package notificationuser_test

import (
	"bytes"
	"context"
	"encoding/base64"
	"encoding/json"
	"errors"
	"io"
	"net/http"
	"testing"
	"time"

	"galaxy/integration/internal/harness"

	"github.com/redis/go-redis/v9"
	"github.com/stretchr/testify/require"
)

const notificationUserIntentsStream = "notification:intents"

func TestNotificationUserEnrichmentPersistsResolvedRecipient(t *testing.T) {
	h := newNotificationUserHarness(t)

	recipient := h.ensureUser(t, "pilot@example.com", "fr-FR")
	messageID := h.publishUserIntent(t, recipient.UserID, "game.turn.ready", "game_master", "enrichment-success", `{"game_id":"game-123","game_name":"Nebula Clash","turn_number":54}`)

	route := h.waitForRoute(t, messageID, "email:user:"+recipient.UserID)
	require.Equal(t, messageID, route.NotificationID)
	require.Equal(t, "email:user:"+recipient.UserID, route.RouteID)
	require.Equal(t, "email", route.Channel)
	require.Equal(t, "user:"+recipient.UserID, route.RecipientRef)
	require.Equal(t, "pilot@example.com", route.ResolvedEmail)
	require.Equal(t, "en", route.ResolvedLocale)

	offset := h.waitForStreamOffset(t)
	require.Equal(t, messageID, offset.LastProcessedEntryID)
}

func TestNotificationUserMissingRecipientIsMalformedAndAdvancesOffset(t *testing.T) {
	h := newNotificationUserHarness(t)

	messageID := h.publishUserIntent(t, "user-missing", "game.turn.ready", "game_master", "missing-user", `{"game_id":"game-123","game_name":"Nebula Clash","turn_number":54}`)

	malformed := h.waitForMalformedIntent(t, messageID)
	require.Equal(t, messageID, malformed.StreamEntryID)
	require.Equal(t, "game.turn.ready", malformed.NotificationType)
	require.Equal(t, "game_master", malformed.Producer)
	require.Equal(t, "recipient_not_found", malformed.FailureCode)

	offset := h.waitForStreamOffset(t)
	require.Equal(t, messageID, offset.LastProcessedEntryID)
}

func TestNotificationUserTemporaryUnavailabilityDoesNotAdvanceOffset(t *testing.T) {
	h := newNotificationUserHarness(t)

	recipient := h.ensureUser(t, "temporary@example.com", "en")
	h.notificationProcess.AllowUnexpectedExit()
	h.userServiceProcess.Stop(t)

	messageID := h.publishUserIntent(t, recipient.UserID, "game.turn.ready", "game_master", "temporary-user-service", `{"game_id":"game-123","game_name":"Nebula Clash","turn_number":54}`)

	require.Never(t, func() bool {
		offset, ok := h.loadStreamOffset(t)
		return ok && offset.LastProcessedEntryID == messageID
	}, time.Second, 50*time.Millisecond)

	exists, err := h.redis.Exists(context.Background(), notificationMalformedIntentKey(messageID)).Result()
	require.NoError(t, err)
	require.Zero(t, exists)

	exists, err = h.redis.Exists(context.Background(), notificationRouteKey(messageID, "email:user:"+recipient.UserID)).Result()
	require.NoError(t, err)
	require.Zero(t, exists)
}

type notificationUserHarness struct {
	redis *redis.Client

	userServiceURL string

	notificationProcess *harness.Process
	userServiceProcess  *harness.Process
}

type ensureByEmailResponse struct {
	Outcome string `json:"outcome"`
	UserID  string `json:"user_id"`
}

type notificationRouteRecord struct {
	NotificationID string `json:"notification_id"`
	RouteID        string `json:"route_id"`
	Channel        string `json:"channel"`
	RecipientRef   string `json:"recipient_ref"`
	Status         string `json:"status"`
	ResolvedEmail  string `json:"resolved_email,omitempty"`
	ResolvedLocale string `json:"resolved_locale,omitempty"`
}

type malformedIntentRecord struct {
	StreamEntryID    string         `json:"stream_entry_id"`
	NotificationType string         `json:"notification_type,omitempty"`
	Producer         string         `json:"producer,omitempty"`
	IdempotencyKey   string         `json:"idempotency_key,omitempty"`
	FailureCode      string         `json:"failure_code"`
	FailureMessage   string         `json:"failure_message"`
	RawFields        map[string]any `json:"raw_fields_json"`
	RecordedAtMS     int64          `json:"recorded_at_ms"`
}

type streamOffsetRecord struct {
	Stream               string `json:"stream"`
	LastProcessedEntryID string `json:"last_processed_entry_id"`
	UpdatedAtMS          int64  `json:"updated_at_ms"`
}

type httpResponse struct {
	StatusCode int
	Body       string
	Header     http.Header
}

func newNotificationUserHarness(t *testing.T) *notificationUserHarness {
	t.Helper()

	redisRuntime := harness.StartRedisContainer(t)
	redisClient := redis.NewClient(&redis.Options{
		Addr:            redisRuntime.Addr,
		Protocol:        2,
		DisableIdentity: true,
	})
	t.Cleanup(func() {
		require.NoError(t, redisClient.Close())
	})

	userServiceAddr := harness.FreeTCPAddress(t)
	notificationInternalAddr := harness.FreeTCPAddress(t)

	userServiceBinary := harness.BuildBinary(t, "userservice", "./user/cmd/userservice")
	notificationBinary := harness.BuildBinary(t, "notification", "./notification/cmd/notification")

	userServiceProcess := harness.StartProcess(t, "userservice", userServiceBinary, map[string]string{
		"USERSERVICE_LOG_LEVEL":          "info",
		"USERSERVICE_INTERNAL_HTTP_ADDR": userServiceAddr,
		"USERSERVICE_REDIS_ADDR":         redisRuntime.Addr,
		"OTEL_TRACES_EXPORTER":           "none",
		"OTEL_METRICS_EXPORTER":          "none",
	})
	waitForUserServiceReady(t, userServiceProcess, "http://"+userServiceAddr)

	notificationProcess := harness.StartProcess(t, "notification", notificationBinary, map[string]string{
		"NOTIFICATION_LOG_LEVEL":                  "info",
		"NOTIFICATION_INTERNAL_HTTP_ADDR":         notificationInternalAddr,
		"NOTIFICATION_REDIS_ADDR":                 redisRuntime.Addr,
		"NOTIFICATION_USER_SERVICE_BASE_URL":      "http://" + userServiceAddr,
		"NOTIFICATION_USER_SERVICE_TIMEOUT":       "250ms",
		"NOTIFICATION_INTENTS_READ_BLOCK_TIMEOUT": "100ms",
		"NOTIFICATION_ROUTE_BACKOFF_MIN":          "100ms",
		"NOTIFICATION_ROUTE_BACKOFF_MAX":          "100ms",
		"OTEL_TRACES_EXPORTER":                    "none",
		"OTEL_METRICS_EXPORTER":                   "none",
	})
	harness.WaitForHTTPStatus(t, notificationProcess, "http://"+notificationInternalAddr+"/readyz", http.StatusOK)

	return &notificationUserHarness{
		redis:               redisClient,
		userServiceURL:      "http://" + userServiceAddr,
		notificationProcess: notificationProcess,
		userServiceProcess:  userServiceProcess,
	}
}

func (h *notificationUserHarness) ensureUser(t *testing.T, email string, preferredLanguage string) ensureByEmailResponse {
	t.Helper()

	response := postJSONValue(t, h.userServiceURL+"/api/v1/internal/users/ensure-by-email", map[string]any{
		"email": email,
		"registration_context": map[string]string{
			"preferred_language": preferredLanguage,
			"time_zone":          "Europe/Kaliningrad",
		},
	})

	var body ensureByEmailResponse
	requireJSONStatus(t, response, http.StatusOK, &body)
	require.Equal(t, "created", body.Outcome)
	require.NotEmpty(t, body.UserID)
	return body
}

func (h *notificationUserHarness) publishUserIntent(t *testing.T, recipientUserID string, notificationType string, producer string, idempotencyKey string, payloadJSON string) string {
	t.Helper()

	messageID, err := h.redis.XAdd(context.Background(), &redis.XAddArgs{
		Stream: notificationUserIntentsStream,
		Values: map[string]any{
			"notification_type":       notificationType,
			"producer":                producer,
			"audience_kind":           "user",
			"recipient_user_ids_json": `["` + recipientUserID + `"]`,
			"idempotency_key":         idempotencyKey,
			"occurred_at_ms":          "1775121700000",
			"payload_json":            payloadJSON,
		},
	}).Result()
	require.NoError(t, err)

	return messageID
}

func (h *notificationUserHarness) waitForRoute(t *testing.T, notificationID string, routeID string) notificationRouteRecord {
	t.Helper()

	key := notificationRouteKey(notificationID, routeID)
	var route notificationRouteRecord
	require.Eventually(t, func() bool {
		payload, err := h.redis.Get(context.Background(), key).Bytes()
		if err != nil {
			return false
		}
		require.NoError(t, decodeJSONPayload(payload, &route))
		return true
	}, 10*time.Second, 50*time.Millisecond)

	return route
}

func (h *notificationUserHarness) waitForMalformedIntent(t *testing.T, streamEntryID string) malformedIntentRecord {
	t.Helper()

	key := notificationMalformedIntentKey(streamEntryID)
	var record malformedIntentRecord
	require.Eventually(t, func() bool {
		payload, err := h.redis.Get(context.Background(), key).Bytes()
		if err != nil {
			return false
		}
		require.NoError(t, decodeStrictJSONPayload(payload, &record))
		return true
	}, 10*time.Second, 50*time.Millisecond)

	return record
}

func (h *notificationUserHarness) waitForStreamOffset(t *testing.T) streamOffsetRecord {
	t.Helper()

	var offset streamOffsetRecord
	require.Eventually(t, func() bool {
		var ok bool
		offset, ok = h.loadStreamOffset(t)
		return ok
	}, 10*time.Second, 50*time.Millisecond)

	return offset
}

func (h *notificationUserHarness) loadStreamOffset(t *testing.T) (streamOffsetRecord, bool) {
	t.Helper()

	payload, err := h.redis.Get(context.Background(), notificationStreamOffsetKey()).Bytes()
	if errors.Is(err, redis.Nil) {
		return streamOffsetRecord{}, false
	}
	require.NoError(t, err)

	var offset streamOffsetRecord
	require.NoError(t, decodeStrictJSONPayload(payload, &offset))
	return offset, true
}

func waitForUserServiceReady(t *testing.T, process *harness.Process, baseURL string) {
	t.Helper()

	client := &http.Client{Timeout: 250 * time.Millisecond}
	t.Cleanup(client.CloseIdleConnections)

	deadline := time.Now().Add(10 * time.Second)
	for time.Now().Before(deadline) {
		request, err := http.NewRequest(http.MethodGet, baseURL+"/api/v1/internal/users/user-missing/exists", nil)
		require.NoError(t, err)

		response, err := client.Do(request)
		if err == nil {
			_, _ = io.Copy(io.Discard, response.Body)
			response.Body.Close()
			if response.StatusCode == http.StatusOK {
				return
			}
		}

		time.Sleep(25 * time.Millisecond)
	}

	t.Fatalf("wait for userservice readiness: timeout\n%s", process.Logs())
}

func postJSONValue(t *testing.T, targetURL string, body any) httpResponse {
	t.Helper()

	payload, err := json.Marshal(body)
	require.NoError(t, err)

	request, err := http.NewRequest(http.MethodPost, targetURL, bytes.NewReader(payload))
	require.NoError(t, err)
	request.Header.Set("Content-Type", "application/json")
	return doRequest(t, request)
}

func requireJSONStatus(t *testing.T, response httpResponse, wantStatus int, target any) {
	t.Helper()

	require.Equal(t, wantStatus, response.StatusCode, "response body: %s", response.Body)
	require.NoError(t, decodeStrictJSONPayload([]byte(response.Body), target))
}

func doRequest(t *testing.T, request *http.Request) httpResponse {
	t.Helper()

	client := &http.Client{
		Timeout: 5 * time.Second,
		Transport: &http.Transport{
			DisableKeepAlives: true,
		},
	}
	t.Cleanup(client.CloseIdleConnections)

	response, err := client.Do(request)
	require.NoError(t, err)
	defer response.Body.Close()

	payload, err := io.ReadAll(response.Body)
	require.NoError(t, err)

	return httpResponse{
		StatusCode: response.StatusCode,
		Body:       string(payload),
		Header:     response.Header.Clone(),
	}
}

func decodeStrictJSONPayload(payload []byte, target any) error {
	decoder := json.NewDecoder(bytes.NewReader(payload))
	decoder.DisallowUnknownFields()

	if err := decoder.Decode(target); err != nil {
		return err
	}
	if err := decoder.Decode(&struct{}{}); err != io.EOF {
		if err == nil {
			return errors.New("unexpected trailing JSON input")
		}
		return err
	}

	return nil
}

func decodeJSONPayload(payload []byte, target any) error {
	decoder := json.NewDecoder(bytes.NewReader(payload))

	if err := decoder.Decode(target); err != nil {
		return err
	}
	if err := decoder.Decode(&struct{}{}); err != io.EOF {
		if err == nil {
			return errors.New("unexpected trailing JSON input")
		}
		return err
	}

	return nil
}

func notificationRouteKey(notificationID string, routeID string) string {
	return "notification:routes:" + encodeKeyComponent(notificationID) + ":" + encodeKeyComponent(routeID)
}

func notificationMalformedIntentKey(streamEntryID string) string {
	return "notification:malformed_intents:" + encodeKeyComponent(streamEntryID)
}

func notificationStreamOffsetKey() string {
	return "notification:stream_offsets:" + encodeKeyComponent(notificationUserIntentsStream)
}

func encodeKeyComponent(value string) string {
	return base64.RawURLEncoding.EncodeToString([]byte(value))
}