#!/usr/bin/env perl

use 5.010;
use Data::Dumper;
use Getopt::Long;
use Pod::Usage;
use Time::Local;
use IO::Handle;
use warnings;
use strict;

my @symbols_search;
my @symbols_exclude;
my @symbols_bidirectional;
my @symbols_groups;
my @symbols_ignored;
my %groups;
my $reject_score = 15.0;
my $junk_score = 6.0;
my $diff_alpha = 0.1;
my $correlations = 0;
my $nrelated = 10;
my $log_file = "";
my $search_pattern = "";
my $startTime="";
my $endTime;
my $num_logs;
my $exclude_logs = 0;
my $man = 0;
my $json = 0;
my $help = 0;

# Associate file extensions with decompressors
my %decompressor = (
    'bz2' => 'bzip2 -cd',
    'gz'  => 'gzip -cd',
    'xz'  => 'xz -cd',
    'zst' => 'zstd -cd',
);

GetOptions(
  "reject-score|r=f"      => \$reject_score,
  "junk-score|j=f"        => \$junk_score,
  "symbol|s=s@"           => \@symbols_search,
  "symbol-bidir|S=s@"     => \@symbols_bidirectional,
  "exclude|X=s@"          => \@symbols_exclude,
  "ignore=s@"             => \@symbols_ignored,
  "group|g=s@"            => \@symbols_groups,
  "log|l=s"               => \$log_file,
  "alpha-score|alpha|a=f" => \$diff_alpha,
  "correlations|c"        => \$correlations,
  "nrelated=i"            => \$nrelated,
  "search-pattern=s"      => \$search_pattern,
  "start=s"               => \$startTime,
  "end=s"                 => \$endTime,
  "num-logs|n=i"          => \$num_logs,
  "exclude-logs|x=i"      => \$exclude_logs,
  "json|j"                => \$json,
  "help|?"                => \$help,
  "man"                   => \$man
) or pod2usage(2);

pod2usage(1) if $help;
pod2usage(-exitval => 0, -verbose => 2) if $man;


# Global vars
my $total = 0;
my $total_spam = 0;
my $total_junk = 0;
my $junk_symbols = 0;
my $spam_symbols = 0;
my $ham_symbols = 0;
my $ham_spam_change = 0;
my $ham_junk_change = 0;
my %sym_res;
my $rspamd_log;
my $enabled = 0;
my $log_file_num = 1;
my $spinner_update_time = 0;

my %action;
my %timeStamp;
my %scanTime = (
    max   => 0,
    total => 0,
);
my %bidir_match;

foreach ( $startTime, $endTime ) { $_ = &normalized_time($_) }

# Convert bidirectional symbols
foreach my $s (@symbols_bidirectional) {
  $bidir_match{$s} = {
    spam => "${s}_SPAM",
    ham  => "${s}_HAM",
  };
  push @symbols_search, $s unless grep /^$s$/, @symbols_search;
}

# Deal with groups
my $group_id = 0;
foreach my $g (@symbols_groups) {
  my @symbols = split /,/,$g;
  my $group_name = "group$group_id";

  foreach my $s (@symbols) {
    $groups{$s} = $group_name;
    push @symbols_search, $s unless grep /^$s$/, @symbols_search;
  }
}

@symbols_search = '.*'
  unless @symbols_search;

if ($log_file eq '-' || $log_file eq '') {
  $rspamd_log = \*STDIN;
  &ProcessLog();
}
elsif ( -d "$log_file" ) {
  my $log_dir = "$log_file";

  my @logs = &GetLogfilesList($log_dir);

  # Process logs
  foreach (@logs) {
    my $ext = (/[^.]+\.?([^.]*?)$/)[0];
    my $dc = $decompressor{$ext} || 'cat';

    open( $rspamd_log, "-|", "$dc $log_dir/$_" )
      or die "cannot execute $dc $log_dir/$_ : $!";

    printf {interactive(*STDERR)} "\033[J  Parsing log files: [%d/%d] %s\033[G", $log_file_num++, scalar @logs, $_;
    $spinner_update_time = 0;   # Force spinner update
    &spinner;

    &ProcessLog;

    close($rspamd_log)
      or warn "cannot close $dc $log_dir/$_: $!";
  }
  print {interactive(*STDERR)} "\033[J\033[G";   # Progress indicator clean-up
}
else {
  my $ext = ($log_file =~ /[^.]+\.?([^.]*?)$/)[0];
  my $dc = $decompressor{$ext} || 'cat';
  open( $rspamd_log, "-|", "$dc $log_file" )
    or die "cannot execute $dc $log_file : $!";
  $spinner_update_time = 0;   # Force spinner update
  &spinner;
  &ProcessLog();
}

my $total_ham = $total - ($total_spam + $total_junk);

if ($json) {
  print "{";
  &Summary();
  print '"symbols":{';
  &SymbolsStat();
  print "}}\n";
}
else {
  &SymbolsStat();
  &Summary();
}

exit;

sub IsIgnored {
  my ($sym) = @_;

  foreach my $ex (@symbols_ignored) {
    if ($sym =~ /^$ex$/) {
      return 1;
    }
  }

  return 0;
}

sub GenRelated {
  my ($htb, $target_sym) = @_;

  my @result;
  my $i = 0;
  foreach my $sym (sort { $htb->{$b} <=> $htb->{$a} } keys %{$htb}) {
    if ($sym ne $target_sym) {
      my @elt = ($sym, $htb->{$sym});
      push @result, \@elt;
      $i ++;
    }

    last if $i > $nrelated;
  }

  return \@result;
}

sub StringifyRelated {
  my ($ar, $total) = @_;
  return join("\n", (map { sprintf "\t%s(%s: %.1f%%)",
    $_->[0], $_->[1], $_->[1] / ($total * 1.0) * 100.0 } @{$ar}));
}

sub SymbolsStat {
  if ($total > 0) {
    my $has_comma = 0;
    while (my ($s, $r) = each(%sym_res)) {
      if ($r->{hits} > 0) {
        my $th = $r->{hits};
        my $sh = $r->{spam_hits};
        my $jh = $r->{junk_hits};
        my $hh = $r->{hits} - $sh - $jh;
        my $htp = $hh * 100.0 / $total_ham if $total_ham != 0;
        my $stp = $sh * 100.0 / $total_spam if $total_spam != 0;
        my $jtp = $jh * 100.0 / $total_junk if $total_junk != 0;

        if ($json) {
          if ($has_comma) {
            print ",";
          }
          else {
            $has_comma = 1;
          }
          print "\"$s\":{";
          JsonObjectElt("avg_weight", $r->{'weight'},"%.4f");
          print ",";
          JsonObjectElt("hits", $th, "%d");
          print ",";
          JsonObjectElt("hits_percentage", $th/$total, "%.4f");
          print ",";
          JsonObjectElt("spam_hits", $sh, "%d");
          print ",";
          JsonObjectElt("spam_to_total", $sh/$th, "%.4f");
          print ",";
          JsonObjectElt("spam_percentage", $stp/100.0 || 0, "%.4f");
          print ",";
          JsonObjectElt("ham_hits", $hh, "%d");
          print ",";
          JsonObjectElt("ham_to_total", $hh/$th, "%.4f");
          print ",";
          JsonObjectElt("ham_percentage", $htp/100.0 || 0, "%.4f");
          print ",";
          JsonObjectElt("junk_hits", $jh, "%d");
          print ",";
          JsonObjectElt("junk_to_total", $jh/$th, "%.4f");
          print ",";
          JsonObjectElt("junk_percentage", $jtp/100.0 || 0, "%.4f");
        }
        else {
          printf "%s   avg. weight %.3f, hits %d(%.3f%%):
  Ham  %7.3f%%, %6d/%-6d (%7.3f%%)
  Spam %7.3f%%, %6d/%-6d (%7.3f%%)
  Junk %7.3f%%, %6d/%-6d (%7.3f%%)
",
            $s, $r->{weight} / $r->{hits}, $th, ($th / $total * 100),
            ($hh / $th * 100), $hh, $total_ham, ($htp or 0),
            ($sh / $th * 100), $sh, $total_spam, ($stp or 0),
            ($jh / $th * 100), $jh, $total_junk, ($jtp or 0);
        }

        my $schp = $r->{spam_change} / $total_spam * 100.0 if $total_spam;
        my $jchp = $r->{junk_change} / $total_junk * 100.0 if $total_junk;

        if ($r->{weight} != 0) {
          if (!$json) {
            if ($r->{weight} > 0) {
              printf "
Spam changes (ham/junk -> spam): %6d/%-6d (%7.3f%%)
Spam  changes / total spam hits: %6d/%-6d (%7.3f%%)
Junk changes      (ham -> junk): %6d/%-6d (%7.3f%%)
Junk  changes / total junk hits: %6d/%-6d (%7.3f%%)
",
                $r->{spam_change}, $th, ($r->{spam_change} / $th * 100),
                $r->{spam_change}, $total_spam, ($schp or 0),
                $r->{junk_change}, $th, ($r->{junk_change} / $th * 100),
                $r->{junk_change}, $total_junk, ($jchp or 0);
            }
            else {
              printf "
Spam changes (spam -> junk/ham): %6d/%-6d (%7.3f%%)
Spam changes / total spam hits : %6d/%-6d (%7.3f%%)
Junk changes (junk -> ham)     : %6d/%-6d (%7.3f%%)
Junk changes / total junk hits : %6d/%-6d (%7.3f%%)
",
                $r->{spam_change}, $th, ($r->{spam_change} / $th * 100),
                $r->{spam_change}, $total_spam, ($schp or 0),
                $r->{junk_change}, $th, ($r->{junk_change} / $th * 100),
                $r->{junk_change}, $total_junk, ($jchp or 0);
            }
          }
          else {
            print ",";
            JsonObjectElt("spam_change", $r->{spam_change}, "%.4f");
            print ",";
            JsonObjectElt("junk_change", $r->{junk_change}, "%.4f");
          }
        }

        if ($correlations) {

          my $spam_related = GenRelated($r->{symbols_met_spam}, $s);
          my $junk_related = GenRelated($r->{symbols_met_junk}, $s);
          my $ham_related = GenRelated($r->{symbols_met_ham}, $s);

          if (!$json) {
            print "Correlations report:\n";

            while (my ($cs, $hits) = each %{$r->{corr}}) {
              my $corr_prob = $r->{'hits'} / $total;
              my $merged_hits = 0;
              if($r->{symbols_met_spam}->{$cs}) {
                $merged_hits += $r->{symbols_met_spam}->{$cs};
              }
              if($r->{symbols_met_junk}->{$cs}) {
                $merged_hits += $r->{symbols_met_junk}->{$cs};
              }
              if($r->{symbols_met_ham}->{$cs}) {
                $merged_hits += $r->{symbols_met_ham}->{$cs};
              }

              if ($merged_hits > 0) {
                printf "Probability of %s when %s fires: %.3f\n", $cs, $s,
                  (($merged_hits / $total) / $corr_prob);
              }
            }

            print "Related symbols report:\n";
            printf "Top related in spam:\n %s\n", StringifyRelated($spam_related,
              $r->{spam_hits});
            printf "Top related in junk:\n %s\n", StringifyRelated($junk_related,
              $r->{junk_hits});
            printf "Top related in ham:\n %s\n", StringifyRelated($ham_related,
              $r->{hits} - $r->{spam_hits} - $r->{junk_hits});
          }
          else {
            print ",";
            print "\"correllations\":{";

            my $has_comma_ = 0;
            while (my ($cs, $hits) = each %{$r->{corr}}) {
              if ($has_comma_) {
                print ",";
              }
              else {
                $has_comma_ = 1;
              }
              my $corr_prob = $hits / $total;
              my $sym_prob = $r->{hits} / $total;
              JsonObjectElt($cs, ($corr_prob / $sym_prob) ,"%.4f");
            }

            print "}";
          }
        }

        print "}" if $json;
      }
      else {
        print "Symbol $s has not been met\n" if !$json;
      }

      print '-' x 80 . "\n" if !$json;
    }
  }
}

sub Summary() {
  if (!$json) {
    print "
=== Summary ", '=' x 68, "
Messages scanned: $total";
    printf " [ %s / %s ]
", $timeStamp{'start'}, $timeStamp{'end'}
      if defined $timeStamp{'start'};
    say '';
    printf "%11s: %6.2f%%, %d\n", $_, 100 * $action{$_} / $total, $action{$_}
      for sort keys %action;
    say '';
    printf "scan time min/avg/max = %.2f/%.2f/%.2f s
", $scanTime{'min'} / 1000,
        ($total) ? $scanTime{'total'} / $total / 1000 : undef,
      $scanTime{'max'} / 1000
      if exists $scanTime{'min'};
    say '=' x 80;
  }
  else {
    JsonObjectElt("total", $total, "%d");
    print ",";

    if (defined $timeStamp{'start'}) {
      JsonObjectElt("start", $timeStamp{'start'});
      print ",";
    }

    if (defined $timeStamp{'end'}) {
      JsonObjectElt("end", $timeStamp{'end'});
      print ",";
    }

    print "\"actions\":{";

    my $has_comma = 0;
    foreach my $a (sort keys %action) {
      if ($has_comma) {
        print ",";
      }
      else {
        $has_comma = 1;
      }
      JsonObjectElt($a, $action{$a}, "%d");
    }
    print "},";
  }
}

sub ProcessRelated {
  my ($symbols, $target, $source) = @_;

  foreach my $s (@{$symbols}) {
    $s =~ /^([^\(]+)(\(([^\)]+)\))?/;
    my $sym_name = $1;
    my $sym_score = 0;

    if ($groups{$sym_name}) {
      $sym_name = $groups{$sym_name};
    }

    next if ($source eq $sym_name);

    next if IsIgnored($sym_name);

    if ($2) {
      $sym_score = $3 * 1.0;

      if (abs($sym_score) < $diff_alpha) {
        next;
      }

      my $bm = $bidir_match{$sym_name};
      if ($bm) {
        if ($sym_score >= 0) {
          $sym_name = $bm->{'spam'};
        }
        else {
          $sym_name = $bm->{'ham'};
        }
      }
    }

    if (exists($target->{$sym_name})) {
      $target->{$sym_name} ++;
    }
    else {
      $target->{$sym_name} = 1;
    }
  }
}

sub ProcessLog {
  my ( $ts_format, @line ) = &log_time_format($rspamd_log);

  while() {
    last if eof $rspamd_log;
    $_ = (@line) ? shift @line : <$rspamd_log>;

    if (!$enabled && ($search_pattern eq "" || /$search_pattern/)) {
      $enabled = 1;
    }

    next if !$enabled;

    if (/^.*rspamd_task_write_log.*$/) {
      &spinner;
      my $ts;
      if ( $ts_format eq 'syslog' ) {
        $ts = syslog2iso( join ' ', ( split /\s+/ )[ 0 .. 2 ] );
      } elsif ( $ts_format eq 'syslog5424' ) {
        /^([0-9-]+)T([0-9:]+)/;
        $ts = "$1 $2";
      } else {
        $ts = join ' ', ( split /\s+/ )[ 0 .. 1 ];
      }

      next if ( $ts lt $startTime );
      next if ( defined $endTime && $ts gt $endTime );

      if ($_ !~ /\(([^()]+)\): \[(NaN|-?\d+(?:\.\d+)?)\/(-?\d+(?:\.\d+)?)\]\s+\[([^\]]+)\].+? time: (\d+\.\d+)ms real/) {
        #print "BAD: $_\n";
        next;
      }

      my @symbols = split /(?:\{[^}]*\})?(?:$|,)/, $4;
      my $scan_time = $5;
      my $act = $1;
      my $score = $2 * 1.0;
      my $skip = 0;

      foreach my $ex (@symbols_exclude) {
        my @found = grep {/^$ex/} @symbols;

        if (scalar(@found) > 0) {
          $skip = 1;
          last;
        }
      }

      next if ( $skip != 0 );

      if (defined($timeStamp{'end'})) {
        $timeStamp{'end'} = $ts if ( $ts gt $timeStamp{'end'} );
      }
      else {
        $timeStamp{'end'} = $ts;
      }

      if (defined($timeStamp{'start'})) {
        $timeStamp{'start'} = $ts if ( $ts lt $timeStamp{'start'} );
      }
      else {
        $timeStamp{'start'} = $ts;
      }

      $scanTime{'min'} = $scan_time if ( !exists $scanTime{'min'} || $scanTime{'min'} > $scan_time );
      $scanTime{'max'} = $scan_time if ( $scanTime{'max'} < $scan_time );
      $scanTime{'total'} += $scan_time;

      $action{$act}++;
      $total ++;

      if ($score >= $reject_score) {
        $total_spam ++;
      }
      elsif ($score >= $junk_score) {
        $total_junk ++;
      }

      my @sym_names;

      foreach my $s (@symbols_search) {
        my @selected = grep /$s/, @symbols;

        if (scalar(@selected) > 0) {

          foreach my $sym (@selected) {
            $sym =~ /^([^\(]+)(\(([^\)]+)\))?/;
            my $sym_name = $1;
            my $sym_score = 0;
            my $orig_name = $sym_name;

            if ($2) {
              $sym_score = $3 * 1.0;

              if (abs($sym_score) < $diff_alpha) {
                next;
              }

              my $bm = $bidir_match{$sym_name};
              if ($bm) {
                if ($sym_score >= 0) {
                  $sym_name = $bm->{'spam'};
                }
                else {
                  $sym_name = $bm->{'ham'};
                }
              }
            }

            next if $orig_name !~ /^$s/;

            if ($groups{$s}) {
              # Replace with group
              $sym_name = $groups{$s};
            }

            push @sym_names, $sym_name;

            if (!$sym_res{$sym_name}) {
              $sym_res{$sym_name} = {
                hits             => 0,
                spam_hits        => 0,
                junk_hits        => 0,
                spam_change      => 0,
                junk_change      => 0,
                weight           => 0,
                corr             => {},
                symbols_met_spam => {},
                symbols_met_ham  => {},
                symbols_met_junk => {},
              };
            }

            my $r = $sym_res{$sym_name};

            $r->{hits} ++;
            $r->{weight} += $sym_score;
            my $is_spam = 0;
            my $is_junk = 0;

            if ($score >= $reject_score) {
              $is_spam = 1;
              $r->{spam_hits} ++;
              if ($correlations) {
                ProcessRelated(\@symbols, $r->{symbols_met_spam}, $sym_name);
              }
            }
            elsif ($score >= $junk_score) {
              $is_junk = 1;
              $r->{junk_hits} ++;
              if ($correlations) {
                ProcessRelated(\@symbols, $r->{symbols_met_junk}, $sym_name);
              }
            }
            else {
              if ($correlations) {
                ProcessRelated(\@symbols, $r->{symbols_met_ham}, $sym_name);
              }
            }

            if ($sym_score != 0) {
              my $score_without = $score - $sym_score;

              if ($sym_score > 0) {
                if ($is_spam && $score_without < $reject_score) {
                  $r->{spam_change} ++;
                }
                if ($is_junk && $score_without < $junk_score) {
                  $r->{junk_change} ++;
                }
              }
              else {
                if (!$is_spam && $score_without >= $reject_score) {
                  $r->{spam_change} ++;
                }
                if (!$is_junk && $score_without >= $junk_score) {
                  $r->{junk_change} ++;
                }
              }
            }
          } # End foreach symbols selected
        }
      }

      if ($correlations) {
        foreach my $sym (@sym_names) {
          next if IsIgnored($sym);
          my $r = $sym_res{$sym};

          foreach my $corr_sym (@sym_names) {
            if ($corr_sym ne $sym) {
              if ($r->{'corr'}->{$corr_sym}) {
                $r->{'corr'}->{$corr_sym} ++;
              }
              else {
                $r->{'corr'}->{$corr_sym} = 1;
              }
            }
          }
        } # End of correlations check
      }
    }
  }
}

sub JsonObjectElt() {
  my ($k, $v) = @_;
  my $f = defined $_[2] ? $_[2] : '%s';

  if ($f eq "%s") {
    $f = "\"%s\"";
  }

  printf "\"%s\":$f", $k, $v;
}

sub GetLogfilesList {
  my ($dir) = @_;
  opendir( DIR, $dir ) or die $!;

  my $pattern = join( '|', keys %decompressor );
  my $re = qr/\.[0-9]+(?:\.(?:$pattern))?/;

  # Add unnumbered logs first
  my @logs =
    grep { -f "$dir/$_" && !/$re/ } readdir(DIR);

  # Add numbered logs
  rewinddir(DIR);
  push( @logs,
    ( sort numeric ( grep { -f "$dir/$_" && /$re/ } readdir(DIR) ) ) );

  closedir(DIR);

  # Select required logs and revers their order
  @logs =
    reverse
      splice( @logs, $exclude_logs, $num_logs ||= @logs - $exclude_logs );

  # Loop through array printing out filenames
  print {interactive(*STDERR)} "\nLog files to process:\n";
  foreach my $file (@logs) {
    print {interactive(*STDERR)} "  $file\n";
  }
  print {interactive(*STDERR)} "\n";

  return @logs;
}

sub log_time_format {
  my $fh = shift;
  my ( $format, $line );
  while (<$fh>) {
    $line = $_;

    # 2017-08-08 00:00:01 #66984(
    # 2017-08-08 00:00:01.001 #66984(
    if (/^\d{4}-\d\d-\d\d \d\d:\d\d:\d\d(\.\d{3})? #\d+\(/) {
      $format = 'rspamd';
      last;
    }

    # Aug  8 00:02:50 #66986(
    elsif (/^\w{3} (?:\s?\d|\d\d) \d\d:\d\d:\d\d #\d+\(/) {
      $format = 'syslog';
      last;
    }

    # Aug  8 00:02:50 hostname rspamd[66986]
    elsif (/^\w{3} (?:\s?\d|\d\d) \d\d:\d\d:\d\d \S+ rspamd\[\d+\]/) {
      $format = 'syslog';
      last;
    }

    # 2018-04-16T06:25:46.012590+02:00 rspamd rspamd[12968]
    elsif(/\d{4}-\d{2}-\d{2}T\d{2}:\d{2}:\d{2}(\.\d{1,6})?(Z|[-+]\d{2}:\d{2}) \S+ rspamd\[\d+\]/) {
      $format = 'syslog5424';
      last;
    }

    # Skip newsyslog messages
    # Aug  8 00:00:00 hostname newsyslog[63284]: logfile turned over
    elsif ( /^\w{3} (?:\s?\d|\d\d) \d\d:\d\d:\d\d\ \S+ newsyslog\[\d+\]: logfile turned over$/ ) {
      next;
    }
    # Skip journalctl messages
    # -- Logs begin at Mon 2018-01-15 11:16:24 MSK, end at Fri 2018-04-27 09:10:30 MSK. --
    elsif ( /^-- Logs begin at \w{3} \d{4}-\d\d-\d\d \d\d:\d\d:\d\d [A-Z]{3}, end at \w{3} \d{4}-\d\d-\d\d \d\d:\d\d:\d\d [A-Z]{3}\. --$/ ) {
      next;
    }
    else {
      print "Unknown log format\n";
      exit 1;
    }
  }
  return ( $format, $line );
}

sub normalized_time {
  return undef
    if !defined( $_ = shift );

  /^\d\d(?::\d\d){0,2}$/
    ? sprintf '%04d-%02d-%02d %s', 1900 + (localtime)[5], 1 + (localtime)[4],
    (localtime)[3], $_
    : $_;
}

sub numeric {
  $a =~ /\.(\d+)\./;
  my $a_num = $1;
  $b =~ /\.(\d+)\./;
  my $b_num = $1;

  $a_num <=> $b_num;
}

sub spinner {
    my @spinner = qw{/ - \ |};
    return
      if ( ( time - $spinner_update_time ) < 1 );
    $spinner_update_time = time;
    printf {interactive(*STDERR)} "%s\r", $spinner[ $spinner_update_time % @spinner ];
    select()->flush();
}

# Convert syslog timestamp to "ISO 8601 like" format
# using current year as syslog does not record the year (nor the timezone)
# or the last year if the guessed time is in the future.
sub syslog2iso {
  my %month_map;
  @month_map{qw(Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec)} = 0 .. 11;

  my ( $month, @t ) =
    $_[0] =~ m/^(\w{3}) \s\s? (\d\d?) \s (\d\d):(\d\d):(\d\d)/x;
  my $epoch =
    timelocal( ( reverse @t ), $month_map{$month}, 1900 + (localtime)[5] );
  sprintf '%04d-%02d-%02d %02d:%02d:%02d',
    1900 + (localtime)[5] - ( $epoch > time ),
    $month_map{$month} + 1, @t;
}

### Imported from IO::Interactive 1.022 Perl module
sub is_interactive {
    my ($out_handle) = (@_, select);    # Default to default output handle

    # Not interactive if output is not to terminal...
    return 0 if not -t $out_handle;

    # If *ARGV is opened, we're interactive if...
    if ( tied(*ARGV) or defined(fileno(ARGV)) ) { # this is what 'Scalar::Util::openhandle *ARGV' boils down to

        # ...it's currently opened to the magic '-' file
        return -t *STDIN if defined $ARGV && $ARGV eq '-';

        # ...it's at end-of-file and the next file is the magic '-' file
        return @ARGV>0 && $ARGV[0] eq '-' && -t *STDIN if eof *ARGV;

        # ...it's directly attached to the terminal
        return -t *ARGV;
    }

    # If *ARGV isn't opened, it will be interactive if *STDIN is attached
    # to a terminal.
    else {
        return -t *STDIN;
    }
}

### Imported from IO::Interactive 1.022 Perl module
local (*DEV_NULL, *DEV_NULL2);
my $dev_null;
BEGIN {
    pipe *DEV_NULL, *DEV_NULL2
        or die "Internal error: can't create null filehandle";
    $dev_null = \*DEV_NULL;
}

### Imported from IO::Interactive 1.022 Perl module
sub interactive {
    my ($out_handle) = (@_, \*STDOUT);      # Default to STDOUT
    return &is_interactive ? $out_handle : $dev_null;
}

__END__

=head1 NAME

rspamd_stats - analyze Rspamd rules by parsing log files

=head1 SYNOPSIS

rspamd_stats [options] [--symbol=SYM1 [--symbol=SYM2...]] [--log file]

 Options:
   --log=file             log file or directory to read (stdin by default)
   --reject-score=score   set reject threshold (15 by default)
   --junk-score=score     set junk score (6.0 by default)
   --symbol=sym           check specified symbol (perl regexps, '.*' by default)
   --alpha-score=score    set ignore score for symbols (0.1 by default)
   --correlations         enable correlations report
   --nrelated=integer     show that amount of related symbols (10 by default)
   --search-pattern       do not process input unless the desired pattern is found
   --start                starting time (oldest) for log parsing
   --end                  ending time (newest) for log parsing
   --num-logs=integer     number of recent logfiles to analyze (all files in the directory by default)
   --exclude-logs=integer number of latest logs to exclude (0 by default)
   --json                 print json output instead of human readable
   --help                 brief help message
   --man                  full documentation

=head1 OPTIONS

=over 8

=item B<--log>

Specifies log file or directory to read data from.
If a directory is specified B<rspamd_stats> analyses files in the directory
including known compressed file types. Number of log files can be limited using
B<--num-logs> and B<--exclude-logs> options. This assumes that files in the log
directory have B<newsyslog(8)>- or B<logrotate(8)>-like name format with numeric
indexes. Files without indexes (generally it is merely one file) are considered
the most recent and files with lower indexes are considered newer.

=item B<--reject-score>

Specifies the reject (spam) threshold.

=item B<--junk-score>

Specifies the junk (add header or rewrite subject) threshold.

=item B<--alpha-score>

Specifies the minimum score for a symbol to be considered by this script.

=item B<--symbol>

Add symbol or pattern (pcre format) to analyze.

=item B<--num-logs>

If set, limits number of analyzed logfiles in the directory to the specified value.

=item B<--exclude-logs>

Number of latest logs to exclude (0 by default).

=item B<--correlations>

Additionally print correlation rate for each symbol displayed. This routine calculates merely paired correlations between symbols.

=item B<--search-pattern>

Do not process input unless finding the specified regular expression. Useful to skip logs to a certain position.

=item  B<--exclude>

Exclude log lines if certain symbols are fired (e.g. GTUBE). You may specify this option multiple time to skip multiple symbols.

=item B<--start>

Select log entries after this time. Format: C<YYYY-MM-DD HH:MM:SS> (can be
truncated to any desired accuracy). If used with B<--end> select entries between
B<--start> and B<--end>. The omitted date defaults to the current date if you
supply the time.

=item B<--end>

Select log entries before this time. Format: C<YYYY-MM-DD HH:MM:SS> (can be
truncated to any desired accuracy). If used with B<--start> select entries between
B<--start> and B<--end>. The omitted date defaults to the current date if you
supply the time.

=item B<--help>

Print a brief help message and exits.

=item B<--man>

Prints the manual page and exits.

=back

=head1 DESCRIPTION

B<rspamd_stats> will read the given log file (or standard input) and provide statistics for the specified symbols:

    Symbol: BAYES_SPAM (weight 3.763) (381985 hits, 26.827%)
    Ham hits: 184557 (48.315%), total ham: 1095487 (ham with BAYES_SPAM: 16.847%)
    Spam hits: 15134 (3.962%), total spam: 16688 (spam with BAYES_SPAM: 90.688%)
    Junk hits: 182294 (47.723%), total junk: 311699 (junk with BAYES_SPAM: 58.484%)
    Spam changes (ham/junk -> spam): 7026 (1.839%), total percentage (changes / spam hits): 42.102%
    Junk changes (ham -> junk): 95192 (24.920%), total percentage (changes / junk hits): 30.540%

Where there are the following attributes:

=over 4

=item *

B<Weight>: average score for a symbols

=item *

B<Total hits>: total number of hits and percentage of symbol hits divided by total number of messages

=item *

B<HAM hits>: provides the following information about B<HAM> messages with the specified symbol (from left to right):

=over 4

=item 1.

B<total symbol hits>: number of messages that has this symbol and are B<HAM>

=item 2.

B<ham percentage>: number of symbol hits divided by overall B<HAM> messages count

=item 3.

B<total ham hits>: overall number of B<HAM> messages

=item 4.

B<ham with symbol percentage>: percentage of number of hits with specified symbol in B<HAM> messages divided by total number of B<HAM> messages.

=back

=item *

B<SPAM hits>: provides the following information about B<SPAM> messages - same as previous but for B<SPAM> class.

=item *

B<Junk hits>: provides the following information about B<Junk> messages - same as previous but for B<JUNK> class.

=item *

B<Spam changes>: displays data about how much messages switched their class because of the specific symbol weight.

=item *

B<Junk changes>: displays data about how much messages switched their class because of the specific symbol weight.

=back

=cut