developwithpassion/expansions

module Expansions
  module ERBTemplateFile
    extend self

    def prepare_template(template)
      token_regex = /(@\w[\w\.\_]+\w@)/

      hits = template.scan(token_regex)
      tags = hits.map do |item|
        item[0].gsub(/@/,'').squeeze
      end
      tags = tags.map{|tag| tag.to_sym}.uniq

      tags.inject(template) do |text, tag|
        text.gsub /@#{tag.to_s}@/, "<%= #{tag.to_s} %>"
      end
    end

    def process_template(template,binding)
      erb = ERB.new(template, 0, "%")
      erb.result(binding)
    end

    def process(args)
      template = prepare_template(File.read(args[:input]))
      result = process_template(template,args[:binding])

      File.open_for_write(args[:output]) do|file|
        file.write(result)
      end
    end
  end
end