module TypeCollection
  # Indicates that a TypeCollection has been extended by a base class that
  # fails to comply with the correct naming convention for TypeCollection
  # to function properly
  class InvalidChildType < StandardError; end

  # Indicates that a request has been made to retrieve a child type that
  # is not currently registered with the type collection
  class UnknownChildType < StandardError; end

  # Extended by TypeCollections to provide class level functionality (almost
  # all functionality is class level as of the current design)
  module ClassMethods
    # Contains the Members mapped by type
    def __tc_members(); @_members ||= { }; end

    # Registers a member
    def __tc_register_member(child)
      type = child.inferred_type()
      if (type.nil?)
        cname = child.name.split("::").last
        pname = self.name.split("::").last
        error = "Invalid name: '#{cname}'! Child class names must end with '#{pname}'."
        raise TypeCollection::InvalidChildType.new(error)
      end
      __tc_members()[type] = child
    end

    # Overrides the default behavior when being extended by a child class.
    # It ensures the child is mapped for future retrieval and checks the
    # subclass name to ensure it is a valid one
    def inherited(child)
      super if (defined?(super))
      unless child.name.nil?
        __tc_collection_root.__tc_register_member(child)
      end
    end
  end
end