Compile assets (Coffee, Sass, Serenadejs) in pure Ruby

compile_asserts.rb

require 'rubygems' 
require 'bundler/setup'
require 'coffee-script'
require 'sass'
require 'fileutils'
require 'execjs'
require 'multi_json'

support_pattern = '{**/*.serenade,**/*.coffee,**/*.sass}'

desc 'Run support task'
task 'support' do
  system %Q(RACK_ENV=development bundle exec rerun --pattern '#{support_pattern}' 'rake compile_assets')
end

desc 'Compile assets CoffeScirpt, Sass, Serenade views'
task 'compile_assets' do
  def path(relative)
    root = File.dirname(__FILE__)
    File.join(root, relative)
  end

  def compile(dirs, target_file)
    target_file = path(target_file)

    dirs.each do |pattern|
      files = Dir.glob(path(pattern))

      unless uptodate?(target_file, files)

        compiled_content = files.map do |file_path|
          puts "Compile #{file_path}"
          yield(File.read(file_path), file_path)
        end.join(' ')

        FileUtils.mkdir_p(File.dirname(target_file))
        File.write(target_file, compiled_content)

      end
    end
  end

  def compile_coffee(dirs, target_file)
    compile(dirs, target_file) do |content|
      CoffeeScript.compile(content)
    end
  end

  def compile_sass(dirs, target_file)
    compile(dirs, target_file) do |content|
      Sass::Engine.new(content).render
    end
  end

  def compile_serenade(dirs, target_file, base_path)
    def parse(content)
      serenadejs_path = path('/public/js/serenade.js')

      context = ExecJS.compile(File.read(serenadejs_path))
      code = "Serenade.view(#{MultiJson.dump(content)}).parse()"
      context.eval(code)
    end
    
    def render(name, template_ast)
      "Serenade.view(#{MultiJson.dump(name)}, #{MultiJson.dump(template_ast)});"
    end

    def name(template_path, base_path)
      absolute_base_path = path(base_path)
      name = template_path.sub(absolute_base_path, '')
      name.sub('/', '_').sub('.serenade', '')
    end

    compile(dirs, target_file) do |content, path|
      render(name(path, base_path), parse(content))
    end
  end

  compile_coffee [ 'views/js/**/*.coffee' ], 'public/scripts.js'
  compile_serenade [ 'views/js/templates/**/*.serenade' ], 'public/templates.js', 'views/js/templates/'
  compile_sass [ 'views/css/**/*.sass' ], 'public/styles.css'

  puts "CoffeeScript, Sass, Serenade complied"
end