#!/usr/bin/perl -w

use strict qw(vars);
use CGI qw/:standard/;

sub fail ($) {
    print(header(-status=>500),
          start_html('Error'),
          h1('Error'),
          escapeHTML($_[0]),
          end_html());
    exit 0;
}

our $R= '/var/lib/collectd/rrd/chiark.greenend.org.uk';

my $self= url(-relative=>1);

our (@graphs, %graphs);

sub graph ($$$) {
    my ($gname, $basis, $args) = @_;
    $basis->{Args}= $args;
    $graphs{$gname}= $basis;
    push @graphs, $gname;
}

graph('Load', { },
      [
       "DEF:load=$R/load/load.rrd:shortterm:AVERAGE",
       (map { "DEF:$_=$R/processes/ps_state-$_.rrd:value:AVERAGE" }
	    qw(blocked running stopped paging sleeping zombies)),
       "AREA:running#88f:running processes:STACK",
       "AREA:blocked#8f8:blocked processes:STACK",
       "AREA:paging#f88:paging processes:STACK",
       "LINE:load#000:load",
       ]);

graph('Processes', { },
      [
       (map { "DEF:$_=$R/processes/ps_state-$_.rrd:value:AVERAGE" }
	    qw(blocked running stopped paging sleeping zombies)),
       "CDEF:busy=0".(join '', map { ",$_,+" } qw(running blocked paging)),
       "AREA:sleeping#ccc:sleeping:STACK",
       "AREA:stopped#f00:stopped:STACK",
       "AREA:zombies#0f0:zombie:STACK",
       "AREA:busy#f00:busy:STACK",
       ]);

graph('CPU', { Units => '[%]' },
      [
       (map {
	   my $thing= $_;
	   (map { "DEF:$thing$_=$R/cpu-$_/cpu-$thing.rrd:value:AVERAGE" }
	        (0..7)),
	   "CDEF:$thing=0".join('', map { ",$thing$_,+" } (0..7)).",8.0,/";
       } qw(idle interrupt nice softirq steal system user wait)),
       "AREA:system#00f:system:STACK",
       "AREA:wait#f88:wait:STACK",
       "AREA:nice#ccc:nice:STACK",
       "AREA:user#080:user:STACK",
       "AREA:softirq#f0f:softirq:STACK",
       "AREA:interrupt#ff0:interrupt:STACK",
       "AREA:steal#0ff:steal:STACK",
       ]);

if (param('debug')) {
    print "Content-Type: text/plain\n\n";
}

my $gname= param('graph');

if ($gname) {
    my $g= $graphs{$gname};
    die unless $g;

    my @args= @{ $g->{Args} };

    my $end= param('end');
    if (defined $end) {
        $end =~ m/^(\d+)$/ or die;
        unshift @args, qw(--end now --start), "end-${end}s";
    }
    if (param('debug')) {
        print((join "\n",@args),"\n"); exit 0;
    }
    print "Content-Type: image/png\n\n";

    my $title= $gname;
    $title .= " $g->{Units}" if $g->{Units};
    unshift @args, '-t', $title;
    
    exec qw(rrdtool graph - -a PNG --full-size-mode -w 380 -h 200), @args;
    die $!;
}

my $detail= param('detail');
if ($detail) {
    die unless $graphs{$detail};
    print header(), start_html(), h1("$detail graphs");
    foreach my $end (qw(3600 86400 604800 2419200)) {
        print "<img src=\"$self?graph=$detail&end=$end\">\n";
    }
    print end_html();
    exit 0;
}

if (param('debug')) {
    use Data::Dumper;
    print Dumper(\%graphs);
    exit 0;
}

print header(), start_html();
print h1('Graphs');

foreach my $gname (@graphs) {
    print "<a href=\"$self?detail=$gname\">"; #,h2($gname),"</a>";
    print "<img src=\"$self?graph=$gname\"></a>\n";
}