package main

import (
	"context"
	"encoding/json"
	"errors"
	"net"
	"slices"
	"strings"
	"sync/atomic"
	"testing"
	"time"

	"github.com/nats-io/nats.go"
	"github.com/nats-io/nats.go/jetstream"
	"golang.org/x/net/dns/dnsmessage"

	"github.com/novox/mesh-controller/internal/broker"
	"github.com/novox/mesh-controller/internal/catalogue"
	"github.com/novox/mesh-controller/internal/conditions"
	"github.com/novox/mesh-controller/internal/link"

	"github.com/novox/mesh-controller/internal/testbus"
)

// The self-check (novox/hq to-be 45 §4): a probe that fails raises its condition, one that cannot run
// raises probe-failed for itself and is never a pass, and every run ends with its heartbeat.

// withProbes runs the test with a registry of its own.
func withProbes(t *testing.T, probes ...probe) {
	t.Helper()
	before := probeRegistry
	probeRegistry = probes
	t.Cleanup(func() { probeRegistry = before })
}

func TestARunKeepsWhatEachProbeFoundAndSaysItsHeartbeat(t *testing.T) {
	failing := conditions.Observation{Scope: conditions.ScopeMachine, ID: "anchor", Token: "refused",
		Severity: conditions.Urgent, Summary: "anchor's node-engine would refuse its declaration"}
	var broken atomic.Bool
	broken.Store(true)
	withProbes(t,
		probe{ID: "P1", Asserts: "passes", Kind: "never", Phase: 1,
			run: func(context.Context, *doctor) ([]conditions.Observation, error) { return nil, nil }},
		probe{ID: "P2", Asserts: "finds a fault", Kind: "declaration-refused", Phase: 1,
			run: func(context.Context, *doctor) ([]conditions.Observation, error) {
				if broken.Load() {
					return []conditions.Observation{failing}, nil
				}
				return nil, nil
			}},
		probe{ID: "P3", Asserts: "cannot run", Kind: "x", Phase: 1,
			run: func(context.Context, *doctor) ([]conditions.Observation, error) {
				if broken.Load() {
					return nil, errors.New("the store is away")
				}
				return nil, nil
			}},
		probe{ID: "P4", Asserts: "hangs", Kind: "x", Phase: 1,
			run: func(ctx context.Context, _ *doctor) ([]conditions.Observation, error) {
				if broken.Load() {
					<-ctx.Done()
					time.Sleep(50 * time.Millisecond)
				}
				return nil, nil
			}},
		probe{ID: "P5", Asserts: "later", Kind: "x", Phase: 2, Deferred: "not yet"},
	)
	before := probeWithin
	probeWithin = 200 * time.Millisecond
	t.Cleanup(func() { probeWithin = before })

	store := conditions.NewInMemory()
	told := &conditions.Told{}
	k := conditions.NewKeeper(t.Context(), conditions.Options{Store: store, History: store})
	defer k.Close(context.Background())
	d := &doctor{keeper: k, teller: told, host: "anchor"}
	// A probe that cannot run is said in the verdict at once, and as a condition when the next run cannot
	// run it either (novox/hq issue 277): one timed-out question is not a probe gone blind.
	first := d.runOnce(t.Context(), "a test")
	if first.Counts != (doctorCounts{Passed: 1, Failed: 1, FailedToRun: 2, Deferred: 1}) {
		t.Fatalf("counted %+v", first.Counts)
	}
	if open, _ := k.Open(t.Context()); len(open) != 1 || open[0].Key != "machine.anchor.refused" {
		t.Fatalf("after one run, open: %+v", open)
	}
	run := d.runOnce(t.Context(), "a test")
	if run.Counts != (doctorCounts{Passed: 1, Failed: 1, FailedToRun: 2, Deferred: 1}) {
		t.Fatalf("counted %+v", run.Counts)
	}
	open, err := k.Open(t.Context())
	if err != nil {
		t.Fatal(err)
	}
	var keys []string
	for _, c := range open {
		keys = append(keys, c.Key+"="+c.Kind)
	}
	for _, want := range []string{"machine.anchor.refused=declaration-refused", "probe.P3.failed=probe-failed",
		"probe.P4.failed=probe-failed"} {
		if !slices.Contains(keys, want) {
			t.Errorf("%s is not open: %v", want, keys)
		}
	}
	// The heartbeat, in the shape mesh-watcher reads (the contract with the operator's channel).
	if len(told.Names) != 2 || told.Names[1] != conditions.HeartbeatEvent {
		t.Fatalf("said %v", told.Names)
	}
	if d.lastRunEnded().IsZero() || d.lastRun().Run != run.Run {
		t.Fatal("the run is not the last verdict")
	}
	body, _ := json.Marshal(run)
	var shape map[string]any
	_ = json.Unmarshal(body, &shape)
	for _, field := range []string{"run", "at", "interval-seconds", "counts", "probes", "controller"} {
		if _, ok := shape[field]; !ok {
			t.Errorf("the heartbeat carries no %q: %s", field, body)
		}
	}

	// Mended: the next run clears every one of them.
	broken.Store(false)
	d.runOnce(t.Context(), "a test")
	if open, _ := k.Open(t.Context()); len(open) != 0 {
		t.Fatalf("a passing run left open %+v", open)
	}
}

// **The registry says what each probe asserts**, and a probe not built says why and when.
func TestTheRegistryIsTheDesignsLiveForm(t *testing.T) {
	seen := map[string]bool{}
	for _, p := range probeRegistry {
		if seen[p.ID] {
			t.Errorf("%s twice", p.ID)
		}
		seen[p.ID] = true
		if p.Asserts == "" || p.From == "" || p.Kind == "" {
			t.Errorf("%s does not say what it asserts, where from, or what it raises", p.ID)
		}
		if (p.run == nil) != (p.Deferred != "") || (p.Deferred != "" && p.Phase <= 1) {
			t.Errorf("%s is run and deferred, or neither, or deferred out of Phase 1: %+v", p.ID, p)
		}
	}
	for _, id := range []string{"D1", "D2", "D3", "D4", "D5", "D6", "D7", "D8", "D9", "D10"} {
		if !seen[id] {
			t.Errorf("to-be 45 §4 has %s and the registry does not", id)
		}
	}
}

// **The doctor and the watchdogs watch each other**: watchdogs that stopped are DW; a self-check that
// stopped is S10 (signals_test.go).
func TestWatchdogsThatStoppedAreSaid(t *testing.T) {
	w := &watchdogs{started: time.Now().Add(-time.Hour)}
	d := &doctor{watchdogs: w, host: "anchor"}
	got, err := probeWatchdogs(t.Context(), d)
	if err != nil || len(got) != 1 || got[0].Severity != conditions.Urgent {
		t.Fatalf("%+v %v", got, err)
	}
	w.ticked = time.Now()
	if got, _ := probeWatchdogs(t.Context(), d); len(got) != 0 {
		t.Fatalf("%+v", got)
	}
}

// **D1 composes every machine of a healthy mesh and the host's own validator takes each.**
func TestEveryMachineOfAHealthyMeshComposesAndValidates(t *testing.T) {
	open := aMesh(t)
	got, err := probeDeclarations(t.Context(), &doctor{open: open})
	if err != nil {
		t.Fatal(err)
	}
	if len(got) != 0 {
		t.Fatalf("a healthy mesh failed D1: %+v", got)
	}
}

// **D1 names a machine nothing can be sent to**, and the network that cannot be computed for it.
func TestAMachineWhoseDeclarationDoesNotComposeIsSaid(t *testing.T) {
	open := aMesh(t)
	ctx := t.Context()
	one, two := rivals()
	register(t, open, one)
	register(t, open, two)
	for _, m := range []string{"rival-one", "rival-two"} {
		if _, err := assign(ctx, open, "laptop", m); err != nil && m == "rival-one" {
			t.Fatal(err)
		}
	}
	got, err := probeDeclarations(ctx, &doctor{open: open})
	linted(got)
	if err != nil {
		t.Fatal(err)
	}
	if len(got) != 1 || got[0].Key() != "machine.laptop.uncomposable" || !strings.Contains(got[0].Summary, "the-seat") {
		t.Fatalf("%+v", got)
	}
}

// **D2: a resolver answering NXDOMAIN for IPv6 is wrong** — musl takes it as no such name (issue 262).
func TestAResolverAnsweringNoSuchNameForIPv6IsWrong(t *testing.T) {
	answerAs := func(rcode dnsmessage.RCode) string {
		conn, err := net.ListenPacket("udp", "127.0.0.1:0")
		if err != nil {
			t.Fatal(err)
		}
		t.Cleanup(func() { _ = conn.Close() })
		go func() {
			buf := make([]byte, 1500)
			for {
				n, from, err := conn.ReadFrom(buf)
				if err != nil {
					return
				}
				var q dnsmessage.Message
				if q.Unpack(buf[:n]) != nil {
					continue
				}
				reply := dnsmessage.Message{Header: dnsmessage.Header{ID: q.ID, Response: true}, Questions: q.Questions}
				if q.Questions[0].Type == dnsmessage.TypeA {
					reply.Answers = []dnsmessage.Resource{{Header: dnsmessage.ResourceHeader{Name: q.Questions[0].Name,
						Type: dnsmessage.TypeA, Class: dnsmessage.ClassINET}, Body: &dnsmessage.AResource{A: [4]byte{10, 77, 0, 1}}}}
				} else {
					reply.RCode = rcode
				}
				packed, _ := reply.Pack()
				_, _ = conn.WriteTo(packed, from)
			}
		}()
		_, port, _ := net.SplitHostPort(conn.LocalAddr().String())
		return port
	}
	before := resolverPort
	t.Cleanup(func() { resolverPort = before })

	resolverPort = answerAs(dnsmessage.RCodeSuccess)
	v4, rcode, err := askResolver(t.Context(), "127.0.0.1", "anchor.internal", dnsmessage.TypeA)
	if err != nil || rcode != dnsmessage.RCodeSuccess || !slices.Equal(v4, []string{"10.77.0.1"}) {
		t.Fatalf("%v %v %v", v4, rcode, err)
	}
	v6, rcode, err := askResolver(t.Context(), "127.0.0.1", "anchor.internal", dnsmessage.TypeAAAA)
	if err != nil || rcode != dnsmessage.RCodeSuccess || len(v6) != 0 {
		t.Fatalf("NODATA read as %v %v %v", v6, rcode, err)
	}
	resolverPort = answerAs(dnsmessage.RCodeNameError)
	if _, rcode, _ := askResolver(t.Context(), "127.0.0.1", "anchor.internal", dnsmessage.TypeAAAA); rcode != dnsmessage.RCodeNameError {
		t.Fatalf("NXDOMAIN read as %v", rcode)
	}
}

// **D6, D7: what the controller defines is what it finds**, and a consumer deleted or a stream
// redefined is said — against a real bus, raised by the same derivation the controller starts with.
func TestNatsTheBusIsWhatTheControllerDefines(t *testing.T) {
	url := testbus.URL(t)
	open := aMesh(t)
	js, err := broker.Dial(url)
	if err != nil {
		t.Fatal(err)
	}
	t.Cleanup(js.Close)
	for _, s := range []string{"CONTROL", "NODES", "ASSIGNMENTS", "EVENTS"} {
		_ = js.Context().DeleteStream(s)
	}
	if _, err := assertBusObjects(t.Context(), open.inventory, js); err != nil {
		t.Fatal(err)
	}
	if err := js.EnsureControllerBuckets(); err != nil {
		t.Fatal(err)
	}
	d := &doctor{open: open, js: js}
	for _, p := range []func(context.Context, *doctor) ([]conditions.Observation, error){probeConsumers, probeStreams} {
		got, err := p(t.Context(), d)
		if err != nil || len(got) != 0 {
			t.Fatalf("a bus just raised fails: %+v %v", got, err)
		}
	}
	if err := js.Context().DeleteConsumer("NODES", "laptop"); err != nil {
		t.Fatal(err)
	}
	info, err := js.Context().StreamInfo("EVENTS")
	if err != nil {
		t.Fatal(err)
	}
	cfg := info.Config
	cfg.MaxMsgsPerSubject = 3
	if _, err := js.Context().UpdateStream(&cfg); err != nil {
		t.Fatal(err)
	}
	consumers, err := probeConsumers(t.Context(), d)
	if err != nil || len(consumers) != 1 || consumers[0].Key() != "bus.NODES.laptop.missing" {
		t.Fatalf("the deleted consumer: %+v %v", consumers, err)
	}
	streams, err := probeStreams(t.Context(), d)
	if err != nil || len(streams) != 1 || !strings.Contains(streams[0].Summary, "per subject") {
		t.Fatalf("the redefined stream: %+v %v", streams, err)
	}
}

// **S9 hears the bus**: a consumer that gives up on a message, and one deleted, as the server says.
func TestNatsTheBusSaysAConsumerGaveUpAndOneWasDeleted(t *testing.T) {
	url := testbus.URL(t)
	conn, err := nats.Connect(url)
	if err != nil {
		t.Fatal(err)
	}
	defer conn.Close()
	heard := make(chan *nats.Msg, 16)
	for _, subject := range broker.BusAdvisories {
		if _, err := conn.ChanSubscribe(subject, heard); err != nil {
			t.Fatal(err)
		}
	}
	api, _ := jetstream.New(conn)
	_ = api.DeleteStream(t.Context(), "SEAT_ADVISED")
	stream, err := api.CreateStream(t.Context(), jetstream.StreamConfig{Name: "SEAT_ADVISED", Subjects: []string{"advised.>"}})
	if err != nil {
		t.Fatal(err)
	}
	defer func() { _ = api.DeleteStream(context.Background(), "SEAT_ADVISED") }()
	consumer, err := stream.CreateConsumer(t.Context(), jetstream.ConsumerConfig{Durable: "SEAT_ADVISED_worker",
		AckPolicy: jetstream.AckExplicitPolicy, MaxDeliver: 1, AckWait: 100 * time.Millisecond})
	if err != nil {
		t.Fatal(err)
	}
	if _, err := api.Publish(t.Context(), "advised.x", []byte("x")); err != nil {
		t.Fatal(err)
	}
	if _, err := consumer.Fetch(1, jetstream.FetchMaxWait(time.Second)); err != nil {
		t.Fatal(err)
	}
	// A seat's worker, so the deletion is of a consumer the mesh names (link.MeshNamed).
	// Not acknowledged: after its one delivery the consumer gives up on it — on the next fetch.
	time.Sleep(300 * time.Millisecond)
	_, _ = consumer.Fetch(1, jetstream.FetchMaxWait(300*time.Millisecond))
	if err := stream.DeleteConsumer(t.Context(), "SEAT_ADVISED_worker"); err != nil {
		t.Fatal(err)
	}
	kinds := map[string]string{}
	deadline := time.After(5 * time.Second)
	for len(kinds) < 2 {
		select {
		case m := <-heard:
			if a, ok := link.ReadAdvisory(m.Subject, m.Data); ok {
				kinds[a.Kind] = a.Said
			}
		case <-deadline:
			t.Fatalf("the bus said only %v", kinds)
		}
	}
	if !strings.Contains(kinds["max-deliveries"], "gave up") || !strings.Contains(kinds["consumer-lost"], "was deleted") {
		t.Fatalf("%v", kinds)
	}
}

// **D10 compares a node-engine with what it is delivered as, not with its commit** (2026-10-06: every
// machine read as behind right after a push sent it the current build — it says the digest-named
// directory it runs from, and the mesh holds a commit).
func TestANodeEngineIsJudgedByTheVersionItIsDeliveredAs(t *testing.T) {
	m := catalogue.Manifest{Module: "mesh-host", Resources: []map[string]any{
		{"id": "launcher", "type": "file", "path": "/usr/lib/nox-mesh-host/launch"},
		{"id": "host", "type": "archive", "path": "/usr/lib/nox-mesh-host/versions/31045596c83a"},
		{"id": "unfilled", "type": "archive", "path": "/usr/lib/x/versions/${version}"},
	}}
	delivered := deliveredVersions(m)
	if !slices.Equal(delivered, []string{"31045596c83a"}) {
		t.Fatalf("%v", delivered)
	}
	commit := "1545b00a9f0c"
	for _, c := range []struct {
		reported string
		behind   bool
	}{
		{"31045596c83a", false}, // the live case: current, and was called behind
		{"0123456789ab", true},  // another delivery
		{"1545b00a", false},     // placed by hand, stamped with the commit
		{"", false},             // not said
	} {
		if got := engineBehind(c.reported, delivered, commit); got != c.behind {
			t.Errorf("%q behind = %v, want %v", c.reported, got, c.behind)
		}
	}
	if engineBehind("31045596c83a", nil, commit) {
		t.Error("behind a mesh that holds no delivered build")
	}
}

// **Every seat verb a probe calls is one it declares, and one the controller is granted** — derived
// from the registry, so a probe added with a question the bus would refuse fails here, not live.
func TestEverySeatVerbAProbeAsksIsGranted(t *testing.T) {
	granted, err := broker.PermissionsFor(broker.Principal{Kind: broker.KindController, PasswordHash: "x"})
	if err != nil {
		t.Fatal(err)
	}
	asked := 0
	for _, p := range probeRegistry {
		for _, v := range p.Asks {
			asked++
			subject := link.NodeSeatToolSubject(v.Seat, v.Verb, "anchor")
			if !slices.ContainsFunc(granted.Publish, func(pattern string) bool { return subjectMatches(pattern, subject) }) {
				t.Errorf("%s asks %s.%s and the controller may not publish %s", p.ID, v.Seat, v.Verb, subject)
			}
			if !slices.Contains(broker.VerbsTheSelfCheckAsks, v) {
				t.Errorf("%s asks %s.%s, which broker.VerbsTheSelfCheckAsks does not name", p.ID, v.Seat, v.Verb)
			}
		}
	}
	if asked == 0 {
		t.Fatal("no probe asks a seat verb: D8 lost its declaration")
	}
	// And a probe asking what it did not declare is refused before anything is sent.
	ctx := context.WithValue(t.Context(), probeAsksKey{}, probe{ID: "DX"})
	if _, err := askSeatTool(ctx, nil, "node-intrusion-prevention", "banned", "anchor"); err == nil ||
		!strings.Contains(err.Error(), "does not declare") {
		t.Fatalf("an undeclared question was asked: %v", err)
	}
}

// subjectMatches is the bus's matching of a permission pattern against a subject.
func subjectMatches(pattern, subject string) bool {
	p, s := strings.Split(pattern, "."), strings.Split(subject, ".")
	for i, tok := range p {
		if tok == ">" {
			return len(s) > i
		}
		if i >= len(s) || (tok != "*" && tok != s[i]) {
			return false
		}
	}
	return len(p) == len(s)
}