#!/usr/bin/perl

use strict;
use warnings;
use Data::Dumper;
use Getopt::Std;

my %opts = ();
getopts('d:rh', \%opts);
print usage() if(!defined $opts{'d'} or $opts{'h'});
my @du = qx(du -h --max-depth=1 $opts{'d'});
my %d = ();

foreach(@du) {
   chomp;
   if(/(\d+)K(.*)$/) { $_ = ($1          *1024)." ".$2; }
   if(/(\d+)M(.*)$/) { $_ = ($1     *1024*1024)." ".$2; }
   if(/(\d+)G(.*)$/) { $_ = ($1*1024*1024*1024)." ".$2; }
   if(/(\d+) (.*)$/) { push @{$d{$1}}, $2; }
}
@du = ();
foreach (sort {$a <=> $b} keys %d) {
   my $key = $_;
   
   if   ($_ > 1073741824) { $key = ($key / 1073741824)."G"; }
   elsif($_ > 1048576)    { $key = ($key / 1048576)   ."M"; }
   elsif($_ > 1024)       { $key = ($key / 1024)      ."K"; }
   foreach my $ele (@{$d{$_}}) {
      push @du, $key."\t".$ele;
   } 
}

if($opts{'r'}) {
   print $_."\n" foreach(reverse @du);
} else {
   print $_."\n" foreach(@du);
}

sub usage {
   print<<EOF; 
du.pl -d <directory> [-r]

Arguments:

mandatory:
-d directory name

optional:
-r if the sort order should be descending
EOF

exit 0;
}