class IPAddr
  # @family is either AF_INET or AF_INET6.
  # @addr is a String represents IP address as an octet string.
  # @mask is a String represents netmask as an octet string.

  def initialize(addr='::', family=Socket::AF_UNSPEC)
    a, m = addr.split('/', 2)
    if family == Socket::AF_UNSPEC
      begin
        @addr = IPSocket.pton(Socket::AF_INET, a)
        @family = Socket::AF_INET
      rescue ArgumentError
        @addr = IPSocket.pton(Socket::AF_INET6, a)
        @family = Socket::AF_INET6
      end
    else
      @addr = IPSocket.pton(family, a)
      @family = family
    end
    if m
      initialize_makemask(m)
      _applymask
    else
      if @family == Socket::AF_INET
        @mask = "\xff" * 4
      elsif @family == Socket::AF_INET6
        @mask = "\xff" * 16
      end
    end
  end

  def initialize_makemask(m)
    if @family == Socket::AF_INET and m.include?('.')
      @mask = IPSocket.pton(Socket::AF_INET, m)
    elsif @family == Socket::AF_INET6 and m.include?(':')
      @mask = IPSocket.pton(Socket::AF_INET6, m)
    else
      ma = []
      mi = m.to_i
      mlen = (ipv4?) ? 32 : 128
      while mlen > 0
        if mi >= 8
          ma << 0xff
        elsif mi <= 0
          ma << 0
        else
          ma << (0xff ^ (0xff >> mi))
        end
        mi -= 8
        mlen -= 8
      end
      @mask = ma.pack("C*")
    end
  end

  def self.new_ntoh(addr)
    raise TypeError, "can't convert to String" unless addr.is_a? String
    if addr.size == 4
      a = IPAddr.new("0.0.0.0")
      f = Socket::AF_INET
    elsif addr.size == 16
      a = IPAddr.new("::")
      f = Socket::AF_INET6
    else
      raise ArgumentError, "length of addr must be 4 or 16"
    end
    a.set2(addr, f)
  end

  # private
  def _applymask
    a = @addr.unpack("C*")
    m = @mask.unpack("C*")
    (0...a.size).each { |i| a[i] &= m[i] }
    @addr = a.pack("C*")
  end

  # private
  def _mask
    @mask
  end

  #def &(other)
  #def <<(num)

  def <=>(other)
    if @family == other.family
      @addr <=> other.hton
    else
      nil
    end
  end

  def ==(other)
    if other.is_a? String
      self.eql? IPAddr.new(other)
    else
      self.eql? other
    end
  end

  #def ===(ipaddr)
  #alias include? ===
  #def >>(num)

  def eql?(other)
    @addr == other.hton and @mask == other._mask and @family == other.family
  end

  def family
    @family
  end

  def hash
    @addr.hash ^ @mask.hash ^ @family.hash
  end

  def hton
    @addr
  end

  def inspect
    def a2s(a)
      if @family == Socket::AF_INET
        return a.unpack("C*").map { |b| format("%u", b) }.join('.')
      else
        bytes = a.unpack("C*").map { |x| format "%02x", x }
        return (0..7).map { |i| bytes[i*2, 2].join }.join(':')
      end
    end
    format "#<%s: %s:%s/%s>",
      self.class, (ipv4? ? 'IPv4' : 'IPv6'), a2s(@addr), a2s(@mask)
  end

  def ipv4?
    @family == Socket::AF_INET
  end

  def ipv6?
    @family == Socket::AF_INET6
  end

  def mask(prefixlen)
    a = @addr.unpack("C*")
    i = prefixlen.divmod(8)[0]             # mruby 1.0.0 lacks Integer#div
    if prefixlen % 8 != 0
      a[i] &= ~(0xff >> (prefixlen % 8))
      i += 1
    end
    (i..a.size-1).each { |i| a[i] = 0 }
    IPAddr.new('::', Socket::AF_INET6).set2(a.pack("C*"), @family)
  end

  # private
  def set2(a, f)
    @addr = a
    @family = f
    if @family == Socket::AF_INET
      @mask = "\xff" * 4
    elsif @family == Socket::AF_INET6
      @mask = "\xff" * 16
    end
    self
  end

  def to_s
    IPAddr.ntop(@addr)
  end

  def ~
    a = @addr.unpack("C*").map { |b| b ^ 0xff }.pack("C*")
    IPAddr.new('::', Socket::AF_INET6).set2(a, @family)
  end

  alias to_string to_s

  # mruby extension
  def is_netaddr?(prefixlen)
    (self <=> self.mask(prefixlen)) == 0
  end

  def is_bcastaddr?(prefixlen)
    i = ~self
    (i <=> i.mask(prefixlen)) == 0
  end
end