Multi-part SMS

send_sms_message.rb

SMS_LENGTH = 160
MPM_SIZE_LONG = 16
MPM_SIZE_SHORT = 14
MPM_SHORT_LIMIT = 1314

def send_sms_message(text, to, from)
  unless text.length > SMS_LENGTH
    deliver_message_via_carrier(text, to, from)
  else
    parts = text.scan(/.{1,#{SMS_LENGTH - (text.length > MPM_SHORT_LIMIT ? MPM_SIZE_LONG : MPM_SIZE_SHORT)}}/)
    parts.to_enum.with_index(1) do |message_part, index|
      deliver_message_via_carrier("#{message_part} - Part #{index} of #{parts.length}", to, from)
    end
  end
end

def deliver_message_via_carrier(text, to, from)
  SMS_CARRIER.deliver_message(text, to, from)
end