#!/bin/env perl

my $days = 20;

# set terminal dumb size 160, 30;
# set grid;
# set format x "%d.%m.%Y";
$C = <<GNUPLOT;
    gnuplot -p -e '
    unset border;
    unset key;

    set colorsequence classic;
    set terminal dumb ansirgb noenhanced size 160,37;

    set title "Login duration during the last $days days" font "sans-serif,12";

    set xdata time;
    set ydata time;
    set xtics nomirror rotate 86400 font "sans-serif,8" scale 0;
    set ytics nomirror        time  font "sans-serif,8" scale 0;

    set autoscale xfix;

    set format x "%a\n|%d\n|%m\n|%y";
    set format y "%M:%S";

    plot 
        "-" using (timecolumn(1, "%Y-%m-%d")):(timecolumn(2, "%M:%S")) with impulses lc rgb "#6000ad"  lt 6 lw 2,
    '
GNUPLOT

my $total = 0; my $count = 0;
# TODO: maybe utmpdump /var/log/wtmp is better?
$O = qx[last --time-format iso reboot -R];
$O =~ s/(\d{4}-\d{2}-\d{2}).*\d{4}-\d{2}-\d{2}.*\((\d{2}):(\d{2})\)/$dates{$1}+=(60.0*$2)+$3/eg;
open (W, '|'.$C) or print $!;
@list = reverse sort keys(%dates);
foreach (splice @list, 0, $days) { 
    my $d = $dates{$_};
    my $m = $d % 60;
    my $h = ($d - $m) / 60;

    $total += $d;
    $count ++;
    # printf(  "%s\t%02d:%02d\n", $_, $h, $m);
    printf(W "%s\t%02d:%02d\n", $_, $h, $m);
}
close(W);


# $total += 7.5 * 60 + 7.5 * 60 + 10 * 60;
printf("summary: %.2f hours per day during the last $count days\n", $total / $days / 60.0);