Graphs with Sinatra and Scruffy

grapher.rb

require 'rubygems'
require 'sinatra'
require 'scruffy'
require 'md5'

get '/' do
  'This is Grapher.'
end

get '/graph/?' do
  title = params[:title] || ""
  type = params[:type].nil? ? :line : params[:type].to_sym
  data = params[:data]
  
  if data.nil?
    redirect '/'
  end
  
  digest = MD5.hexdigest(title.to_s + type.to_s + data.to_s)
  file = "graphs/#{digest}.png"
  if !File.exists?(file)
    graph = Scruffy::Graph.new(:title => title)

    sets = data.split(":")
    sets.each do |s|
      s = s.split(",")
      t = s.shift
      s.map! { |i| i = i.to_i }
      graph.add(type, t, s)
    end

    graph.render(:to => file, :as => 'PNG')
  end

  send_file file, :type => 'image/png', :disposition => 'inline'
end