#!/usr/bin/perl
use strict;

### configuration items ###
my $FILENAME = "/web/stonehenge-proxy/var/log/access_log";
my $TAILING = 16;
my $URGENT = 5;                 # this many seconds stays white
my $OLD = 55;                   # this many seconds after urgent is dark
### end configuration items ###

my @data;
use CGI qw(:html);
use POE qw(Component::Server::HTTP Wheel::FollowTail);

POE::Component::Server::HTTP->new
  (
   Port => 42042,
   ContentHandler =>
   {"/" => sub {
      my ($request, $response) = @_;
      
      $response->code(RC_OK);
      $response->content_type("text/html");
      $response->content
        (join "",
         start_html(
                    -title => "web tail on $FILENAME",
                    -bgcolor => 'black',
                    -head => ["<meta http-equiv=refresh content='5;URL=#bottom'>"],
                    ),
         table (map {
           my ($stamp, $message) = @$_;
           my $age = time - $stamp;
           my $color;
           if ($age < $URGENT) {
             $color = 'white';
           } else {
             $age -= $URGENT;
             $age = $OLD if $age > $OLD;
             my $c = 255 * (1 - $age / $OLD);
             $color = sprintf '#%02x%02x%02x', $c, 255, $c;
           }
           Tr(td({valign => 'top'},
                 font({color => 'cyan'},
                      sprintf "%02d:%02d:%02d", (localtime $stamp)[2,1,0])),
              td(font({color => $color, face => 'courier'},
                      escapeHTML($message))));
            } @data),
         a({name => "bottom"}),
         end_html,
        );
      return RC_OK;
    }},
  );


POE::Session->create
  (
   inline_states =>
   {
    _start => sub {
      $_[HEAP]->{wheel} =
        POE::Wheel::FollowTail->new
            (
             Filename => $FILENAME,
             InputEvent => 'got_line',
             SeekBack => 8192,
            );
    },
    got_line => sub {
      push @data, [time, $_[ARG0]];
      splice @data, 0, -$TAILING if @data > $TAILING;
    },
   },
  );

$poe_kernel->run();