!/usr/bin/perl
#
# This program will outline the top users of a file system.
#

use strict;
use Getopt::Long;

my $max_users=10;
my @fs=();
my @file_list=();
my @dir_list=();
my %filehash;

GetOptions( "fs=s@"     => \@fs,
            "users=i"   => \$max_users
          );

&help() if not @fs;

foreach my $fs (@fs) {
    my %sorthash;
    my $i=0;
    undef(%filehash);
    print "$fs:\n";
    &processFileSystem($fs);

    foreach my $uid (keys %filehash) {
        next if ($uid eq "");
        my $name = (getpwuid($uid)) || "uid($uid)";
        push @{$sorthash{$filehash{$uid}}}, $name;
    }

    foreach my $size (reverse sort numerically keys %sorthash) {
        last if not ($i < $max_users);
        foreach my $user ( @{ $sorthash{$size} } ) {
            &printUser($user,$size);
            $i++;
        }
    }
    print "\n";
}

sub processFileSystem( ) {
    my $dir = shift @_;
    my @readdir_list;

    opendir "currdir", $dir;
    @readdir_list = readdir "currdir";
    close "currdir";
    foreach my $curr (@readdir_list) {
        next if $curr =~ /^\.{1,2}$/;
        if ( -d "$dir/$curr" ) {
            &processFileSystem("$dir/$curr");
        } else {
            my ( @stat ) = stat "$dir/$curr";
            $filehash{$stat[4]} += $stat[7];
        }
    }
}

sub printUser() {
    my ( $user, $size ) = @_;
    my $label;
    if      ( $size >= ( 1024 * 1024 * 1024 ) ) {
        $size       /= ( 1024 * 1024 * 1024 );
        $label       = "Gb";
    } elsif ( $size >= ( 1024 * 1024 ) ) {
        $size       /= ( 1024 * 1024 );
        $label       = "Mb";
    } elsif ( $size >= ( 1024 ) ) {
        $size       /= ( 1024 );
        $label       = "Kb";
    } else {
        $label       = "bytes";
    }

    printf "    %-12s is using %7.2f %s\n", $user, $size, $label;
}

sub numerically() {$a <=> $b}

sub help() {
    print "Syntax:\n\t$0 [--users=i] --fs=/path1 [--fs=/path2] ...\n";
    exit(0);
}