#!/usr/bin/env perl

use strict;

my $b = ($ARGV[0] eq 'b') ? 1 : 0;

for my $file (<*.mkv>) {
    my ($trn, @tracks);

    print "$file\n";
    my @out = `mkvinfo --ui-language en "$file"`;
    foreach (@out) {
        $trn++ if /^\| \+ A track/;
        $tracks[$trn].=$_ if /^\|  \+/;
    }

    my @keep;
    foreach (@tracks) {
        next unless /type: audio/;
        next if /Language: rus/;
        my ($track) = /Track number: (\d+)/;
        push @keep, --$track;
    }
    my $keep_tracks = join ',', @keep;
    die unless $keep_tracks;

    my $newfile = "_$file";
    `mkvmerge -o "$newfile" -a $keep_tracks "$file"`;
    unless ($b) {
        unlink $file;
        rename $newfile, $file;
    }
}