asset bundler

auto-asset-bundling-with-js-minifier.rake

file "public/stylesheets/cache/bundle.css" => FileList["public/stylesheets/*.css"] do |t|
  File.open(t.name, 'w') do |bundle|
    bundle.write( t.prerequisites.map {|css| File.read(css) }.join("\n") )
  end
  puts "***\nWrote #{t.prerequisites.size} Javascript files into bundle.css"
end


file "public/javascripts/cache/bundle.js" => FileList["public/javascripts/*.js"] do |t|
  # load Rails
  require File.join(Rails.root + "config", "environment")

  # find out which js files need to be loaded first
  priority   = ActionView::Helpers::AssetTagHelper.register_javascript_expansion({})[:defaults]

  # fix priority filenames
  priority.map! {|file| "public/javascripts/#{file.chomp('.js')}.js" }
  # prepend the priority assets
  sources = ((priority & t.prerequisites) + t.prerequisites.sort).uniq

  # Use Google's Closure compiler for compacting
  compiler = File.join(File.dirname(__FILE__), 'google_closure_compiler.jar')
  sh "java -jar #{compiler} --compilation_level=SIMPLE_OPTIMIZATIONS #{sources.map{|f|"--js=#{f} "}} --js_output_file=#{t.name}"

  puts "***\nWrote #{sources.size} Javascript files into bundle.js"
end

namespace :assets do
  task :compile => :bundle do
    system "git commit #{File.join(Rails.root, "public")}/*/bundle.* -m 'updating asset bundles'"
  end
  task :bundle => ["bundle:javascripts", "bundle:stylesheets"]
  namespace :bundle do
    task :javascripts => "public/javascripts/cache/bundle.js"
    task :stylesheets => [:run_sass, "public/stylesheets/cache/bundle.css"]
    task :run_sass do
      require File.join(Rails.root + "config", "environment")
      Sass::Plugin.update_stylesheets
    end
  end
end