class CopyNamingAlgorithm
  DEFAULT_MAX_LENGTH = 255
  DEFAULT_MAX_COPIES = 255
  DEFAULT_SEPARATOR_BEFORE_COPY_NUMBER = "_"

  def copy_addition
    raise NotImplementedError
  end

  def separator_before_copy_number
    DEFAULT_SEPARATOR_BEFORE_COPY_NUMBER
  end

  def max_length
    DEFAULT_MAX_LENGTH
  end

  def max_copies
    DEFAULT_MAX_COPIES
  end

  def get_already_used_name_entities(base_name)
    raise NotImplementedError
  end

  def get_name_for_entity(name_entity)
    name_entity
  end

  def create_copy_name(name_to_copy)
    # remove copy addition and number
    base_name = name_to_copy.gsub(/#{Regexp.quote(self.copy_addition)}(#{Regexp.quote(separator_before_copy_number)}\d+)?\z/,'')
    name_entities_to_check_against = get_already_used_name_entities(base_name).collect{|entity| self.get_name_for_entity(entity)}.to_a
    (0..max_copies-1).each {|copy_num|
      name_to_test = generate_name(base_name, copy_num)
      if (name_entities_to_check_against.none? {|entity_name| entity_name == name_to_test})
        return name_to_test
      end
    }

    raise ArgumentError.new("It's not possible to generate a UNIQUE name using name_to_copy: #{name_to_copy} copy_addition: #{self.copy_addition} separator_before_copy_number: #{self.separator_before_copy_number} max_copy_num: #{self.max_copies}  max_length: #{self.max_length}")
  end

  def generate_name(name_to_copy, copy_num)
    what_to_add = self.copy_addition + self.separator_before_copy_number + generate_copy_number(copy_num)

    # is what_to_add longer than max length? If so, it's not possible to create a copy
    if (what_to_add.length > self.max_length)
      raise ArgumentError.new("It's not possible to generate a name using name_to_copy: #{name_to_copy} copy_addition: #{self.copy_addition} separator_before_copy_number: #{self.separator_before_copy_number} copy_num: #{copy_num} max_length: #{self.max_length}")
    end
    max_length_for_name_to_copy = self.max_length - what_to_add.length
    name_to_copy[0..max_length_for_name_to_copy-1] + what_to_add
  end

  def generate_copy_number(unprefixed_copy_number)
    number_of_digits = Math.log10(self.max_copies).floor + 1
    "%0#{number_of_digits}d" % unprefixed_copy_number
  end

end