package watcher_test

import (
	"context"
	"log/slog"
	"slices"
	"testing"

	"sneak.berlin/go/dnswatcher/internal/livednstest"
	"sneak.berlin/go/dnswatcher/internal/resolver"
	"sneak.berlin/go/dnswatcher/internal/state"
	"sneak.berlin/go/dnswatcher/internal/watcher"
)

// cnameHost is a CNAME into another zone: its nameservers answer with
// the CNAME and no address.
const cnameHost = "www.python.org"

// TestCNAMEIntoAnotherZonePortAndTLSChecks checks cnameHost against
// live DNS. Its port and TLS checks must use the addresses at the end
// of its CNAME chain.
func TestCNAMEIntoAnotherZonePortAndTLSChecks(t *testing.T) {
	t.Parallel()

	cfg := defaultTestConfig(t)
	cfg.Hostnames = []string{cnameHost}

	deps := runChecks(t, cfg, nil, nil)

	snap := deps.state.GetSnapshot()
	hs := snap.Hostnames[cnameHost]

	if len(hs.CNAMEAddresses) == 0 {
		t.Fatalf(
			"%s: no addresses saved from following its CNAME; if it "+
				"is no longer a CNAME into another zone, this test "+
				"needs another name",
			cnameHost,
		)
	}

	for _, ip := range hs.CNAMEAddresses {
		ps, ok := snap.Ports[ip+":443"]
		if !ok || !slices.Contains(ps.Hostnames, cnameHost) {
			t.Errorf("no port state for %s at %s:443", cnameHost, ip)
		}

		certKey := ip + ":443:" + cnameHost
		if _, ok := snap.Certificates[certKey]; !ok {
			t.Errorf("no certificate state %s", certKey)
		}
	}
}

// TestCNAMEThatCannotBeFollowedKeepsPrevious gives a name under
// .invalid, whose lookup fails, answers with a CNAME and no address.
// The addresses the previous check saved from following its CNAME are
// kept.
func TestCNAMEThatCannotBeFollowedKeepsPrevious(t *testing.T) {
	t.Parallel()

	const name = "www.example.invalid"

	w := watcher.NewForTest(
		nil, nil, resolver.NewFromLogger(slog.Default()), nil, nil, nil,
	)

	current := hostnameState(map[string]map[string][]string{
		nsA: {"CNAME": {"target.example.invalid."}},
	})
	prev := &state.HostnameState{CNAMEAddresses: []string{oldIP}}

	// The result is the same whether or not live DNS answers, so the
	// lookup is not retried.
	_ = livednstest.Run(func(ctx context.Context) error {
		w.ResolveCNAMEAddresses(ctx, name, current, prev)

		return nil
	})

	if !slices.Equal(current.CNAMEAddresses, prev.CNAMEAddresses) {
		t.Errorf(
			"saved %v, want %v",
			current.CNAMEAddresses, prev.CNAMEAddresses,
		)
	}
}