Generate Unique User Referral Code

User.rb

class User < ApplicationRecord
  
  validates_length_of :first_name, :last_name, minimum: 2
  validates :refferal_code, presence: true, uniqueness: true
  
  before_validation :set_referral_code
  
  
  private
  
  def set_referral_code
    return true if referral_code.present?
    referral_code = new_referral_code
  end
  
  def new_referral_code
    count = 0
    token = nil
    
    loop do
      token = (first_name + last_name).upcase[0..2] + rand.to_s[2..5]
      break if User.where(refferal_code: token).empty?
    end
    
    if count > 5
      raise 'Took too long to generate a unique code'
    end
      
    token
  end
  
end