class EncodeCandidateEmails < ActiveRecord::Migration[5.0]
  def change
    sql = "select id, email from candidates;"
    candidates = ActiveRecord::Base.connection.execute(sql).to_h

    candidates.each do |id, email|
      sql = if base64?(email)
              # going down - decrypt
              "UPDATE candidates set email = '#{CryptSerializer.load email}' WHERE id = #{id};"
            else
              # going up - encrypt emails
              "UPDATE candidates set email = '#{CryptSerializer.dump email}' WHERE id = #{id};"
            end
      ActiveRecord::Base.connection.execute(sql)
    end
  end

  private

    def base64? string
      Base64.urlsafe_decode64 string
      true
    rescue ArgumentError
      false
    end
end