module Devise
  module Mailers
    module Helpers
      extend ActiveSupport::Concern

      included do
        include Devise::Controllers::ScopedViews
        attr_reader :scope_name, :resource
      end

      protected

      # Configure default email options
      def devise_mail(record, action)
        initialize_from_record(record)
        mail headers_for(action)
      end

      def initialize_from_record(record)
        @scope_name = Devise::Mapping.find_scope!(record)
        @resource   = instance_variable_set("@#{devise_mapping.name}", record)
      end

      def devise_mapping
        @devise_mapping ||= Devise.mappings[scope_name]
      end

      def headers_for(action)
        headers = {
          :subject       => translate(devise_mapping, action),
          :from          => mailer_sender(devise_mapping),
          :to            => resource.email,
          :template_path => template_paths
        }

        if resource.respond_to?(:headers_for)
          headers.merge!(resource.headers_for(action))
        end

        unless headers.key?(:reply_to)
          headers[:reply_to] = headers[:from]
        end

        headers
      end

      def mailer_sender(mapping)
        if default_params[:from].present?
          default_params[:from]
        elsif Devise.mailer_sender.is_a?(Proc)
          Devise.mailer_sender.call(mapping.name)
        else
          Devise.mailer_sender
        end
      end

      def template_paths
        template_path = [self.class.mailer_name]
        template_path.unshift "#{@devise_mapping.scoped_path}/mailer" if self.class.scoped_views?
        template_path
      end

      # Setup a subject doing an I18n lookup. At first, it attemps to set a subject
      # based on the current mapping:
      #
      #   en:
      #     devise:
      #       mailer:
      #         confirmation_instructions:
      #           user_subject: '...'
      #
      # If one does not exist, it fallbacks to ActionMailer default:
      #
      #   en:
      #     devise:
      #       mailer:
      #         confirmation_instructions:
      #           subject: '...'
      #
      def translate(mapping, key)
        I18n.t(:"#{mapping.name}_subject", :scope => [:devise, :mailer, key],
          :default => [:subject, key.to_s.humanize])
      end
    end
  end
end