package eventbus

import (
	"context"
	"encoding/json"
	"errors"
	"strings"
	"testing"
	"time"

	"github.com/nats-io/nats.go"

	"lingniu-vehicle-ingest/go/vehicle-gateway/internal/envelope"
)

func TestNATSSinkRoutesRawAndUnifiedSubjects(t *testing.T) {
	publisher := &recordingNATSPublisher{}
	sink := newNATSSinkWithPublisher(publisher, NATSConfig{
		RawSubjects: map[envelope.Protocol]string{
			envelope.ProtocolJT808: "vehicle.raw.jt808.v1",
		},
		UnifiedSubject: "vehicle.event.unified.v1",
	})
	env := envelope.FrameEnvelope{Protocol: envelope.ProtocolJT808, Phone: "13307795425", MessageID: "0x0200"}

	if err := sink.PublishRaw(context.Background(), env); err != nil {
		t.Fatalf("PublishRaw() error = %v", err)
	}
	if err := sink.PublishUnified(context.Background(), env); err != nil {
		t.Fatalf("PublishUnified() error = %v", err)
	}

	if got, want := publisher.messages[0].subject, "vehicle.raw.jt808.v1"; got != want {
		t.Fatalf("raw subject = %q, want %q", got, want)
	}
	if got, want := publisher.messages[1].subject, "vehicle.event.unified.v1"; got != want {
		t.Fatalf("unified subject = %q, want %q", got, want)
	}
	var decoded envelope.FrameEnvelope
	if err := json.Unmarshal(publisher.messages[0].data, &decoded); err != nil {
		t.Fatalf("raw payload is not envelope json: %v", err)
	}
	if decoded.Phone != "13307795425" {
		t.Fatalf("decoded phone = %q", decoded.Phone)
	}
}

func TestNATSSinkDefaultsToGoRawSubjects(t *testing.T) {
	publisher := &recordingNATSPublisher{}
	sink := newNATSSinkWithPublisher(publisher, NATSConfig{})

	err := sink.PublishRaw(context.Background(), envelope.FrameEnvelope{
		Protocol:     envelope.ProtocolJT808,
		Phone:        "13307795425",
		ReceivedAtMS: 1782918600000,
	})
	if err != nil {
		t.Fatalf("PublishRaw() error = %v", err)
	}
	if got, want := publisher.messages[0].subject, "vehicle.raw.go.jt808.v1"; got != want {
		t.Fatalf("subject = %q, want %q", got, want)
	}
}

func TestNATSSinkPublishesDurableRecords(t *testing.T) {
	publisher := &recordingNATSPublisher{}
	sink := newNATSSinkWithPublisher(publisher, NATSConfig{
		RawSubjects: map[envelope.Protocol]string{
			envelope.ProtocolJT808: "vehicle.raw.go.jt808.v1",
		},
		FieldsSubjects: map[envelope.Protocol]string{
			envelope.ProtocolJT808: "vehicle.fields.go.jt808.v1",
		},
		UnifiedSubject: "vehicle.event.go.unified.v1",
	})
	env := envelope.FrameEnvelope{Protocol: envelope.ProtocolJT808, Phone: "13307795425", MessageID: "0x0200"}

	err := sink.PublishRecords(context.Background(), []durableRecord{
		{Kind: "raw", Envelope: env},
		{Kind: "fields", Envelope: env},
		{Kind: "unified", Envelope: env},
	})
	if err != nil {
		t.Fatalf("PublishRecords() error = %v", err)
	}
	if len(publisher.messages) != 3 {
		t.Fatalf("published messages = %d, want 3", len(publisher.messages))
	}
	for i, want := range []string{
		"vehicle.raw.go.jt808.v1",
		"vehicle.fields.go.jt808.v1",
		"vehicle.event.go.unified.v1",
	} {
		if got := publisher.messages[i].subject; got != want {
			t.Fatalf("message %d subject = %q, want %q", i, got, want)
		}
	}
}

func TestNATSMessageIDSeparatesKindAndSubject(t *testing.T) {
	env := envelope.FrameEnvelope{Protocol: envelope.ProtocolJT808, Phone: "13307795425", MessageID: "0x0200", Sequence: 7}

	raw := natsMessageID("raw", "vehicle.raw.go.jt808.v1", env)
	rawRetry := natsMessageID("raw", "vehicle.raw.go.jt808.v1", env)
	fields := natsMessageID("fields", "vehicle.fields.go.jt808.v1", env)
	unified := natsMessageID("unified", "vehicle.event.go.unified.v1", env)
	rawOtherSubject := natsMessageID("raw", "vehicle.raw.go.gb32960.v1", env)

	if raw != rawRetry {
		t.Fatalf("same kind/subject/event id should be stable: %q vs %q", raw, rawRetry)
	}
	if raw == fields || raw == unified || raw == rawOtherSubject {
		t.Fatalf("message ids should be unique per kind and subject: raw=%q fields=%q unified=%q rawOther=%q", raw, fields, unified, rawOtherSubject)
	}
	if !strings.Contains(raw, env.StableEventID()) {
		t.Fatalf("message id %q should retain stable event id %q", raw, env.StableEventID())
	}
}

func TestNATSSinkPublishRecordsRejectsUnknownKind(t *testing.T) {
	sink := newNATSSinkWithPublisher(&recordingNATSPublisher{}, NATSConfig{})

	err := sink.PublishRecords(context.Background(), []durableRecord{
		{Kind: "unknown", Envelope: envelope.FrameEnvelope{Protocol: envelope.ProtocolJT808}},
	})
	if err == nil || !strings.Contains(err.Error(), "unknown durable record kind") {
		t.Fatalf("PublishRecords() error = %v, want unknown kind", err)
	}
}

func TestNATSSinkAsyncPublishCompletesOnlyAfterPubAck(t *testing.T) {
	future := newTestPubAckFuture()
	asyncPublisher := &recordingNATSAsyncPublisher{future: future}
	sink := newNATSSinkWithPublishers(&recordingNATSPublisher{}, asyncPublisher, NATSConfig{})
	record := durableRecord{Kind: "raw", Envelope: normalizeDurableEnvelope(durableTestEnvelope())}
	completed := make(chan error, 1)

	if err := sink.PublishRecordAsync(record, func(err error) { completed <- err }); err != nil {
		t.Fatalf("PublishRecordAsync() error = %v", err)
	}
	select {
	case err := <-completed:
		t.Fatalf("completion fired before PubAck: %v", err)
	case <-time.After(10 * time.Millisecond):
	}
	if got, want := asyncPublisher.subject, "vehicle.raw.go.jt808.v1"; got != want {
		t.Fatalf("async subject = %q, want %q", got, want)
	}
	var decoded envelope.FrameEnvelope
	if err := json.Unmarshal(asyncPublisher.data, &decoded); err != nil {
		t.Fatalf("decode async payload: %v", err)
	}
	if decoded.EventID != record.Envelope.EventID {
		t.Fatalf("async event id = %q, want %q", decoded.EventID, record.Envelope.EventID)
	}

	future.ok <- &nats.PubAck{Stream: "VEHICLE_RAW", Sequence: 1}
	select {
	case err := <-completed:
		if err != nil {
			t.Fatalf("completion error = %v", err)
		}
	case <-time.After(time.Second):
		t.Fatal("completion did not fire after PubAck")
	}
}

func TestNATSSinkAsyncPublishPropagatesFutureError(t *testing.T) {
	future := newTestPubAckFuture()
	sink := newNATSSinkWithPublishers(
		&recordingNATSPublisher{},
		&recordingNATSAsyncPublisher{future: future},
		NATSConfig{},
	)
	completed := make(chan error, 1)
	errWant := errors.New("jetstream ack timeout")

	if err := sink.PublishRecordAsync(durableRecord{
		Kind:     "raw",
		Envelope: normalizeDurableEnvelope(durableTestEnvelope()),
	}, func(err error) { completed <- err }); err != nil {
		t.Fatalf("PublishRecordAsync() error = %v", err)
	}
	future.err <- errWant
	select {
	case err := <-completed:
		if !errors.Is(err, errWant) {
			t.Fatalf("completion error = %v, want %v", err, errWant)
		}
	case <-time.After(time.Second):
		t.Fatal("completion did not fire after future error")
	}
}

func TestNATSSinkValidatesDurableRecordBeforeOutboxPersistence(t *testing.T) {
	sink := newNATSSinkWithPublisher(&recordingNATSPublisher{}, NATSConfig{})
	err := sink.ValidateRecord(durableRecord{
		Kind:     "raw",
		Envelope: envelope.FrameEnvelope{Protocol: envelope.Protocol("UNKNOWN")},
	})
	if err == nil || !strings.Contains(err.Error(), "raw subject not configured") {
		t.Fatalf("ValidateRecord() error = %v", err)
	}
}

func TestValidateNATSConfigRejectsRawFieldsSubjectOverlap(t *testing.T) {
	err := ValidateNATSConfig(NATSConfig{
		RawSubjects: map[envelope.Protocol]string{
			envelope.ProtocolJT808: "vehicle.same.jt808",
		},
		FieldsSubjects: map[envelope.Protocol]string{
			envelope.ProtocolJT808: "vehicle.same.jt808",
		},
	})
	if err == nil {
		t.Fatal("ValidateNATSConfig() error = nil, want overlap rejection")
	}
	if !strings.Contains(err.Error(), "nats subject") {
		t.Fatalf("error = %q, want nats subject hint", err)
	}
}

func TestValidateNATSConfigRejectsKnownProtocolSubjectMismatch(t *testing.T) {
	err := ValidateNATSConfig(NATSConfig{
		RawSubjects: map[envelope.Protocol]string{
			envelope.ProtocolJT808: "vehicle.raw.go.gb32960.v1",
		},
	})
	if err == nil {
		t.Fatal("ValidateNATSConfig() error = nil, want raw protocol mismatch")
	}
	if !strings.Contains(err.Error(), "must match protocol") {
		t.Fatalf("error = %q, want protocol mismatch hint", err)
	}

	err = ValidateNATSConfig(NATSConfig{
		FieldsSubjects: map[envelope.Protocol]string{
			envelope.ProtocolGB32960: "vehicle.fields.go.yutong-mqtt.v1",
		},
	})
	if err == nil {
		t.Fatal("ValidateNATSConfig() error = nil, want fields protocol mismatch")
	}
	if !strings.Contains(err.Error(), "must match protocol") {
		t.Fatalf("error = %q, want protocol mismatch hint", err)
	}
}

type recordingNATSPublisher struct {
	messages []recordedNATSMessage
}

type recordedNATSMessage struct {
	subject string
	data    []byte
}

func (p *recordingNATSPublisher) Publish(_ context.Context, subject string, data []byte, _ ...NATSPublishOption) error {
	p.messages = append(p.messages, recordedNATSMessage{subject: subject, data: append([]byte(nil), data...)})
	return nil
}

type recordingNATSAsyncPublisher struct {
	subject string
	data    []byte
	future  nats.PubAckFuture
	err     error
}

func (p *recordingNATSAsyncPublisher) PublishAsync(subject string, data []byte, _ ...NATSPublishOption) (nats.PubAckFuture, error) {
	p.subject = subject
	p.data = append([]byte(nil), data...)
	return p.future, p.err
}

type testPubAckFuture struct {
	ok  chan *nats.PubAck
	err chan error
	msg *nats.Msg
}

func newTestPubAckFuture() *testPubAckFuture {
	return &testPubAckFuture{
		ok:  make(chan *nats.PubAck, 1),
		err: make(chan error, 1),
		msg: &nats.Msg{},
	}
}

func (f *testPubAckFuture) Ok() <-chan *nats.PubAck { return f.ok }

func (f *testPubAckFuture) Err() <-chan error { return f.err }

func (f *testPubAckFuture) Msg() *nats.Msg { return f.msg }