module PageTitleHelper

  class PageTitleBuilder

    class << self

      def build(template)

        new(template).build

      end

    end

     attr_reader :template

    delegate :assigns, to: :template

    delegate :params, to: :template

    delegate :translate, to: :template

    delegate :[], :has_key?, to: :assigns

    def initialize(template)

      @template = template

    end

    def build

      translate key, options

    end

    private

    def controller

      @controller ||= params[:controller].tr('/', '_')

    end

    def action

      @action ||= params[:action]

    end

    def key

      @key ||= :"#{controller}.#{action}"

    end

    def options

      {}.tap do |opts|

        opts[:scope]        = :page_titles

        opts[:default]      = [:"#{controller}.default", :default]

        opts[:constituency] = constituency.name if constituency?

        opts[:postcode]     = formatted_postcode if postcode?

        if postcode?

          opts[:count] = 1

        else

          opts[:count] = 0

        end

        if petition?

          opts[:petition] = petition.action

          if controller == 'sponsors'

            opts[:creator] = petition.creator.name

          end

        end

      end

    end

    %w[constituency petition postcode].each do |object|

      define_method :"#{object}?" do

        send(:"#{object}").present?

      end

      define_method :"#{object}" do

        send(:[], object)

      end

    end

    def formatted_postcode

      postcode.gsub(/\A(.+)(.{3})\z/, '\1 \2')

    end

  end

  def page_title

    PageTitleBuilder.build(self)

  end

end