minify_resources.rb

#!/usr/bin/env ruby

module MinifyResources
	CSS_BLOB  = 'public/css/common.css'
	CSS_DIR   = 'public/css'
	CSS_LIST  = 'public/css/manifest.txt'
	CSS_FILES = File.exists?(CSS_LIST) ? IO.read(CSS_LIST).scan(/\S+/) : Dir.chdir(CSS_DIR) { Dir['*.css'] }

	JS_BLOB   = 'public/blob.js'
	JS_DIR    = 'public/js'
	JS_LIST   = 'public/js/manifest.txt'
	JS_FILES  = File.exists?(JS_LIST) ? IO.read(JS_LIST).scan(/\S+/) : Dir.chdir(JS_DIR) { Dir['*.js'] }

	def self.minify_all
		require 'jsmin'
		require 'cssmin'
		minify(::JSMin,  JS_DIR,  JS_FILES,  JS_BLOB)
		minify(::CSSMin, CSS_DIR, CSS_FILES, CSS_BLOB)
	end

	def self.minify(lib, source_dir, files, output)
		return if files.empty?
		raw_size = 0
		minified = files.map do |file|
			raw = IO.read(File.join(source_dir, file))
			raw_size += raw.length
			lib.minify(raw.dup)
		end.join
		min_size = minified.length
		existing = File.exists?(output) && IO.read(output)

		if minified == existing
			puts "No change to #{output}"
		else
			File.open(output, 'w') { |f| f << minified }

			puts '%i files => %s; %s => %s (%.1f%% reduction)' % [
				files.length,
				output,
				raw_size,
				min_size,
				100 * (raw_size - min_size) / raw_size
			]
		end
	end
end

MinifyResources.minify_all if __FILE__ == $PROGRAM_NAME