aether/event_test.go

package aether

import (
	"encoding/json"
	"errors"
	"fmt"
	"strings"
	"testing"
	"time"
)

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

	data, err := json.Marshal(event)
	if err != nil {
		t.Fatalf("failed to marshal Event: %v", err)
	}

	var decoded Event
	if err := json.Unmarshal(data, &decoded); err != nil {
		t.Fatalf("failed to unmarshal Event: %v", err)
	}

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

func TestEvent_JSONFieldNames(t *testing.T) {
	event := &Event{
		ID:        "evt-123",
		EventType: "TestEvent",
		ActorID:   "actor-456",
		CommandID: "cmd-789",
		Version:   1,
		Data:      map[string]interface{}{},
		Timestamp: time.Now(),
	}

	data, err := json.Marshal(event)
	if err != nil {
		t.Fatalf("failed to marshal Event: %v", err)
	}

	jsonStr := string(data)

	expectedFields := []string{
		`"id"`,
		`"eventType"`,
		`"actorId"`,
		`"commandId"`,
		`"version"`,
		`"data"`,
		`"timestamp"`,
	}

	for _, field := range expectedFields {
		if !strings.Contains(jsonStr, field) {
			t.Errorf("expected JSON field %s not found in: %s", field, jsonStr)
		}
	}
}

func TestEvent_OmitEmptyCommandID(t *testing.T) {
	event := &Event{
		ID:        "evt-123",
		EventType: "TestEvent",
		ActorID:   "actor-456",
		Version:   1,
		Data:      map[string]interface{}{},
		Timestamp: time.Now(),
	}

	data, err := json.Marshal(event)
	if err != nil {
		t.Fatalf("failed to marshal Event: %v", err)
	}

	if strings.Contains(string(data), `"commandId"`) {
		t.Error("expected commandId to be omitted when empty")
	}
}

func TestActorSnapshot_JSONSerialization(t *testing.T) {
	ts := time.Date(2026, 1, 9, 12, 0, 0, 0, time.UTC)
	snapshot := &ActorSnapshot{
		ActorID: "actor-123",
		Version: 10,
		State: map[string]interface{}{
			"balance":  500.00,
			"status":   "active",
			"metadata": map[string]interface{}{"region": "us-west"},
		},
		Timestamp: ts,
	}

	data, err := json.Marshal(snapshot)
	if err != nil {
		t.Fatalf("failed to marshal ActorSnapshot: %v", err)
	}

	var decoded ActorSnapshot
	if err := json.Unmarshal(data, &decoded); err != nil {
		t.Fatalf("failed to unmarshal ActorSnapshot: %v", err)
	}

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

func TestActorSnapshot_JSONFieldNames(t *testing.T) {
	snapshot := &ActorSnapshot{
		ActorID:   "actor-123",
		Version:   1,
		State:     map[string]interface{}{},
		Timestamp: time.Now(),
	}

	data, err := json.Marshal(snapshot)
	if err != nil {
		t.Fatalf("failed to marshal ActorSnapshot: %v", err)
	}

	jsonStr := string(data)

	expectedFields := []string{
		`"actorId"`,
		`"version"`,
		`"state"`,
		`"timestamp"`,
	}

	for _, field := range expectedFields {
		if !strings.Contains(jsonStr, field) {
			t.Errorf("expected JSON field %s not found in: %s", field, jsonStr)
		}
	}
}

func TestEvent_EmptyData(t *testing.T) {
	event := &Event{
		ID:        "evt-empty",
		EventType: "EmptyEvent",
		ActorID:   "actor-123",
		Version:   1,
		Data:      map[string]interface{}{},
		Timestamp: time.Now(),
	}

	data, err := json.Marshal(event)
	if err != nil {
		t.Fatalf("failed to marshal Event with empty data: %v", err)
	}

	var decoded Event
	if err := json.Unmarshal(data, &decoded); err != nil {
		t.Fatalf("failed to unmarshal Event with empty data: %v", err)
	}

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

func TestEvent_NilData(t *testing.T) {
	event := &Event{
		ID:        "evt-nil",
		EventType: "NilDataEvent",
		ActorID:   "actor-123",
		Version:   1,
		Data:      nil,
		Timestamp: time.Now(),
	}

	data, err := json.Marshal(event)
	if err != nil {
		t.Fatalf("failed to marshal Event with nil data: %v", err)
	}

	var decoded Event
	if err := json.Unmarshal(data, &decoded); err != nil {
		t.Fatalf("failed to unmarshal Event with nil data: %v", err)
	}

	if decoded.Data != nil {
		t.Errorf("expected nil Data, got %v", decoded.Data)
	}
}

func TestActorSnapshot_EmptyState(t *testing.T) {
	snapshot := &ActorSnapshot{
		ActorID:   "actor-empty",
		Version:   1,
		State:     map[string]interface{}{},
		Timestamp: time.Now(),
	}

	data, err := json.Marshal(snapshot)
	if err != nil {
		t.Fatalf("failed to marshal ActorSnapshot with empty state: %v", err)
	}

	var decoded ActorSnapshot
	if err := json.Unmarshal(data, &decoded); err != nil {
		t.Fatalf("failed to unmarshal ActorSnapshot with empty state: %v", err)
	}

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

func TestActorSnapshot_NilState(t *testing.T) {
	snapshot := &ActorSnapshot{
		ActorID:   "actor-nil",
		Version:   1,
		State:     nil,
		Timestamp: time.Now(),
	}

	data, err := json.Marshal(snapshot)
	if err != nil {
		t.Fatalf("failed to marshal ActorSnapshot with nil state: %v", err)
	}

	var decoded ActorSnapshot
	if err := json.Unmarshal(data, &decoded); err != nil {
		t.Fatalf("failed to unmarshal ActorSnapshot with nil state: %v", err)
	}

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

func TestEvent_LargePayload(t *testing.T) {
	largeString := strings.Repeat("x", 1024*1024) // 1MB string

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

	data, err := json.Marshal(event)
	if err != nil {
		t.Fatalf("failed to marshal Event with large payload: %v", err)
	}

	var decoded Event
	if err := json.Unmarshal(data, &decoded); err != nil {
		t.Fatalf("failed to unmarshal Event with large payload: %v", err)
	}

	if decoded.Data["largeField"] != largeString {
		t.Error("large payload was not preserved correctly")
	}
}

func TestActorSnapshot_LargePayload(t *testing.T) {
	largeString := strings.Repeat("y", 1024*1024) // 1MB string

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

	data, err := json.Marshal(snapshot)
	if err != nil {
		t.Fatalf("failed to marshal ActorSnapshot with large payload: %v", err)
	}

	var decoded ActorSnapshot
	if err := json.Unmarshal(data, &decoded); err != nil {
		t.Fatalf("failed to unmarshal ActorSnapshot with large payload: %v", err)
	}

	if decoded.State["largeField"] != largeString {
		t.Error("large payload was not preserved correctly")
	}
}

func TestEvent_SpecialCharacters(t *testing.T) {
	specialStrings := map[string]interface{}{
		"unicode":    "Hello, \u4e16\u754c! \U0001F600",
		"newlines":   "line1\nline2\r\nline3",
		"tabs":       "col1\tcol2\tcol3",
		"quotes":     `"quoted" and 'single'`,
		"backslash":  `path\to\file`,
		"nullchar":   "before\x00after",
		"html":       "<script>alert('xss')</script>",
		"json_chars": `{"nested": "value"}`,
	}

	event := &Event{
		ID:        "evt-special",
		EventType: "Special\nChars",
		ActorID:   "actor-\t123",
		Version:   1,
		Data:      specialStrings,
		Timestamp: time.Now(),
	}

	data, err := json.Marshal(event)
	if err != nil {
		t.Fatalf("failed to marshal Event with special characters: %v", err)
	}

	var decoded Event
	if err := json.Unmarshal(data, &decoded); err != nil {
		t.Fatalf("failed to unmarshal Event with special characters: %v", err)
	}

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

	if decoded.EventType != event.EventType {
		t.Errorf("EventType with special chars mismatch: got %q, want %q", decoded.EventType, event.EventType)
	}
	if decoded.ActorID != event.ActorID {
		t.Errorf("ActorID with special chars mismatch: got %q, want %q", decoded.ActorID, event.ActorID)
	}
}

func TestActorSnapshot_SpecialCharacters(t *testing.T) {
	specialState := map[string]interface{}{
		"unicode":  "\u00e9\u00e8\u00ea",
		"emoji":    "\U0001F4BB\U0001F680",
		"brackets": "[]{}()",
	}

	snapshot := &ActorSnapshot{
		ActorID:   "actor-\u00e9",
		Version:   1,
		State:     specialState,
		Timestamp: time.Now(),
	}

	data, err := json.Marshal(snapshot)
	if err != nil {
		t.Fatalf("failed to marshal ActorSnapshot with special characters: %v", err)
	}

	var decoded ActorSnapshot
	if err := json.Unmarshal(data, &decoded); err != nil {
		t.Fatalf("failed to unmarshal ActorSnapshot with special characters: %v", err)
	}

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

func TestEvent_TimestampTimezones(t *testing.T) {
	timezones := []struct {
		name string
		loc  *time.Location
	}{
		{"UTC", time.UTC},
		{"FixedEast", time.FixedZone("EST", -5*3600)},
		{"FixedWest", time.FixedZone("PST", -8*3600)},
		{"FixedPositive", time.FixedZone("JST", 9*3600)},
	}

	for _, tz := range timezones {
		t.Run(tz.name, func(t *testing.T) {
			ts := time.Date(2026, 6, 15, 14, 30, 45, 123456789, tz.loc)
			event := &Event{
				ID:        "evt-tz",
				EventType: "TimezoneTest",
				ActorID:   "actor-123",
				Version:   1,
				Data:      map[string]interface{}{},
				Timestamp: ts,
			}

			data, err := json.Marshal(event)
			if err != nil {
				t.Fatalf("failed to marshal Event: %v", err)
			}

			var decoded Event
			if err := json.Unmarshal(data, &decoded); err != nil {
				t.Fatalf("failed to unmarshal Event: %v", err)
			}

			// JSON timestamp preserves the instant in time (Unix time)
			// but may normalize to UTC on decode
			if !decoded.Timestamp.Equal(ts) {
				t.Errorf("Timestamp instant mismatch: got %v, want %v", decoded.Timestamp.Unix(), ts.Unix())
			}
		})
	}
}

func TestActorSnapshot_TimestampTimezones(t *testing.T) {
	timezones := []struct {
		name string
		loc  *time.Location
	}{
		{"UTC", time.UTC},
		{"FixedEast", time.FixedZone("CET", 1*3600)},
		{"FixedWest", time.FixedZone("HST", -10*3600)},
	}

	for _, tz := range timezones {
		t.Run(tz.name, func(t *testing.T) {
			ts := time.Date(2026, 12, 31, 23, 59, 59, 999999999, tz.loc)
			snapshot := &ActorSnapshot{
				ActorID:   "actor-tz",
				Version:   100,
				State:     map[string]interface{}{},
				Timestamp: ts,
			}

			data, err := json.Marshal(snapshot)
			if err != nil {
				t.Fatalf("failed to marshal ActorSnapshot: %v", err)
			}

			var decoded ActorSnapshot
			if err := json.Unmarshal(data, &decoded); err != nil {
				t.Fatalf("failed to unmarshal ActorSnapshot: %v", err)
			}

			if !decoded.Timestamp.Equal(ts) {
				t.Errorf("Timestamp instant mismatch: got %v, want %v", decoded.Timestamp.Unix(), ts.Unix())
			}
		})
	}
}

func TestEvent_TimestampNanosecondPrecision(t *testing.T) {
	ts := time.Date(2026, 1, 9, 12, 0, 0, 123456789, time.UTC)
	event := &Event{
		ID:        "evt-nano",
		EventType: "NanoTest",
		ActorID:   "actor-123",
		Version:   1,
		Data:      map[string]interface{}{},
		Timestamp: ts,
	}

	data, err := json.Marshal(event)
	if err != nil {
		t.Fatalf("failed to marshal Event: %v", err)
	}

	var decoded Event
	if err := json.Unmarshal(data, &decoded); err != nil {
		t.Fatalf("failed to unmarshal Event: %v", err)
	}

	// Go's time.Time JSON marshaling uses RFC3339Nano which preserves nanoseconds
	if decoded.Timestamp.Nanosecond() != ts.Nanosecond() {
		t.Errorf("Nanosecond precision lost: got %d, want %d", decoded.Timestamp.Nanosecond(), ts.Nanosecond())
	}
}

func TestEvent_ZeroTimestamp(t *testing.T) {
	event := &Event{
		ID:        "evt-zero",
		EventType: "ZeroTimeTest",
		ActorID:   "actor-123",
		Version:   1,
		Data:      map[string]interface{}{},
		Timestamp: time.Time{},
	}

	data, err := json.Marshal(event)
	if err != nil {
		t.Fatalf("failed to marshal Event with zero timestamp: %v", err)
	}

	var decoded Event
	if err := json.Unmarshal(data, &decoded); err != nil {
		t.Fatalf("failed to unmarshal Event with zero timestamp: %v", err)
	}

	if !decoded.Timestamp.IsZero() {
		t.Errorf("expected zero timestamp, got %v", decoded.Timestamp)
	}
}

func TestEvent_NestedData(t *testing.T) {
	nestedData := map[string]interface{}{
		"level1": map[string]interface{}{
			"level2": map[string]interface{}{
				"level3": map[string]interface{}{
					"value": "deeply nested",
				},
			},
		},
		"array": []interface{}{"a", "b", "c"},
		"mixed": []interface{}{
			map[string]interface{}{"key": "value"},
			123.0,
			true,
			nil,
		},
	}

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

	data, err := json.Marshal(event)
	if err != nil {
		t.Fatalf("failed to marshal Event with nested data: %v", err)
	}

	var decoded Event
	if err := json.Unmarshal(data, &decoded); err != nil {
		t.Fatalf("failed to unmarshal Event with nested data: %v", err)
	}

	// Verify nested structure is preserved
	level1, ok := decoded.Data["level1"].(map[string]interface{})
	if !ok {
		t.Fatal("level1 is not a map")
	}
	level2, ok := level1["level2"].(map[string]interface{})
	if !ok {
		t.Fatal("level2 is not a map")
	}
	level3, ok := level2["level3"].(map[string]interface{})
	if !ok {
		t.Fatal("level3 is not a map")
	}
	if level3["value"] != "deeply nested" {
		t.Errorf("deeply nested value mismatch: got %v", level3["value"])
	}
}

func TestEvent_NumericTypes(t *testing.T) {
	event := &Event{
		ID:        "evt-numeric",
		EventType: "NumericTest",
		ActorID:   "actor-123",
		Version:   1,
		Data: map[string]interface{}{
			"integer":  42,
			"float":    3.14159,
			"negative": -100,
			"zero":     0,
			"large":    1e15,
		},
		Timestamp: time.Now(),
	}

	data, err := json.Marshal(event)
	if err != nil {
		t.Fatalf("failed to marshal Event with numeric data: %v", err)
	}

	var decoded Event
	if err := json.Unmarshal(data, &decoded); err != nil {
		t.Fatalf("failed to unmarshal Event with numeric data: %v", err)
	}

	// JSON numbers decode as float64
	if decoded.Data["integer"].(float64) != 42 {
		t.Errorf("integer mismatch: got %v", decoded.Data["integer"])
	}
	if decoded.Data["float"].(float64) != 3.14159 {
		t.Errorf("float mismatch: got %v", decoded.Data["float"])
	}
}

func TestEvent_BooleanAndNull(t *testing.T) {
	event := &Event{
		ID:        "evt-bool-null",
		EventType: "BoolNullTest",
		ActorID:   "actor-123",
		Version:   1,
		Data: map[string]interface{}{
			"trueVal":  true,
			"falseVal": false,
			"nullVal":  nil,
		},
		Timestamp: time.Now(),
	}

	data, err := json.Marshal(event)
	if err != nil {
		t.Fatalf("failed to marshal Event: %v", err)
	}

	var decoded Event
	if err := json.Unmarshal(data, &decoded); err != nil {
		t.Fatalf("failed to unmarshal Event: %v", err)
	}

	if decoded.Data["trueVal"] != true {
		t.Errorf("trueVal mismatch: got %v", decoded.Data["trueVal"])
	}
	if decoded.Data["falseVal"] != false {
		t.Errorf("falseVal mismatch: got %v", decoded.Data["falseVal"])
	}
	if decoded.Data["nullVal"] != nil {
		t.Errorf("nullVal mismatch: got %v", decoded.Data["nullVal"])
	}
}

func TestEvent_VersionEdgeCases(t *testing.T) {
	testCases := []struct {
		name    string
		version int64
	}{
		{"zero", 0},
		{"one", 1},
		{"large", 9223372036854775807}, // MaxInt64
		{"negative", -1},
	}

	for _, tc := range testCases {
		t.Run(tc.name, func(t *testing.T) {
			event := &Event{
				ID:        "evt-version",
				EventType: "VersionTest",
				ActorID:   "actor-123",
				Version:   tc.version,
				Data:      map[string]interface{}{},
				Timestamp: time.Now(),
			}

			data, err := json.Marshal(event)
			if err != nil {
				t.Fatalf("failed to marshal Event: %v", err)
			}

			var decoded Event
			if err := json.Unmarshal(data, &decoded); err != nil {
				t.Fatalf("failed to unmarshal Event: %v", err)
			}

			if decoded.Version != tc.version {
				t.Errorf("Version mismatch: got %d, want %d", decoded.Version, tc.version)
			}
		})
	}
}

func TestActorSnapshot_VersionEdgeCases(t *testing.T) {
	testCases := []struct {
		name    string
		version int64
	}{
		{"zero", 0},
		{"one", 1},
		{"large", 9223372036854775807},
	}

	for _, tc := range testCases {
		t.Run(tc.name, func(t *testing.T) {
			snapshot := &ActorSnapshot{
				ActorID:   "actor-version",
				Version:   tc.version,
				State:     map[string]interface{}{},
				Timestamp: time.Now(),
			}

			data, err := json.Marshal(snapshot)
			if err != nil {
				t.Fatalf("failed to marshal ActorSnapshot: %v", err)
			}

			var decoded ActorSnapshot
			if err := json.Unmarshal(data, &decoded); err != nil {
				t.Fatalf("failed to unmarshal ActorSnapshot: %v", err)
			}

			if decoded.Version != tc.version {
				t.Errorf("Version mismatch: got %d, want %d", decoded.Version, tc.version)
			}
		})
	}
}

// Tests for Event Metadata support

func TestEvent_MetadataJSONSerialization(t *testing.T) {
	ts := time.Date(2026, 1, 9, 12, 0, 0, 0, time.UTC)
	event := &Event{
		ID:        "evt-meta",
		EventType: "OrderPlaced",
		ActorID:   "order-456",
		Version:   1,
		Data:      map[string]interface{}{"total": 100.50},
		Metadata: map[string]string{
			"correlationId": "corr-123",
			"causationId":   "cause-456",
			"userId":        "user-789",
		},
		Timestamp: ts,
	}

	data, err := json.Marshal(event)
	if err != nil {
		t.Fatalf("failed to marshal Event with metadata: %v", err)
	}

	var decoded Event
	if err := json.Unmarshal(data, &decoded); err != nil {
		t.Fatalf("failed to unmarshal Event with metadata: %v", err)
	}

	if decoded.Metadata == nil {
		t.Fatal("expected Metadata to be present after unmarshal")
	}
	if decoded.Metadata["correlationId"] != "corr-123" {
		t.Errorf("correlationId mismatch: got %q, want %q", decoded.Metadata["correlationId"], "corr-123")
	}
	if decoded.Metadata["causationId"] != "cause-456" {
		t.Errorf("causationId mismatch: got %q, want %q", decoded.Metadata["causationId"], "cause-456")
	}
	if decoded.Metadata["userId"] != "user-789" {
		t.Errorf("userId mismatch: got %q, want %q", decoded.Metadata["userId"], "user-789")
	}
}

func TestEvent_MetadataOmitEmpty(t *testing.T) {
	event := &Event{
		ID:        "evt-no-meta",
		EventType: "TestEvent",
		ActorID:   "actor-123",
		Version:   1,
		Data:      map[string]interface{}{},
		Metadata:  nil,
		Timestamp: time.Now(),
	}

	data, err := json.Marshal(event)
	if err != nil {
		t.Fatalf("failed to marshal Event: %v", err)
	}

	if strings.Contains(string(data), `"metadata"`) {
		t.Error("expected metadata to be omitted when nil")
	}
}

func TestEvent_EmptyMetadata(t *testing.T) {
	event := &Event{
		ID:        "evt-empty-meta",
		EventType: "TestEvent",
		ActorID:   "actor-123",
		Version:   1,
		Data:      map[string]interface{}{},
		Metadata:  map[string]string{},
		Timestamp: time.Now(),
	}

	data, err := json.Marshal(event)
	if err != nil {
		t.Fatalf("failed to marshal Event with empty metadata: %v", err)
	}

	var decoded Event
	if err := json.Unmarshal(data, &decoded); err != nil {
		t.Fatalf("failed to unmarshal Event with empty metadata: %v", err)
	}

	// Empty map should be omitted with omitempty
	if strings.Contains(string(data), `"metadata"`) {
		t.Error("expected empty metadata to be omitted")
	}
}

func TestEvent_SetMetadata(t *testing.T) {
	event := &Event{
		ID:        "evt-set-meta",
		EventType: "TestEvent",
		ActorID:   "actor-123",
		Version:   1,
	}

	// Metadata should be nil initially
	if event.Metadata != nil {
		t.Error("expected Metadata to be nil initially")
	}

	// SetMetadata should initialize the map
	event.SetMetadata("key1", "value1")
	if event.Metadata == nil {
		t.Fatal("expected Metadata to be initialized after SetMetadata")
	}
	if event.Metadata["key1"] != "value1" {
		t.Errorf("key1 mismatch: got %q, want %q", event.Metadata["key1"], "value1")
	}

	// SetMetadata should work with existing map
	event.SetMetadata("key2", "value2")
	if event.Metadata["key2"] != "value2" {
		t.Errorf("key2 mismatch: got %q, want %q", event.Metadata["key2"], "value2")
	}
	if event.Metadata["key1"] != "value1" {
		t.Errorf("key1 was overwritten: got %q", event.Metadata["key1"])
	}
}

func TestEvent_GetMetadata(t *testing.T) {
	event := &Event{
		ID:        "evt-get-meta",
		EventType: "TestEvent",
		ActorID:   "actor-123",
		Version:   1,
	}

	// GetMetadata on nil map should return empty string
	if got := event.GetMetadata("nonexistent"); got != "" {
		t.Errorf("expected empty string for nil Metadata, got %q", got)
	}

	// Initialize metadata and test
	event.Metadata = map[string]string{"key": "value"}
	if got := event.GetMetadata("key"); got != "value" {
		t.Errorf("GetMetadata mismatch: got %q, want %q", got, "value")
	}

	// Non-existent key should return empty string
	if got := event.GetMetadata("nonexistent"); got != "" {
		t.Errorf("expected empty string for nonexistent key, got %q", got)
	}
}

func TestEvent_CorrelationIDHelpers(t *testing.T) {
	event := &Event{
		ID:        "evt-corr",
		EventType: "TestEvent",
		ActorID:   "actor-123",
		Version:   1,
	}

	// GetCorrelationID on nil metadata
	if got := event.GetCorrelationID(); got != "" {
		t.Errorf("expected empty correlation ID, got %q", got)
	}

	// SetCorrelationID
	event.SetCorrelationID("corr-abc-123")
	if got := event.GetCorrelationID(); got != "corr-abc-123" {
		t.Errorf("GetCorrelationID mismatch: got %q, want %q", got, "corr-abc-123")
	}

	// Verify it uses the correct metadata key
	if event.Metadata[MetadataKeyCorrelationID] != "corr-abc-123" {
		t.Errorf("expected correlationId key to be set")
	}
}

func TestEvent_CausationIDHelpers(t *testing.T) {
	event := &Event{
		ID:        "evt-cause",
		EventType: "TestEvent",
		ActorID:   "actor-123",
		Version:   1,
	}

	// GetCausationID on nil metadata
	if got := event.GetCausationID(); got != "" {
		t.Errorf("expected empty causation ID, got %q", got)
	}

	// SetCausationID
	event.SetCausationID("cause-xyz-789")
	if got := event.GetCausationID(); got != "cause-xyz-789" {
		t.Errorf("GetCausationID mismatch: got %q, want %q", got, "cause-xyz-789")
	}

	// Verify it uses the correct metadata key
	if event.Metadata[MetadataKeyCausationID] != "cause-xyz-789" {
		t.Errorf("expected causationId key to be set")
	}
}

func TestEvent_UserIDHelpers(t *testing.T) {
	event := &Event{
		ID:        "evt-user",
		EventType: "TestEvent",
		ActorID:   "actor-123",
		Version:   1,
	}

	event.SetUserID("user-john-doe")
	if got := event.GetUserID(); got != "user-john-doe" {
		t.Errorf("GetUserID mismatch: got %q, want %q", got, "user-john-doe")
	}

	if event.Metadata[MetadataKeyUserID] != "user-john-doe" {
		t.Errorf("expected userId key to be set")
	}
}

func TestEvent_TraceIDHelpers(t *testing.T) {
	event := &Event{
		ID:        "evt-trace",
		EventType: "TestEvent",
		ActorID:   "actor-123",
		Version:   1,
	}

	event.SetTraceID("trace-abc-def-ghi")
	if got := event.GetTraceID(); got != "trace-abc-def-ghi" {
		t.Errorf("GetTraceID mismatch: got %q, want %q", got, "trace-abc-def-ghi")
	}

	if event.Metadata[MetadataKeyTraceID] != "trace-abc-def-ghi" {
		t.Errorf("expected traceId key to be set")
	}
}

func TestEvent_SpanIDHelpers(t *testing.T) {
	event := &Event{
		ID:        "evt-span",
		EventType: "TestEvent",
		ActorID:   "actor-123",
		Version:   1,
	}

	event.SetSpanID("span-123-456")
	if got := event.GetSpanID(); got != "span-123-456" {
		t.Errorf("GetSpanID mismatch: got %q, want %q", got, "span-123-456")
	}

	if event.Metadata[MetadataKeySpanID] != "span-123-456" {
		t.Errorf("expected spanId key to be set")
	}
}

func TestEvent_WithMetadataFrom(t *testing.T) {
	source := &Event{
		ID:        "evt-source",
		EventType: "SourceEvent",
		ActorID:   "actor-123",
		Version:   1,
		Metadata: map[string]string{
			"correlationId": "corr-123",
			"causationId":   "cause-456",
			"customKey":     "customValue",
		},
	}

	target := &Event{
		ID:        "evt-target",
		EventType: "TargetEvent",
		ActorID:   "actor-456",
		Version:   2,
	}

	// Copy metadata from source to target
	target.WithMetadataFrom(source)

	if target.Metadata == nil {
		t.Fatal("expected Metadata to be initialized after WithMetadataFrom")
	}
	if target.Metadata["correlationId"] != "corr-123" {
		t.Errorf("correlationId not copied: got %q", target.Metadata["correlationId"])
	}
	if target.Metadata["causationId"] != "cause-456" {
		t.Errorf("causationId not copied: got %q", target.Metadata["causationId"])
	}
	if target.Metadata["customKey"] != "customValue" {
		t.Errorf("customKey not copied: got %q", target.Metadata["customKey"])
	}
}

func TestEvent_WithMetadataFromNilSource(t *testing.T) {
	target := &Event{
		ID:        "evt-target",
		EventType: "TargetEvent",
		ActorID:   "actor-456",
		Version:   2,
	}

	// WithMetadataFrom should handle nil source gracefully
	target.WithMetadataFrom(nil)
	if target.Metadata != nil {
		t.Error("expected Metadata to remain nil after WithMetadataFrom(nil)")
	}

	// WithMetadataFrom should handle source with nil metadata
	source := &Event{
		ID:        "evt-source",
		EventType: "SourceEvent",
		ActorID:   "actor-123",
		Version:   1,
		Metadata:  nil,
	}
	target.WithMetadataFrom(source)
	if target.Metadata != nil {
		t.Error("expected Metadata to remain nil when source has nil Metadata")
	}
}

func TestEvent_WithMetadataFromPreservesExisting(t *testing.T) {
	source := &Event{
		ID:        "evt-source",
		EventType: "SourceEvent",
		ActorID:   "actor-123",
		Version:   1,
		Metadata: map[string]string{
			"sourceKey": "sourceValue",
		},
	}

	target := &Event{
		ID:        "evt-target",
		EventType: "TargetEvent",
		ActorID:   "actor-456",
		Version:   2,
		Metadata: map[string]string{
			"existingKey": "existingValue",
		},
	}

	target.WithMetadataFrom(source)

	// Both keys should be present
	if target.Metadata["existingKey"] != "existingValue" {
		t.Errorf("existingKey was lost: got %q", target.Metadata["existingKey"])
	}
	if target.Metadata["sourceKey"] != "sourceValue" {
		t.Errorf("sourceKey not copied: got %q", target.Metadata["sourceKey"])
	}
}

func TestEvent_MetadataSpecialCharacters(t *testing.T) {
	event := &Event{
		ID:        "evt-special-meta",
		EventType: "TestEvent",
		ActorID:   "actor-123",
		Version:   1,
		Metadata: map[string]string{
			"unicode":    "Hello, \u4e16\u754c!",
			"newlines":   "line1\nline2",
			"quotes":     `"quoted"`,
			"backslash":  `path\to\file`,
			"empty":      "",
			"whitespace": "  spaces  ",
		},
	}

	data, err := json.Marshal(event)
	if err != nil {
		t.Fatalf("failed to marshal Event with special metadata: %v", err)
	}

	var decoded Event
	if err := json.Unmarshal(data, &decoded); err != nil {
		t.Fatalf("failed to unmarshal Event with special metadata: %v", err)
	}

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

func TestMetadataKeyConstants(t *testing.T) {
	// Verify the constant values are as expected
	if MetadataKeyCorrelationID != "correlationId" {
		t.Errorf("MetadataKeyCorrelationID wrong: got %q", MetadataKeyCorrelationID)
	}
	if MetadataKeyCausationID != "causationId" {
		t.Errorf("MetadataKeyCausationID wrong: got %q", MetadataKeyCausationID)
	}
	if MetadataKeyUserID != "userId" {
		t.Errorf("MetadataKeyUserID wrong: got %q", MetadataKeyUserID)
	}
	if MetadataKeyTraceID != "traceId" {
		t.Errorf("MetadataKeyTraceID wrong: got %q", MetadataKeyTraceID)
	}
	if MetadataKeySpanID != "spanId" {
		t.Errorf("MetadataKeySpanID wrong: got %q", MetadataKeySpanID)
	}
}

func TestEvent_MetadataJSONFieldName(t *testing.T) {
	event := &Event{
		ID:        "evt-field-name",
		EventType: "TestEvent",
		ActorID:   "actor-123",
		Version:   1,
		Data:      map[string]interface{}{},
		Metadata: map[string]string{
			"key": "value",
		},
		Timestamp: time.Now(),
	}

	data, err := json.Marshal(event)
	if err != nil {
		t.Fatalf("failed to marshal Event: %v", err)
	}

	// Check for correct JSON field name (camelCase)
	if !strings.Contains(string(data), `"metadata"`) {
		t.Errorf("expected 'metadata' JSON field, got: %s", string(data))
	}
}

func TestEvent_MetadataAllHelpersRoundTrip(t *testing.T) {
	// Test that all helper methods work together in a roundtrip
	event := &Event{
		ID:        "evt-all-helpers",
		EventType: "TestEvent",
		ActorID:   "actor-123",
		Version:   1,
		Data:      map[string]interface{}{},
		Timestamp: time.Now(),
	}

	event.SetCorrelationID("corr-1")
	event.SetCausationID("cause-2")
	event.SetUserID("user-3")
	event.SetTraceID("trace-4")
	event.SetSpanID("span-5")

	data, err := json.Marshal(event)
	if err != nil {
		t.Fatalf("failed to marshal Event: %v", err)
	}

	var decoded Event
	if err := json.Unmarshal(data, &decoded); err != nil {
		t.Fatalf("failed to unmarshal Event: %v", err)
	}

	if decoded.GetCorrelationID() != "corr-1" {
		t.Errorf("GetCorrelationID mismatch: got %q", decoded.GetCorrelationID())
	}
	if decoded.GetCausationID() != "cause-2" {
		t.Errorf("GetCausationID mismatch: got %q", decoded.GetCausationID())
	}
	if decoded.GetUserID() != "user-3" {
		t.Errorf("GetUserID mismatch: got %q", decoded.GetUserID())
	}
	if decoded.GetTraceID() != "trace-4" {
		t.Errorf("GetTraceID mismatch: got %q", decoded.GetTraceID())
	}
	if decoded.GetSpanID() != "span-5" {
		t.Errorf("GetSpanID mismatch: got %q", decoded.GetSpanID())
	}
}

// Tests for ReplayError and ReplayResult types

func TestReplayError_Error(t *testing.T) {
	err := &ReplayError{
		SequenceNumber: 42,
		RawData:        []byte(`invalid json`),
		Err:            json.Unmarshal([]byte(`{`), &struct{}{}),
	}

	errMsg := err.Error()
	if !strings.Contains(errMsg, "42") {
		t.Errorf("expected error message to contain sequence number, got: %s", errMsg)
	}
	if !strings.Contains(errMsg, "unmarshal") || !strings.Contains(errMsg, "failed") {
		t.Errorf("expected error message to contain 'failed' and 'unmarshal', got: %s", errMsg)
	}
}

func TestReplayError_Unwrap(t *testing.T) {
	innerErr := json.Unmarshal([]byte(`{`), &struct{}{})
	err := &ReplayError{
		SequenceNumber: 1,
		RawData:        []byte(`{`),
		Err:            innerErr,
	}

	unwrapped := err.Unwrap()
	if unwrapped != innerErr {
		t.Errorf("expected Unwrap to return inner error")
	}
}

func TestReplayResult_HasErrors(t *testing.T) {
	tests := []struct {
		name     string
		result   *ReplayResult
		expected bool
	}{
		{
			name:     "no errors",
			result:   &ReplayResult{Events: []*Event{}, Errors: []ReplayError{}},
			expected: false,
		},
		{
			name:     "nil errors slice",
			result:   &ReplayResult{Events: []*Event{}, Errors: nil},
			expected: false,
		},
		{
			name: "has errors",
			result: &ReplayResult{
				Events: []*Event{},
				Errors: []ReplayError{
					{SequenceNumber: 1, RawData: []byte(`bad`), Err: nil},
				},
			},
			expected: true,
		},
		{
			name: "has events and errors",
			result: &ReplayResult{
				Events: []*Event{{ID: "evt-1"}},
				Errors: []ReplayError{
					{SequenceNumber: 2, RawData: []byte(`bad`), Err: nil},
				},
			},
			expected: true,
		},
	}

	for _, tt := range tests {
		t.Run(tt.name, func(t *testing.T) {
			if got := tt.result.HasErrors(); got != tt.expected {
				t.Errorf("HasErrors() = %v, want %v", got, tt.expected)
			}
		})
	}
}

func TestReplayResult_EmptyResult(t *testing.T) {
	result := &ReplayResult{
		Events: []*Event{},
		Errors: []ReplayError{},
	}

	if result.HasErrors() {
		t.Error("expected HasErrors() to return false for empty result")
	}
	if len(result.Events) != 0 {
		t.Errorf("expected 0 events, got %d", len(result.Events))
	}
}

func TestReplayError_WithZeroSequence(t *testing.T) {
	err := &ReplayError{
		SequenceNumber: 0,
		RawData:        []byte(`corrupted`),
		Err:            json.Unmarshal([]byte(`not-json`), &struct{}{}),
	}

	errMsg := err.Error()
	if !strings.Contains(errMsg, "sequence 0") {
		t.Errorf("expected error message to contain 'sequence 0', got: %s", errMsg)
	}
}

func TestReplayError_WithLargeRawData(t *testing.T) {
	largeData := make([]byte, 1024*1024) // 1MB
	for i := range largeData {
		largeData[i] = 'x'
	}

	err := &ReplayError{
		SequenceNumber: 999,
		RawData:        largeData,
		Err:            json.Unmarshal(largeData, &struct{}{}),
	}

	// Should be able to create the error without issues
	if len(err.RawData) != 1024*1024 {
		t.Errorf("expected RawData to be preserved, got length %d", len(err.RawData))
	}

	// Error() should still work
	_ = err.Error()
}

// Tests for VersionConflictError

func TestVersionConflictError_Error(t *testing.T) {
	err := &VersionConflictError{
		ActorID:          "order-123",
		AttemptedVersion: 3,
		CurrentVersion:   5,
	}

	errMsg := err.Error()

	// Verify error message contains all context
	if !strings.Contains(errMsg, "order-123") {
		t.Errorf("error message should contain ActorID, got: %s", errMsg)
	}
	if !strings.Contains(errMsg, "3") {
		t.Errorf("error message should contain AttemptedVersion, got: %s", errMsg)
	}
	if !strings.Contains(errMsg, "5") {
		t.Errorf("error message should contain CurrentVersion, got: %s", errMsg)
	}
	if !strings.Contains(errMsg, "version conflict") {
		t.Errorf("error message should contain 'version conflict', got: %s", errMsg)
	}
}

func TestVersionConflictError_Fields(t *testing.T) {
	err := &VersionConflictError{
		ActorID:          "actor-456",
		AttemptedVersion: 10,
		CurrentVersion:   8,
	}

	if err.ActorID != "actor-456" {
		t.Errorf("ActorID mismatch: got %q, want %q", err.ActorID, "actor-456")
	}
	if err.AttemptedVersion != 10 {
		t.Errorf("AttemptedVersion mismatch: got %d, want %d", err.AttemptedVersion, 10)
	}
	if err.CurrentVersion != 8 {
		t.Errorf("CurrentVersion mismatch: got %d, want %d", err.CurrentVersion, 8)
	}
}

func TestVersionConflictError_Unwrap(t *testing.T) {
	err := &VersionConflictError{
		ActorID:          "actor-789",
		AttemptedVersion: 2,
		CurrentVersion:   1,
	}

	unwrapped := err.Unwrap()
	if unwrapped != ErrVersionConflict {
		t.Errorf("Unwrap should return ErrVersionConflict sentinel")
	}
}

func TestVersionConflictError_ErrorsIs(t *testing.T) {
	err := &VersionConflictError{
		ActorID:          "test-actor",
		AttemptedVersion: 5,
		CurrentVersion:   4,
	}

	// Test that errors.Is works with sentinel
	if !errors.Is(err, ErrVersionConflict) {
		t.Error("errors.Is(err, ErrVersionConflict) should return true")
	}

	// Test that other errors don't match
	if errors.Is(err, errors.New("other error")) {
		t.Error("errors.Is should not match unrelated errors")
	}
}

func TestVersionConflictError_ErrorsAs(t *testing.T) {
	originalErr := &VersionConflictError{
		ActorID:          "actor-unwrap",
		AttemptedVersion: 7,
		CurrentVersion:   6,
	}

	var versionErr *VersionConflictError
	if !errors.As(originalErr, &versionErr) {
		t.Fatalf("errors.As should succeed with VersionConflictError")
	}

	// Verify fields are accessible through unwrapped error
	if versionErr.ActorID != "actor-unwrap" {
		t.Errorf("ActorID mismatch after As: got %q", versionErr.ActorID)
	}
	if versionErr.AttemptedVersion != 7 {
		t.Errorf("AttemptedVersion mismatch after As: got %d", versionErr.AttemptedVersion)
	}
	if versionErr.CurrentVersion != 6 {
		t.Errorf("CurrentVersion mismatch after As: got %d", versionErr.CurrentVersion)
	}
}

func TestVersionConflictError_CanReadCurrentVersion(t *testing.T) {
	// This test verifies that applications can read CurrentVersion for retry strategies
	err := &VersionConflictError{
		ActorID:          "order-abc",
		AttemptedVersion: 2,
		CurrentVersion:   10,
	}

	var versionErr *VersionConflictError
	if !errors.As(err, &versionErr) {
		t.Fatal("failed to unwrap VersionConflictError")
	}

	// Application can use CurrentVersion to decide retry strategy
	nextVersion := versionErr.CurrentVersion + 1

	if nextVersion != 11 {
		t.Errorf("application should be able to compute next version: got %d, want 11", nextVersion)
	}

	// Application can log detailed context
	logMsg := fmt.Sprintf("Version conflict for actor %q: attempted %d, current %d, will retry with %d",
		versionErr.ActorID, versionErr.AttemptedVersion, versionErr.CurrentVersion, nextVersion)

	if !strings.Contains(logMsg, "order-abc") {
		t.Errorf("application context logging failed: %s", logMsg)
	}
}

func TestVersionConflictError_EdgeCases(t *testing.T) {
	testCases := []struct {
		name    string
		actorID string
		attemp  int64
		current int64
	}{
		{"zero current", "actor-1", 1, 0},
		{"large numbers", "actor-2", 1000000, 999999},
		{"max int64", "actor-3", 9223372036854775807, 9223372036854775806},
		{"negative attempt", "actor-4", -1, -2},
		{"empty actor id", "", 1, 0},
		{"special chars in actor id", "actor@#$%", 2, 1},
	}

	for _, tc := range testCases {
		t.Run(tc.name, func(t *testing.T) {
			err := &VersionConflictError{
				ActorID:          tc.actorID,
				AttemptedVersion: tc.attemp,
				CurrentVersion:   tc.current,
			}

			// Should not panic
			msg := err.Error()
			if msg == "" {
				t.Error("Error() should return non-empty string")
			}

			// Should be wrapped correctly
			if err.Unwrap() != ErrVersionConflict {
				t.Error("Unwrap should return ErrVersionConflict")
			}

			// errors.Is should work
			if !errors.Is(err, ErrVersionConflict) {
				t.Error("errors.Is should work for edge case")
			}
		})
	}
}

func TestErrVersionConflict_Sentinel(t *testing.T) {
	// Verify the sentinel error is correctly defined
	if ErrVersionConflict == nil {
		t.Fatal("ErrVersionConflict should not be nil")
	}

	expectedMsg := "version conflict"
	if ErrVersionConflict.Error() != expectedMsg {
		t.Errorf("ErrVersionConflict message mismatch: got %q, want %q", ErrVersionConflict.Error(), expectedMsg)
	}

	// Test that it's usable with errors.Is
	if !errors.Is(ErrVersionConflict, ErrVersionConflict) {
		t.Error("ErrVersionConflict should match itself with errors.Is")
	}
}