#!/usr/bin/perl -w
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=head1 NAME

fp-fn-statistics - Display statistics about the quality of scores

=head1 SYNOPSIS

fp-fn-statistics [options]

  Options: 
    -c,--cffile=path	  Use path as the rules directory
    -s,--scoreset=n	  Use scoreset n
    -t,--threshold=n      Use a spam/ham threshold of n (default: 5)
    --lambda=n            Use a lambda value of n
    --spam=file           Location of mass-check spam log (spam.log)
    --ham=file            Location of mass-check ham log (ham.log)
    --fplog=file          File to which false positive logs should be saved
    --fnlog=file          File to which false negative logs should be saved

=head1 DESCRIPTION

B<fp-fn-statistics> first calculates the score each message from a
masses.log would have under a new set of scores. It then aggregates
the number of messages correctly and incorrectly found as spam and
ham, and their average scores.

In addition, B<fp-fn-statistics> determines the "Total Cost Ratio" as
a result of the false positives and negatives mentioned above. This
calculation takes into the value of lambda, which represents the cost
of recovering a false positive, where 1 indicates a message is tagged
only, 9 means the message is mailed back to sender asking for a token
(TMDA style) and 999 means a message is delted. The default, 5,
represents the message being moved to an infrequently read folder.

B<fp-fn-statistics> can also save false positive and false negatives
logs to a file for future analysis. If this is all you're doing, it
could be accomplished a lot quicker with B<grep>, but why not reinvent
the wheel?

=cut

use Getopt::Long;
use strict;

our ($opt_cffile, $opt_lambda, $opt_threshold, $opt_scoreset, $opt_spam, $opt_ham, $opt_fplog, $opt_fnlog);

$opt_cffile = "../rules";
$opt_threshold = 5;
$opt_spam = 'spam.log';
$opt_ham = 'ham.log';
$opt_scoreset = 0;

GetOptions("c|cffile=s" => \$opt_cffile,
	   "lambda=f" => \$opt_lambda,
	   "t|threshold=f" => \$opt_threshold,
	   "spam=s" => \$opt_spam,
	   "ham=s" => \$opt_ham,
	   "s|scoreset=i" => \$opt_scoreset,
	   "fplog=s" => \$opt_fplog,
	   "fnlog=s" => \$opt_fnlog
	  );

# If desired, report false positives and false negatives for analysis
if (defined $opt_fnlog) { open (FNLOG, ">$opt_fnlog"); }
if (defined $opt_fplog) { open (FPLOG, ">$opt_fplog"); }

# lambda value for TCR equation, representing the cost of of an FP vs. the
# cost of a FN.  Some example values are: 1 = tagged only, 9 = mailed back
# to sender asking for token, 999 = blocking or deleting a message.
#
# We roughly aim for a value representing "moved to infrequently-read folder".

my $lambda = 50;
if ($opt_lambda) { $lambda = $opt_lambda; }

our (%scores, %allrules, %rules);

readscores();

die "wrong scoreset in tmp/rules.pl" unless $allrules{_scoreset} == $opt_scoreset;

print "Reading per-message hit stat logs and scores...\n";
my ($num_spam, $num_ham);
my ($ga_yy, $ga_ny, $ga_yn, $ga_nn, $yyscore, $ynscore, $nyscore, $nnscore);

readlogs();

evaluate();

# show memory usage before we exit
# print "Running \"ps aux\"...\n";
# open(PS, "ps aux|");
# while(<PS>) {
# print if $. == 1 || /\b$$\b/;
# }
# close(PS);

exit 0;

# arguments are $isspam, $count, \@tests, $msgline;
sub log_line_count {
  my $score = 0;
  $score += $scores{$_} for @{$_[2]};

  if ($_[0]) {
    $num_spam++;
    if ($score >= $opt_threshold) {
      $ga_yy++;
      $yyscore += $score;
    }
    else {
      $ga_yn++;
      $ynscore += $score;
      if (defined $opt_fnlog) {
	print FNLOG $_[3];
      }
    }
  }
  else {
    $num_ham++;
    if ($score >= $opt_threshold) {
      #print STDERR "FP: $id\n";
      $ga_ny++;
      $nyscore += $score;
      if (defined $opt_fplog) {
	print FPLOG $_[3];
      }
    }
    else {
      $ga_nn++;
      $nnscore += $score;
    }
  }
}

sub readlogs {
  my $msgline;
  my $count = 0;
  $num_spam = $num_ham = 0;

  $ga_yy = $ga_ny = $ga_yn = $ga_nn = 0;
  $yyscore = $ynscore = $nyscore = $nnscore = 0.0;

  foreach my $file ($opt_spam, $opt_ham) {
    open (IN, "<$file") || die "Could not open file '$file': $!";

    my $isspam = ($file eq $opt_spam);
    my $caught;			# 1st parameter of log line
    my $rules;			# 4th parameter of log line

    while (defined($msgline = <IN>)) {
      ($caught, undef, undef, $rules) = split(' ', $msgline);

      # only take lines starting with Y or .
      next unless ($caught eq 'Y' || $caught eq '.') && $rules;

      # get tests, but ignore unknown tests and subrules
      my @tests = grep { defined $scores{$_} && !$allrules{$_}->{issubrule} }
	split(/,/, $rules);

      # run handler
      log_line_count($isspam, $count, \@tests, $msgline);

      # increment line
      $count++;
    }
    close IN;
  }
}

sub readscores {
  print "Reading scores from \"$opt_cffile\"...\n";
  my $cmd = "../build/parse-rules-for-masses -o ./tmp/rules_$$.pl -d \"$opt_cffile\" -s $opt_scoreset";
  warn "[$cmd]\n";
  system ($cmd) and die;
  require "./tmp/rules_$$.pl";
  unlink "./tmp/rules_$$.pl";
  %allrules = %rules;           # ensure it stays global
}

sub evaluate {
   printf ("\n# SUMMARY for threshold %3.1f:\n", $opt_threshold);
   printf "# Correctly non-spam: %6d  %4.2f%%\n",
       $ga_nn, ($ga_nn /  $num_ham) * 100.0;
   printf "# Correctly spam:     %6d  %4.2f%%\n",
       $ga_yy, ($ga_yy /  $num_spam) * 100.0;
   printf "# False positives:    %6d  %4.2f%%\n",
       $ga_ny, ($ga_ny /  $num_ham) * 100.0;
   printf "# False negatives:    %6d  %4.2f%%\n",
       $ga_yn, ($ga_yn /  $num_spam) * 100.0;

  # convert to the TCR metrics used in the published lit
  my $nspamspam = $ga_yy;
  my $nspamlegit = $ga_yn;
  my $nlegitspam = $ga_ny;
  my $nlegitlegit = $ga_yn;
  my $nlegit = $num_ham;
  my $nspam = $num_spam;

  my $werr = ($lambda * $nlegitspam + $nspamlegit)
                  / ($lambda * $nlegit + $nspam);

  my $werr_base = $nspam
                  / ($lambda * $nlegit + $nspam);

  $werr ||= 0.000001;     # avoid / by 0
  my $tcr = $werr_base / $werr;

  my $sr = ($nspamspam / $nspam) * 100.0;
  my $sp = ($nspamspam / ($nspamspam + $nlegitspam)) * 100.0;
  printf "# TCR(l=%s): %3.6f  SpamRecall: %3.3f%%  SpamPrec: %3.3f%%\n",
    $lambda, $tcr, $sr, $sp;
}