gistfile1.rb

require 'net/https'
require 'open-uri'

module AppCache
  extend self

  def run(host = "http://***.***.***")
    @host = host
    puts "Loading manifest..."
    puts "Total Size => #{total.to_human}"
  end

  def total
    assets.inject(0) {|sum, asset| sum + size(asset)}
  end

  def assets
    filter manifest.scan(/^CACHE:([^[NET]]*)/)[0][0].split(/\r?\n/)
  end

  def filter(lines)
    lines.reject! {|line| line.empty? || /^#/ =~ line}
  end

  def manifest
    open("#{@host}/manifest/cache.manifest").read
  end

  def size(asset)
    uri = URI /^http/ !~ asset ? "#{@host}#{asset}" : asset
    Net::HTTP.start(uri.host, uri.port) do |http|
      request = Net::HTTP::Get.new uri.request_uri
      http.request request do |response|
        return response['content-length'].to_i
      end
    end
  end
end

class Numeric
  def to_human
    units = %w{b Kb Mb Gb Tb}
    e = (Math.log(self)/Math.log(1024)).floor
    s = "%.1f" % (to_f / 1024**e)
    s.sub(/\.?0*$/, units[e])
  end
end

AppCache.run