package netsplit

import (
	"net/netip"

	"go4.org/netipx"
)

/*
GetSplitter returns the first (should be *only*) non-nill NetSplitter on a StructuredResults.

If none is found, splitter will be nil but no panic/error will occur.
*/
func (s *StructuredResults) GetSplitter() (splitter NetSplitter) {

	if s == nil || s.Splitter == nil {
		return
	}

	/*
		TODO(?): It'd be nice if I could just reflect .Interface() this
					to a NetSplitter but I think I'd then have to typeswitch
					into the real type regardless, which is lame.
	*/

	if s.Splitter.CIDR != nil {
		splitter = s.Splitter.CIDR
	} else if s.Splitter.Host != nil {
		splitter = s.Splitter.Host
	} else if s.Splitter.Subnet != nil {
		splitter = s.Splitter.Subnet
	} else if s.Splitter.VLSM != nil {
		splitter = s.Splitter.VLSM
	}

	return
}

/*
Uncontain returns a set of values that "unstructure" a StructuredResults.

(Essentially the opposite procedure of Contain().)
*/
func (s *StructuredResults) Uncontain() (origPfx *netip.Prefix, nets []*netip.Prefix, remaining *netipx.IPSet, splitter NetSplitter, err error) {

	var ipsb *netipx.IPSetBuilder

	if s == nil {
		return
	}

	origPfx = s.Original
	if s.Allocated != nil {
		nets = make([]*netip.Prefix, len(s.Allocated))
		for idx, i := range s.Allocated {
			nets[idx] = i.Network
		}
	}
	if s.Unallocated != nil {
		ipsb = new(netipx.IPSetBuilder)
		for _, i := range s.Unallocated {
			if i.Network != nil {
				ipsb.AddPrefix(*i.Network)
			}
		}
		if remaining, err = ipsb.IPSet(); err != nil {
			return
		}
	}

	splitter = s.GetSplitter()

	return
}