module Crawlable
  class Rack
    
    def initialize(app)
      @app = app
    end
    
    def call(env)
      if using_heroku?(env) || true
        if file = Crawlable::Sitemap.find(env['REQUEST_PATH'], heroku_writable_directory)
          return sitemap(file)
        elsif file = Crawlable::Feed.find(env['REQUEST_PATH'], heroku_writable_directory)
          return feed(file)
        end
      end
      @app.call(env)
    end
    
    def sitemap(file)
      [200, { 'Cache-Control'  => 'public, max-age=86400', 'Content-Length' => File.size(file).to_s, 'Content-Type'   => 'text/xml' }, IO.read(file)]
    end
    
    def feed(file)
      [200, { 'Cache-Control'  => 'public, max-age=86400', 'Content-Length' => File.size(file).to_s, 'Content-Type'   => 'text/xml' }, IO.read(file)]
    end
    
    def heroku_writable_directory
      "#{Rails.root}/tmp"
    end
    
    def using_heroku?(env)
      if env["HEROKU"].nil?
        if env["HEROKU_PORT"].nil? && ENV["HEROKU_TYPE"].nil?
          env["HEROKU"] = false
        else
          env["HEROKU"] = true
        end
      end
      
      env["HEROKU"] == true
    end
    
  end
end