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

use WWW::Mechanize;
use XML::LibXML;

use constant {
    PM_URL => 'http://www.perlmonks.org/bare/?node_id=',
    # Node ids:
    LOGIN  => 109,
    XP     => 32704,
};

print "User? ";
chomp(my $user = <>);
print "Pass? ";
chomp(my $pass = <>);

my $mech = 'WWW::Mechanize'->new;
$mech->get(PM_URL . LOGIN);

$mech->submit_form(
                   form_number => 1,
                   fields      => { user   => $user,
                                    passwd => $pass,
                                  },
                  );

my %out;
my $limit  = 500;
my $offset = 0;

while (1) {
    $mech->get(PM_URL . XP . ";limit=$limit;offset=$offset");
    my $xml = 'XML::LibXML'->load_xml(string => $mech->content);

    my @nodes = $xml->findnodes('/USERNODES/NODE');
    last unless @nodes;

    for my $node (@nodes) {
        my ($date, $xp) = map $node->getAttribute($_), qw(createtime reputation);
        substr $date, 7, length($date), q{}; # Group by month.
        $out{$date}{count}++;
        $out{$date}{sum} += $xp;
    }

    $offset += $limit;
}

open my $OUT, '>', 'xp.out' or die $!;
for my $date (sort keys %out) {
    print {$OUT} "$date\t", $out{$date}{sum} / $out{$date}{count}, "\n";
}
close $OUT or die $!;

=for gnuplot

set xdata time
set timefmt '%Y-%m'
set xtics format '%Y-%m'
plot 'xp.out' using 1:2:(2e6) with boxes fs solid

=cut