#!/usr/bin/perl
use strict;
use warnings;

use Getopt::Long;

my $mailto = 'linerva-root@mit.edu';
my $ssh = 0;

GetOptions("ssh"      => \$ssh,
           "mailto=s" => \$mailto)
or die ("Bad arguments\n");

my (undef,undef,undef,undef,$mon,undef,undef,undef,undef) = localtime(time);
$mon--; $mon = 11 if $mon < 0;

my @months = qw(January February March April May June July August
                September October November December);
$mon = $months[$mon];

# last -f /var/log/wtmp.1 | cut -f 1 -d ' ' | sort -nr | uniq -c | sort -nr

my $pipe;

if($ssh) {
    open($pipe, "-|", "ssh", "linerva.mit.edu", "last -f /var/log/wtmp.1 | cut -f 1 -d ' ' | sort -nr | uniq -c");
} else {
    open($pipe, "-|", "last -f /var/log/wtmp.1 | cut -f 1 -d ' ' | sort -nr | uniq -c | sort -nr");
}

my $mail;
open($mail, "|-", '/usr/bin/mutt', '-x', $mailto, '-s', "Linerva usage for $mon");

my %users;

my %buckets = (
    1    => 0,
    10   => 0,
    100  => 0,
    1000 => 0);

print $mail "Linerva usage for $mon:\n\n";

while(defined(my $line = <$pipe>)) {
    chomp($line);
    $line =~ s/^\s+//; $line =~ s/\s+$//;
    my ($count, $who) = split /\s/, $line;
    next unless $who;

    for my $i (1,10,100,1000) {
        $buckets{$i}++ if $count >= $i;
    }
    $users{$who} = $count;
}

close($pipe);

print $mail <<EOF;
Distinct Users:
$buckets{1}
10 Logins:
$buckets{10}
100 Logins:
$buckets{100}
1000 Logins:
$buckets{1000}
EOF

my @users = sort{$users{$b} <=> $users{$a} || $a cmp $b} keys %users;

for my $u (@users) {
    printf $mail '% 6d %s', $users{$u}, $u;
    print $mail "\n";
}

close($mail);