package control_test

import (
	"net/netip"
	"testing"

	"vppn/peer/control"
)

func TestRoundTrip(t *testing.T) {
	cases := []struct {
		name string
		ping control.Ping
	}{
		{
			name: "zero",
			ping: control.Ping{},
		},
		{
			name: "client ping",
			ping: control.Ping{
				PingTS: 1234567890,
				SrcV4:  netip.MustParseAddrPort("1.2.3.4:51820"),
				Dst:    netip.MustParseAddrPort("5.6.7.8:51820"),
			},
		},
		{
			name: "server response",
			ping: control.Ping{
				PingTS: 1234567890,
				SrcV4:  netip.MustParseAddrPort("5.6.7.8:51820"),
				Dst:    netip.MustParseAddrPort("1.2.3.4:9999"),
			},
		},
		{
			name: "IPv6 only",
			ping: control.Ping{
				PingTS: 999,
				SrcV6:  netip.MustParseAddrPort("[2001:db8::1]:51820"),
				Dst:    netip.MustParseAddrPort("[2001:db8::2]:51820"),
			},
		},
		{
			name: "dual stack",
			ping: control.Ping{
				PingTS: 555,
				SrcV4:  netip.MustParseAddrPort("1.2.3.4:51820"),
				SrcV6:  netip.MustParseAddrPort("[2001:db8::1]:51820"),
				Dst:    netip.MustParseAddrPort("5.6.7.8:9999"),
			},
		},
		{
			name: "no src known",
			ping: control.Ping{
				Dst: netip.MustParseAddrPort("5.6.7.8:51820"),
			},
		},
	}

	for _, tc := range cases {
		t.Run(tc.name, func(t *testing.T) {
			var buf [control.Size]byte
			tc.ping.Marshal(buf[:])
			got, err := control.Unmarshal(buf)
			if err != nil {
				t.Fatalf("Unmarshal: %v", err)
			}
			if got != tc.ping {
				t.Fatalf("round-trip mismatch:\n  got  %+v\n  want %+v", got, tc.ping)
			}
		})
	}
}

func TestUnmarshalBadVersion(t *testing.T) {
	var buf [control.Size]byte
	buf[0] = 99
	if _, err := control.Unmarshal(buf); err == nil {
		t.Fatal("expected error for unknown version, got nil")
	}
}

func TestZeroEncoding(t *testing.T) {
	var buf [control.Size]byte
	(control.Ping{}).Marshal(buf[:])
	for i, b := range buf {
		if i == 0 {
			continue // version byte
		}
		if b != 0 {
			t.Fatalf("expected zero encoding at byte %d, got %d", i, b)
		}
	}
}

func TestRoleFor(t *testing.T) {
	lo := netip.MustParseAddr("10.0.0.1")
	hi := netip.MustParseAddr("10.0.0.2")

	if control.RoleFor(lo, hi) != control.Client {
		t.Error("lower IP should be client")
	}
	if control.RoleFor(hi, lo) != control.Server {
		t.Error("higher IP should be server")
	}
}