
    return interpolate($message) if $message;

    return
        'Cannot programmatically discover what parameters this policy takes.';
}

#-----------------------------------------------------------------------------
# Apparently, some perls do not implicitly stringify overloading
# objects before doing a comparison.  This causes a couple of our
# sorting tests to fail.  To work around this, we overload C<cmp> to
# do it explicitly.
#
# 20060503 - More information:  This problem has been traced to
# Test::Simple versions <= 0.60, not perl itself.  Upgrading to
# Test::Simple v0.62 will fix the problem.  But rather than forcing
# everyone to upgrade, I have decided to leave this workaround in
# place.

sub _compare { return "$_[0]" cmp "$_[1]" }

1;

__END__

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

=pod

=head1 NAME

Perl::Critic::Policy - Base class for all Policy modules.


=head1 DESCRIPTION

Perl::Critic::Policy is the abstract base class for all Policy
objects.  If you're developing your own Policies, your job is to
implement and override its methods in a subclass.  To work with the
L<Perl::Critic|Perl::Critic> engine, your implementation must behave
as described below.  For a detailed explanation on how to make new
Policy modules, please see the
L<Perl::Critic::DEVELOPER|Perl::Critic::DEVELOPER> document included
in this distribution.


=head1 INTERFACE SUPPORT

This is considered to be a public class.  Any changes to its interface
will go through a deprecation cycle.


=head1 METHODS

=over

=item C<< new( ... ) >>

Don't call this.  As a Policy author, do not implement this.  Use the
C<initialize_if_enabled()> method for your Policy setup.  See the
L<developer|Perl::Critic::DEVELOPER> documentation for more.


=item C<< initialize_if_enabled( $config ) >>

This receives an instance of
L<Perl::Critic::PolicyConfig|Perl::Critic::PolicyConfig> as a
parameter, and is only invoked if this Policy is enabled by the user.
Thus, this is the preferred place for subclasses to do any
initialization.

Implementations of this method should return a boolean value
indicating whether the Policy should continue to be enabled.  For most
subclasses, this will always be C<$TRUE>.  Policies that depend upon
external modules or other system facilities that may or may not be
available should test for the availability of these dependencies and
return C<$FALSE> if they are not.


=item C<< prepare_to_scan_document( $document ) >>

The parameter is about to be scanned by this Policy.  Whatever this
Policy wants to do in terms of preparation should happen here.
Returns a boolean value indicating whether the document should be
scanned at all; if this is a false value, this Policy won't be applied
to the document.  By default, does nothing but return C<$TRUE>.


=item C< violates( $element, $document ) >

Given a L<PPI::Element|PPI::Element> and a
L<PPI::Document|PPI::Document>, returns one or more
L<Perl::Critic::Violation|Perl::Critic::Violation> objects if the
C<$element> violates this Policy.  If there are no violations, then it
returns an empty list.  If the Policy encounters an exception, then it
should C<croak> with an error message and let the caller decide how to
handle it.

C<violates()> is an abstract method and it will abort if you attempt
to invoke it directly.  It is the heart of all Policy modules, and
your subclass B<must> override this method.


=item C< violation( $description, $explanation, $element ) >

Returns a reference to a new C<Perl::Critic::Violation> object. The
arguments are a description of the violation (as string), an
explanation for the policy (as string) or a series of page numbers in
PBP (as an ARRAY ref), a reference to the L<PPI|PPI> element that
caused the violation.

These are the same as the constructor to
L<Perl::Critic::Violation|Perl::Critic::Violation>, but without the
severity.  The Policy itself knows the severity.


=item C< new_parameter_value_exception( $option_name, $option_value, $source, $message_suffix ) >

Create a
L<Perl::Critic::Exception::Configuration::Option::Policy::ParameterValue|Perl::Critic::Exception::Configuration::Option::Policy::ParameterValue>
for this Policy.


=item C< throw_parameter_value_exception( $option_name, $option_value, $source, $message_suffix ) >

Create and throw a
L<Perl::Critic::Exception::Configuration::Option::Policy::ParameterValue|Perl::Critic::Exception::Configuration::Option::Policy::ParameterValue>.
Useful in parameter parser implementations.


=item C< get_long_name() >

Return the full package name of this policy.


=item C< get_short_name() >

Return the name of this policy without the "Perl::Critic::Policy::"
prefix.


=item C< is_enabled() >

Answer whether this policy is really active or not.  Returns a true
value if it is, a false, yet defined, value if it isn't, and an
undefined value if it hasn't yet been decided whether it will be.


=item C< applies_to() >

Returns a list of the names of PPI classes that this Policy cares
about.  By default, the result is C<PPI::Element>.  Overriding this
method in Policy subclasses should lead to significant performance
increases.


=item C< default_maximum_violations_per_document() >

Returns the default maximum number of violations for this policy to
report per document.  By default, this not defined, but subclasses may
override this.


=item C< get_maximum_violations_per_document() >

Returns the maximum number of violations this policy will report for a
single document.  If this is not defined, then there is no limit.  If
L</set_maximum_violations_per_document()> has not been invoked, then
L</default_maximum_violations_per_document()> is returned.


=item C< set_maximum_violations_per_document() >

Specify the maximum violations that this policy should report for a
document.


=item C< default_severity() >

Returns the default severity for violating this Policy.  See the
C<$SEVERITY> constants in L<Perl::Critic::Utils|Perl::Critic::Utils>
for an enumeration of possible severity values.  By default, this
method returns C<$SEVERITY_LOWEST>.  Authors of Perl::Critic::Policy
subclasses should override this method to return a value that they
feel is appropriate for their Policy.  In general, Polices that are
widely accepted or tend to prevent bugs should have a higher severity
than those that are more subjective or cosmetic in nature.


=item C< get_severity() >

Returns the severity of violating this Policy.  If the severity has
not been explicitly defined by calling C<set_severity>, then the
C<default_severity> is returned.  See the C<$SEVERITY> constants in
L<Perl::Critic::Utils|Perl::Critic::Utils> for an enumeration of
possible severity values.


=item C< set_severity( $N ) >

Sets the severity for violating this Policy.  Clients of
Perl::Critic::Policy objects can call this method to assign a
different severity to the Policy if they don't agree with the
C<default_severity>.  See the C<$SEVERITY> constants in
L<Perl::Critic::Utils|Perl::Critic::Utils> for an enumeration of
possible values.


=item C< default_themes() >

Returns a sorted list of the default themes associated with this
Policy.  The default method returns an empty list.  Policy authors
should override this method to return a list of themes that are
appropriate for their policy.


=item C< get_themes() >

Returns a sorted list of the themes associated with this Policy.  If
you haven't added themes or set the themes explicitly, this method
just returns the default themes.


=item C< set_themes( @THEME_LIST ) >

Sets the themes associated with this Policy.  Any existing themes are
overwritten.  Duplicate themes will be removed.


=item C< add_themes( @THEME_LIST ) >

Appends additional themes to this Policy.  Any existing themes are
preserved.  Duplicate themes will be removed.


=item C< get_abstract() >

Retrieve the abstract for this policy (the part of the NAME section of
the POD after the module name), if it is available.


=item C< get_raw_abstract() >

Retrieve the abstract for this policy (the part of the NAME section of
the POD after the module name), if it is available, in the unparsed
form.


=item C< parameter_metadata_available() >

Returns whether information about the parameters is available.


=item C< get_parameters() >

Returns a reference to an array containing instances of
L<Perl::Critic::PolicyParameter|Perl::Critic::PolicyParameter>.

Note that this will return an empty list if the parameters for this
policy are unknown.  In order to differentiate between this
circumstance and the one where this policy does not take any
parameters, it is necessary to call C<parameter_metadata_available()>.


=item C<set_format( $format )>

Class method.  Sets the format for all Policy objects when they are
evaluated in string context.  The default is C<"%p\n">.  See
L<"OVERLOADS"> for formatting options.


=item C<get_format()>

Class method. Returns the current format for all Policy objects when
they are evaluated in string context.


=item C<to_string()>

Returns a string representation of the policy.  The content of the
string depends on the current value returned by C<get_format()>.
See L<"OVERLOADS"> for the details.


=item C<is_safe()>

Answer whether this Policy can be used to analyze untrusted code, i.e. the
Policy doesn't have any potential side effects.

This method returns a true value by default.

An "unsafe" policy might attempt to compile the code, which, if you have
C<BEGIN> or C<CHECK> blocks that affect files or connect to databases, is not
a safe thing to do.  If you are writing a such a Policy, then you should
override this method to return false.

By default L<Perl::Critic|Perl::Critic> will not run unsafe policies.



=back


=head1 DOCUMENTATION

When your Policy module first C<use>s
L<Perl::Critic::Violation|Perl::Critic::Violation>, it will try and
extract the DESCRIPTION section of your Policy module's POD.  This
information is displayed by Perl::Critic if the verbosity level is set
accordingly.  Therefore, please include a DESCRIPTION section in the
POD for any Policy modules that you author.  Thanks.


=head1 OVERLOADS

Perl::Critic::Violation overloads the C<""> operator to produce neat
little messages when evaluated in string context.

Formats are a combination of literal and escape characters similar to
the way C<sprintf> works.  If you want to know the specific formatting
capabilities, look at L<String::Format|String::Format>. Valid escape
characters are:


=over

=item C<%P>

Name of the Policy module.


=item C<%p>

Name of the Policy without the C<Perl::Critic::Policy::> prefix.


=item C<%a>

The policy abstract.


=item C<%O>

List of supported policy parameters.  Takes an option of a format
string for L<Perl::Critic::PolicyParameter/"to_formatted_string">.
For example, this can be used like C<%{%n - %d\n}O> to get a list of
parameter names followed by their descriptions.


=item C<%U>

A message stating that the parameters for the policy are unknown if
C<parameter_metadata_available()> returns false.  Takes an option of
what the message should be, which defaults to "Cannot programmatically
discover what parameters this policy takes.".  The value of this
option is interpolated in order to expand the standard escape
sequences (C<\n>, C<\t>, etc.).


=item C<%S>

The default severity level of the policy.


=item C<%s>

The current severity level of the policy.


=item C<%T>

The default themes for the policy.


=item C<%t>

The current themes for the policy.


=item C<%V>

The default maximum number of violations per document of the policy.


=item C<%v>

The current maximum number of violations per document of the policy.


=back


=head1 AUTHOR

Jeffrey Ryan Thalhammer <jeff@imaginative-software.com>


=head1 COPYRIGHT

Copyright (c) 2005-2011 Imaginative Software Systems.  All rights reserved.

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

=cut

# Local Variables:
#   mode: cperl
#   cperl-indent-level: 4
#   fill-column: 78
#   indent-tabs-mode: nil
#   c-indentation-style: bsd
# End:
# ex: set ts=8 sts=4 sw=4 tw=78 ft=perl expandtab shiftround :
