# File: Factoids.pm
# Author: pragma_
#
# Purpose: Provides functionality for factoids and a type of external module execution.

# 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::Factoids;

use warnings;
use strict;

use feature 'unicode_strings';

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

use HTML::Entities;
use Time::HiRes qw(gettimeofday);
use Time::Duration qw(duration);
use Carp ();
use POSIX qw(strftime);
use Text::ParseWords;
use JSON;

use PBot::FactoidCommands;
use PBot::FactoidModuleLauncher;
use PBot::DualIndexHashObject;

use PBot::Utils::Indefinite;
use PBot::Utils::ValidateString;

sub new {
  Carp::croak("Options to Factoids 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) = @_;

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

  $self->{factoids} = PBot::DualIndexHashObject->new(name => 'Factoids', filename => $filename, pbot => $self->{pbot});

  $self->{pbot}                  = $self->{pbot};
  $self->{commands}              = PBot::FactoidCommands->new(pbot => $self->{pbot});
  $self->{factoidmodulelauncher} = PBot::FactoidModuleLauncher->new(pbot => $self->{pbot});

  $self->{pbot}->{registry}->add_default('text', 'factoids', 'default_rate_limit',  15);
  $self->{pbot}->{registry}->add_default('text', 'factoids', 'max_name_length',     100);
  $self->{pbot}->{registry}->add_default('text', 'factoids', 'max_content_length',  1024 * 8);
  $self->{pbot}->{registry}->add_default('text', 'factoids', 'max_channel_length',  20);

  $self->{pbot}->{atexit}->register(sub { $self->save_factoids; return; });

  $self->load_factoids;
}

sub load_factoids {
  my $self = shift;

  $self->{factoids}->load;

  my ($text, $regex, $modules);
  foreach my $channel (keys %{ $self->{factoids}->{hash} }) {
    foreach my $trigger (keys %{ $self->{factoids}->{hash}->{$channel} }) {
      next if $trigger eq '_name';
      $self->{pbot}->{logger}->log("Missing type for $channel->$trigger\n") if not $self->{factoids}->{hash}->{$channel}->{$trigger}->{type};
      $text++   if $self->{factoids}->{hash}->{$channel}->{$trigger}->{type} eq 'text';
      $regex++  if $self->{factoids}->{hash}->{$channel}->{$trigger}->{type} eq 'regex';
      $modules++ if $self->{factoids}->{hash}->{$channel}->{$trigger}->{type} eq 'module';
    }
  }
  $self->{pbot}->{logger}->log("  " . ($text + $regex + $modules) . " factoids loaded ($text text, $regex regexs, $modules modules).\n");
}

sub save_factoids {
  my $self = shift;
  $self->{factoids}->save;
  $self->export_factoids;
}

sub add_factoid {
  my $self = shift;
  my ($type, $channel, $owner, $trigger, $action, $dont_save) = @_;

  $type = lc $type;
  $channel = '.*' if $channel !~ /^#/;

  my $data;

  if (exists $self->{factoids}->{hash}->{lc $channel} and exists $self->{factoids}->{hash}->{lc $channel}->{lc $trigger}) {
    # only update action field if force-adding it through factadd -f
    $data = $self->{factoids}->{hash}->{lc $channel}->{lc $trigger};
    $data->{action} = $action;
    $data->{type} = $type;
  } else {
    $data = {
      enabled    => 1,
      type       => $type,
      action     => $action,
      owner      => $owner,
      created_on => scalar gettimeofday,
      ref_count  => 0,
      ref_user   => "nobody",
      rate_limit => $self->{pbot}->{registry}->get_value('factoids', 'default_rate_limit')
    };
  }

  $self->{factoids}->add($channel, $trigger, $data, $dont_save);

  unless ($dont_save) {
    $self->{commands}->log_factoid($channel, $trigger, $owner, "created: $action");
  }
}

sub remove_factoid {
  my $self = shift;
  my ($channel, $trigger) = @_;

  $channel = '.*' if $channel !~ /^#/;
  $channel = lc $channel;
  $trigger = lc $trigger;

  delete $self->{factoids}->{hash}->{$channel}->{$trigger};

  if (scalar keys %{ $self->{factoids}->{hash}->{$channel} } == 1) {
    delete $self->{factoids}->{hash}->{$channel};
  }

  $self->save_factoids;
}

sub export_factoids {
  my $self = shift;
  my $filename;

  if (@_) { $filename = shift; } else { $filename = $self->{pbot}->{registry}->get_value('general', 'data_dir') . '/factoids.html'; }
  return if not defined $filename;

  open FILE, "> $filename" or return "Could not open export path.";

  my $botnick = $self->{pbot}->{registry}->get_value('irc', 'botnick');
  my $time = localtime;
  print FILE "<html><head>\n<link href='css/blue.css' rel='stylesheet' type='text/css'>\n";
  print FILE '<script type="text/javascript" src="js/jquery-latest.js"></script>' . "\n";
  print FILE '<script type="text/javascript" src="js/jquery.tablesorter.js"></script>' . "\n";
  print FILE '<script type="text/javascript" src="js/picnet.table.filter.min.js"></script>' . "\n";
  print FILE "</head>\n<body><i>Last updated at $time</i>\n";
  print FILE "<hr><h2>$botnick\'s factoids</h2>\n";

  my $i = 0;
  my $table_id = 1;

  foreach my $channel (sort keys %{ $self->{factoids}->{hash} }) {
    next if not scalar keys %{ $self->{factoids}->{hash}->{$channel} };
    my $chan = $self->{factoids}->{hash}->{$channel}->{_name};
    $chan = 'global' if $chan eq '.*';

    print FILE "<a href='#" . encode_entities($chan) . "'>" . encode_entities($chan) . "</a><br>\n";
  }

  foreach my $channel (sort keys %{ $self->{factoids}->{hash} }) {
    next if not scalar keys %{ $self->{factoids}->{hash}->{$channel} };
    my $chan = $self->{factoids}->{hash}->{$channel}->{_name};
    $chan = 'global' if $chan eq '.*';
    print FILE "<a name='" . encode_entities($chan) . "'></a>\n";
    print FILE "<hr>\n<h3>" . encode_entities($chan) . "</h3>\n<hr>\n";
    print FILE "<table border=\"0\" id=\"table$table_id\" class=\"tablesorter\">\n";
    print FILE "<thead>\n<tr>\n";
    print FILE "<th>owner</th>\n";
    print FILE "<th>created on</th>\n";
    print FILE "<th>times referenced</th>\n";
    print FILE "<th>factoid</th>\n";
    print FILE "<th>last edited by</th>\n";
    print FILE "<th>edited date</th>\n";
    print FILE "<th>last referenced by</th>\n";
    print FILE "<th>last referenced date</th>\n";
    print FILE "</tr>\n</thead>\n<tbody>\n";
    $table_id++;

    foreach my $trigger (sort keys %{ $self->{factoids}->{hash}->{$channel} }) {
      next if $trigger eq '_name';
      my $trigger_name = $self->{factoids}->{hash}->{$channel}->{$trigger}->{_name};
      if ($self->{factoids}->{hash}->{$channel}->{$trigger}->{type} eq 'text') {
        $i++;
        if ($i % 2) {
          print FILE "<tr bgcolor=\"#dddddd\">\n";
        } else {
          print FILE "<tr>\n";
        }

        print FILE "<td>" . encode_entities($self->{factoids}->{hash}->{$channel}->{$trigger}->{owner}) . "</td>\n";
        print FILE "<td>" . encode_entities(strftime "%Y/%m/%d %H:%M:%S", localtime $self->{factoids}->{hash}->{$channel}->{$trigger}->{created_on}) . "</td>\n";

        print FILE "<td>" . $self->{factoids}->{hash}->{$channel}->{$trigger}->{ref_count} . "</td>\n";

        my $action = $self->{factoids}->{hash}->{$channel}->{$trigger}->{action};

        if ($action =~ m/https?:\/\/[^ ]+/) {
          $action =~ s/(.*?)http(s?:\/\/[^ ]+)/encode_entities($1) . "<a href='http" . encode_entities($2) . "'>http" . encode_entities($2) . "<\/a>"/ge;
          $action =~ s/(.*)<\/a>(.*$)/"$1<\/a>" . encode_entities($2)/e;
        } else {
          $action = encode_entities($action);
        }

        if (exists $self->{factoids}->{hash}->{$channel}->{$trigger}->{action_with_args}) {
          my $with_args = $self->{factoids}->{hash}->{$channel}->{$trigger}->{action_with_args};
          $with_args =~ s/(.*?)http(s?:\/\/[^ ]+)/encode_entities($1) . "<a href='http" . encode_entities($2) . "'>http" . encode_entities($2) . "<\/a>"/ge;
          $with_args =~ s/(.*)<\/a>(.*$)/"$1<\/a>" . encode_entities($2)/e;
          print FILE "<td width=100%><b>" . encode_entities($trigger_name) . "</b> is $action<br><br><b>with_args:</b> " . encode_entities($with_args) . "</td>\n";
        } else {
          print FILE "<td width=100%><b>" . encode_entities($trigger_name) . "</b> is $action</td>\n";
        }

        if (exists $self->{factoids}->{hash}->{$channel}->{$trigger}->{edited_by}) {
          print FILE "<td>" . $self->{factoids}->{hash}->{$channel}->{$trigger}->{edited_by} . "</td>\n";
          print FILE "<td>" . encode_entities(strftime "%Y/%m/%d %H:%M:%S", localtime $self->{factoids}->{hash}->{$channel}->{$trigger}->{edited_on}) . "</td>\n";
        } else {
          print FILE "<td></td>\n";
          print FILE "<td></td>\n";
        }

        print FILE "<td>" . encode_entities($self->{factoids}->{hash}->{$channel}->{$trigger}->{ref_user}) . "</td>\n";

        if (exists $self->{factoids}->{hash}->{$channel}->{$trigger}->{last_referenced_on}) {
          print FILE "<td>" . encode_entities(strftime "%Y/%m/%d %H:%M:%S", localtime $self->{factoids}->{hash}->{$channel}->{$trigger}->{last_referenced_on}) . "</td>\n";
        } else {
          print FILE "<td></td>\n";
        }

        print FILE "</tr>\n";
      }
    }
    print FILE "</tbody>\n</table>\n";
  }

  print FILE "<hr>$i factoids memorized.<br>";
  print FILE "<hr><i>Last updated at $time</i>\n";

  print FILE "<script type='text/javascript'>\n";
  $table_id--;
  print FILE '$(document).ready(function() {' . "\n";
  while ($table_id > 0) {
    print FILE '$("#table' . $table_id . '").tablesorter();' . "\n";
    print FILE '$("#table' . $table_id . '").tableFilter();' . "\n";
    $table_id--;
  }
  print FILE "});\n";
  print FILE "</script>\n";
  print FILE "</body>\n</html>\n";

  close(FILE);

  return "/say $i factoids exported.";
}

sub find_factoid {
  my ($self, $from, $keyword, %opts) = @_;

  my %default_opts = (
    arguments => '',
    exact_channel => 0,
    exact_trigger => 0,
    find_alias => 0
  );

  %opts = (%default_opts, %opts);

  my $debug = 0;

  if ($debug) {
    use Data::Dumper;
    my $dump = Dumper \%opts;
    $self->{pbot}->{logger}->log("find_factiod: from: $from, kw: $keyword, opts: $dump\n");
  }

  $from = '.*' if not defined $from or $from !~ /^#/;
  $from = lc $from;
  $keyword = lc $keyword;

  $self->{pbot}->{logger}->log("from: $from\n") if $debug;

  my $arguments = $opts{arguments};

  my @result = eval {
    my @results;
    for (my $depth = 0; $depth < 5; $depth++) {
      my $string = $keyword . (length $arguments ? " $arguments" : "");
      $self->{pbot}->{logger}->log("string: $string\n") if $debug;
      # check factoids
      foreach my $channel (sort keys %{ $self->{factoids}->{hash} }) {
        if ($opts{exact_channel}) {
          if ($opts{exact_trigger} == 1) {
            next unless $from eq lc $channel;
          } else {
            next unless $from eq lc $channel or $channel eq '.*';
          }
        }

        foreach my $trigger (keys %{ $self->{factoids}->{hash}->{$channel} }) {
          next if $trigger eq '_name';
          if ($keyword eq $trigger) {
            $self->{pbot}->{logger}->log("return $channel: $trigger\n") if $debug;

            if ($opts{find_alias} && $self->{factoids}->{hash}->{$channel}->{$trigger}->{action} =~ /^\/call\s+(.*)$/ms) {
              my $command;
              if (length $arguments) {
                $command = "$1 $arguments";
              } else {
                $command = $1;
              }
              my $arglist = $self->{pbot}->{interpreter}->make_args($command);
              ($keyword, $arguments) = $self->{pbot}->{interpreter}->split_args($arglist, 2, 0, 1);
              goto NEXT_DEPTH;
            }

            if ($opts{exact_channel} == 1) {
              return ($channel, $trigger);
            } else {
              push @results, [$channel, $trigger];
            }
          }
        }
      }

      # then check regex factoids
      if (not $opts{exact_trigger}) {
        foreach my $channel (sort keys %{ $self->{factoids}->{hash} }) {
          if ($opts{exact_channel}) {
            next unless $from eq lc $channel or $channel eq '.*';
          }

          foreach my $trigger (sort keys %{ $self->{factoids}->{hash}->{$channel} }) {
            next if $trigger eq '_name';
            if ($self->{factoids}->{hash}->{$channel}->{$trigger}->{type} eq 'regex') {
              $self->{pbot}->{logger}->log("checking regex $string =~ m/$trigger/i\n") if $debug >= 2;
              if ($string =~ m/$trigger/i) {
                $self->{pbot}->{logger}->log("return regex $channel: $trigger\n") if $debug;

                if ($opts{find_alias}) {
                  my $command = $self->{factoids}->{hash}->{$channel}->{$trigger}->{action};
                  my $arglist = $self->{pbot}->{interpreter}->make_args($command);
                  ($keyword, $arguments) = $self->{pbot}->{interpreter}->split_args($arglist, 2, 0, 1);
                  $string = $keyword . (length $arguments ? " $arguments" : "");
                  goto NEXT_DEPTH;
                }

                if ($opts{exact_channel} == 1) {
                  return ($channel, $trigger);
                } else {
                  push @results, [$channel, $trigger];
                }
              }
            }
          }
        }
      }

      NEXT_DEPTH:
      last if not $opts{find_alias};
    }

    if ($debug) {
      if (not @results) {
        $self->{pbot}->{logger}->log("find_factoid: no match\n");
      } else {
        $self->{pbot}->{logger}->log("find_factoid: got results: " . (join ', ', map { "$_->[0] -> $_->[1]" } @results) . "\n");
      }
    }
    return @results;
  };

  if ($@) {
    $self->{pbot}->{logger}->log("find_factoid: bad regex: $@\n");
    return undef;
  }

  return @result;
}

sub escape_json {
  my ($self, $text) = @_;
  my $thing = {thing => $text};
  my $json = encode_json $thing;
  $json =~ s/^{".*":"//;
  $json =~ s/"}$//;
  return $json;
}

sub expand_special_vars {
  my ($self, $from, $nick, $root_keyword, $action) = @_;

  $action =~ s/\$nick:json|\$\{nick:json\}/$self->escape_json($nick)/ge;
  $action =~ s/\$channel:json|\$\{channel:json\}/$self->escape_json($from)/ge;
  $action =~ s/\$randomnick:json|\$\{randomnick:json\}/my $random = $self->{pbot}->{nicklist}->random_nick($from); $random ? $self->escape_json($random) : $self->escape_json($nick)/ge;
  $action =~ s/\$0:json|\$\{0:json\}/$self->escape_json($root_keyword)/ge;

  $action =~ s/\$nick|\$\{nick\}/$nick/g;
  $action =~ s/\$channel|\$\{channel\}/$from/g;
  $action =~ s/\$randomnick|\$\{randomnick\}/my $random = $self->{pbot}->{nicklist}->random_nick($from); $random ? $random : $nick/ge;
  $action =~ s/\$0\b|\$\{0\}\b/$root_keyword/g;

  return validate_string($action, $self->{pbot}->{registry}->get_value('factoids', 'max_content_length'));
}

sub expand_factoid_vars {
  my ($self, $stuff, @exclude) = @_;

  my $from = length $stuff->{ref_from} ? $stuff->{ref_from} :  $stuff->{from};
  my $nick = $stuff->{nick};
  my $root_keyword = $stuff->{keyword_override} ? $stuff->{keyword_override} : $stuff->{root_keyword};
  my $action = $stuff->{action};

  my $debug = 0;
  my $depth = 0;

  if ($debug) {
    $self->{pbot}->{logger}->log("enter expand_factoid_vars\n");
    use Data::Dumper;
    $self->{pbot}->{logger}->log(Dumper $stuff);
  }

  if ($action =~ m/^\/call --keyword-override=([^ ]+)/i) {
    $root_keyword = $1;
  }

  while (1) {
    last if ++$depth >= 1000;

    my $offset = 0;
    my $matches = 0;
    my $expansions = 0;
    $action =~ s/\$0/$root_keyword/g;
    my $const_action = $action;

    $self->{pbot}->{logger}->log("action: $const_action\n") if $debug;

    while ($const_action =~ /(\ba\s*|\ban\s*)?(?<!\\)\$(?:(\{[a-zA-Z0-9_:#]+\}|[a-zA-Z0-9_:#]+))/gi) {
      my ($a, $v) = ($1, $2);
      $a = '' if not defined $a;
      next if not defined $v;

      my $original_v = $v;
      my $test_v = $v;

      $test_v =~ s/(.):$/$1/; # remove trailing : only if at least one character precedes it
      next if $test_v =~ m/^_/; # special character prefix skipped for shell/code-factoids/etc
      next if $test_v =~ m/^(?:nick|channel|randomnick|arglen|args|arg\[.+\]|[_0])(?:\:json)*$/i; # don't override special variables
      next if @exclude && grep { $test_v =~ m/^\Q$_\E$/i } @exclude;
      last if ++$depth >= 1000;

      $self->{pbot}->{logger}->log("v: [$original_v], test v: [$test_v]\n") if $debug;

      $matches++;

      $test_v =~ s/\{(.+)\}/$1/;

      my $modifier = '';
      if ($test_v =~ s/(:.*)$//) {
        $modifier = $1;
      }

      if ($modifier =~ m/^:(#[^:]+|global)/i) {
        $from = $1;
        $from = '.*' if lc $from eq 'global';
      }

      my $recurse = 0;
      ALIAS:
      my @factoids = $self->find_factoid($from, $test_v, exact_channel => 2, exact_trigger => 2);
      next if not @factoids or not $factoids[0];

      my ($var_chan, $var) = ($factoids[0]->[0], $factoids[0]->[1]);

      if ($self->{factoids}->{hash}->{$var_chan}->{$var}->{action} =~ m{^/call (.*)}ms) {
        $test_v = $1;
        next if ++$recurse > 100;
        goto ALIAS;
      }

      if ($self->{factoids}->{hash}->{$var_chan}->{$var}->{type} eq 'text') {
        my $change = $self->{factoids}->{hash}->{$var_chan}->{$var}->{action};
        my @list = $self->{pbot}->{interpreter}->split_line($change);
        my @mylist;
        for (my $i = 0; $i <= $#list; $i++) {
          push @mylist, $list[$i] if defined $list[$i] and length $list[$i];
        }
        my $line = int(rand($#mylist + 1));
        if (not $mylist[$line] =~ s/^"(.*)"$/$1/) {
          $mylist[$line] =~ s/^'(.*)'$/$1/;
        }

        foreach my $mod (split /:/, $modifier) {
          next if not length $mod;

          if ($mylist[$line] =~ /^\$\{\$([a-zA-Z0-9_:#]+)\}(.*)$/) {
            $mylist[$line] = "\${\$$1:$mod}$2";
            next;
          } elsif ($mylist[$line] =~ /^\$\{([a-zA-Z0-9_:#]+)\}(.*)$/) {
            $mylist[$line] = "\${$1:$mod}$2";
            next;
          } elsif ($mylist[$line] =~ /^\$\$([a-zA-Z0-9_:#]+)(.*)$/) {
            $mylist[$line] = "\${\$$1:$mod}$2";
            next;
          } elsif ($mylist[$line] =~ /^\$([a-zA-Z0-9_:#]+)(.*)$/) {
            $mylist[$line] = "\${$1:$mod}$2";
            next;
          }

          given ($mod) {
            when ('uc') {
              $mylist[$line] = uc $mylist[$line];
            }
            when ('lc') {
              $mylist[$line] = lc $mylist[$line];
            }
            when ('ucfirst') {
              $mylist[$line] = ucfirst $mylist[$line];
            }
            when ('title') {
              $mylist[$line] = ucfirst lc $mylist[$line];
              $mylist[$line] =~ s/ (\w)/' ' . uc $1/ge;
            }
            when ('json') {
              $mylist[$line] = $self->escape_json($mylist[$line]);
            }
          }
        }

        my $replacement = $mylist[$line];

        if ($a) {
          my $fixed_a = select_indefinite_article $mylist[$line];
          $fixed_a = ucfirst $fixed_a if $a =~ m/^A/;
          $replacement = "$fixed_a $mylist[$line]";
        }

        if ($debug and $offset == 0) {
          $self->{pbot}->{logger}->log(("-" x 40) . "\n");
        }

        $original_v = quotemeta $original_v;
        $original_v =~ s/\\:/:/g;

        if (not length $mylist[$line]) {
          $self->{pbot}->{logger}->log("No length!\n") if $debug;
          if ($debug) {
            $self->{pbot}->{logger}->log("before: v: $original_v, offset: $offset\n");
            $self->{pbot}->{logger}->log("$action\n");
            $self->{pbot}->{logger}->log((" " x $offset) . "^\n");
          }

          substr($action, $offset) =~ s/$a\$$original_v ?/$replacement/;
          $offset += $-[0] + length $replacement;

          if ($debug) {
            $self->{pbot}->{logger}->log("after: r: EMPTY \$-[0]: $-[0], offset: $offset\n");
            $self->{pbot}->{logger}->log("$action\n");
            $self->{pbot}->{logger}->log((" " x $offset) . "^\n");
          }
        } else {
          if ($debug) {
            $self->{pbot}->{logger}->log("before: v: $original_v, offset: $offset\n");
            $self->{pbot}->{logger}->log("$action\n");
            $self->{pbot}->{logger}->log((" " x $offset) . "^\n");
          }

          substr($action, $offset) =~ s/$a\$$original_v/$replacement/;
          $offset += $-[0] + length $replacement;

          if ($debug) {
            $self->{pbot}->{logger}->log("after: r: $replacement, \$-[0]: $-[0], offset: $offset\n");
            $self->{pbot}->{logger}->log("$action\n");
            $self->{pbot}->{logger}->log((" " x $offset) . "^\n");
          }
        }
        $expansions++;
      }
    }
    last if $matches == 0 or $expansions == 0;
  }

  $action =~ s/\\\$/\$/g;

  unless (@exclude) {
    $action = $self->expand_special_vars($from, $nick, $root_keyword, $action);
  }

  return validate_string($action, $self->{pbot}->{registry}->get_value('factoids', 'max_content_length'));
}

sub expand_action_arguments {
  my ($self, $action, $input, $nick) = @_;

  $action = validate_string($action, $self->{pbot}->{registry}->get_value('factoids', 'max_content_length'));
  $input = validate_string($input, $self->{pbot}->{registry}->get_value('factoids', 'max_content_length'));

  my %h;
  if (not defined $input or $input eq '') {
    %h = (args => $nick);
  } else {
    %h = (args => $input);
  }

  my $jsonargs = encode_json \%h;
  $jsonargs =~ s/^{".*":"//;
  $jsonargs =~ s/"}$//;

  if (not defined $input or $input eq '') {
    $input = "";
    $action =~ s/\$args:json|\$\{args:json\}/$jsonargs/ge;
    $action =~ s/\$args(?![[\w])|\$\{args(?![[\w])\}/$nick/g;
  } else {
    $action =~ s/\$args:json|\$\{args:json\}/$jsonargs/g;
    $action =~ s/\$args(?![[\w])|\$\{args(?![[\w])\}/$input/g;
  }

  my @args = $self->{pbot}->{interpreter}->split_line($input);
  $action =~ s/\$arglen\b|\$\{arglen\}/scalar @args/eg;

  my $depth = 0;
  my $const_action = $action;
  while ($const_action =~ m/\$arg\[([^]]+)]|\$\{arg\[([^]]+)]\}/g) {
    my $arg = defined $2 ? $2 : $1;

    last if ++$depth >= 100;

    if ($arg eq '*') {
      if (not defined $input or $input eq '') {
        $action =~ s/\$arg\[\*\]|\$\{arg\[\*\]\}/$nick/;
      } else {
        $action =~ s/\$arg\[\*\]|\$\{arg\[\*\]\}/$input/;
      }
      next;
    }

    if ($arg =~ m/([^:]*):(.*)/) {
      my $arg1 = $1;
      my $arg2 = $2;

      my $arg1i = $arg1;
      my $arg2i = $arg2;

      $arg1i = 0 if $arg1i eq '';
      $arg2i = $#args if $arg2i eq '';
      $arg2i = $#args if $arg2i > $#args;

      my @values = eval {
        local $SIG{__WARN__} = sub {};
        return @args[$arg1i .. $arg2i];
      };

      if ($@) {
        next;
      } else {
        my $string = join(' ', @values);

        if ($string eq '') {
          $action =~ s/\s*\$\{arg\[$arg1:$arg2\]\}// || $action =~ s/\s*\$arg\[$arg1:$arg2\]//;
        } else {
          $action =~ s/\$\{arg\[$arg1:$arg2\]\}/$string/ || $action =~ s/\$arg\[$arg1:$arg2\]/$string/;
        }
      }

      next;
    }

    my $value = eval {
      local $SIG{__WARN__} = sub {};
      return $args[$arg];
    };

    if ($@) {
      next;
    } else {

      if (not defined $value) {
        if ($arg == 0) {
          $action =~ s/\$\{arg\[$arg\]\}/$nick/ || $action =~ s/\$arg\[$arg\]/$nick/;
        } else {
          $action =~ s/\s*\$\{arg\[$arg\]\}// || $action =~ s/\s*\$arg\[$arg\]//;
        }
      } else {
        $action =~ s/\$arg\{\[$arg\]\}/$value/ || $action =~ s/\$arg\[$arg\]/$value/;
      }
    }
  }

  return $action;
}

sub execute_code_factoid_using_vm {
  my ($self, $stuff) = @_;

  unless (exists $self->{factoids}->{hash}->{lc $stuff->{channel}}->{lc $stuff->{keyword}}->{interpolate} and $self->{factoids}->{hash}->{lc $stuff->{channel}}->{lc $stuff->{keyword}}->{interpolate} eq '0') {
    if ($stuff->{code} =~ m/(?:\$\{?nick\b|\$\{?args\b|\$\{?arg\[)/ and length $stuff->{arguments}) {
      $stuff->{no_nickoverride} = 1;
    } else {
      $stuff->{no_nickoverride} = 0;
    }

    $stuff->{action} = $stuff->{code};
    $stuff->{code} = $self->expand_factoid_vars($stuff);

    if ($self->{factoids}->{hash}->{lc $stuff->{channel}}->{lc $stuff->{keyword}}->{'allow_empty_args'}) {
      $stuff->{code} = $self->expand_action_arguments($stuff->{code}, $stuff->{arguments}, '');
    } else {
      $stuff->{code} = $self->expand_action_arguments($stuff->{code}, $stuff->{arguments}, $stuff->{nick});
    }
  } else {
    $stuff->{no_nickoverride} = 0;
  }

  my %h = (nick => $stuff->{nick}, channel => $stuff->{from}, lang => $stuff->{lang}, code => $stuff->{code}, arguments => $stuff->{arguments}, factoid => "$stuff->{channel}:$stuff->{keyword}");

  if (exists $self->{factoids}->{hash}->{lc $stuff->{channel}}->{lc $stuff->{keyword}}->{'persist-key'}) {
    $h{'persist-key'} = $self->{factoids}->{hash}->{lc $stuff->{channel}}->{lc $stuff->{keyword}}->{'persist-key'};
  }

  my $json = encode_json \%h;

  $stuff->{special} = 'code-factoid';
  $stuff->{root_channel} = $stuff->{channel};
  $stuff->{keyword} = 'compiler';
  $stuff->{arguments} = $json;
  $stuff->{args_utf8} = 1;

  $self->{pbot}->{factoids}->{factoidmodulelauncher}->execute_module($stuff);
  return "";
}

sub execute_code_factoid {
  my ($self, @args) = @_;
  return $self->execute_code_factoid_using_vm(@args);
}

sub interpreter {
  my ($self, $stuff) = @_;
  my $pbot = $self->{pbot};

  if ($self->{pbot}->{registry}->get_value('general', 'debugcontext')) {
    use Data::Dumper;
    $Data::Dumper::Sortkeys  = 1;
    $self->{pbot}->{logger}->log("Factoids::interpreter\n");
    $self->{pbot}->{logger}->log(Dumper $stuff);
  }

  return undef if not length $stuff->{keyword} or $stuff->{interpret_depth} > $self->{pbot}->{registry}->get_value('interpreter', 'max_recursion');

  $stuff->{from} = lc $stuff->{from};

  my $strictnamespace = $self->{pbot}->{registry}->get_value($stuff->{from}, 'strictnamespace');

  if (not defined $strictnamespace) {
    $strictnamespace = $self->{pbot}->{registry}->get_value('general', 'strictnamespace');
  }

  # search for factoid against global channel and current channel (from unless ref_from is defined)
  my $original_keyword = $stuff->{keyword};
  my ($channel, $keyword) = $self->find_factoid($stuff->{ref_from} ? $stuff->{ref_from} : $stuff->{from}, $stuff->{keyword}, arguments => $stuff->{arguments}, exact_channel => 1);

  if (not $stuff->{ref_from} or $stuff->{ref_from} eq '.*' or $stuff->{ref_from} eq $stuff->{from}) {
    $stuff->{ref_from} = "";
  }

  if (defined $channel and not $channel eq '.*' and not $channel eq lc $stuff->{from}) {
    $stuff->{ref_from} = $channel;
  }

  $stuff->{arguments} = "" if not defined $stuff->{arguments};

  # if no match found, attempt to call factoid from another channel if it exists there
  if (not defined $keyword) {
    my $string = "$original_keyword $stuff->{arguments}";
    my $lc_keyword = lc $original_keyword;
    my $comma = "";
    my $found = 0;
    my $chans = "";
    my ($fwd_chan, $fwd_trig);

    # build string of which channels contain the keyword, keeping track of the last one and count
    foreach my $chan (keys %{ $self->{factoids}->{hash} }) {
      foreach my $trig (keys %{ $self->{factoids}->{hash}->{$chan} }) {
        next if $trig eq '_name';
        my $type = $self->{factoids}->{hash}->{$chan}->{$trig}->{type};
        if (($type eq 'text' or $type eq 'module') and $trig eq $lc_keyword) {
          $chans .= $comma . $self->{factoids}->{hash}->{$chan}->{_name};
          $comma = ", ";
          $found++;
          $fwd_chan = $chan;
          $fwd_trig = $trig;
          last;
        }
      }
    }

    my $ref_from = $stuff->{ref_from} ? "[$stuff->{ref_from}] " : "";

    # if multiple channels have this keyword, then ask user to disambiguate
    if ($found > 1) {
      return undef if $stuff->{referenced};
      return $ref_from . "Ambiguous keyword '$original_keyword' exists in multiple channels (use 'fact <channel> $original_keyword' to choose one): $chans";
    }
    # if there's just one other channel that has this keyword, trigger that instance
    elsif ($found == 1) {
      $pbot->{logger}->log("Found '$original_keyword' as '$fwd_trig' in [$fwd_chan]\n");
      $stuff->{keyword} = $fwd_trig;
      $stuff->{interpret_depth}++;
      $stuff->{ref_from} = $fwd_chan;
      return $pbot->{factoids}->interpreter($stuff);
    }
    # otherwise keyword hasn't been found, display similiar matches for all channels
    else {
      # if a non-nick argument was supplied, e.g., a sentence using the bot's nick, don't say anything
      return undef if length $stuff->{arguments} and not $self->{pbot}->{nicklist}->is_present($stuff->{from}, $stuff->{arguments});

      my $namespace = $strictnamespace ? $stuff->{from} : '.*';
      $namespace = '.*' if $namespace !~ /^#/;

      my $namespace_regex = $namespace;
      if ($strictnamespace) {
        $namespace_regex = "(?:" . (quotemeta $namespace) . '|\\.\\*)';
      }

      my $matches = $self->{commands}->factfind($stuff->{from}, $stuff->{nick}, $stuff->{user}, $stuff->{host}, quotemeta($original_keyword) . " -channel $namespace_regex");

      # found factfind matches
      if ($matches !~ m/^No factoids/) {
        return undef if $stuff->{referenced};
        return "No such factoid '$original_keyword'; $matches";
      }

      # otherwise find levenshtein closest matches
      $matches = $self->{factoids}->levenshtein_matches($namespace, lc $original_keyword, 0.50, $strictnamespace);

      # don't say anything if nothing similiar was found
      return undef if $matches eq 'none';
      return undef if $stuff->{referenced};

      my $ref_from = $stuff->{ref_from} ? "[$stuff->{ref_from}] " : "";
      return $ref_from . "No such factoid '$original_keyword'; did you mean $matches?";
    }
  }

  my $channel_name = $self->{factoids}->{hash}->{$channel}->{_name};
  my $trigger_name = $self->{factoids}->{hash}->{$channel}->{$keyword}->{_name};
  $channel_name = 'global' if $channel_name eq '.*';
  $trigger_name = "\"$trigger_name\"" if $trigger_name =~ / /;

  $stuff->{keyword} = $keyword;
  $stuff->{trigger} = $keyword;
  $stuff->{channel} = $channel;
  $stuff->{original_keyword} = $original_keyword;
  $stuff->{channel_name} = $channel_name;
  $stuff->{trigger_name} = $trigger_name;

  return undef if $stuff->{referenced} and $self->{factoids}->{hash}->{$channel}->{$keyword}->{noembed};

  if (exists $self->{factoids}->{hash}->{$channel}->{$keyword}->{locked_to_channel}) {
    if ($stuff->{ref_from} ne "") { # called from another channel
      return "$trigger_name may be invoked only in $stuff->{ref_from}.";
    }
  }

  if (exists $self->{factoids}->{hash}->{$channel}->{$keyword}->{last_referenced_on}) {
    if (exists $self->{factoids}->{hash}->{$channel}->{$keyword}->{last_referenced_in}) {
      if ($self->{factoids}->{hash}->{$channel}->{$keyword}->{last_referenced_in} eq $stuff->{from}) {
        my $ratelimit = $self->{pbot}->{registry}->get_value($stuff->{from}, 'ratelimit_override');
        $ratelimit = $self->{factoids}->{hash}->{$channel}->{$keyword}->{rate_limit} if not defined $ratelimit;
        if (gettimeofday - $self->{factoids}->{hash}->{$channel}->{$keyword}->{last_referenced_on} < $ratelimit) {
          my $ref_from = $stuff->{ref_from} ? "[$stuff->{ref_from}] " : "";
          return "/msg $stuff->{nick} $ref_from'$trigger_name' is rate-limited; try again in " . duration ($ratelimit - int(gettimeofday - $self->{factoids}->{hash}->{$channel}->{$keyword}->{last_referenced_on})) . "." unless $self->{pbot}->{users}->loggedin_admin($channel, "$stuff->{nick}!$stuff->{user}\@$stuff->{host}");
        }
      }
    }
  }

  $self->{factoids}->{hash}->{$channel}->{$keyword}->{ref_count}++;
  $self->{factoids}->{hash}->{$channel}->{$keyword}->{ref_user} = "$stuff->{nick}!$stuff->{user}\@$stuff->{host}";
  $self->{factoids}->{hash}->{$channel}->{$keyword}->{last_referenced_on} = gettimeofday;
  $self->{factoids}->{hash}->{$channel}->{$keyword}->{last_referenced_in} = $stuff->{from} || "stdin";

  my $action;

  if (exists $self->{factoids}->{hash}->{$channel}->{$keyword}->{usage} and not length $stuff->{arguments} and $self->{factoids}->{hash}->{$channel}->{$keyword}->{requires_arguments}) {
    $stuff->{alldone} = 1;
    my $usage = $self->{factoids}->{hash}->{$channel}->{$keyword}->{usage};
    $usage =~ s/\$0|\$\{0\}/$trigger_name/g;
    return $usage;
  }

  if (length $stuff->{arguments} and exists $self->{factoids}->{hash}->{$channel}->{$keyword}->{action_with_args}) {
    $action = $self->{factoids}->{hash}->{$channel}->{$keyword}->{action_with_args};
  } else {
    $action = $self->{factoids}->{hash}->{$channel}->{$keyword}->{action};
  }

  if ($action =~ m{^/code\s+([^\s]+)\s+(.+)$}msi) {
    my ($lang, $code) = ($1, $2);

    if (exists $self->{factoids}->{hash}->{$channel}->{$keyword}->{usage} and not length $stuff->{arguments}) {
      $stuff->{alldone} = 1;
      my $usage = $self->{factoids}->{hash}->{$channel}->{$keyword}->{usage};
      $usage =~ s/\$0|\$\{0\}/$trigger_name/g;
      return $usage;
    }

    $stuff->{lang} = $lang;
    $stuff->{code} = $code;
    $self->execute_code_factoid($stuff);
    return "";
  }

  return $self->handle_action($stuff, $action);
}

sub handle_action {
  my ($self, $stuff, $action) = @_;

  if ($self->{pbot}->{registry}->get_value('general', 'debugcontext')) {
    use Data::Dumper;
    $Data::Dumper::Sortkeys  = 1;
    $self->{pbot}->{logger}->log("Factoids::handle_action [$action]\n");
    $self->{pbot}->{logger}->log(Dumper $stuff);
  }

  return "" if not length $action;

  my ($channel, $keyword) = ($stuff->{channel}, $stuff->{trigger});
  my ($channel_name, $trigger_name) = ($stuff->{channel_name}, $stuff->{trigger_name});
  my $ref_from = $stuff->{ref_from} ? "[$stuff->{ref_from}] " : "";

  unless (exists $self->{factoids}->{hash}->{$channel}->{$keyword}->{interpolate} and $self->{factoids}->{hash}->{$channel}->{$keyword}->{interpolate} eq '0') {
    my ($root_channel, $root_keyword) = $self->find_factoid($stuff->{ref_from} ? $stuff->{ref_from} : $stuff->{from}, $stuff->{root_keyword}, arguments => $stuff->{arguments}, exact_channel => 1);
    if (not defined $root_channel or not defined $root_keyword) {
      $root_channel = $channel;
      $root_keyword = $keyword;
    }
    if (not length $stuff->{keyword_override} and length $self->{factoids}->{hash}->{$root_channel}->{$root_keyword}->{keyword_override}) {
      $stuff->{keyword_override} = $self->{factoids}->{hash}->{$root_channel}->{$root_keyword}->{keyword_override};
    }
    $stuff->{action} = $action;
    $action = $self->expand_factoid_vars($stuff);
  }

  if (length $stuff->{arguments}) {
    if ($action =~ m/\$\{?args/ or $action =~ m/\$\{?arg\[/) {
      unless (defined $self->{factoids}->{hash}->{$channel}->{$keyword}->{interpolate} and $self->{factoids}->{hash}->{$channel}->{$keyword}->{interpolate} eq '0') {
        $action = $self->expand_action_arguments($action, $stuff->{arguments}, $stuff->{nick});
        $stuff->{no_nickoverride} = 1;
      } else {
        $stuff->{no_nickoverride} = 0;
      }
      $stuff->{arguments} = "";
      $stuff->{original_arguments} = "";
    } else {
      if ($self->{factoids}->{hash}->{$channel}->{$keyword}->{type} eq 'text') {
        my $target = $self->{pbot}->{nicklist}->is_present_similar($stuff->{from}, $stuff->{arguments});

        if ($target and $action !~ /\$\{?(?:nick|args)\b/) {
          $stuff->{nickoverride} = $target unless $stuff->{force_nickoverride};
          $stuff->{no_nickoverride} = 0;
        } else {
          $stuff->{no_nickoverride} = 1;
        }
      }
    }
  } else {
    # no arguments supplied, replace $args with $nick/$tonick, etc
    if (exists $self->{factoids}->{hash}->{$channel}->{$keyword}->{usage}) {
      $action = "/say " . $self->{factoids}->{hash}->{$channel}->{$keyword}->{usage};
      $action =~ s/\$0|\$\{0\}/$trigger_name/g;
      $stuff->{alldone} = 1;
    } else {
      if ($self->{factoids}->{hash}->{$channel}->{$keyword}->{'allow_empty_args'}) {
        $action = $self->expand_action_arguments($action, undef, '');
      } else {
        $action = $self->expand_action_arguments($action, undef, $stuff->{nick});
      }
    }
    $stuff->{no_nickoverride} = 0;
  }

  # Check if it's an alias
  if ($action =~ /^\/call\s+(.*)$/msi) {
    my $command = $1;
    $command =~ s/\n$//;
    unless ($self->{factoids}->{hash}->{$channel}->{$keyword}->{'require_explicit_args'}) {
      my $args = $stuff->{arguments};
      $command .= " $args" if length $args and not $stuff->{special} eq 'code-factoid';
      $stuff->{arguments} = '';
    }

    unless ($self->{factoids}->{hash}->{$channel}->{$keyword}->{'no_keyword_override'}) {
      if ($command =~ s/\s*--keyword-override=([^ ]+)\s*//) {
        $stuff->{keyword_override} = $1;
      }
    }

    $stuff->{command} = $command;
    $stuff->{aliased} = 1;

    $self->{pbot}->{logger}->log("[" . (defined $stuff->{from} ? $stuff->{from} : "stdin") . "] ($stuff->{nick}!$stuff->{user}\@$stuff->{host}) $trigger_name aliased to: $command\n");

    if (defined $self->{factoids}->{hash}->{$channel}->{$keyword}->{'cap-override'}) {
        if ($self->{factoids}->{hash}->{$channel}->{$keyword}->{'locked'}) {
          $self->{pbot}->{logger}->log("Capability override set to $self->{factoids}->{hash}->{$channel}->{$keyword}->{'cap-override'}\n");
          $stuff->{'cap-override'} = $self->{factoids}->{hash}->{$channel}->{$keyword}->{'cap-override'};
        } else {
          $self->{pbot}->{logger}->log("Ignoring cap-override of $self->{factoids}->{hash}->{$channel}->{$keyword}->{'cap-override'} on unlocked factoid\n");
        }
    }

    return $self->{pbot}->{interpreter}->interpret($stuff);
  }

  $self->{pbot}->{logger}->log("(" . (defined $stuff->{from} ? $stuff->{from} : "(undef)") . "): $stuff->{nick}!$stuff->{user}\@$stuff->{host}: $trigger_name: action: \"$action\"\n");

  if ($self->{factoids}->{hash}->{$channel}->{$keyword}->{enabled} == 0) {
    $self->{pbot}->{logger}->log("$trigger_name disabled.\n");
    return "/msg $stuff->{nick} ${ref_from}$trigger_name is currently disabled.";
  }

  unless (exists $self->{factoids}->{hash}->{$channel}->{$keyword}->{interpolate} and $self->{factoids}->{hash}->{$channel}->{$keyword}->{interpolate} eq '0') {
    my ($root_channel, $root_keyword) = $self->find_factoid($stuff->{ref_from} ? $stuff->{ref_from} : $stuff->{from}, $stuff->{root_keyword}, arguments => $stuff->{arguments}, exact_channel => 1);
    if (not defined $root_channel or not defined $root_keyword) {
      $root_channel = $channel;
      $root_keyword = $keyword;
    }
    if (not length $stuff->{keyword_override} and length $self->{factoids}->{hash}->{$root_channel}->{$root_keyword}->{keyword_override}) {
      $stuff->{keyword_override} = $self->{factoids}->{hash}->{$root_channel}->{$root_keyword}->{keyword_override};
    }
    $stuff->{action} = $action;
    $action = $self->expand_factoid_vars($stuff);

    if ($self->{factoids}->{hash}->{$channel}->{$keyword}->{'allow_empty_args'}) {
      $action = $self->expand_action_arguments($action, $stuff->{arguments}, '');
    } else {
      $action = $self->expand_action_arguments($action, $stuff->{arguments}, $stuff->{nick});
    }
  }

  return $action if $stuff->{special} eq 'code-factoid';

  if ($self->{factoids}->{hash}->{$channel}->{$keyword}->{type} eq 'module') {
    my $preserve_whitespace = $self->{factoids}->{hash}->{$channel}->{$keyword}->{preserve_whitespace};
    $preserve_whitespace = 0 if not defined $preserve_whitespace;

    $stuff->{preserve_whitespace} = $preserve_whitespace;
    $stuff->{root_keyword} = $keyword unless defined $stuff->{root_keyword};
    $stuff->{root_channel} = $channel;

    my $result = $self->{factoidmodulelauncher}->execute_module($stuff);
    if (length $result) {
      return $ref_from . $result;
    } else {
      return "";
    }
  }
  elsif ($self->{factoids}->{hash}->{$channel}->{$keyword}->{type} eq 'text') {
    # Don't allow user-custom /msg factoids, unless factoid triggered by admin
    if ($action =~ m/^\/msg/i) {
      my $admin = $self->{pbot}->{users}->loggedin_admin($stuff->{from}, "$stuff->{nick}!$stuff->{user}\@$stuff->{host}");
      if (not $admin) {
        $self->{pbot}->{logger}->log("[ABUSE] Bad factoid (contains /msg): $action\n");
        return "You must be an admin to use /msg in a factoid.";
      }
    }

    if ($ref_from) {
      if ($action =~ s/^\/say\s+/$ref_from/i || $action =~ s/^\/me\s+(.*)/\/me $1 $ref_from/i
        || $action =~ s/^\/msg\s+([^ ]+)/\/msg $1 $ref_from/i) {
        return $action;
      } else {
        return $ref_from . "$trigger_name is $action";
      }
    } else {
      if ($action =~ m/^\/(?:say|me|msg)/i) {
        return $action;
      } else {
        return "/say $trigger_name is $action";
      }
    }
  } elsif ($self->{factoids}->{hash}->{$channel}->{$keyword}->{type} eq 'regex') {
    my $result = eval {
      my $string = "$stuff->{original_keyword}" . (defined $stuff->{arguments} ? " $stuff->{arguments}" : "");
      my $cmd;
      if ($string =~ m/$keyword/i) {
        $self->{pbot}->{logger}->log("[$string] matches [$keyword] - calling [" . $action . "$']\n");
        $cmd = $action . $';
        my ($a, $b, $c, $d, $e, $f, $g, $h, $i, $before, $after) = ($1, $2, $3, $4, $5, $6, $7, $8, $9, $`, $');
        $cmd =~ s/\$1/$a/g;
        $cmd =~ s/\$2/$b/g;
        $cmd =~ s/\$3/$c/g;
        $cmd =~ s/\$4/$d/g;
        $cmd =~ s/\$5/$e/g;
        $cmd =~ s/\$6/$f/g;
        $cmd =~ s/\$7/$g/g;
        $cmd =~ s/\$8/$h/g;
        $cmd =~ s/\$9/$i/g;
        $cmd =~ s/\$`/$before/g;
        $cmd =~ s/\$'/$after/g;
        $cmd =~ s/^\s+//;
        $cmd =~ s/\s+$//;
      } else {
        $cmd = $action;
      }

      $stuff->{command} = $cmd;
      return $self->{pbot}->{interpreter}->interpret($stuff);
    };

    if ($@) {
      $self->{pbot}->{logger}->log("Regex fail: $@\n");
      return "";
    }

    if (length $result) {
      return $ref_from . $result;
    } else {
      return "";
    }
  } else {
    $self->{pbot}->{logger}->log("($stuff->{from}): $stuff->{nick}!$stuff->{user}\@$stuff->{host}): Unknown command type for '$trigger_name'\n");
    return "/me blinks." . " $ref_from";
  }
}

1;