app.psgi

use strict;
use warnings;
use Plack::Request;
use Plack::MIME;
use Plack::App::Directory;
use FindBin;

my $java_bin = `which java` =~ s/[\n\r]//gr
    or die 'Install Java :(';

my $graphviz_dot = `which dot` =~ s/[\n\r]//gr
    or warn 'Running without graphviz';

my $plant_uml_jar = "$FindBin::Bin/plantuml.jar";
unless (-f $plant_uml_jar) {
    print "Initializing...";
    system qq(wget -O $plant_uml_jar http://jaist.dl.sourceforge.net/project/plantuml/plantuml.jar);
    exit;
}

sub {
    my $req  = Plack::Request->new(shift);
    my $path = ($req->path_info =~ s/[\/\\\0]//gr);

    if ($path eq '/' || $path eq 'favicon.ico' || not $path) {
        return Plack::App::Directory->new->to_app->($req->env);
    }

    if ($path =~ /uml$/ && $req->query_parameters->{render}) {
        my $cmd = join " ",
            "env",
            "JAVA_BIN='$java_bin'",
            "GRAPHVIZ_DOT='$graphviz_dot'",
            "$java_bin -jar $plant_uml_jar",
            "-SdefaultFontName='Hiragino Kaku Gothic Pro W3'",
            "-charset utf8",
            "'$path'";

        system $cmd;
        $path =~ s/uml$/png/;
    }

    my $content_type = Plack::MIME->mime_type($path) || 'text/plain; charset=UTF-8';

    open my $image, '<', $path or die $!;
    return [200, ['Content-Type' => $content_type], $image];
};

graphviz.md

Optional

If you need graphviz, install Xcode and dispatch following command.

brew update
brew install gts
brew install graphviz