subnet calculator

subnet_calculator.rb

# https://github.com/ipaddress-gem/ipaddress
require 'ipaddress'

class Calculator
  def self.run(top, parts: nil, prefixes: nil)
    top = IPAddress(top)
    subnets = by_parts(top, parts) if parts
    subnets = by_prefixes(top, prefixes) if prefixes
    subnets
  end

  def self.by_parts(parent, parts)
    part = parts.shift
    subnets = parent.split(part)
    return subnets if parts.length == 0
    subnets.map { |subnet| by_parts(subnet, parts.dup) }
  end

  def self.by_prefixes(parent, prefixes)
    prefix = prefixes.shift
    subnets = parent.subnet(prefix)
    return subnets if prefixes.length == 0
    subnets.map { |subnet| by_prefixes(subnet, prefixes.dup) }
  end

  def self.print_subnets(subnets, array: false)
    subnets.each do |ss|
      if ss.is_a?(Array)
        if ss[0].is_a?(IPAddress) && array
          p ss.map(&:to_string)
        else
          print_subnets(ss, array: array)
        end
        puts ""
      else
        puts ss.to_string
      end
    end
  end
end

# divide to 16 parts, then to 4 subnets for each part
subnets = Calculator.run("172.25.0.0/16", parts: [16, 4])
# Calculator.print_subnets(subnets)
Calculator.print_subnets(subnets, array: true)

# divide to /20 parts, then to /22 subnets for each part
# subnets = Calculator.run("172.25.0.0/16", prefixes: [20, 22])
# Calculator.print_subnets(subnets, array: true)