package incus

import (
	"net/netip"
	"testing"
)

func TestPickSubnetAvoidsTaken(t *testing.T) {
	taken := []netip.Prefix{
		netip.MustParsePrefix("10.0.0.0/8"),      // the LAN, a /8
		netip.MustParsePrefix("172.16.100.0/24"), // first choice gone
		netip.MustParsePrefix("172.16.101.0/24"), // and the second
		netip.MustParsePrefix("172.28.0.0/14"),   // Docker's configured pool
		netip.MustParsePrefix("192.168.80.0/20"), // a Docker network
	}
	got := PickSubnet(taken)
	if got.String() != "172.16.102.0/24" {
		t.Fatalf("got %s", got)
	}
	if Gateway(got) != "172.16.102.1/24" {
		t.Fatalf("gateway %s", Gateway(got))
	}
}

func TestPickSubnetWholeBlockTaken(t *testing.T) {
	// 172.16.0.0/12 covers every 172.16.x candidate; the picker must move to 192.168
	got := PickSubnet([]netip.Prefix{netip.MustParsePrefix("172.16.0.0/12")})
	if got.String() != "192.168.254.0/24" {
		t.Fatalf("got %s", got)
	}
}

func TestOverlapsEitherWay(t *testing.T) {
	a := netip.MustParsePrefix("172.16.5.0/24")
	if !overlaps(a, netip.MustParsePrefix("172.16.0.0/12")) || !overlaps(netip.MustParsePrefix("172.16.0.0/12"), a) {
		t.Fatal("a /24 inside a /12 overlaps both ways")
	}
	if overlaps(a, netip.MustParsePrefix("172.16.6.0/24")) {
		t.Fatal("neighbours do not overlap")
	}
}