# File: AntiSpam.pm
# Author: pragma_
#
# Purpose: Checks if a message is spam

# This Source Code Form is subject to the terms of the Mozilla Public
# License, v. 2.0. If a copy of the MPL was not distributed with this
# file, You can obtain one at http://mozilla.org/MPL/2.0/.

package PBot::AntiSpam;

use warnings;
use strict;

use feature 'unicode_strings';

use feature 'switch';
no if $] >= 5.018, warnings => "experimental::smartmatch";

use PBot::DualIndexHashObject;

use Carp ();
use Time::HiRes qw(gettimeofday);
use POSIX qw/strftime/;

sub new {
  Carp::croak("Options to " . __FILE__ . " should be key/value pairs, not hash reference") if ref($_[1]) eq 'HASH';
  my ($class, %conf) = @_;
  my $self = bless {}, $class;
  $self->initialize(%conf);
  return $self;
}

sub initialize {
  my ($self, %conf) = @_;

  $self->{pbot} = delete $conf{pbot} // Carp::croak("Missing pbot reference to " . __FILE__);

  my $filename = delete $conf{spamkeywords_file} // $self->{pbot}->{registry}->get_value('general', 'data_dir') . '/spam_keywords';
  $self->{keywords} = PBot::DualIndexHashObject->new(name => 'SpamKeywords', filename => $filename, pbot => $self->{pbot});
  $self->{keywords}->load;

  $self->{pbot}->{registry}->add_default('text', 'antispam', 'enforce',  $conf{enforce_antispam} // 1);
  $self->{pbot}->{commands}->register(sub { $self->antispam_cmd(@_) }, "antispam", 1);
  $self->{pbot}->{capabilities}->add('admin', 'can-antispam', 1);
}

sub is_spam {
  my ($self, $namespace, $text, $all_namespaces) = @_;
  my $lc_namespace = lc $namespace;

  return 0 if not $self->{pbot}->{registry}->get_value('antispam', 'enforce');
  return 0 if $self->{pbot}->{registry}->get_value($namespace, 'dont_enforce_antispam');

  my $ret = eval {
    foreach my $space (keys %{ $self->{keywords}->{hash} }) {
      if ($all_namespaces or $lc_namespace eq $space) {
        foreach my $keyword (keys %{ $self->{keywords}->{hash}->{$space} }) {
          next if $keyword eq '_name';
          return 1 if $text =~ m/$keyword/i;
        }
      }
    }
    return 0;
  };

  if ($@) {
    $self->{pbot}->{logger}->log("Error in is_spam: $@");
    return 0;
  }
  $self->{pbot}->{logger}->log("AntiSpam: spam detected!\n") if $ret;
  return $ret;
}

sub antispam_cmd {
  my ($self, $from, $nick, $user, $host, $arguments, $stuff) = @_;

  my $arglist = $stuff->{arglist};

  my $command = $self->{pbot}->{interpreter}->shift_arg($arglist);

  return "Usage: antispam <command>, where commands are: list/show, add, remove, set, unset" if not defined $command;

  given ($command) {
    when ($_ eq "list" or $_ eq "show") {
      my $text = "Spam keywords:\n";
      my $entries = 0;
      foreach my $namespace (keys %{ $self->{keywords}->{hash} }) {
        $text .= "  $self->{keywords}->{hash}->{$namespace}->{_name}:\n";
        foreach my $keyword (keys %{ $self->{keywords}->{hash}->{$namespace} }) {
          next if $keyword eq '_name';
          $text .= "    $self->{keywords}->{hash}->{$namespace}->{$keyword}->{_name},\n";
          $entries++;
        }
      }
      $text .= "none" if $entries == 0;
      return $text;
    }
    when ("set") {
      my ($namespace, $keyword, $flag, $value) = $self->{pbot}->{interpreter}->split_args($arglist, 4);
      return "Usage: antispam set <namespace> <regex> [flag [value]]" if not defined $namespace or not defined $keyword;

      if (not exists $self->{keywords}->{hash}->{lc $namespace}) {
        return "There is no such namespace `$namespace`.";
      }

      if (not exists $self->{keywords}->{hash}->{lc $namespace}->{lc $keyword}) {
        return "There is no such regex `$keyword` for namespace `$self->{keywords}->{hash}->{$namespace}->{_name}`.";
      }

      if (not defined $flag) {
        my $text = "Flags:\n";
        my $comma = '';
        foreach $flag (keys %{ $self->{keywords}->{hash}->{lc $namespace}->{lc $keyword} }) {
          if ($flag eq 'created_on') {
            my $timestamp = strftime "%a %b %e %H:%M:%S %Z %Y", localtime $self->{keywords}->{hash}->{lc $namespace}->{lc $keyword}->{$flag};
            $text .= $comma . "created_on: $timestamp";
          } else {
            $value = $self->{keywords}->{hash}->{lc $namespace}->{lc $keyword}->{$flag};
            $text .= $comma .  "$flag: $value";
          }
          $comma = ",\n  ";
        }
        return $text;
      }

      if (not defined $value) {
        $value = $self->{keywords}->{hash}->{lc $namespace}->{lc $keyword}->{$flag};
        if (not defined $value) {
          return "/say $flag is not set.";
        } else {
          return "/say $flag is set to $value";
        }
      }

      $self->{keywords}->{hash}->{lc $namespace}->{lc $keyword}->{$flag} = $value;
      $self->{keywords}->save;
      return "Flag set.";
    }
    when ("unset") {
      my ($namespace, $keyword, $flag) = $self->{pbot}->{interpreter}->split_args($arglist, 3);
      return "Usage: antispam unset <namespace> <regex> <flag>" if not defined $namespace or not defined $keyword or not defined $flag;

      if (not exists $self->{keywords}->{hash}->{lc $namespace}) {
        return "There is no such namespace `$namespace`.";
      }

      if (not exists $self->{keywords}->{hash}->{lc $namespace}->{lc $keyword}) {
        return "There is no such keyword `$keyword` for namespace `$namespace`.";
      }

      if (not exists $self->{keywords}->{hash}->{lc $namespace}->{lc $keyword}->{$flag}) {
        return "There is no such flag `$flag` for regex `$keyword` for namespace `$namespace`.";
      }

      delete $self->{keywords}->{hash}->{lc $namespace}->{lc $keyword}->{$flag};
      $self->{keywords}->save;
      return "Flag unset.";
    }
    when ("add") {
      my ($namespace, $keyword) = $self->{pbot}->{interpreter}->split_args($arglist, 2);
      return "Usage: antispam add <namespace> <regex>" if not defined $namespace or not defined $keyword;
      my $data = {
        owner => "$nick!$user\@$host",
        created_on => scalar gettimeofday
      };
      $self->{keywords}->add($namespace, $keyword, $data);
      return "/say Added `$keyword`.";
    }
    when ("remove") {
      my ($namespace, $keyword) = $self->{pbot}->{interpreter}->split_args($arglist, 2);
      return "Usage: antispam remove <namespace> <regex>" if not defined $namespace or not defined $keyword;
      return $self->{keywords}->remove($namespace, $keyword);
    }
    default {
      return "Unknown command '$command'; commands are: list/show, add, remove";
    }
  }
}

1;