#!/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 (@sections, %sections, %graphs);

our @timeranges= (3600, map { $_*86400 } qw(1 7 28), 13*7+1);

sub graph ($$$$) {
    my ($section, $gname, $basis, $args) = @_;
    $basis->{Args}= $args;
    $basis->{Slower}= 0 unless exists $basis->{Slower};
    $graphs{$section,$gname}= $basis;
    if (!exists $sections{$section}) {
	push @sections, $section;
    }
    push @{ $sections{$section} }, $gname;
}

graph('General', '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('General', '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('General', '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",
       ]);

graph('General', 'Memory', { },
      [
       (map { "DEF:swap_$_=$R/swap/swap-$_.rrd:value:AVERAGE" }
	    qw(free used cached)),
       (map { "DEF:mem_$_=$R/memory/memory-$_.rrd:value:AVERAGE" }
	    qw(buffered free used cached)),
       "CDEF:c_swap_used=0,swap_used,-",
       "CDEF:c_swap_cached=0,swap_cached,-",
       "CDEF:c_swap_free=0,swap_free,-",
       "AREA:c_swap_used#000:used swap",
       "AREA:c_swap_cached#888:\"cached\" swap:STACK",
#       "AREA:c_swap_free#88f:free swap:STACK",
       "AREA:mem_used#ff0:used memory",
       "AREA:mem_buffered#00f:page cache:STACK",
       "AREA:mem_cached#008:buffer cache:STACK",
       "AREA:mem_free#ccc:unused memory:STACK",
       ]);

foreach my $src (<$R/df/df-*.rrd>) {
    my $vol= $src;
    $vol =~ s,.*/,,;
    $vol =~ s,^df-,,;
    $vol =~ s,\.rrd$,,;
    graph('Disk space', $vol, {
	     Slower => 1,
          },
	  [ '-A','-l',0,'-r',
	   qw(-b 1024 -l 0),
	   (map { "DEF:$_=$src:$_:AVERAGE" } qw(free used)),
	   "AREA:used#000:used:STACK",
	   "AREA:free#88f:free:STACK",
	   ]);
}

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

our @navsettings;

sub navsetting ($) {
    my ($nav) = @_;
    my $var= $nav->{Variable};
    $$var= param($nav->{Param});
    $$var= $nav->{Default} if !defined $$var;
    die $nav->{Param} unless grep { $_ eq $$var } @{ $nav->{Values} };
    push @navsettings, $nav;
}

our $section;

navsetting({
    Desc => 'Section',
    Param => 'section',
    Variable => \$section,
    Default => $sections[0],
    Values => [@sections],
    Show => sub { return $_[0]; }
});


my $gname= param('graph');

sub num_param ($$$$) {
    my ($param,$def,$min,$max) = @_;
    my $v= param($param);
    return $def if !defined $v;
    $v =~ m/^([1-9]\d{0,8})$/ or die;
    $v= $1;
    die unless $v >= $min && $v <= $max;
    return $v + 0;
}

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

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

    my $width= num_param('w',370,100,1600);
    my $height= num_param('h',200,100,1600);

    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',$width, '-h',$height,
	  @args);
    die $!;
}

sub start_page ($) {
    my ($title) = @_;
    print header(), start_html($title);
    my $outerdelim= '';
    foreach my $nav (@navsettings) {
	print $outerdelim;
	print $nav->{Desc}, ": ";
	my $delim= '';
	my $current= $nav->{Variable};  $current= $$current;
	foreach my $couldbe (@{ $nav->{Values} }) {
	    print $delim;
	    my $show= $nav->{Show}($couldbe);
	    if ($couldbe eq $current) {
		print "<b>$show</b>";
	    } else {
		print "<a href=\"$self";
		my $delim2= '?';
		foreach my $nav2 (@navsettings) {
		    my $current2= $nav2->{Variable};  $current2= $$current2;
		    $current2= $couldbe if $nav2->{Param} eq $nav->{Param};
		    next if $current2 eq $nav2->{Default};
		    print $delim2, "$nav2->{Param}=$current2";
		    $delim2= '&';
	        }
		print "\">$show</a>";
	    }
	    $delim= ' | ';
	}
	$outerdelim= "<br>\n";
    }
    print "\n";

    print h1("$title");
}

my $detail= param('detail');
if ($detail) {
    my $g= $graphs{$section,$detail};
    die unless $g;
    start_page("$detail graphs");
    foreach my $end (@timeranges[$g->{Slower}..$g->{Slower}+3]) {
	my $imgurl= "$self?graph=$detail&section=$section&end=$end";
        print "<a href=\"$imgurl&w=780&h=800\"><img src=\"$imgurl\"></a>\n";
    }
    print end_html();
    exit 0;
}

our $sloth;

navsetting({
    Desc => 'Time interval',
    Param => 'sloth',
    Variable => \$sloth,
    Default => 1,
    Values => [0..2],
    Show => sub {
	my ($sl) = @_;
	return ('Narrower', 'Normal', 'Wider')[$sl];
    }
});

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

start_page("$section graphs");

foreach my $gname (@{ $sections{$section} }) {
    my $g= $graphs{$section,$gname};
    print "<a href=\"$self?detail=$gname&section=$section\">";
    my $end= $timeranges[$g->{Slower}+$sloth];
    my $imgurl= "$self?graph=$gname&section=$section&end=$end";
    print "<img src=\"$imgurl\"></a>\n";
}