module Twilio
  module REST
    class ListResource
      include Utils

      def initialize(uri, client)
        @resource_name = self.class.name.split('::')[-1]
        @instance_class = Twilio::REST.const_get @resource_name.chop
        @uri, @client = uri, client
      end

      def inspect # :nodoc:
        "<#{self.class} @uri=#{@uri}>"
      end

      ##
      # Grab a list of this kind of resource and return it as an array. The
      # array includes a special attribute named +total+ which will return the
      # total number of items in the list on Twilio's server. This may differ
      # from the +size+ and +length+ attributes of the returned array since
      # by default Twilio will only return 50 resources, and the maximum number
      # of resources you can request is 1000.
      #
      # The optional +params+ hash allows you to filter the list returned. The
      # filters for each list resource type are defined by Twilio
      def list(params = {})
        raise "Can't get a resource list without a REST Client" unless @client
        response = @client.get @uri, params
        resources = response[detwilify(@resource_name)]
        resource_list = resources.map do |resource|
          @instance_class.new "#{@uri}/#{resource[instance_sid_key]}", @client,
            resource
        end
        # set the +total+ property on the array
        resource_list.instance_eval {
          eigenclass = class << self; self; end
          eigenclass.send :define_method, :total, &lambda {response['total']}
        }
        # update the list's internal total if we just fetched the whole list
        @total = response['total'] if params.empty?
        resource_list
      end

      ##
      # Ask Twilio for the total number of items in the list and cache it.
      # Calling this method makes an HTTP GET request to <tt>@uri</tt> with a
      # page size parameter of 1 to minimize data over the wire while still
      # obtaining the total. Don't use this or #total if you are planning to
      # call #list anyway, since the array returned from #list will have a
      # +total+ attribute as well.
      def total!
        raise "Can't get a resource total without a REST Client" unless @client
        response = @client.get @uri, :page_size => 1
        @total = response['total']
      end

      ##
      # Return the cached total number of items in the list, or fetch and cache.
      def total
        @total ||= total!
      end

      ##
      # Return an empty instance resource object with the proper URI. Note that
      # this will never raise a Twilio::REST::RequestError on 404 since no HTTP
      # request is made. The HTTP request is made when attempting to access an
      # attribute of the returned instance resource object, such as
      # its #date_created or #voice_url attributes.
      def get(sid)
        @instance_class.new "#{@uri}/#{sid}", @client
      end
      alias :find :get # for the ActiveRecord lovers

      ##
      # Return a newly created resource. Some +params+ may be required. Consult
      # the Twilio REST API documentation related to the kind of resource you
      # are attempting to create for details. Calling this method makes an HTTP
      # POST request to <tt>@uri</tt> with the given params
      def create(params = {})
        raise "Can't create a resource without a REST Client" unless @client
        response = @client.post @uri, params
        @instance_class.new "#{@uri}/#{response['sid']}", @client, response
      end

      private

      ##
      # Return the JSON key containing the sid of each instance. Overridden for
      # conference participants and perhaps other resources.
      def instance_sid_key
        'sid'
      end
    end
  end
end