#!/usr/bin/perl -w

use locale;
use Data::Dumper;
use Lingua::PT::PLNbase;
use MLDBM qw/DB_File Storable/;
use Fcntl;

use Memoize;
memoize('getB');
memoize('getA');


my $db = shift;

my %DB;

my $f1 = shift;
my $f2 = shift;

die "Can't open '$f1'" unless -f $f1;
die "Can't open '$f2'" unless -f $f2;

my @s1 = atomiza(lc(`cat $f1`));
my @s2 = atomiza(lc(`cat $f2`));

my $Size1 = scalar @s1;
my $Size2 = scalar @s2;

tie %DB, 'MLDBM', $db, O_RDONLY, 0640, or die $!;

my $TOT = 0;
for $i (0..$Size1-1) {
  next if length($s1[$i]) < 2;

  for $j (0..$Size2-1) {
    next if length($s2[$j]) < 2;

    if (abs($i/$Size1-$j/$Size2) < .05) {
      $TOT += prob(\%DB, $s1[$i], $s2[$j])
    }
  }
}


$TOT = $TOT / (($Size1 + $Size2)/2);

printf("%.5f\n", $TOT);

untie %DB;


sub getA {
  my ($db,$a) = @_;

  if (exists($db->{"A_$a"})) {
    $db->{"A_$a"}{trans}
  } else {
    +{}
  }
}


sub getB {
  my ($db,$b) = @_;
  if (exists($db->{"B_$b"})) {
    $db->{"B_$b"}{trans}
  } else {
    +{}
  }
}

sub prob {
  my ($db,$l,$r) = @_;

  my $x;
  my $ret = 0;

  $x = getA($db,$l);
  if (exists($x->{$r})) {
    $ret += 100*$x->{$r};
  }

  $x = getB($db,$r);
  if (exists($x->{$l})) {
    $ret += 100*$x->{$l};
  }

  $ret /= 2;

  $ret *= (1-abs($i/$Size1 - $j/$Size2));


  $ret;
}