# encoding: utf-8

require "i18n"

module Assertion

  # Module defines how to translate messages describing the desired state
  # of the current assertion
  #
  # You need to declare a hash of attributes to be added to the translation.
  #
  # @example
  #   class MyClass
  #     include Assertion::Translator
  #     def attributes
  #       {}
  #     end
  #   end
  #
  #   item = MyClass.new
  #   item.message(true)
  #   # => "translation missing: en.assertion.my_class.truthy"
  #   item.message(false)
  #   # => "translation missing: en.assertion.my_class.falsey"
  #
  # @author Andrew Kozin <Andrew.Kozin@gmail.com>
  #
  class Translator

    # The gem-specific root scope for translations
    #
    # @return [Symbol]
    #
    ROOT = :assertion

    # The states to be translated with their dictionary names
    #
    # @return [Hash<Object => Symbol>]
    #
    DICTIONARY = { true => :truthy, false => :falsey }

    # Provides a scope for the class
    #
    # @param [Class] klass
    #
    # @return [Array<Symbol>]
    #
    def self.scope(klass)
      [ROOT, Inflector[:to_snake_path][klass.name].to_sym]
    end

    # @!attribute [r] scope
    #
    # @return [Array<Symbol>] the scope for translations
    #
    attr_reader :scope

    # @!attribute [r] scope
    #
    # @return [Class] the assertion whose state should be translated
    #
    attr_reader :assertion

    # @!scope class
    # @!method new(assertion)
    # Creates a state translator for the given assertion class
    #
    # @param [Class] assertion
    #
    # @return [Assertion::Translator]

    # @private
    def initialize(assertion)
      @assertion = assertion
      @scope = self.class.scope(assertion)
      freeze
    end

    # Returns the message describing the desired state of given assertion
    #
    # The translation is provided for the gem-specific scope for the
    # current class
    #
    # @param [Boolean] state The state of the assertion
    # @param [Hash] args The hash of arguments to be avaliable in a translation
    #
    # @return [String] The translation
    #
    def call(state, args = {})
      I18n.translate DICTIONARY[state ? true : false], args.merge(scope: scope)
    end

  end # class Translator

end # module Assertion