require "uniq_token/version"

module UniqToken
  extend ActiveSupport::Concern

  def random_str length
    chars = [('a'..'z'), ('A'..'Z'), ('0'..'9')].map(&:to_a).flatten
    (0...length).map { chars[rand(chars.length)] }.join
  end

  module ClassMethods
    def unique_token field, options
      prefix = options[:prefix].present? ? options[:prefix] : ''
      length = options[:length].to_i > 0 ? options[:length].to_i : 64
      suffix = options[:suffix].present? ? options[:suffix] : ''

      before_validation { |record|
        if record[field].blank?
          record[field] = loop do
            random_token = "#{prefix}#{random_str(length)}#{suffix}"
            break random_token unless record.class.exists?("#{field}": random_token)
          end
        end
      }
    end
  end
end

class ActiveRecord::Base
  include UniqToken
end