package rings

import "net/netip"

// RingTwoPrefix represents the services of a cluster
//
// Ring 2 subnets are of the form `10.(region_id).0.0/20`,
// using the address space that would belong to the ring 3
// region_id 0.
func RingTwoPrefix(region RegionID) (cidr netip.Prefix, err error) {
	switch {
	case !region.Valid():
		err = ErrOutOfRange(region, "region")
	default:
		addr := AddrFrom4(10, uint(region), 0, 0)
		cidr = netip.PrefixFrom(addr, RingTwoBits)
	}
	return cidr, err
}