require "identification/parser/parser"

module Identification
  module Parser
    # Represents a DVLA parser.
    #
    # @private     
    class DVLA < Parser
      def self.parse(driver_number)
        # Remove whitespace
        driver_number.gsub!(/\s+/, '')

        return { validity: false } if driver_number.length != 18 && driver_number.length != 16

        doc_data = Hash.new(6)

        # Document will be valid unless an error occurs.
        doc_data[:validity] = true

        # Document may not be valid, but still, continue parsing.
        doc_data[:validity] = false unless dvla_check_line_checksum(driver_number)

        doc_data[:last_name] = driver_number[0...5].sub(/9+/, '')

        doc_data[:first_initials] = driver_number[11...13].sub(/9+/, '')

        if driver_number.length == 18
          doc_data[:license_numbers] = driver_number[16...18]
        else
          doc_data[:license_numbers] = '00'
        end      

        doc_data[:date_of_birth] = yymmdd_to_ruby_date(driver_number[5...11])

        if driver_number[6] == '5' || driver_number == '6'
          doc_data[:gender] = 'F'
        else
          doc_data[:gender] = 'M'
        end

        # In case of an invalid date...
        doc_data[:validity] = false if doc_data[:date_of_birth] == false

        return doc_data
      end

      def self.yymmdd_to_ruby_date(input_date)
        # Change the month back (if gender is set to F)
        input_date[1] = '0' if input_date[1] == '5'
        input_date[1] = '1' if input_date[1] == '6'

        # Put to YYMMDD format
        new_date = String.new(input_date)
        new_date[1] = input_date[5]
        new_date[2] = input_date[1]
        new_date[3] = input_date[2]
        new_date[4] = input_date[3]
        new_date[5] = input_date[4]
        super(new_date) 
      end

      def self.dvla_check_line_checksum(driver_number)
        # Awaiting response from DVLA...
        # Boilerplate content for now...

        their_check_digit = driver_number[13...16]

        # Returning true until I know how to calculate check digits
        true
      end

      private_class_method :dvla_check_line_checksum
    end
  end
end