package store

import (
	"errors"
	"fmt"
	"sync"
	"sync/atomic"
	"testing"
	"time"

	"git.flowmade.one/flowmade-one/aether"
)

// === Event Store Tests ===

func TestNewInMemoryEventStore(t *testing.T) {
	store := NewInMemoryEventStore()

	if store == nil {
		t.Fatal("NewInMemoryEventStore returned nil")
	}
	if store.events == nil {
		t.Error("events map is nil")
	}
}

func TestSaveEvent_SingleEvent(t *testing.T) {
	store := NewInMemoryEventStore()

	event := &aether.Event{
		ID:        "evt-123",
		EventType: "OrderPlaced",
		ActorID:   "order-456",
		Version:   1,
		Data: map[string]interface{}{
			"total": 100.50,
		},
		Timestamp: time.Now(),
	}

	err := store.SaveEvent(event)
	if err != nil {
		t.Fatalf("SaveEvent failed: %v", err)
	}

	// Verify event was persisted
	events, err := store.GetEvents("order-456", 0)
	if err != nil {
		t.Fatalf("GetEvents failed: %v", err)
	}
	if len(events) != 1 {
		t.Fatalf("expected 1 event, got %d", len(events))
	}
	if events[0].ID != "evt-123" {
		t.Errorf("event ID mismatch: got %q, want %q", events[0].ID, "evt-123")
	}
}

func TestSaveEvent_MultipleEvents(t *testing.T) {
	store := NewInMemoryEventStore()

	for i := 1; i <= 5; i++ {
		event := &aether.Event{
			ID:        fmt.Sprintf("evt-%d", i),
			EventType: "OrderUpdated",
			ActorID:   "order-456",
			Version:   int64(i),
			Data:      map[string]interface{}{},
			Timestamp: time.Now(),
		}
		if err := store.SaveEvent(event); err != nil {
			t.Fatalf("SaveEvent failed for event %d: %v", i, err)
		}
	}

	events, err := store.GetEvents("order-456", 0)
	if err != nil {
		t.Fatalf("GetEvents failed: %v", err)
	}
	if len(events) != 5 {
		t.Errorf("expected 5 events, got %d", len(events))
	}
}

func TestSaveEvent_MultipleActors(t *testing.T) {
	store := NewInMemoryEventStore()

	// Save events for different actors
	actors := []string{"actor-1", "actor-2", "actor-3"}
	for _, actorID := range actors {
		for i := 1; i <= 3; i++ {
			event := &aether.Event{
				ID:        fmt.Sprintf("evt-%s-%d", actorID, i),
				EventType: "TestEvent",
				ActorID:   actorID,
				Version:   int64(i),
				Data:      map[string]interface{}{},
				Timestamp: time.Now(),
			}
			if err := store.SaveEvent(event); err != nil {
				t.Fatalf("SaveEvent failed: %v", err)
			}
		}
	}

	// Verify each actor has its own events
	for _, actorID := range actors {
		events, err := store.GetEvents(actorID, 0)
		if err != nil {
			t.Fatalf("GetEvents failed for %s: %v", actorID, err)
		}
		if len(events) != 3 {
			t.Errorf("expected 3 events for %s, got %d", actorID, len(events))
		}
		for _, event := range events {
			if event.ActorID != actorID {
				t.Errorf("event has wrong ActorID: got %q, want %q", event.ActorID, actorID)
			}
		}
	}
}

func TestSaveEvent_PreservesAllFields(t *testing.T) {
	store := NewInMemoryEventStore()

	ts := time.Date(2026, 1, 9, 12, 0, 0, 0, time.UTC)
	event := &aether.Event{
		ID:        "evt-123",
		EventType: "OrderPlaced",
		ActorID:   "order-456",
		CommandID: "cmd-789",
		Version:   42,
		Data: map[string]interface{}{
			"total":    100.50,
			"currency": "USD",
		},
		Timestamp: ts,
	}

	if err := store.SaveEvent(event); err != nil {
		t.Fatalf("SaveEvent failed: %v", err)
	}

	events, err := store.GetEvents("order-456", 0)
	if err != nil {
		t.Fatalf("GetEvents failed: %v", err)
	}

	retrieved := events[0]
	if retrieved.ID != event.ID {
		t.Errorf("ID mismatch: got %q, want %q", retrieved.ID, event.ID)
	}
	if retrieved.EventType != event.EventType {
		t.Errorf("EventType mismatch: got %q, want %q", retrieved.EventType, event.EventType)
	}
	if retrieved.ActorID != event.ActorID {
		t.Errorf("ActorID mismatch: got %q, want %q", retrieved.ActorID, event.ActorID)
	}
	if retrieved.CommandID != event.CommandID {
		t.Errorf("CommandID mismatch: got %q, want %q", retrieved.CommandID, event.CommandID)
	}
	if retrieved.Version != event.Version {
		t.Errorf("Version mismatch: got %d, want %d", retrieved.Version, event.Version)
	}
	if !retrieved.Timestamp.Equal(event.Timestamp) {
		t.Errorf("Timestamp mismatch: got %v, want %v", retrieved.Timestamp, event.Timestamp)
	}
	if retrieved.Data["total"] != event.Data["total"] {
		t.Errorf("Data.total mismatch: got %v, want %v", retrieved.Data["total"], event.Data["total"])
	}
	if retrieved.Data["currency"] != event.Data["currency"] {
		t.Errorf("Data.currency mismatch: got %v, want %v", retrieved.Data["currency"], event.Data["currency"])
	}
}

func TestGetEvents_RetrievesInOrder(t *testing.T) {
	store := NewInMemoryEventStore()

	// Save events in order
	for i := 1; i <= 10; i++ {
		event := &aether.Event{
			ID:        fmt.Sprintf("evt-%d", i),
			EventType: "TestEvent",
			ActorID:   "actor-123",
			Version:   int64(i),
			Data:      map[string]interface{}{},
			Timestamp: time.Now(),
		}
		if err := store.SaveEvent(event); err != nil {
			t.Fatalf("SaveEvent failed: %v", err)
		}
	}

	events, err := store.GetEvents("actor-123", 0)
	if err != nil {
		t.Fatalf("GetEvents failed: %v", err)
	}

	// Verify events are returned in insertion order
	for i, event := range events {
		expectedID := fmt.Sprintf("evt-%d", i+1)
		if event.ID != expectedID {
			t.Errorf("event %d: got ID %q, want %q", i, event.ID, expectedID)
		}
		expectedVersion := int64(i + 1)
		if event.Version != expectedVersion {
			t.Errorf("event %d: got Version %d, want %d", i, event.Version, expectedVersion)
		}
	}
}

func TestGetEvents_FromVersionFilters(t *testing.T) {
	store := NewInMemoryEventStore()

	// Save events with versions 1-10
	for i := 1; i <= 10; i++ {
		event := &aether.Event{
			ID:        fmt.Sprintf("evt-%d", i),
			EventType: "TestEvent",
			ActorID:   "actor-123",
			Version:   int64(i),
			Data:      map[string]interface{}{},
			Timestamp: time.Now(),
		}
		if err := store.SaveEvent(event); err != nil {
			t.Fatalf("SaveEvent failed: %v", err)
		}
	}

	testCases := []struct {
		name        string
		fromVersion int64
		expected    int
		minVersion  int64
	}{
		{"from version 0", 0, 10, 1},
		{"from version 1", 1, 10, 1},
		{"from version 5", 5, 6, 5},
		{"from version 10", 10, 1, 10},
		{"from version 11", 11, 0, 0},
	}

	for _, tc := range testCases {
		t.Run(tc.name, func(t *testing.T) {
			events, err := store.GetEvents("actor-123", tc.fromVersion)
			if err != nil {
				t.Fatalf("GetEvents failed: %v", err)
			}

			if len(events) != tc.expected {
				t.Errorf("expected %d events, got %d", tc.expected, len(events))
			}

			// Verify all returned events have version >= fromVersion
			for _, event := range events {
				if event.Version < tc.fromVersion {
					t.Errorf("event version %d is less than fromVersion %d", event.Version, tc.fromVersion)
				}
			}

			// Verify minimum version if events exist
			if len(events) > 0 && events[0].Version != tc.minVersion {
				t.Errorf("first event version: got %d, want %d", events[0].Version, tc.minVersion)
			}
		})
	}
}

func TestGetEvents_FromVersionZero(t *testing.T) {
	store := NewInMemoryEventStore()

	event := &aether.Event{
		ID:        "evt-1",
		EventType: "TestEvent",
		ActorID:   "actor-123",
		Version:   1,
		Data:      map[string]interface{}{},
		Timestamp: time.Now(),
	}
	if err := store.SaveEvent(event); err != nil {
		t.Fatalf("SaveEvent failed: %v", err)
	}

	// fromVersion 0 should return all events
	events, err := store.GetEvents("actor-123", 0)
	if err != nil {
		t.Fatalf("GetEvents failed: %v", err)
	}
	if len(events) != 1 {
		t.Errorf("expected 1 event with fromVersion 0, got %d", len(events))
	}
}

func TestGetLatestVersion_ReturnsCorrectVersion(t *testing.T) {
	store := NewInMemoryEventStore()

	// Save events with strictly increasing versions
	versions := []int64{1, 2, 3, 4, 5}
	for i, version := range versions {
		event := &aether.Event{
			ID:        fmt.Sprintf("evt-%d", i),
			EventType: "TestEvent",
			ActorID:   "actor-123",
			Version:   version,
			Data:      map[string]interface{}{},
			Timestamp: time.Now(),
		}
		if err := store.SaveEvent(event); err != nil {
			t.Fatalf("SaveEvent failed: %v", err)
		}
	}

	latestVersion, err := store.GetLatestVersion("actor-123")
	if err != nil {
		t.Fatalf("GetLatestVersion failed: %v", err)
	}

	// Should return the highest version (5)
	if latestVersion != 5 {
		t.Errorf("expected latest version 5, got %d", latestVersion)
	}
}

func TestGetLatestVersion_SingleEvent(t *testing.T) {
	store := NewInMemoryEventStore()

	event := &aether.Event{
		ID:        "evt-1",
		EventType: "TestEvent",
		ActorID:   "actor-123",
		Version:   42,
		Data:      map[string]interface{}{},
		Timestamp: time.Now(),
	}
	if err := store.SaveEvent(event); err != nil {
		t.Fatalf("SaveEvent failed: %v", err)
	}

	latestVersion, err := store.GetLatestVersion("actor-123")
	if err != nil {
		t.Fatalf("GetLatestVersion failed: %v", err)
	}

	if latestVersion != 42 {
		t.Errorf("expected latest version 42, got %d", latestVersion)
	}
}

func TestGetLatestVersion_UpdatesAfterNewEvent(t *testing.T) {
	store := NewInMemoryEventStore()

	// Save first event
	event1 := &aether.Event{
		ID:        "evt-1",
		EventType: "TestEvent",
		ActorID:   "actor-123",
		Version:   1,
		Data:      map[string]interface{}{},
		Timestamp: time.Now(),
	}
	if err := store.SaveEvent(event1); err != nil {
		t.Fatalf("SaveEvent failed: %v", err)
	}

	version1, err := store.GetLatestVersion("actor-123")
	if err != nil {
		t.Fatalf("GetLatestVersion failed: %v", err)
	}
	if version1 != 1 {
		t.Errorf("expected version 1, got %d", version1)
	}

	// Save second event with higher version
	event2 := &aether.Event{
		ID:        "evt-2",
		EventType: "TestEvent",
		ActorID:   "actor-123",
		Version:   10,
		Data:      map[string]interface{}{},
		Timestamp: time.Now(),
	}
	if err := store.SaveEvent(event2); err != nil {
		t.Fatalf("SaveEvent failed: %v", err)
	}

	version2, err := store.GetLatestVersion("actor-123")
	if err != nil {
		t.Fatalf("GetLatestVersion failed: %v", err)
	}
	if version2 != 10 {
		t.Errorf("expected version 10, got %d", version2)
	}
}

func TestGetEvents_NonExistentActor(t *testing.T) {
	store := NewInMemoryEventStore()

	// Save event for one actor
	event := &aether.Event{
		ID:        "evt-1",
		EventType: "TestEvent",
		ActorID:   "actor-123",
		Version:   1,
		Data:      map[string]interface{}{},
		Timestamp: time.Now(),
	}
	if err := store.SaveEvent(event); err != nil {
		t.Fatalf("SaveEvent failed: %v", err)
	}

	// Get events for non-existent actor
	events, err := store.GetEvents("non-existent-actor", 0)
	if err != nil {
		t.Fatalf("GetEvents should not error for non-existent actor: %v", err)
	}

	if events == nil {
		t.Error("GetEvents should return non-nil slice for non-existent actor")
	}
	if len(events) != 0 {
		t.Errorf("expected 0 events for non-existent actor, got %d", len(events))
	}
}

func TestGetLatestVersion_NonExistentActor(t *testing.T) {
	store := NewInMemoryEventStore()

	// Get latest version for non-existent actor
	version, err := store.GetLatestVersion("non-existent-actor")
	if err != nil {
		t.Fatalf("GetLatestVersion should not error for non-existent actor: %v", err)
	}

	if version != 0 {
		t.Errorf("expected version 0 for non-existent actor, got %d", version)
	}
}

func TestGetLatestVersion_EmptyStore(t *testing.T) {
	store := NewInMemoryEventStore()

	version, err := store.GetLatestVersion("any-actor")
	if err != nil {
		t.Fatalf("GetLatestVersion should not error for empty store: %v", err)
	}

	if version != 0 {
		t.Errorf("expected version 0 for empty store, got %d", version)
	}
}

func TestGetEvents_EmptyStore(t *testing.T) {
	store := NewInMemoryEventStore()

	events, err := store.GetEvents("any-actor", 0)
	if err != nil {
		t.Fatalf("GetEvents should not error for empty store: %v", err)
	}

	if events == nil {
		t.Error("GetEvents should return non-nil slice for empty store")
	}
	if len(events) != 0 {
		t.Errorf("expected 0 events for empty store, got %d", len(events))
	}
}

func TestConcurrentSaveEvent(t *testing.T) {
	store := NewInMemoryEventStore()

	numGoroutines := 100
	eventsPerGoroutine := 10

	var wg sync.WaitGroup
	wg.Add(numGoroutines)

	for g := 0; g < numGoroutines; g++ {
		go func(goroutineID int) {
			defer wg.Done()
			for i := 0; i < eventsPerGoroutine; i++ {
				event := &aether.Event{
					ID:        fmt.Sprintf("evt-%d-%d", goroutineID, i),
					EventType: "TestEvent",
					ActorID:   fmt.Sprintf("actor-%d", goroutineID),
					Version:   int64(i + 1),
					Data:      map[string]interface{}{},
					Timestamp: time.Now(),
				}
				if err := store.SaveEvent(event); err != nil {
					t.Errorf("SaveEvent failed: %v", err)
				}
			}
		}(g)
	}

	wg.Wait()

	// Verify each actor has the correct number of events
	for g := 0; g < numGoroutines; g++ {
		actorID := fmt.Sprintf("actor-%d", g)
		events, err := store.GetEvents(actorID, 0)
		if err != nil {
			t.Errorf("GetEvents failed for %s: %v", actorID, err)
			continue
		}
		if len(events) != eventsPerGoroutine {
			t.Errorf("expected %d events for %s, got %d", eventsPerGoroutine, actorID, len(events))
		}
	}
}

func TestConcurrentSaveAndGet(t *testing.T) {
	store := NewInMemoryEventStore()

	// Pre-populate with some events
	for i := 1; i <= 10; i++ {
		event := &aether.Event{
			ID:        fmt.Sprintf("evt-%d", i),
			EventType: "TestEvent",
			ActorID:   "actor-123",
			Version:   int64(i),
			Data:      map[string]interface{}{},
			Timestamp: time.Now(),
		}
		if err := store.SaveEvent(event); err != nil {
			t.Fatalf("SaveEvent failed: %v", err)
		}
	}

	var wg sync.WaitGroup
	numReaders := 50
	numWriters := 10
	readsPerReader := 100
	writesPerWriter := 10

	// Start readers
	wg.Add(numReaders)
	for r := 0; r < numReaders; r++ {
		go func() {
			defer wg.Done()
			for i := 0; i < readsPerReader; i++ {
				events, err := store.GetEvents("actor-123", 0)
				if err != nil {
					t.Errorf("GetEvents failed: %v", err)
				}
				if len(events) < 10 {
					t.Errorf("expected at least 10 events, got %d", len(events))
				}

				_, err = store.GetLatestVersion("actor-123")
				if err != nil {
					t.Errorf("GetLatestVersion failed: %v", err)
				}
			}
		}()
	}

	// Start writers - each writer gets their own actor to avoid version conflicts
	wg.Add(numWriters)
	for w := 0; w < numWriters; w++ {
		go func(writerID int) {
			defer wg.Done()
			actorID := fmt.Sprintf("writer-actor-%d", writerID)
			for i := 0; i < writesPerWriter; i++ {
				event := &aether.Event{
					ID:        fmt.Sprintf("evt-writer-%d-%d", writerID, i),
					EventType: "TestEvent",
					ActorID:   actorID,
					Version:   int64(i + 1),
					Data:      map[string]interface{}{},
					Timestamp: time.Now(),
				}
				if err := store.SaveEvent(event); err != nil {
					t.Errorf("SaveEvent failed: %v", err)
				}
			}
		}(w)
	}

	wg.Wait()

	// Verify actor-123 still has its original events
	events, err := store.GetEvents("actor-123", 0)
	if err != nil {
		t.Fatalf("GetEvents failed: %v", err)
	}

	if len(events) != 10 {
		t.Errorf("expected 10 events for actor-123, got %d", len(events))
	}

	// Verify each writer's actor has the correct events
	for w := 0; w < numWriters; w++ {
		actorID := fmt.Sprintf("writer-actor-%d", w)
		events, err := store.GetEvents(actorID, 0)
		if err != nil {
			t.Errorf("GetEvents failed for %s: %v", actorID, err)
			continue
		}
		if len(events) != writesPerWriter {
			t.Errorf("expected %d events for %s, got %d", writesPerWriter, actorID, len(events))
		}
	}
}

func TestConcurrentGetLatestVersion(t *testing.T) {
	store := NewInMemoryEventStore()

	// Save initial event
	event := &aether.Event{
		ID:        "evt-1",
		EventType: "TestEvent",
		ActorID:   "actor-123",
		Version:   100,
		Data:      map[string]interface{}{},
		Timestamp: time.Now(),
	}
	if err := store.SaveEvent(event); err != nil {
		t.Fatalf("SaveEvent failed: %v", err)
	}

	var wg sync.WaitGroup
	numGoroutines := 100
	wg.Add(numGoroutines)

	for i := 0; i < numGoroutines; i++ {
		go func() {
			defer wg.Done()
			for j := 0; j < 100; j++ {
				version, err := store.GetLatestVersion("actor-123")
				if err != nil {
					t.Errorf("GetLatestVersion failed: %v", err)
				}
				if version < 100 {
					t.Errorf("expected version >= 100, got %d", version)
				}
			}
		}()
	}

	wg.Wait()
}

func TestEventStoreInterface(t *testing.T) {
	// Verify InMemoryEventStore implements EventStore interface
	var _ aether.EventStore = (*InMemoryEventStore)(nil)
}

func TestSaveEvent_NilData(t *testing.T) {
	store := NewInMemoryEventStore()

	event := &aether.Event{
		ID:        "evt-nil",
		EventType: "NilDataEvent",
		ActorID:   "actor-123",
		Version:   1,
		Data:      nil,
		Timestamp: time.Now(),
	}

	if err := store.SaveEvent(event); err != nil {
		t.Fatalf("SaveEvent failed with nil data: %v", err)
	}

	events, err := store.GetEvents("actor-123", 0)
	if err != nil {
		t.Fatalf("GetEvents failed: %v", err)
	}

	if events[0].Data != nil {
		t.Errorf("expected nil Data, got %v", events[0].Data)
	}
}

func TestSaveEvent_EmptyData(t *testing.T) {
	store := NewInMemoryEventStore()

	event := &aether.Event{
		ID:        "evt-empty",
		EventType: "EmptyDataEvent",
		ActorID:   "actor-123",
		Version:   1,
		Data:      map[string]interface{}{},
		Timestamp: time.Now(),
	}

	if err := store.SaveEvent(event); err != nil {
		t.Fatalf("SaveEvent failed with empty data: %v", err)
	}

	events, err := store.GetEvents("actor-123", 0)
	if err != nil {
		t.Fatalf("GetEvents failed: %v", err)
	}

	if len(events[0].Data) != 0 {
		t.Errorf("expected empty Data map, got %v", events[0].Data)
	}
}

func TestGetEvents_VersionEdgeCases(t *testing.T) {
	store := NewInMemoryEventStore()

	// Save events with edge case versions (strictly increasing)
	versions := []int64{1, 100, 9223372036854775807} // one, 100, MaxInt64
	for i, version := range versions {
		event := &aether.Event{
			ID:        fmt.Sprintf("evt-%d", i),
			EventType: "TestEvent",
			ActorID:   "actor-123",
			Version:   version,
			Data:      map[string]interface{}{},
			Timestamp: time.Now(),
		}
		if err := store.SaveEvent(event); err != nil {
			t.Fatalf("SaveEvent failed for version %d: %v", version, err)
		}
	}

	// Test fromVersion 0 returns all
	events, err := store.GetEvents("actor-123", 0)
	if err != nil {
		t.Fatalf("GetEvents failed: %v", err)
	}
	if len(events) != 3 {
		t.Errorf("expected 3 events, got %d", len(events))
	}

	// Test fromVersion MaxInt64 returns only that event
	events, err = store.GetEvents("actor-123", 9223372036854775807)
	if err != nil {
		t.Fatalf("GetEvents failed: %v", err)
	}
	if len(events) != 1 {
		t.Errorf("expected 1 event, got %d", len(events))
	}
}

func TestGetLatestVersion_VersionEdgeCases(t *testing.T) {
	store := NewInMemoryEventStore()

	// Save event with MaxInt64 version
	event := &aether.Event{
		ID:        "evt-max",
		EventType: "TestEvent",
		ActorID:   "actor-123",
		Version:   9223372036854775807,
		Data:      map[string]interface{}{},
		Timestamp: time.Now(),
	}
	if err := store.SaveEvent(event); err != nil {
		t.Fatalf("SaveEvent failed: %v", err)
	}

	latestVersion, err := store.GetLatestVersion("actor-123")
	if err != nil {
		t.Fatalf("GetLatestVersion failed: %v", err)
	}

	if latestVersion != 9223372036854775807 {
		t.Errorf("expected MaxInt64 version, got %d", latestVersion)
	}
}

func TestSaveEvent_SpecialActorIDs(t *testing.T) {
	store := NewInMemoryEventStore()

	specialIDs := []string{
		"simple",
		"with-dashes",
		"with_underscores",
		"with.dots",
		"with:colons",
		"with/slashes",
		"user@example.com",
		"unicode-世界",
		"",
	}

	for _, actorID := range specialIDs {
		event := &aether.Event{
			ID:        fmt.Sprintf("evt-%s", actorID),
			EventType: "TestEvent",
			ActorID:   actorID,
			Version:   1,
			Data:      map[string]interface{}{},
			Timestamp: time.Now(),
		}
		if err := store.SaveEvent(event); err != nil {
			t.Errorf("SaveEvent failed for actorID %q: %v", actorID, err)
			continue
		}

		events, err := store.GetEvents(actorID, 0)
		if err != nil {
			t.Errorf("GetEvents failed for actorID %q: %v", actorID, err)
			continue
		}
		if len(events) != 1 {
			t.Errorf("expected 1 event for actorID %q, got %d", actorID, len(events))
		}
	}
}

// === Version Validation Tests ===

func TestSaveEvent_RejectsLowerVersion(t *testing.T) {
	store := NewInMemoryEventStore()

	// Save first event with version 5
	event1 := &aether.Event{
		ID:        "evt-1",
		EventType: "TestEvent",
		ActorID:   "actor-123",
		Version:   5,
		Data:      map[string]interface{}{},
		Timestamp: time.Now(),
	}
	if err := store.SaveEvent(event1); err != nil {
		t.Fatalf("SaveEvent failed for first event: %v", err)
	}

	// Attempt to save event with lower version (should fail)
	event2 := &aether.Event{
		ID:        "evt-2",
		EventType: "TestEvent",
		ActorID:   "actor-123",
		Version:   3,
		Data:      map[string]interface{}{},
		Timestamp: time.Now(),
	}
	err := store.SaveEvent(event2)
	if err == nil {
		t.Fatal("expected error when saving event with lower version, got nil")
	}

	// Verify it's a VersionConflictError
	if !errors.Is(err, aether.ErrVersionConflict) {
		t.Errorf("expected ErrVersionConflict, got %v", err)
	}

	var versionErr *aether.VersionConflictError
	if !errors.As(err, &versionErr) {
		t.Fatalf("expected VersionConflictError, got %T", err)
	}

	if versionErr.ActorID != "actor-123" {
		t.Errorf("ActorID mismatch: got %q, want %q", versionErr.ActorID, "actor-123")
	}
	if versionErr.CurrentVersion != 5 {
		t.Errorf("CurrentVersion mismatch: got %d, want %d", versionErr.CurrentVersion, 5)
	}
	if versionErr.AttemptedVersion != 3 {
		t.Errorf("AttemptedVersion mismatch: got %d, want %d", versionErr.AttemptedVersion, 3)
	}
}

func TestSaveEvent_RejectsEqualVersion(t *testing.T) {
	store := NewInMemoryEventStore()

	// Save first event with version 5
	event1 := &aether.Event{
		ID:        "evt-1",
		EventType: "TestEvent",
		ActorID:   "actor-123",
		Version:   5,
		Data:      map[string]interface{}{},
		Timestamp: time.Now(),
	}
	if err := store.SaveEvent(event1); err != nil {
		t.Fatalf("SaveEvent failed for first event: %v", err)
	}

	// Attempt to save event with equal version (should fail)
	event2 := &aether.Event{
		ID:        "evt-2",
		EventType: "TestEvent",
		ActorID:   "actor-123",
		Version:   5,
		Data:      map[string]interface{}{},
		Timestamp: time.Now(),
	}
	err := store.SaveEvent(event2)
	if err == nil {
		t.Fatal("expected error when saving event with equal version, got nil")
	}

	if !errors.Is(err, aether.ErrVersionConflict) {
		t.Errorf("expected ErrVersionConflict, got %v", err)
	}
}

func TestSaveEvent_RejectsZeroVersion(t *testing.T) {
	store := NewInMemoryEventStore()

	// Version 0 should be rejected (not strictly greater than initial 0)
	event := &aether.Event{
		ID:        "evt-1",
		EventType: "TestEvent",
		ActorID:   "actor-new",
		Version:   0,
		Data:      map[string]interface{}{},
		Timestamp: time.Now(),
	}
	err := store.SaveEvent(event)
	if err == nil {
		t.Fatal("expected error when saving event with version 0, got nil")
	}

	if !errors.Is(err, aether.ErrVersionConflict) {
		t.Errorf("expected ErrVersionConflict, got %v", err)
	}
}

func TestSaveEvent_RejectsNegativeVersion(t *testing.T) {
	store := NewInMemoryEventStore()

	event := &aether.Event{
		ID:        "evt-neg",
		EventType: "TestEvent",
		ActorID:   "actor-123",
		Version:   -1,
		Data:      map[string]interface{}{},
		Timestamp: time.Now(),
	}
	err := store.SaveEvent(event)
	if err == nil {
		t.Fatal("expected error when saving event with negative version, got nil")
	}

	if !errors.Is(err, aether.ErrVersionConflict) {
		t.Errorf("expected ErrVersionConflict, got %v", err)
	}
}

func TestSaveEvent_ConcurrentWritesToSameActor(t *testing.T) {
	store := NewInMemoryEventStore()

	numGoroutines := 100
	var successCount int64
	var conflictCount int64
	var wg sync.WaitGroup

	// All goroutines try to save version 1
	wg.Add(numGoroutines)
	for i := 0; i < numGoroutines; i++ {
		go func(id int) {
			defer wg.Done()
			event := &aether.Event{
				ID:        fmt.Sprintf("evt-%d", id),
				EventType: "TestEvent",
				ActorID:   "actor-contested",
				Version:   1,
				Data:      map[string]interface{}{"goroutine": id},
				Timestamp: time.Now(),
			}
			err := store.SaveEvent(event)
			if err == nil {
				atomic.AddInt64(&successCount, 1)
			} else if errors.Is(err, aether.ErrVersionConflict) {
				atomic.AddInt64(&conflictCount, 1)
			} else {
				t.Errorf("unexpected error: %v", err)
			}
		}(i)
	}

	wg.Wait()

	// Exactly one should succeed, rest should conflict
	if successCount != 1 {
		t.Errorf("expected exactly 1 success, got %d", successCount)
	}
	if conflictCount != int64(numGoroutines-1) {
		t.Errorf("expected %d conflicts, got %d", numGoroutines-1, conflictCount)
	}

	// Verify only one event was stored
	events, err := store.GetEvents("actor-contested", 0)
	if err != nil {
		t.Fatalf("GetEvents failed: %v", err)
	}
	if len(events) != 1 {
		t.Errorf("expected 1 event, got %d", len(events))
	}
}

func BenchmarkSaveEvent(b *testing.B) {
	store := NewInMemoryEventStore()

	b.ResetTimer()
	for i := 0; i < b.N; i++ {
		event := &aether.Event{
			ID:        fmt.Sprintf("evt-%d", i),
			EventType: "BenchmarkEvent",
			ActorID:   "actor-123",
			Version:   int64(i + 1),
			Data:      map[string]interface{}{"value": i},
			Timestamp: time.Now(),
		}
		store.SaveEvent(event)
	}
}

func BenchmarkGetEvents(b *testing.B) {
	store := NewInMemoryEventStore()

	// Pre-populate with events
	for i := 0; i < 1000; i++ {
		event := &aether.Event{
			ID:        fmt.Sprintf("evt-%d", i),
			EventType: "BenchmarkEvent",
			ActorID:   "actor-123",
			Version:   int64(i + 1),
			Data:      map[string]interface{}{},
			Timestamp: time.Now(),
		}
		store.SaveEvent(event)
	}

	b.ResetTimer()
	for i := 0; i < b.N; i++ {
		store.GetEvents("actor-123", 0)
	}
}

func BenchmarkGetLatestVersion(b *testing.B) {
	store := NewInMemoryEventStore()

	// Pre-populate with events
	for i := 0; i < 1000; i++ {
		event := &aether.Event{
			ID:        fmt.Sprintf("evt-%d", i),
			EventType: "BenchmarkEvent",
			ActorID:   "actor-123",
			Version:   int64(i + 1),
			Data:      map[string]interface{}{},
			Timestamp: time.Now(),
		}
		store.SaveEvent(event)
	}

	b.ResetTimer()
	for i := 0; i < b.N; i++ {
		store.GetLatestVersion("actor-123")
	}
}

// === Snapshot Store Tests ===

func TestSaveSnapshot_PersistsCorrectly(t *testing.T) {
	store := NewInMemoryEventStore()

	snapshot := &aether.ActorSnapshot{
		ActorID: "actor-123",
		Version: 10,
		State: map[string]interface{}{
			"balance": 100.50,
			"status":  "active",
		},
		Timestamp: time.Date(2026, 1, 9, 12, 0, 0, 0, time.UTC),
	}

	err := store.SaveSnapshot(snapshot)
	if err != nil {
		t.Fatalf("SaveSnapshot failed: %v", err)
	}

	// Verify snapshot was persisted by retrieving it
	retrieved, err := store.GetLatestSnapshot("actor-123")
	if err != nil {
		t.Fatalf("GetLatestSnapshot failed: %v", err)
	}

	if retrieved == nil {
		t.Fatal("expected snapshot to be persisted, got nil")
	}

	if retrieved.ActorID != snapshot.ActorID {
		t.Errorf("ActorID mismatch: got %q, want %q", retrieved.ActorID, snapshot.ActorID)
	}
	if retrieved.Version != snapshot.Version {
		t.Errorf("Version mismatch: got %d, want %d", retrieved.Version, snapshot.Version)
	}
	if retrieved.State["balance"] != snapshot.State["balance"] {
		t.Errorf("State.balance mismatch: got %v, want %v", retrieved.State["balance"], snapshot.State["balance"])
	}
	if retrieved.State["status"] != snapshot.State["status"] {
		t.Errorf("State.status mismatch: got %v, want %v", retrieved.State["status"], snapshot.State["status"])
	}
	if !retrieved.Timestamp.Equal(snapshot.Timestamp) {
		t.Errorf("Timestamp mismatch: got %v, want %v", retrieved.Timestamp, snapshot.Timestamp)
	}
}

func TestSaveSnapshot_NilSnapshot(t *testing.T) {
	store := NewInMemoryEventStore()

	err := store.SaveSnapshot(nil)
	if err == nil {
		t.Error("expected error when saving nil snapshot, got nil")
	}
}

func TestSaveSnapshot_MultipleSnapshots(t *testing.T) {
	store := NewInMemoryEventStore()

	// Save multiple snapshots for the same actor
	for i := 1; i <= 5; i++ {
		snapshot := &aether.ActorSnapshot{
			ActorID: "actor-multi",
			Version: int64(i * 10),
			State: map[string]interface{}{
				"iteration": i,
			},
			Timestamp: time.Now(),
		}
		if err := store.SaveSnapshot(snapshot); err != nil {
			t.Fatalf("SaveSnapshot failed for version %d: %v", i*10, err)
		}
	}

	// Verify all snapshots were saved by checking the latest
	retrieved, err := store.GetLatestSnapshot("actor-multi")
	if err != nil {
		t.Fatalf("GetLatestSnapshot failed: %v", err)
	}

	if retrieved.Version != 50 {
		t.Errorf("expected latest version 50, got %d", retrieved.Version)
	}
}

func TestGetLatestSnapshot_ReturnsMostRecent(t *testing.T) {
	store := NewInMemoryEventStore()

	// Save snapshots in non-sequential order to test version comparison
	versions := []int64{5, 15, 10, 25, 20}
	for _, v := range versions {
		snapshot := &aether.ActorSnapshot{
			ActorID: "actor-latest",
			Version: v,
			State: map[string]interface{}{
				"version": v,
			},
			Timestamp: time.Now(),
		}
		if err := store.SaveSnapshot(snapshot); err != nil {
			t.Fatalf("SaveSnapshot failed for version %d: %v", v, err)
		}
	}

	latest, err := store.GetLatestSnapshot("actor-latest")
	if err != nil {
		t.Fatalf("GetLatestSnapshot failed: %v", err)
	}

	if latest == nil {
		t.Fatal("expected snapshot, got nil")
	}

	if latest.Version != 25 {
		t.Errorf("expected latest version 25, got %d", latest.Version)
	}

	// Verify the state matches the snapshot with version 25
	if latest.State["version"].(int64) != 25 {
		t.Errorf("expected state.version to be 25, got %v", latest.State["version"])
	}
}

func TestGetLatestSnapshot_NoSnapshotExists(t *testing.T) {
	store := NewInMemoryEventStore()

	// Query for a non-existent actor
	snapshot, err := store.GetLatestSnapshot("non-existent-actor")
	if err != nil {
		t.Fatalf("GetLatestSnapshot failed: %v", err)
	}

	if snapshot != nil {
		t.Errorf("expected nil for non-existent actor, got %+v", snapshot)
	}
}

func TestGetLatestSnapshot_EmptyActorID(t *testing.T) {
	store := NewInMemoryEventStore()

	// Save a snapshot with empty actor ID
	snapshot := &aether.ActorSnapshot{
		ActorID:   "",
		Version:   1,
		State:     map[string]interface{}{},
		Timestamp: time.Now(),
	}
	if err := store.SaveSnapshot(snapshot); err != nil {
		t.Fatalf("SaveSnapshot failed: %v", err)
	}

	// Retrieve with empty actor ID
	retrieved, err := store.GetLatestSnapshot("")
	if err != nil {
		t.Fatalf("GetLatestSnapshot failed: %v", err)
	}

	if retrieved == nil {
		t.Fatal("expected snapshot with empty actorID, got nil")
	}
}

func TestSnapshotVersioning_RespectedAcrossActors(t *testing.T) {
	store := NewInMemoryEventStore()

	// Save snapshots for different actors
	actors := []string{"actor-a", "actor-b", "actor-c"}
	for i, actorID := range actors {
		snapshot := &aether.ActorSnapshot{
			ActorID: actorID,
			Version: int64((i + 1) * 100), // Different versions per actor
			State: map[string]interface{}{
				"actor": actorID,
			},
			Timestamp: time.Now(),
		}
		if err := store.SaveSnapshot(snapshot); err != nil {
			t.Fatalf("SaveSnapshot failed for %s: %v", actorID, err)
		}
	}

	// Verify each actor has their own snapshot with correct version
	for i, actorID := range actors {
		snapshot, err := store.GetLatestSnapshot(actorID)
		if err != nil {
			t.Fatalf("GetLatestSnapshot failed for %s: %v", actorID, err)
		}

		expectedVersion := int64((i + 1) * 100)
		if snapshot.Version != expectedVersion {
			t.Errorf("actor %s: expected version %d, got %d", actorID, expectedVersion, snapshot.Version)
		}
	}
}

func TestSnapshotVersioning_LowerVersionAfterHigher(t *testing.T) {
	store := NewInMemoryEventStore()

	// Save a high version first
	highSnapshot := &aether.ActorSnapshot{
		ActorID: "actor-order",
		Version: 100,
		State: map[string]interface{}{
			"marker": "high",
		},
		Timestamp: time.Now(),
	}
	if err := store.SaveSnapshot(highSnapshot); err != nil {
		t.Fatalf("SaveSnapshot failed: %v", err)
	}

	// Save a lower version after
	lowSnapshot := &aether.ActorSnapshot{
		ActorID: "actor-order",
		Version: 50,
		State: map[string]interface{}{
			"marker": "low",
		},
		Timestamp: time.Now(),
	}
	if err := store.SaveSnapshot(lowSnapshot); err != nil {
		t.Fatalf("SaveSnapshot failed: %v", err)
	}

	// GetLatestSnapshot should return the higher version (100), not the most recently saved
	latest, err := store.GetLatestSnapshot("actor-order")
	if err != nil {
		t.Fatalf("GetLatestSnapshot failed: %v", err)
	}

	if latest.Version != 100 {
		t.Errorf("expected version 100, got %d", latest.Version)
	}
	if latest.State["marker"] != "high" {
		t.Errorf("expected marker 'high', got %v", latest.State["marker"])
	}
}

func TestSnapshotDataIntegrity_ComplexState(t *testing.T) {
	store := NewInMemoryEventStore()

	complexState := map[string]interface{}{
		"string":  "hello",
		"integer": 42,
		"float":   3.14159,
		"boolean": true,
		"null":    nil,
		"array":   []interface{}{"a", "b", "c"},
		"nested": map[string]interface{}{
			"level1": map[string]interface{}{
				"level2": "deep value",
			},
		},
	}

	snapshot := &aether.ActorSnapshot{
		ActorID:   "actor-complex",
		Version:   1,
		State:     complexState,
		Timestamp: time.Now(),
	}

	if err := store.SaveSnapshot(snapshot); err != nil {
		t.Fatalf("SaveSnapshot failed: %v", err)
	}

	retrieved, err := store.GetLatestSnapshot("actor-complex")
	if err != nil {
		t.Fatalf("GetLatestSnapshot failed: %v", err)
	}

	// Verify all fields
	if retrieved.State["string"] != "hello" {
		t.Errorf("string mismatch: got %v", retrieved.State["string"])
	}
	if retrieved.State["integer"] != 42 {
		t.Errorf("integer mismatch: got %v", retrieved.State["integer"])
	}
	if retrieved.State["float"] != 3.14159 {
		t.Errorf("float mismatch: got %v", retrieved.State["float"])
	}
	if retrieved.State["boolean"] != true {
		t.Errorf("boolean mismatch: got %v", retrieved.State["boolean"])
	}
	if retrieved.State["null"] != nil {
		t.Errorf("null mismatch: got %v", retrieved.State["null"])
	}

	// Verify array
	arr, ok := retrieved.State["array"].([]interface{})
	if !ok {
		t.Fatal("array is not []interface{}")
	}
	if len(arr) != 3 || arr[0] != "a" || arr[1] != "b" || arr[2] != "c" {
		t.Errorf("array mismatch: got %v", arr)
	}

	// Verify nested structure
	nested, ok := retrieved.State["nested"].(map[string]interface{})
	if !ok {
		t.Fatal("nested is not map[string]interface{}")
	}
	level1, ok := nested["level1"].(map[string]interface{})
	if !ok {
		t.Fatal("level1 is not map[string]interface{}")
	}
	if level1["level2"] != "deep value" {
		t.Errorf("nested value mismatch: got %v", level1["level2"])
	}
}

func TestSnapshotDataIntegrity_SpecialCharacters(t *testing.T) {
	store := NewInMemoryEventStore()

	specialState := map[string]interface{}{
		"unicode":   "Hello, 世界!",
		"emoji":     "😀🚀",
		"newlines":  "line1\nline2\r\nline3",
		"tabs":      "col1\tcol2",
		"quotes":    `"double" and 'single'`,
		"backslash": `path\to\file`,
	}

	snapshot := &aether.ActorSnapshot{
		ActorID:   "actor-special",
		Version:   1,
		State:     specialState,
		Timestamp: time.Now(),
	}

	if err := store.SaveSnapshot(snapshot); err != nil {
		t.Fatalf("SaveSnapshot failed: %v", err)
	}

	retrieved, err := store.GetLatestSnapshot("actor-special")
	if err != nil {
		t.Fatalf("GetLatestSnapshot failed: %v", err)
	}

	for key, expected := range specialState {
		if retrieved.State[key] != expected {
			t.Errorf("State[%q] mismatch: got %q, want %q", key, retrieved.State[key], expected)
		}
	}
}

func TestSnapshotDataIntegrity_EmptyState(t *testing.T) {
	store := NewInMemoryEventStore()

	snapshot := &aether.ActorSnapshot{
		ActorID:   "actor-empty",
		Version:   1,
		State:     map[string]interface{}{},
		Timestamp: time.Now(),
	}

	if err := store.SaveSnapshot(snapshot); err != nil {
		t.Fatalf("SaveSnapshot failed: %v", err)
	}

	retrieved, err := store.GetLatestSnapshot("actor-empty")
	if err != nil {
		t.Fatalf("GetLatestSnapshot failed: %v", err)
	}

	if len(retrieved.State) != 0 {
		t.Errorf("expected empty state, got %v", retrieved.State)
	}
}

func TestSnapshotDataIntegrity_NilState(t *testing.T) {
	store := NewInMemoryEventStore()

	snapshot := &aether.ActorSnapshot{
		ActorID:   "actor-nil",
		Version:   1,
		State:     nil,
		Timestamp: time.Now(),
	}

	if err := store.SaveSnapshot(snapshot); err != nil {
		t.Fatalf("SaveSnapshot failed: %v", err)
	}

	retrieved, err := store.GetLatestSnapshot("actor-nil")
	if err != nil {
		t.Fatalf("GetLatestSnapshot failed: %v", err)
	}

	if retrieved.State != nil {
		t.Errorf("expected nil state, got %v", retrieved.State)
	}
}

func TestSnapshotDataIntegrity_LargeState(t *testing.T) {
	store := NewInMemoryEventStore()

	// Create a large state with many entries using unique keys
	largeState := make(map[string]interface{})
	for i := 0; i < 1000; i++ {
		largeState[fmt.Sprintf("key-%d", i)] = i
	}

	snapshot := &aether.ActorSnapshot{
		ActorID:   "actor-large",
		Version:   1,
		State:     largeState,
		Timestamp: time.Now(),
	}

	if err := store.SaveSnapshot(snapshot); err != nil {
		t.Fatalf("SaveSnapshot failed: %v", err)
	}

	retrieved, err := store.GetLatestSnapshot("actor-large")
	if err != nil {
		t.Fatalf("GetLatestSnapshot failed: %v", err)
	}

	if len(retrieved.State) != len(largeState) {
		t.Errorf("state size mismatch: got %d, want %d", len(retrieved.State), len(largeState))
	}
}

func TestSnapshotDataIntegrity_TimestampPreserved(t *testing.T) {
	store := NewInMemoryEventStore()

	// Test various timestamps
	timestamps := []time.Time{
		time.Date(2026, 1, 9, 12, 0, 0, 0, time.UTC),
		time.Date(2020, 6, 15, 23, 59, 59, 999999999, time.UTC),
		time.Time{}, // Zero time
	}

	for i, ts := range timestamps {
		actorID := fmt.Sprintf("actor-ts-%d", i)
		snapshot := &aether.ActorSnapshot{
			ActorID:   actorID,
			Version:   1,
			State:     map[string]interface{}{},
			Timestamp: ts,
		}

		if err := store.SaveSnapshot(snapshot); err != nil {
			t.Fatalf("SaveSnapshot failed: %v", err)
		}

		retrieved, err := store.GetLatestSnapshot(actorID)
		if err != nil {
			t.Fatalf("GetLatestSnapshot failed: %v", err)
		}

		if !retrieved.Timestamp.Equal(ts) {
			t.Errorf("timestamp %d mismatch: got %v, want %v", i, retrieved.Timestamp, ts)
		}
	}
}

func TestSnapshotVersioning_ZeroVersion(t *testing.T) {
	store := NewInMemoryEventStore()

	snapshot := &aether.ActorSnapshot{
		ActorID:   "actor-zero-version",
		Version:   0,
		State:     map[string]interface{}{"initial": true},
		Timestamp: time.Now(),
	}

	if err := store.SaveSnapshot(snapshot); err != nil {
		t.Fatalf("SaveSnapshot failed: %v", err)
	}

	retrieved, err := store.GetLatestSnapshot("actor-zero-version")
	if err != nil {
		t.Fatalf("GetLatestSnapshot failed: %v", err)
	}

	if retrieved.Version != 0 {
		t.Errorf("expected version 0, got %d", retrieved.Version)
	}
}

func TestSnapshotVersioning_LargeVersion(t *testing.T) {
	store := NewInMemoryEventStore()

	largeVersion := int64(9223372036854775807) // MaxInt64

	snapshot := &aether.ActorSnapshot{
		ActorID:   "actor-large-version",
		Version:   largeVersion,
		State:     map[string]interface{}{"maxed": true},
		Timestamp: time.Now(),
	}

	if err := store.SaveSnapshot(snapshot); err != nil {
		t.Fatalf("SaveSnapshot failed: %v", err)
	}

	retrieved, err := store.GetLatestSnapshot("actor-large-version")
	if err != nil {
		t.Fatalf("GetLatestSnapshot failed: %v", err)
	}

	if retrieved.Version != largeVersion {
		t.Errorf("expected version %d, got %d", largeVersion, retrieved.Version)
	}
}

func TestSnapshotStore_ImplementsInterface(t *testing.T) {
	// Verify InMemoryEventStore implements SnapshotStore interface
	var _ aether.SnapshotStore = (*InMemoryEventStore)(nil)
}

func TestConcurrentSaveSnapshot(t *testing.T) {
	store := NewInMemoryEventStore()

	numGoroutines := 100
	snapshotsPerGoroutine := 10

	var wg sync.WaitGroup
	wg.Add(numGoroutines)

	for g := 0; g < numGoroutines; g++ {
		go func(goroutineID int) {
			defer wg.Done()
			for i := 0; i < snapshotsPerGoroutine; i++ {
				snapshot := &aether.ActorSnapshot{
					ActorID: fmt.Sprintf("actor-%d", goroutineID),
					Version: int64(i + 1),
					State: map[string]interface{}{
						"goroutine": goroutineID,
						"iteration": i,
					},
					Timestamp: time.Now(),
				}
				if err := store.SaveSnapshot(snapshot); err != nil {
					t.Errorf("SaveSnapshot failed: %v", err)
				}
			}
		}(g)
	}

	wg.Wait()

	// Verify each actor has snapshots
	for g := 0; g < numGoroutines; g++ {
		actorID := fmt.Sprintf("actor-%d", g)
		snapshot, err := store.GetLatestSnapshot(actorID)
		if err != nil {
			t.Errorf("GetLatestSnapshot failed for %s: %v", actorID, err)
			continue
		}
		if snapshot == nil {
			t.Errorf("expected snapshot for %s, got nil", actorID)
			continue
		}
		if snapshot.Version != int64(snapshotsPerGoroutine) {
			t.Errorf("expected latest version %d for %s, got %d", snapshotsPerGoroutine, actorID, snapshot.Version)
		}
	}
}

func TestConcurrentSaveAndGetSnapshot(t *testing.T) {
	store := NewInMemoryEventStore()

	// Pre-populate with initial snapshot
	initialSnapshot := &aether.ActorSnapshot{
		ActorID: "actor-123",
		Version: 1,
		State: map[string]interface{}{
			"initial": true,
		},
		Timestamp: time.Now(),
	}
	if err := store.SaveSnapshot(initialSnapshot); err != nil {
		t.Fatalf("SaveSnapshot failed: %v", err)
	}

	var wg sync.WaitGroup
	numReaders := 50
	numWriters := 10
	readsPerReader := 100
	writesPerWriter := 10

	// Start readers
	wg.Add(numReaders)
	for r := 0; r < numReaders; r++ {
		go func() {
			defer wg.Done()
			for i := 0; i < readsPerReader; i++ {
				snapshot, err := store.GetLatestSnapshot("actor-123")
				if err != nil {
					t.Errorf("GetLatestSnapshot failed: %v", err)
				}
				if snapshot == nil {
					t.Error("expected snapshot, got nil")
				}
			}
		}()
	}

	// Start writers
	wg.Add(numWriters)
	for w := 0; w < numWriters; w++ {
		go func(writerID int) {
			defer wg.Done()
			for i := 0; i < writesPerWriter; i++ {
				snapshot := &aether.ActorSnapshot{
					ActorID: "actor-123",
					Version: int64(100 + writerID*writesPerWriter + i),
					State: map[string]interface{}{
						"writer": writerID,
						"index":  i,
					},
					Timestamp: time.Now(),
				}
				if err := store.SaveSnapshot(snapshot); err != nil {
					t.Errorf("SaveSnapshot failed: %v", err)
				}
			}
		}(w)
	}

	wg.Wait()

	// Verify final state - should have the highest version
	snapshot, err := store.GetLatestSnapshot("actor-123")
	if err != nil {
		t.Fatalf("GetLatestSnapshot failed: %v", err)
	}
	if snapshot == nil {
		t.Fatal("expected snapshot, got nil")
	}
	// The highest version should be around 100 + (numWriters-1)*writesPerWriter + (writesPerWriter-1)
	// which is 100 + 9*10 + 9 = 199
	expectedMaxVersion := int64(100 + (numWriters-1)*writesPerWriter + (writesPerWriter - 1))
	if snapshot.Version != expectedMaxVersion {
		t.Errorf("expected latest version %d, got %d", expectedMaxVersion, snapshot.Version)
	}
}