#!/usr/bin/perl

use strict;
use DBI;
use Getopt::Long;
use Sys::Hostname;

my $database = 'atloffice';
my $user = 'postgres';
my $hostname = '10.28.128.143';

my %querys = (
# State
    "activeconn"        =>      qq{SELECT SUM(numbackends) FROM pg_stat_database},
# Locks
    "exclusivelock"             =>      qq{SELECT COUNT(*) FROM pg_locks WHERE mode='ExclusiveLock'},
# Checkpoints
    "buffers_alloc"             =>      qq{SELECT buffers_alloc FROM pg_stat_bgwriter},
);

GetOptions(
    'help!' => \&usage,
    'user=s' => \$user,
    'database=s' => \$database,

    'activeconn' => sub { print query_database($querys{activeconn}) },
    'exclusivelock' => sub { print query_database($querys{exclusivelock}) },
    'buffers_alloc' => sub { print query_database($querys{buffers_alloc}) }
) or die "$0: try --help for more information\n";

sub query_database {
        my $query = shift(@_);
        my $dbh = DBI->connect("dbi:Pg:dbname=$database;host=$hostname",$user);
        my $sth = $dbh->prepare("$query") or die $|;
        $sth->execute;

        while (my @array = $sth->fetchrow_array)  {
                return @array[0];
        }
}

sub usage {
    print "[-] $0 script to  monitor PostgreSQL databases,\n";
    print "Usage: $0 [--OPTION]\n";

    while ( my($key, undef) = each %querys ) {
        print "\t--".$key."\n";
    }

    exit 0
}

if (!$ARGV) { usage }