package worker

import (
	"context"
	"errors"
	"io"
	"log/slog"
	"testing"
	"time"

	"galaxy/mail/internal/adapters/redisstate"
	"galaxy/mail/internal/service/acceptgenericdelivery"

	"github.com/alicebob/miniredis/v2"
	"github.com/redis/go-redis/v9"
	"github.com/stretchr/testify/require"
)

func TestCommandConsumerAcceptsRenderedCommand(t *testing.T) {
	t.Parallel()

	fixture := newCommandConsumerFixture(t)
	messageID := addRenderedCommand(t, fixture.client, "mail-123", "notification:mail-123")

	ctx, cancel := context.WithCancel(context.Background())
	done := make(chan error, 1)
	go func() {
		done <- fixture.consumer.Run(ctx)
	}()

	require.Eventually(t, func() bool {
		delivery, found, err := fixture.acceptanceStore.GetDelivery(context.Background(), "mail-123")
		if err != nil || !found {
			return false
		}
		entryID, found, err := fixture.offsetStore.Load(context.Background(), fixture.stream)
		return err == nil && found && entryID == messageID && delivery.DeliveryID == "mail-123"
	}, 5*time.Second, 20*time.Millisecond)

	cancel()
	require.ErrorIs(t, <-done, context.Canceled)
}

func TestCommandConsumerAcceptsTemplateCommand(t *testing.T) {
	t.Parallel()

	fixture := newCommandConsumerFixture(t)
	messageID := addTemplateCommand(t, fixture.client, "mail-124", "notification:mail-124")

	ctx, cancel := context.WithCancel(context.Background())
	done := make(chan error, 1)
	go func() {
		done <- fixture.consumer.Run(ctx)
	}()

	require.Eventually(t, func() bool {
		delivery, found, err := fixture.acceptanceStore.GetDelivery(context.Background(), "mail-124")
		if err != nil || !found {
			return false
		}
		entryID, found, err := fixture.offsetStore.Load(context.Background(), fixture.stream)
		return err == nil && found && entryID == messageID && delivery.TemplateID == "game.turn.ready"
	}, 5*time.Second, 20*time.Millisecond)

	cancel()
	require.ErrorIs(t, <-done, context.Canceled)
}

func TestCommandConsumerRecordsMalformedCommandAndContinues(t *testing.T) {
	t.Parallel()

	fixture := newCommandConsumerFixture(t)
	malformedID := addMalformedRenderedCommand(t, fixture.client, "mail-bad", "notification:mail-bad")
	validID := addRenderedCommand(t, fixture.client, "mail-125", "notification:mail-125")

	ctx, cancel := context.WithCancel(context.Background())
	done := make(chan error, 1)
	go func() {
		done <- fixture.consumer.Run(ctx)
	}()

	require.Eventually(t, func() bool {
		_, deliveryFound, deliveryErr := fixture.acceptanceStore.GetDelivery(context.Background(), "mail-125")
		entry, malformedFound, malformedErr := fixture.malformedStore.Get(context.Background(), malformedID)
		entryID, offsetFound, offsetErr := fixture.offsetStore.Load(context.Background(), fixture.stream)
		return deliveryErr == nil &&
			malformedErr == nil &&
			offsetErr == nil &&
			deliveryFound &&
			malformedFound &&
			entry.FailureCode == "invalid_payload" &&
			offsetFound &&
			entryID == validID
	}, 5*time.Second, 20*time.Millisecond)

	cancel()
	require.ErrorIs(t, <-done, context.Canceled)
}

func TestCommandConsumerRestartsFromSavedOffset(t *testing.T) {
	t.Parallel()

	fixture := newCommandConsumerFixture(t)
	firstID := addRenderedCommand(t, fixture.client, "mail-126", "notification:mail-126")

	firstCtx, firstCancel := context.WithCancel(context.Background())
	firstDone := make(chan error, 1)
	go func() {
		firstDone <- fixture.consumer.Run(firstCtx)
	}()

	require.Eventually(t, func() bool {
		entryID, found, err := fixture.offsetStore.Load(context.Background(), fixture.stream)
		return err == nil && found && entryID == firstID
	}, 5*time.Second, 20*time.Millisecond)

	firstCancel()
	require.ErrorIs(t, <-firstDone, context.Canceled)

	secondID := addRenderedCommand(t, fixture.client, "mail-127", "notification:mail-127")

	secondCtx, secondCancel := context.WithCancel(context.Background())
	secondDone := make(chan error, 1)
	go func() {
		secondDone <- fixture.consumer.Run(secondCtx)
	}()

	require.Eventually(t, func() bool {
		_, firstFound, firstErr := fixture.acceptanceStore.GetDelivery(context.Background(), "mail-126")
		_, secondFound, secondErr := fixture.acceptanceStore.GetDelivery(context.Background(), "mail-127")
		entryID, offsetFound, offsetErr := fixture.offsetStore.Load(context.Background(), fixture.stream)
		return firstErr == nil &&
			secondErr == nil &&
			offsetErr == nil &&
			firstFound &&
			secondFound &&
			offsetFound &&
			entryID == secondID
	}, 5*time.Second, 20*time.Millisecond)

	secondCancel()
	require.ErrorIs(t, <-secondDone, context.Canceled)
}

func TestCommandConsumerDoesNotDuplicateAcceptanceAfterOffsetSaveFailure(t *testing.T) {
	t.Parallel()

	fixture := newCommandConsumerFixture(t)
	messageID := addRenderedCommand(t, fixture.client, "mail-128", "notification:mail-128")
	failingOffsetStore := &scriptedOffsetStore{
		saveErrs: []error{errors.New("offset unavailable")},
	}
	consumer := newCommandConsumerForTest(t, fixture.client, fixture.stream, fixture.acceptor, fixture.malformedStore, failingOffsetStore)

	err := consumer.Run(context.Background())
	require.Error(t, err)
	require.ErrorContains(t, err, "save stream offset")

	delivery, found, err := fixture.acceptanceStore.GetDelivery(context.Background(), "mail-128")
	require.NoError(t, err)
	require.True(t, found)
	require.Equal(t, "mail-128", delivery.DeliveryID.String())

	indexCard, err := fixture.client.ZCard(context.Background(), redisstate.Keyspace{}.CreatedAtIndex()).Result()
	require.NoError(t, err)
	require.EqualValues(t, 1, indexCard)

	replayConsumer := newCommandConsumerForTest(t, fixture.client, fixture.stream, fixture.acceptor, fixture.malformedStore, failingOffsetStore)
	replayCtx, replayCancel := context.WithCancel(context.Background())
	replayDone := make(chan error, 1)
	go func() {
		replayDone <- replayConsumer.Run(replayCtx)
	}()

	require.Eventually(t, func() bool {
		return failingOffsetStore.lastEntryID == messageID
	}, 5*time.Second, 20*time.Millisecond)

	replayCancel()
	require.ErrorIs(t, <-replayDone, context.Canceled)

	indexCard, err = fixture.client.ZCard(context.Background(), redisstate.Keyspace{}.CreatedAtIndex()).Result()
	require.NoError(t, err)
	require.EqualValues(t, 1, indexCard)

	scheduleCard, err := fixture.client.ZCard(context.Background(), redisstate.Keyspace{}.AttemptSchedule()).Result()
	require.NoError(t, err)
	require.EqualValues(t, 1, scheduleCard)
}

func TestCommandConsumerRecordsIdempotencyConflictAsMalformed(t *testing.T) {
	t.Parallel()

	fixture := newCommandConsumerFixture(t)
	addRenderedCommand(t, fixture.client, "mail-129", "notification:shared")
	conflictID := addRenderedCommandWithSubject(t, fixture.client, "mail-130", "notification:shared", "Different subject")

	ctx, cancel := context.WithCancel(context.Background())
	done := make(chan error, 1)
	go func() {
		done <- fixture.consumer.Run(ctx)
	}()

	require.Eventually(t, func() bool {
		_, firstFound, firstErr := fixture.acceptanceStore.GetDelivery(context.Background(), "mail-129")
		_, secondFound, secondErr := fixture.acceptanceStore.GetDelivery(context.Background(), "mail-130")
		entry, malformedFound, malformedErr := fixture.malformedStore.Get(context.Background(), conflictID)
		return firstErr == nil &&
			secondErr == nil &&
			malformedErr == nil &&
			firstFound &&
			!secondFound &&
			malformedFound &&
			entry.FailureCode == "idempotency_conflict"
	}, 5*time.Second, 20*time.Millisecond)

	cancel()
	require.ErrorIs(t, <-done, context.Canceled)
}

type commandConsumerFixture struct {
	client          *redis.Client
	stream          string
	consumer        *CommandConsumer
	acceptor        *acceptgenericdelivery.Service
	acceptanceStore *redisstate.GenericAcceptanceStore
	malformedStore  *redisstate.MalformedCommandStore
	offsetStore     *redisstate.StreamOffsetStore
}

func newCommandConsumerFixture(t *testing.T) commandConsumerFixture {
	t.Helper()

	server := miniredis.RunT(t)
	client := redis.NewClient(&redis.Options{Addr: server.Addr()})
	t.Cleanup(func() { require.NoError(t, client.Close()) })

	acceptanceStore, err := redisstate.NewGenericAcceptanceStore(client)
	require.NoError(t, err)
	now := time.Now().UTC().Truncate(time.Millisecond)
	acceptor, err := acceptgenericdelivery.New(acceptgenericdelivery.Config{
		Store:          acceptanceStore,
		Clock:          testClock{now: now},
		IdempotencyTTL: redisstate.IdempotencyTTL,
	})
	require.NoError(t, err)

	malformedStore, err := redisstate.NewMalformedCommandStore(client)
	require.NoError(t, err)
	offsetStore, err := redisstate.NewStreamOffsetStore(client)
	require.NoError(t, err)

	stream := redisstate.Keyspace{}.DeliveryCommands()
	consumer := newCommandConsumerForTest(t, client, stream, acceptor, malformedStore, offsetStore)

	return commandConsumerFixture{
		client:          client,
		stream:          stream,
		consumer:        consumer,
		acceptor:        acceptor,
		acceptanceStore: acceptanceStore,
		malformedStore:  malformedStore,
		offsetStore:     offsetStore,
	}
}

func newCommandConsumerForTest(
	t *testing.T,
	client *redis.Client,
	stream string,
	acceptor AcceptGenericDeliveryUseCase,
	malformedRecorder MalformedCommandRecorder,
	offsetStore StreamOffsetStore,
) *CommandConsumer {
	t.Helper()

	consumer, err := NewCommandConsumer(CommandConsumerConfig{
		Client:            client,
		Stream:            stream,
		BlockTimeout:      20 * time.Millisecond,
		Acceptor:          acceptor,
		MalformedRecorder: malformedRecorder,
		OffsetStore:       offsetStore,
		Clock:             testClock{now: time.Now().UTC().Truncate(time.Millisecond)},
	}, testLogger())
	require.NoError(t, err)

	return consumer
}

func addRenderedCommand(t *testing.T, client *redis.Client, deliveryID string, idempotencyKey string) string {
	t.Helper()

	return addRenderedCommandWithSubject(t, client, deliveryID, idempotencyKey, "Turn ready")
}

func addRenderedCommandWithSubject(t *testing.T, client *redis.Client, deliveryID string, idempotencyKey string, subject string) string {
	t.Helper()

	messageID, err := client.XAdd(context.Background(), &redis.XAddArgs{
		Stream: redisstate.Keyspace{}.DeliveryCommands(),
		Values: map[string]any{
			"delivery_id":     deliveryID,
			"source":          "notification",
			"payload_mode":    "rendered",
			"idempotency_key": idempotencyKey,
			"requested_at_ms": "1775121700000",
			"payload_json":    `{"to":["pilot@example.com"],"cc":[],"bcc":[],"reply_to":["noreply@example.com"],"subject":"` + subject + `","text_body":"Turn 54 is ready.","html_body":"<p>Turn 54 is ready.</p>","attachments":[]}`,
		},
	}).Result()
	require.NoError(t, err)

	return messageID
}

func addTemplateCommand(t *testing.T, client *redis.Client, deliveryID string, idempotencyKey string) string {
	t.Helper()

	messageID, err := client.XAdd(context.Background(), &redis.XAddArgs{
		Stream: redisstate.Keyspace{}.DeliveryCommands(),
		Values: map[string]any{
			"delivery_id":     deliveryID,
			"source":          "notification",
			"payload_mode":    "template",
			"idempotency_key": idempotencyKey,
			"requested_at_ms": "1775121700001",
			"payload_json":    `{"to":["pilot@example.com"],"cc":[],"bcc":[],"reply_to":[],"template_id":"game.turn.ready","locale":"fr-FR","variables":{"turn_number":54},"attachments":[]}`,
		},
	}).Result()
	require.NoError(t, err)

	return messageID
}

func addMalformedRenderedCommand(t *testing.T, client *redis.Client, deliveryID string, idempotencyKey string) string {
	t.Helper()

	messageID, err := client.XAdd(context.Background(), &redis.XAddArgs{
		Stream: redisstate.Keyspace{}.DeliveryCommands(),
		Values: map[string]any{
			"delivery_id":     deliveryID,
			"source":          "notification",
			"payload_mode":    "rendered",
			"idempotency_key": idempotencyKey,
			"requested_at_ms": "1775121700000",
			"payload_json":    `{"to":["pilot@example.com"],"cc":[],"bcc":[],"reply_to":[],"text_body":"Turn 54 is ready.","attachments":[]}`,
		},
	}).Result()
	require.NoError(t, err)

	return messageID
}

type testClock struct {
	now time.Time
}

func (clock testClock) Now() time.Time {
	return clock.now
}

type scriptedOffsetStore struct {
	lastEntryID string
	found       bool
	saveErrs    []error
	saveCalls   int
}

func (store *scriptedOffsetStore) Load(context.Context, string) (string, bool, error) {
	if !store.found {
		return "", false, nil
	}

	return store.lastEntryID, true, nil
}

func (store *scriptedOffsetStore) Save(_ context.Context, _ string, entryID string) error {
	if store.saveCalls < len(store.saveErrs) && store.saveErrs[store.saveCalls] != nil {
		store.saveCalls++
		return store.saveErrs[store.saveCalls-1]
	}

	store.saveCalls++
	store.lastEntryID = entryID
	store.found = true
	return nil
}

func testLogger() *slog.Logger {
	return slog.New(slog.NewJSONHandler(io.Discard, nil))
}