package watcher_test

import (
	"bytes"
	"context"
	"log/slog"
	"reflect"
	"strings"
	"testing"
	"time"

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

// TestCancelledCheckSavesNothing runs a check with its context already
// cancelled, which is how the rest of a check runs once shutdown cuts it
// short. The real resolver drops the DNS lookup without sending a query,
// and the real port and TLS checkers fail without connecting. The port
// and certificate state the last check saved must stay as it was, and
// nothing may be notified.
func TestCancelledCheckSavesNothing(t *testing.T) {
	t.Parallel()

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

	// newTestWatcher's watcher has stand-in checkers. This one, on the
	// same state and notifier, has the real ones.
	_, deps := newTestWatcher(t, cfg)
	w := watcher.NewForTest(
		cfg,
		deps.state,
		resolver.NewFromLogger(slog.Default()),
		portcheck.NewStandalone(),
		tlscheck.NewStandalone(),
		deps.notifier,
	)

	// The last check found host at a local address, with both ports
	// open and a good certificate.
	const localIP = "127.0.0.1"

	deps.state.SetHostnameState(host, hostnameState(
		map[string]map[string][]string{nsA: {"A": {localIP}}},
	))

	ports := map[string]*state.PortState{
		localIP + ":80":  {Open: true, Hostnames: []string{host}},
		localIP + ":443": {Open: true, Hostnames: []string{host}},
	}
	for key, ps := range ports {
		deps.state.SetPortState(key, ps)
	}

	certKey := localIP + ":443:" + host
	cert := &state.CertificateState{CommonName: host, Status: "ok"}
	deps.state.SetCertificateState(certKey, cert)

	ctx, cancel := context.WithCancel(t.Context())
	cancel()

	w.RunOnce(ctx)

	for key, want := range ports {
		got, _ := deps.state.GetPortState(key)
		if !reflect.DeepEqual(got, want) {
			t.Errorf("port %s saved as %+v, want %+v", key, got, want)
		}
	}

	got, _ := deps.state.GetCertificateState(certKey)
	if !reflect.DeepEqual(got, cert) {
		t.Errorf("certificate saved as %+v, want %+v", got, cert)
	}

	notifications := deps.notifier.getNotifications()
	if len(notifications) != 0 {
		t.Errorf("sent %v, want no notifications", notifications)
	}
}

// newLoggingWatcher returns a watcher for a domain and a hostname, with
// the real resolver, that writes what it logs at warning level or above
// into the returned buffer.
func newLoggingWatcher(t *testing.T) (*watcher.Watcher, *bytes.Buffer) {
	t.Helper()

	cfg := defaultTestConfig(t)
	cfg.Domains = []string{testSmallDomain}
	cfg.Hostnames = []string{host}

	w, _ := newTestWatcher(t, cfg)

	logs := &bytes.Buffer{}
	w.SetLogger(slog.New(slog.NewJSONHandler(
		logs, &slog.HandlerOptions{Level: slog.LevelWarn},
	)))

	return w, logs
}

// TestLookupCutShortIsNotLogged checks a domain and a hostname, looks
// up a nameserver's addresses and follows a CNAME, with the context
// cancelled, as shutdown leaves it. The real resolver fails each lookup
// without sending a query. Shutdown cutting a lookup short is not a
// failure, so nothing may be logged at warning level or above.
func TestLookupCutShortIsNotLogged(t *testing.T) {
	t.Parallel()

	w, logs := newLoggingWatcher(t)

	ctx, cancel := context.WithCancel(t.Context())
	cancel()

	w.RunOnce(ctx)
	w.ResolveNameserverAddresses(ctx, []string{nsA}, nil)
	w.ResolveCNAMEAddresses(ctx, host, cnameState(), nil)

	if logs.Len() > 0 {
		t.Errorf("logged at warning level or above:\n%s", logs)
	}
}

// TestLookupOutOfTimeIsLoggedAsError does what
// TestLookupCutShortIsNotLogged does, with the context's deadline passed
// instead. A lookup that ran out of time did fail, so the domain's NS
// lookup, the hostname's lookup, the nameserver's address lookup and the
// CNAME's are each logged as an error.
func TestLookupOutOfTimeIsLoggedAsError(t *testing.T) {
	t.Parallel()

	w, logs := newLoggingWatcher(t)

	ctx, cancel := context.WithDeadline(t.Context(), time.Now())
	t.Cleanup(cancel)

	w.RunOnce(ctx)
	w.ResolveNameserverAddresses(ctx, []string{nsA}, nil)
	w.ResolveCNAMEAddresses(ctx, host, cnameState(), nil)

	const want = 4

	lines := strings.Count(logs.String(), "\n")
	errorLines := strings.Count(logs.String(), `"level":"ERROR"`)

	if lines != want || errorLines != want {
		t.Errorf("logged:\n%s\nwant %d lines, each at error level", logs, want)
	}
}