# Copyright (C) 2012-2014 Zammad Foundation, http://zammad-foundation.org/

class Ticket
  class Number
    module Date
      extend self

      def generate

        # get config
        config = Setting.get('ticket_number_date')

        t = Time.zone.now
        date = t.strftime('%Y-%m-%d')

        # read counter
        counter_increment = nil
        Ticket::Counter.transaction do
          counter = Ticket::Counter.where( generator: 'Date' ).lock(true).first
          if !counter
            counter = Ticket::Counter.new( generator: 'Date', content: '0' )
          end

          # increase counter
          counter_increment, date_file = counter.content.to_s.split(';')
          if date_file == date
            counter_increment = counter_increment.to_i + 1
          else
            counter_increment = 1
          end

          # store new counter value
          counter.content = counter_increment.to_s + ';' + date
          counter.save
        end

        system_id = Setting.get('system_id') || ''
        number = t.strftime('%Y%m%d') + system_id.to_s + sprintf( '%04d', counter_increment)

        # calculate a checksum
        # The algorithm to calculate the checksum is derived from the one
        # Deutsche Bundesbahn (german railway company) uses for calculation
        # of the check digit of their vehikel numbering.
        # The checksum is calculated by alternately multiplying the digits
        # with 1 and 2 and adding the resulsts from left to right of the
        # vehikel number. The modulus to 10 of this sum is substracted from
        # 10. See: http://www.pruefziffernberechnung.de/F/Fahrzeugnummer.shtml
        # (german)
        if config[:checksum]
          chksum = 0
          mult   = 1
          (1..number.length).each do |i|
            digit = number.to_s[i, 1]
            chksum = chksum + ( mult * digit.to_i )
            mult += 1
            if mult == 3
              mult = 1
            end
          end
          chksum %= 10
          chksum = 10 - chksum
          if chksum == 10
            chksum = 1
          end
          number += chksum.to_s
        end
        number
      end

      def check(string)

        # get config
        system_id           = Setting.get('system_id') || ''
        ticket_hook         = Setting.get('ticket_hook')
        ticket_hook_divider = Setting.get('ticket_hook_divider') || ''
        ticket              = nil

        # probe format
        if string =~ /#{ticket_hook}#{ticket_hook_divider}(#{system_id}\d{2,50})/i
          ticket = Ticket.where( number: $1 ).first
        elsif string =~ /#{ticket_hook}\s{0,2}(#{system_id}\d{2,50})/i
          ticket = Ticket.where( number: $1 ).first
        end
        ticket
      end
    end
  end
end