#!/usr/bin/env ruby
require 'trollop'
require 'pp'

opts = Trollop::options do
  version "#{$0} (c) 2008 Nate Murray"
  banner <<-EOS
http://gist.github.com/16729

A tiny utility to generate graphviz dot files from objects that use pluginaweek's
excellent state_machine library. (http://github.com/pluginaweek/state_machine/tree/master)


Usage:
       #{$0} [opts] rails_root class"

Examples: 
       #{$0} /path/to/rails_root Order

       #{$0} . Order | dot -Tsvg -Grankdir=LR > graph.svg; open graph.svg 

Options:
EOS

  opt :machine, "Which machine to read from a the class", :type => String, :default => "state"
  opt :name, "The name of the graph", :type => String, :default => "state"
  opt :font_name, "The name of the font to use", :type => String, :default => "Gill Sans"

end

unless ARGV.size >= 2
  puts "Usage: #{$0} [opts] rails_root class"
  puts "Try: #{$0} --help to see all options"
  exit
end

rails_root, klass = ARGV[0], ARGV[1]
require rails_root + "/config/environment.rb"

puts "digraph #{opts[:name]} {"

machine =  klass.constantize.state_machines[opts[:machine]]

machine.states.each do |state|
  shape = state == machine.instance_variable_get("@initial_state") ? "doublecircle" : "circle"
  puts %Q{#{state} [width=1,height=1,fixedsize=true,shape=#{shape},fontname="#{opts[:font_name]}"];}
end
puts

machine.events.each do |event_name,event|
  event.transitions.each do |transition|
     if transition.options.has_key?(:to) && transition.options.has_key?(:from)
       froms = transition.options[:from].kind_of?(Array) ? transition.options[:from] : [ transition.options[:from] ]
       froms.each do |from|
         puts %Q{#{from} -> #{transition.options[:to]} [label="#{event_name}",fontname="#{opts[:font_name]}"];}
       end
     end
  end
end

puts "}"