# encoding: UTF-8

module BEncodr
  module List
    module Generic
      module InstanceMethods
        # Encodes object into a bencoded list. BEncoded strings are length-prefixed base ten followed by a colon and
        # the string. Object must implement to_a or to_ary.
        #
        #   [].bencodr #=> "le"
        #
        # @return [::String] the bencoded list
        def bencode
          (respond_to?(:to_ary) ? to_ary : to_a).bencode
        end
      end
    end

    # Registers a class as an object that can be converted into a bencoded list. Class must have instance method to_a
    # or to_ary.
    #
    #   class MyClass
    #     def to_a
    #       [1, :cat]
    #     end
    #   end
    #
    #   BEncodr::Integer.register MyClass
    #   my_class = MyClass.new
    #   my_class.bencodr  #=> "li1e3:cate"
    #
    # @param [Class#to_a, Class#to_ary] type the class to add the bencodr instance method to
    def self.register(type)
      type.send :include, Generic::InstanceMethods
    end

    module Array
      module InstanceMethods
        # Encodes an array into a bencoded list. Bencoded lists are encoded as an 'l' followed by their elements (also
        # bencoded) followed by an 'e'.
        #
        #   [:eggs, "ham", 3, 4.1].bencodr #=> "l4:eggs3:hami3ei4ee"
        #
        # @return [::String] the bencoded list
        def bencode
          collect do |element|
            element.bencode
          end.unshift(:l).push(:e).join
        end
      end

      ::Array.send :include, InstanceMethods
    end
  end
end