# encoding: utf-8
require_relative "base"

module Hexx
  module Creators

    # @api hide
    # @abstract
    # The base class for both instance and module dependencies.
    class Dependency < Base

      # @api hide
      # @!scope class
      # @!method add(target, name, default)
      # Reloads the Base class initializer by adding the default implementation
      # for the dependency.
      #
      # @param  (see Hexx::Creators::Base)
      # @param  [Module] default The default implementation for the dependency.
      # @raise  (see Hexx::Creators::Dependency#validate)
      # @return [Hexx::Creators::Dependency] the dependency object.
      def initialize(target, name, default)
        super target, name
        @default = default
      end

      # @!attribute default
      # The default implementation for the dependency
      # @return [Module] the default implementation
      attr_accessor :default

      # @api hide
      # Validates parameters for the dependency declaration.
      #
      # Adds validation of the dependency default implementation to the
      # {Hexx::Helper::Base#validate}.
      #
      # @raise  (see Hexx::Creators::Base#validate)
      # @raise  (see Hexx::Creators::Dependency#check_default)
      # @return [Hexx::Creators::Dependency] +self+
      def validate
        check_default
        super
      end

      private

      # @api hide
      # The dependency getter
      def getter
        "def #{ name };
           @#{ name } ||= #{ default_name };
           return @#{ name } if @#{ name };
           fail NotImplementedError
             .new \"DI: #{ target.name }##{ name } not implemented\";
         end"
      end

      # @api hide
      # The dependency setter
      def setter
        "def #{ name }=(value);
           if value.nil? || value.is_a?(Module);
             @#{ name } = value;
             #{ name };
           else;
             fail TypeError.new \"DI: \#{ value.inspect } is not a module\";
           end;
         end"
      end

      # @api hide
      # @raise [TypeError] if the default implementation is neither a class,
      #   nor module
      def check_default
        return if default.nil? || default.is_a?(Module)
        fail TypeError.new "#{ default.inspect } is neither a class nor module"
      end

      # @api hide
      # Returns the name of the default implementation of the dependency.
      def default_name
        @default_name ||= default ? default.name : "nil"
      end
    end
  end
end