# encoding: utf-8

module Hexx

  # Contains methods to declare and inject module dependencies.
  #
  # Allows to provide DJ framework for the gem.
  #
  # @example
  #   # Declare the dependencies for the gem root module
  #
  #   # lib/my_gem.rb
  #   module MyGem
  #     extend Hexx::Configurable
  #     self.depends_on :get_item, :add_item
  #     self.depends_on :delete_item, default: DeleteItem
  #   end
  #
  #   # Inject dependencies (as a constant or its name)
  #
  #   # config/my_gem.rb
  #   MyGem.configure do |config|
  #     config.get_item = AnotherGem::Services::Get
  #     config.add_item
  #   end
  #
  #   # Use dependency in the module code (models, services, etc.)
  #   # When the dependency hasn't been set, fails with +NotImplementedError+
  #
  #   MyGem.get_item # => AnotherGem::Services::Get
  #   MyGem.get_item # => DeleteItem
  #   MyGem.add_item # fails with a NotImplementedError
  module Configurable

    # Yields a block and gives it self
    #
    # @example
    #   module MyGem
    #     extend Hexx::Configurable
    #   end
    #
    #   MyGem.configure do |config|
    #     c # => MyGem
    #   end
    #
    # @yield The block.
    # @yieldparam [Hexx::Configurable] +self+.
    def configure
      yield(self)
    end

    # @!method depends_on(*names, options)
    # Declares a dependency getter and setter.
    #
    # @example
    #   module MyGem
    #     extend Hexx::Configurable
    #     self.depends_on :some_class
    #   end
    #
    #   MyGem.some_class = String
    #   # => "String"
    #   MyGem.some_class # => String
    #
    #   MyGem.some_class = "String"
    #   # => "String"
    #   MyGem.some_class # => String
    #
    #   MyGem.some_class = :String
    #   # => "String"
    #   MyGem.some_class # => String
    #
    # @example Dependencies can be declared by a plain list of names
    #   module MyGem
    #     extend Hexx::Configurable
    #     self.depends_on :some_class, "another_class"
    #   end
    #
    # @example Dependencies can be declared by an array of names
    #   module MyGem
    #     extend Hexx::Configurable
    #     self.depends_on %w(some_class another_class)
    #   end
    #
    # @example A dependency can have default implementation
    #   module MyGem
    #     extend Hexx::Configurable
    #     self.depends_on :item, default: Item
    #   end
    #
    # @param [Array<String, Symbol>] names The list of names for dependencies.
    # @param [Hash] options The list of options for dependency declaration.
    # @option options [Module, nil] :default (nil) The default implementation
    #   for the dependency.
    def depends_on(*names, default: nil)
      names.flatten.each do |name|
        Creators::ModuleDependency.add self, name, default
      end
    end
  end
end