module Hashie::Extensions::Dash::PropertyTranslation::ClassMethods

def define_translation(from, property_name, translator)
  translations_hash[from][property_name] = translator
end

def define_writer_for_source_property(property)
  define_method "#{property}=" do |val|
    __translations[property].each do |name, with|
      self[name] = with.respond_to?(:call) ? with.call(val) : val
    end
  end
end

def fail_self_transformation_error!(property_name)
  raise ArgumentError,
        "Property name (#{property_name}) and :from option must not be the same"
end

def inherited(klass)
  super
  klass.instance_variable_set(:@transforms, transforms.dup)
  klass.instance_variable_set(:@translations_hash, translations_hash.dup)
end

def inverse_translations
  @inverse_translations ||= {}.tap do |translations|
    translations_hash.each do |(property_name, property_translations)|
      property_translations.each_key do |key|
        translations[key] = property_name
      end
    end
  end
end

def permitted_input_keys
  @permitted_input_keys ||=
    properties
    .map { |property| inverse_translations.fetch property, property }
end

def property(property_name, options = {})
  super
  from = options[:from]
  converter = options[:with]
  transformer = options[:transform_with]
  if from
    fail_self_transformation_error!(property_name) if property_name == from
    define_translation(from, property_name, converter || transformer)
    define_writer_for_source_property(from)
  elsif valid_transformer?(transformer)
    transforms[property_name] = transformer
  end
end

def transformation_exists?(name)
  transforms.key? name
end

def transformed_property(property_name, value)
  transforms[property_name].call(value)
end

def translation_exists?(name)
  translations_hash.key? name
end

def translations
  @translations ||= {}.tap do |translations|
    translations_hash.each do |(property_name, property_translations)|
      translations[property_name] =
        if property_translations.size > 1
          property_translations.keys
        else
          property_translations.keys.first
        end
    end
  end
end

def valid_transformer?(transformer)
  transformer.respond_to? :call
end