require "rack/jquery_ui/version"
require "rack/jquery/helpers"

# @see http://rack.github.io/
module Rack

  # jQuery CDN script tags and fallback in one neat package.
  class JQueryUI
    include JQuery::Helpers

    # The usual file name.
    JQUERY_UI_FILE_NAME = "jquery-ui.min.js"


    # Namespaced for convenience, to help with checking
    # which CDN supports what.
    module CDNs

      # Script tags for the Media Temple CDN
      MEDIA_TEMPLE = "http://code.jquery.com/ui/#{JQUERY_UI_VERSION}/jquery-ui.min.js"

      # Script tags for the Google CDN
      GOOGLE = "//ajax.googleapis.com/ajax/libs/jqueryui/#{JQUERY_UI_VERSION}/jquery-ui.min.js"

      # Script tags for the Microsoft CDN
      MICROSOFT = "//ajax.aspnetcdn.com/ajax/jquery.ui/#{JQUERY_UI_VERSION}/jquery-ui.min.js"


      # Script tags for the Cloudflare CDN
      CLOUDFLARE = "//cdnjs.cloudflare.com/ajax/libs/jqueryui/#{JQUERY_UI_VERSION}/jquery-ui.min.js"
    end


    # path to the fallback script
    FALLBACK_PATH = "/js/jquery-ui/#{JQUERY_UI_VERSION}/#{JQUERY_UI_FILE_NAME}"

    # This javascript checks if the jQuery-UI object has loaded. If not, that most likely means the CDN is unreachable, so it uses the local minified jQuery.
    FALLBACK = <<STR
<script type="text/javascript">
  !window.jQuery.ui && document.write(unescape("%3Cscript src='#{FALLBACK_PATH}' type='text/javascript'%3E%3C/script%3E"))
</script>
STR


    # @param [Hash] env The rack env hash.
    # @param [Hash] options
    # @option options [Symbol,false,nil] :organisation Choose which CDN to use, either :google, :microsoft or :media_temple, or :cloudflare. Pass in `false` to force use of the local jQuery script. `nil` will force choosing the default CDN.
    # @option options [true, false] :debug If you need the unminified version from the CDN for debugging then pass this in. The unminified scripts aren't included via the fallback to keep the library light, so this won't change anything if fallback is used.
    # @return [String] The HTML script tags to get the CDN.
    # @example
    #   # in a Haml file… (but could be any type of template)
    #   # For the default
    #   Rack::JQueryUI.cdn env
    #
    #   # Choose the organisation
    #   Rack::JQueryUI.cdn env, :organisation => :cloudflare
    #
    #   # Raise an error if the organisation doesn't
    #   # support this version of jQuery UI
    #   Rack::JQueryUI.cdn env, :raise => true
    #
    #   # Use the unminified version from the CDN
    #   Rack::JQueryUI.cdn env, :debug => true
    #
    def self.cdn( env, options={} )
      if env.nil? || env.has_key?(:organisation)
        fail ArgumentError, "The Rack::JQueryUI.cdn method needs the Rack environment passed to it, or at the very least, an empty hash."
      end
      raise = (opt = options[:raise]).nil? ?
                opt :
                (env["rack.jquery_ui.raise"] || false)

      organisation =  options[:organisation]
      if organisation.nil? # because false is valid
        organisation = env["rack.jquery_ui.organisation"] ||
                        :media_temple
      end

      unless organisation == false
        script_src = if organisation === :media_temple         
            CDNs::MEDIA_TEMPLE
          elsif organisation === :microsoft
            CDNs::MICROSOFT
          elsif organisation === :cloudflare
            CDNs::CLOUDFLARE
          elsif organisation === :google
            CDNs::GOOGLE
          else
            CDNs::MEDIA_TEMPLE
        end
          
        debug = options.fetch :debug, false
  
        script_src = "#{script_src[0..-7]}js" if debug
        "<script src='#{script_src}'></script>\n#{FALLBACK}"
      else
        "<script src='#{FALLBACK_PATH}'></script>"
      end
    end


    # Default options hash for the middleware.
    DEFAULT_OPTIONS = {
      :http_path  => "/js/jquery-ui/#{JQUERY_UI_VERSION}",
      :raise      =>  false
    }


    # @param [#call] app
    # @param [Hash] options
    # @option options [String] :http_path If you wish the jQuery fallback route to be "/js/jquery-ui/1.10.1/jquery-ui.min.js" (or whichever version this is at) then do nothing, that's the default. If you want the path to be "/assets/javascripts/jquery-ui/1.10.1/jquery-ui.min.js" then pass in `:http_path => "/assets/javascripts/#{Rack::JQueryUI::JQUERY_UI_VERSION}".
    # @note ***Don't leave out the version number!***. The scripts provided by jQuery don't contain the version in the filename like the jQuery scripts do, which means that organising them and sending the right headers back is bound to go wrong unless you put the version number somewhere in the route. You have been warned!
    # @option options [TrueClass] :raise If one of the CDNs does not support then raise an error if it is chosen. Defaults to false.
    # @example
    #   # The default:
    #   use Rack::JQueryUI
    #   # With a different route to the fallback:
    #   use Rack::JQueryUI, :http_path => "/assets/js/#{Rack::JQueryUI::JQUERY_UI_VERSION}"
    def initialize( app, options={} )
      @app, @options  = app, DEFAULT_OPTIONS.merge(options)
      @http_path_to_jquery = ::File.join @options[:http_path], JQUERY_UI_FILE_NAME
      @raise = @options.fetch :raise, false
      @organisation = options.fetch :organisation, :media_temple
    end


    # @param [Hash] env Rack request environment hash.
    def call( env )
      dup._call env
    end


    # For thread safety
    # @param (see #call)
    def _call( env )
      request = Rack::Request.new(env.dup)
      env.merge! "rack.jquery_ui.organisation" => @organisation
      env.merge! "rack.jquery_ui.raise" => @raise
      if request.path_info == @http_path_to_jquery
        response = Rack::Response.new
        # for caching
        response.headers.merge! caching_headers( "#{JQUERY_UI_FILE_NAME}-#{JQUERY_UI_VERSION}", JQUERY_UI_VERSION_DATE)

        # There's no need to test if the IF_MODIFIED_SINCE against the release date because the header will only be passed if the file was previously accessed by the requester, and the file is never updated. If it is updated then it is accessed by a different path.
        if request.env['HTTP_IF_MODIFIED_SINCE']
          response.status = 304
        else
          response.status = 200
          response.write ::File.read( ::File.expand_path "../../../vendor/assets/javascripts/jquery-ui/#{JQUERY_UI_VERSION}/#{JQUERY_UI_FILE_NAME}", __FILE__)
        end
        response.finish
      else
        @app.call(env)
      end
    end # call

  end
end