dkubb/yardstick

# encoding: utf-8

require 'forwardable'

module Yardstick
  # Base class of every rule
  #
  # @abstract
  class Rule
    extend Forwardable

    class << self
      # Description of the rule
      #
      # This is shown when a rule is invalid
      #
      # @return [String]
      #
      # @api private
      attr_accessor :description

      private :description=
    end

    # Register rule in Document
    #
    # @param [Class] subclass
    #   class that is inheriting from this class
    #
    # @return [undefined]
    #
    # @api private
    def self.inherited(subclass)
      Document.register_rule(subclass)
    end
    private_class_method :inherited

    # Macro for describing current rule
    #
    # @param text [String]
    #
    # @return [RuleDescription]
    #
    # @api private
    def self.describe(text)
      self.description = RuleDescription.parse(text)
    end

    # Makes a new instance of rule using given config
    #
    # @param [Yardstick::Document] document
    #   document that will be measured
    # @param [Yardstick::Config] config
    #   a configuration
    #
    # @return [Yardstick::Rule]
    #
    # @api private
    def self.coerce(document, config)
      new(document, config.for_rule(self))
    end

    # Return document that current rule is using
    #
    # @return [Document]
    #
    # @api private
    attr_reader :document

    # Initializes a rule
    #
    # @param [Yardstick::Document] document
    # @param [Yardstick::RuleConfig] config
    #   rule configuration
    #
    # @return [Yardstick::Rule]
    #
    # @api private
    def initialize(document, config = RuleConfig.new)
      @document = document
      @config   = config
    end

    def_delegators :@document, :has_tag?, :api?, :tag_types, :tag_text, :summary_text, :visibility

    # Checks if rule is enabled in current context
    #
    # @return [Boolean]
    #   true if enabled
    #
    # @api private
    def enabled?
      @config.enabled_for_path?(@document.path)
    end

    # Checks if the rule is validatable for given document
    #
    # @return [Boolean]
    #
    # @api private
    def validatable?
      true
    end
  end
end