// Package crypto provides comprehensive audit logging for role-based encryption.
//
// This module implements enterprise-grade audit logging with features including:
// - Comprehensive access logging with tamper-proof trails
// - Real-time security event monitoring and alerting
// - Compliance reporting for SOC 2, ISO 27001, and GDPR
// - Anomaly detection and behavioral analysis
// - Forensic investigation support
// - Performance metrics and operational insights
//
// Security Features:
// - Immutable audit logs with cryptographic integrity
// - Real-time anomaly detection and alerting
// - Correlation of events across multiple data sources
// - Automated compliance reporting
// - Integration with SIEM systems
//
// Compliance Standards:
// - SOC 2 Type II requirements
// - ISO 27001 audit trail requirements
// - GDPR data access logging
// - NIST Cybersecurity Framework logging
//
// Cross-references:
//   - pkg/crypto/role_crypto.go: Role-based encryption logging
//   - pkg/crypto/key_manager.go: Key management audit events
//   - pkg/slurp/context/types.go: Context access logging

package crypto

import (
	"crypto/sha256"
	"encoding/hex"
	"fmt"
	"sort"
	"sync"
	"time"

	"chorus.services/bzzz/pkg/config"
)

// AuditLoggerImpl implements comprehensive audit logging
type AuditLoggerImpl struct {
	mu                 sync.RWMutex
	config             *config.Config
	storage            AuditStorage
	processor          EventProcessor
	alertManager       AlertManager
	complianceReporter ComplianceReporter
	metricsCollector   MetricsCollector
	anomalyDetector    AnomalyDetector
	
	// Runtime state
	eventBuffer        []*AuditEvent
	bufferSize         int
	flushInterval      time.Duration
	lastFlush          time.Time
	totalEvents        int64
	failedEvents       int64
	
	// Event correlation
	correlationEngine  *EventCorrelationEngine
	sessionTracker     *SessionTracker
	threatIntelligence *ThreatIntelligence
}

// AuditStorage interface for persistent audit log storage
type AuditStorage interface {
	StoreEvent(event *AuditEvent) error
	StoreBatch(events []*AuditEvent) error
	QueryEvents(criteria *AuditQueryCriteria) ([]*AuditEvent, error)
	GetEventByID(eventID string) (*AuditEvent, error)
	CreateIndex(field string) error
	BackupAuditLogs(criteria *BackupCriteria) (*AuditBackup, error)
	RestoreAuditLogs(backup *AuditBackup) error
	PurgeOldEvents(before time.Time) (int, error)
}

// EventProcessor interface for processing audit events
type EventProcessor interface {
	ProcessEvent(event *AuditEvent) (*ProcessedEvent, error)
	EnrichEvent(event *AuditEvent) (*EnrichedEvent, error)
	ClassifyEvent(event *AuditEvent) (*EventClassification, error)
	ValidateEvent(event *AuditEvent) error
}

// AlertManager interface for security alerting
type AlertManager interface {
	SendAlert(alert *SecurityAlert) error
	CreateAlert(event *AuditEvent, severity AlertSeverity, reason string) *SecurityAlert
	GetActiveAlerts() ([]*SecurityAlert, error)
	AcknowledgeAlert(alertID string, acknowledgedBy string) error
	EscalateAlert(alertID string, escalationLevel int) error
}

// ComplianceReporter interface for compliance reporting
type ComplianceReporter interface {
	GenerateSOC2Report(period *ReportingPeriod) (*ComplianceReport, error)
	GenerateISO27001Report(period *ReportingPeriod) (*ComplianceReport, error)
	GenerateGDPRReport(period *ReportingPeriod) (*ComplianceReport, error)
	GenerateCustomReport(criteria *ReportCriteria) (*ComplianceReport, error)
	ValidateCompliance(standard string) (*ComplianceValidation, error)
}

// MetricsCollector interface for metrics collection
type MetricsCollector interface {
	RecordMetric(metric *SecurityMetric) error
	GetMetrics(criteria *MetricsCriteria) ([]*SecurityMetric, error)
	GetDashboardData() (*SecurityDashboard, error)
	GeneratePerformanceReport() (*PerformanceReport, error)
}

// AnomalyDetector interface for anomaly detection
type AnomalyDetector interface {
	AnalyzeEvent(event *AuditEvent) (*AnomalyResult, error)
	UpdateBaseline(events []*AuditEvent) error
	GetAnomalyScore(event *AuditEvent) (float64, error)
	DetectPatterns(events []*AuditEvent) ([]*SuspiciousPattern, error)
}

// EnrichedEvent represents an audit event with additional context
type EnrichedEvent struct {
	Original          *AuditEvent            `json:"original"`
	GeoLocation       *GeoLocation           `json:"geo_location,omitempty"`
	ThreatIntel       *ThreatIntelData       `json:"threat_intel,omitempty"`
	UserBehavior      *UserBehaviorProfile   `json:"user_behavior,omitempty"`
	RiskScore         float64                `json:"risk_score"`
	CorrelatedEvents  []string               `json:"correlated_events"`
	EnrichmentTime    time.Duration          `json:"enrichment_time"`
	EnrichedAt        time.Time              `json:"enriched_at"`
}

// ProcessedEvent represents a processed audit event
type ProcessedEvent struct {
	Event             *AuditEvent            `json:"event"`
	ProcessingResult  string                 `json:"processing_result"`
	Actions           []*AutomatedAction     `json:"actions"`
	Alerts            []*SecurityAlert       `json:"alerts"`
	ProcessedAt       time.Time              `json:"processed_at"`
	ProcessingTime    time.Duration          `json:"processing_time"`
}

// EventClassification represents classification of an audit event
type EventClassification struct {
	EventID           string                 `json:"event_id"`
	Category          string                 `json:"category"`          // access, authentication, authorization, etc.
	Subcategory       string                 `json:"subcategory"`       // login, logout, read, write, etc.
	RiskLevel         RiskLevel              `json:"risk_level"`
	Confidence        float64                `json:"confidence"`
	ClassificationRules []string             `json:"classification_rules"`
	ClassifiedAt      time.Time              `json:"classified_at"`
}

// RiskLevel represents risk levels for events
type RiskLevel string

const (
	RiskLevelLow      RiskLevel = "low"
	RiskLevelMedium   RiskLevel = "medium"
	RiskLevelHigh     RiskLevel = "high"
	RiskLevelCritical RiskLevel = "critical"
)

// SecurityAlert represents a security alert
type SecurityAlert struct {
	AlertID           string                 `json:"alert_id"`
	EventID           string                 `json:"event_id"`
	AlertType         string                 `json:"alert_type"`
	Severity          AlertSeverity          `json:"severity"`
	Title             string                 `json:"title"`
	Description       string                 `json:"description"`
	RecommendedActions []string              `json:"recommended_actions"`
	
	// Status tracking
	Status            AlertStatus            `json:"status"`
	CreatedAt         time.Time              `json:"created_at"`
	AcknowledgedAt    *time.Time             `json:"acknowledged_at,omitempty"`
	AcknowledgedBy    string                 `json:"acknowledged_by,omitempty"`
	ResolvedAt        *time.Time             `json:"resolved_at,omitempty"`
	ResolvedBy        string                 `json:"resolved_by,omitempty"`
	
	// Context
	AffectedUsers     []string               `json:"affected_users"`
	AffectedResources []string               `json:"affected_resources"`
	CorrelatedAlerts  []string               `json:"correlated_alerts"`
	Metadata          map[string]interface{} `json:"metadata"`
}

// AlertSeverity represents alert severity levels
type AlertSeverity string

const (
	AlertSeverityInfo     AlertSeverity = "info"
	AlertSeverityLow      AlertSeverity = "low"
	AlertSeverityMedium   AlertSeverity = "medium"
	AlertSeverityHigh     AlertSeverity = "high"
	AlertSeverityCritical AlertSeverity = "critical"
)

// AlertStatus represents alert status
type AlertStatus string

const (
	AlertStatusOpen         AlertStatus = "open"
	AlertStatusAcknowledged AlertStatus = "acknowledged"
	AlertStatusInvestigating AlertStatus = "investigating"
	AlertStatusResolved     AlertStatus = "resolved"
	AlertStatusFalsePositive AlertStatus = "false_positive"
)

// AutomatedAction represents an automated response action
type AutomatedAction struct {
	ActionID          string                 `json:"action_id"`
	ActionType        string                 `json:"action_type"`
	Target            string                 `json:"target"`
	Parameters        map[string]interface{} `json:"parameters"`
	ExecutedAt        time.Time              `json:"executed_at"`
	Result            string                 `json:"result"`
	ErrorMessage      string                 `json:"error_message,omitempty"`
}

// ComplianceReport represents a compliance report
type ComplianceReport struct {
	ReportID          string                 `json:"report_id"`
	Standard          string                 `json:"standard"`          // SOC2, ISO27001, GDPR, etc.
	Period            *ReportingPeriod       `json:"period"`
	GeneratedAt       time.Time              `json:"generated_at"`
	GeneratedBy       string                 `json:"generated_by"`
	
	// Report content
	Summary           *ComplianceSummary     `json:"summary"`
	Findings          []*ComplianceFinding   `json:"findings"`
	Recommendations   []*ComplianceRecommendation `json:"recommendations"`
	Evidence          []*ComplianceEvidence  `json:"evidence"`
	
	// Compliance status
	OverallStatus     ComplianceStatus       `json:"overall_status"`
	ComplianceScore   float64                `json:"compliance_score"`
	RiskAssessment    *RiskAssessment        `json:"risk_assessment"`
}

// ReportingPeriod represents a time period for reporting
type ReportingPeriod struct {
	StartTime         time.Time              `json:"start_time"`
	EndTime           time.Time              `json:"end_time"`
	Description       string                 `json:"description"`
}

// ComplianceSummary provides high-level compliance information
type ComplianceSummary struct {
	TotalEvents       int                    `json:"total_events"`
	AccessEvents      int                    `json:"access_events"`
	SecurityEvents    int                    `json:"security_events"`
	ViolationEvents   int                    `json:"violation_events"`
	UnauthorizedAccess int                   `json:"unauthorized_access"`
	DataExfiltration  int                    `json:"data_exfiltration"`
	PolicyViolations  int                    `json:"policy_violations"`
}

// ComplianceFinding represents a compliance finding
type ComplianceFinding struct {
	FindingID         string                 `json:"finding_id"`
	Control           string                 `json:"control"`           // Control ID from standard
	Description       string                 `json:"description"`
	Severity          string                 `json:"severity"`
	Status            string                 `json:"status"`            // compliant, non-compliant, partial
	Evidence          []string               `json:"evidence"`          // Event IDs as evidence
	Remediation       string                 `json:"remediation"`
}

// ComplianceRecommendation represents a compliance recommendation
type ComplianceRecommendation struct {
	RecommendationID  string                 `json:"recommendation_id"`
	Priority          string                 `json:"priority"`
	Description       string                 `json:"description"`
	Implementation    string                 `json:"implementation"`
	Timeline          string                 `json:"timeline"`
	Cost              string                 `json:"cost"`
}

// ComplianceEvidence represents evidence for compliance
type ComplianceEvidence struct {
	EvidenceID        string                 `json:"evidence_id"`
	Type              string                 `json:"type"`              // event, log, document, etc.
	Description       string                 `json:"description"`
	Reference         string                 `json:"reference"`         // Event ID, document path, etc.
	CollectedAt       time.Time              `json:"collected_at"`
	Integrity         *IntegrityVerification `json:"integrity"`
}

// ComplianceStatus represents compliance status
type ComplianceStatus string

const (
	ComplianceStatusCompliant     ComplianceStatus = "compliant"
	ComplianceStatusNonCompliant  ComplianceStatus = "non_compliant"
	ComplianceStatusPartial       ComplianceStatus = "partial"
	ComplianceStatusUnknown       ComplianceStatus = "unknown"
)

// SecurityMetric represents a security metric
type SecurityMetric struct {
	MetricID          string                 `json:"metric_id"`
	MetricName        string                 `json:"metric_name"`
	MetricType        string                 `json:"metric_type"`       // counter, gauge, histogram
	Value             float64                `json:"value"`
	Unit              string                 `json:"unit"`
	Tags              map[string]string      `json:"tags"`
	Timestamp         time.Time              `json:"timestamp"`
	Description       string                 `json:"description"`
}

// SecurityDashboard represents dashboard data
type SecurityDashboard struct {
	GeneratedAt       time.Time              `json:"generated_at"`
	ActiveAlerts      int                    `json:"active_alerts"`
	CriticalAlerts    int                    `json:"critical_alerts"`
	TotalEvents       int64                  `json:"total_events"`
	FailedAccess      int                    `json:"failed_access"`
	SuccessfulAccess  int                    `json:"successful_access"`
	UniqueSessions    int                    `json:"unique_sessions"`
	AnomalyScore      float64                `json:"anomaly_score"`
	ComplianceScore   float64                `json:"compliance_score"`
	SecurityScore     float64                `json:"security_score"`
	
	// Trend data
	TrendData         *TrendData             `json:"trend_data"`
	TopRisks          []*RiskItem            `json:"top_risks"`
	RecentEvents      []*AuditEvent          `json:"recent_events"`
}

// TrendData represents trending security data
type TrendData struct {
	TimeRange         string                 `json:"time_range"`
	EventTrends       map[string][]int       `json:"event_trends"`
	AccessTrends      map[string][]int       `json:"access_trends"`
	AlertTrends       map[string][]int       `json:"alert_trends"`
	ComplianceTrends  []float64              `json:"compliance_trends"`
}

// RiskItem represents a risk item for dashboard
type RiskItem struct {
	RiskID            string                 `json:"risk_id"`
	Description       string                 `json:"description"`
	RiskScore         float64                `json:"risk_score"`
	Likelihood        string                 `json:"likelihood"`
	Impact            string                 `json:"impact"`
	Mitigation        string                 `json:"mitigation"`
	LastUpdated       time.Time              `json:"last_updated"`
}

// AnomalyResult represents result of anomaly detection
type AnomalyResult struct {
	EventID           string                 `json:"event_id"`
	IsAnomaly         bool                   `json:"is_anomaly"`
	AnomalyScore      float64                `json:"anomaly_score"`
	AnomalyType       string                 `json:"anomaly_type"`
	Confidence        float64                `json:"confidence"`
	Explanation       string                 `json:"explanation"`
	SimilarEvents     []string               `json:"similar_events"`
	AnalyzedAt        time.Time              `json:"analyzed_at"`
}

// SuspiciousPattern represents a detected suspicious pattern
type SuspiciousPattern struct {
	PatternID         string                 `json:"pattern_id"`
	PatternType       string                 `json:"pattern_type"`
	Description       string                 `json:"description"`
	EventIDs          []string               `json:"event_ids"`
	Confidence        float64                `json:"confidence"`
	RiskScore         float64                `json:"risk_score"`
	DetectedAt        time.Time              `json:"detected_at"`
	Recommendation    string                 `json:"recommendation"`
}

// EventCorrelationEngine correlates events across time and context
type EventCorrelationEngine struct {
	mu                sync.RWMutex
	correlationRules  []*CorrelationRule
	eventWindow       time.Duration
	eventCache        map[string]*AuditEvent
	correlationIndex  map[string][]string    // Field -> Event IDs
}

// CorrelationRule defines how events should be correlated
type CorrelationRule struct {
	RuleID            string                 `json:"rule_id"`
	Name              string                 `json:"name"`
	Description       string                 `json:"description"`
	Conditions        []*CorrelationCondition `json:"conditions"`
	TimeWindow        time.Duration          `json:"time_window"`
	Priority          int                    `json:"priority"`
	Enabled           bool                   `json:"enabled"`
	Actions           []*CorrelationAction   `json:"actions"`
}

// CorrelationCondition defines a condition for event correlation
type CorrelationCondition struct {
	Field             string                 `json:"field"`
	Operator          string                 `json:"operator"`
	Value             interface{}            `json:"value"`
	CaseSensitive     bool                   `json:"case_sensitive"`
}

// CorrelationAction defines an action to take when correlation is found
type CorrelationAction struct {
	ActionType        string                 `json:"action_type"`
	Parameters        map[string]interface{} `json:"parameters"`
}

// SessionTracker tracks user sessions and behavior
type SessionTracker struct {
	mu                sync.RWMutex
	activeSessions    map[string]*UserSession
	sessionTimeout    time.Duration
	behaviorProfiles  map[string]*UserBehaviorProfile
}

// UserSession represents an active user session
type UserSession struct {
	SessionID         string                 `json:"session_id"`
	UserID            string                 `json:"user_id"`
	StartTime         time.Time              `json:"start_time"`
	LastActivity      time.Time              `json:"last_activity"`
	Activities        []*SessionActivity     `json:"activities"`
	IPAddress         string                 `json:"ip_address"`
	UserAgent         string                 `json:"user_agent"`
	Location          *GeoLocation           `json:"location,omitempty"`
	RiskScore         float64                `json:"risk_score"`
}

// SessionActivity represents an activity within a session
type SessionActivity struct {
	ActivityID        string                 `json:"activity_id"`
	ActivityType      string                 `json:"activity_type"`
	Resource          string                 `json:"resource"`
	Action            string                 `json:"action"`
	Result            string                 `json:"result"`
	Timestamp         time.Time              `json:"timestamp"`
	Duration          time.Duration          `json:"duration"`
	Metadata          map[string]interface{} `json:"metadata"`
}

// UserBehaviorProfile represents a user's behavioral profile
type UserBehaviorProfile struct {
	UserID            string                 `json:"user_id"`
	CreatedAt         time.Time              `json:"created_at"`
	UpdatedAt         time.Time              `json:"updated_at"`
	
	// Behavioral patterns
	TypicalHours      []int                  `json:"typical_hours"`
	TypicalDays       []time.Weekday         `json:"typical_days"`
	TypicalLocations  []*GeoLocation         `json:"typical_locations"`
	TypicalResources  []string               `json:"typical_resources"`
	AccessPatterns    map[string]int         `json:"access_patterns"`
	
	// Statistics
	TotalSessions     int                    `json:"total_sessions"`
	AverageSessionDuration time.Duration     `json:"average_session_duration"`
	MostActiveHour    int                    `json:"most_active_hour"`
	LastSeen          time.Time              `json:"last_seen"`
	
	// Risk factors
	AnomalyCount      int                    `json:"anomaly_count"`
	BaselineRiskScore float64                `json:"baseline_risk_score"`
	RecentRiskScore   float64                `json:"recent_risk_score"`
}

// GeoLocation represents geographical location information
type GeoLocation struct {
	Country           string                 `json:"country"`
	Region            string                 `json:"region"`
	City              string                 `json:"city"`
	Latitude          float64                `json:"latitude"`
	Longitude         float64                `json:"longitude"`
	ISP               string                 `json:"isp"`
	Organization      string                 `json:"organization"`
	Timezone          string                 `json:"timezone"`
}

// ThreatIntelligence provides threat intelligence data
type ThreatIntelligence struct {
	mu                sync.RWMutex
	threatFeeds       map[string]*ThreatFeed
	indicators        map[string]*ThreatIndicator
	lastUpdate        time.Time
}

// ThreatFeed represents a threat intelligence feed
type ThreatFeed struct {
	FeedID            string                 `json:"feed_id"`
	Name              string                 `json:"name"`
	Source            string                 `json:"source"`
	LastUpdate        time.Time              `json:"last_update"`
	Indicators        []*ThreatIndicator     `json:"indicators"`
	Confidence        float64                `json:"confidence"`
	Enabled           bool                   `json:"enabled"`
}

// ThreatIndicator represents a threat indicator
type ThreatIndicator struct {
	IndicatorID       string                 `json:"indicator_id"`
	Type              string                 `json:"type"`              // ip, domain, hash, etc.
	Value             string                 `json:"value"`
	ThreatType        string                 `json:"threat_type"`
	Confidence        float64                `json:"confidence"`
	FirstSeen         time.Time              `json:"first_seen"`
	LastSeen          time.Time              `json:"last_seen"`
	Description       string                 `json:"description"`
	Tags              []string               `json:"tags"`
}

// ThreatIntelData represents threat intelligence data for an event
type ThreatIntelData struct {
	HasThreatIndicators bool                 `json:"has_threat_indicators"`
	Indicators          []*ThreatIndicator   `json:"indicators"`
	ThreatScore         float64              `json:"threat_score"`
	ThreatTypes         []string             `json:"threat_types"`
	RecommendedActions  []string             `json:"recommended_actions"`
}

// NewAuditLogger creates a new comprehensive audit logger
func NewAuditLogger(cfg *config.Config, storage AuditStorage) (*AuditLoggerImpl, error) {
	logger := &AuditLoggerImpl{
		config:        cfg,
		storage:       storage,
		eventBuffer:   make([]*AuditEvent, 0),
		bufferSize:    1000,
		flushInterval: 5 * time.Minute,
		lastFlush:     time.Now(),
	}

	// Initialize components
	logger.correlationEngine = &EventCorrelationEngine{
		correlationRules: []*CorrelationRule{},
		eventWindow:      1 * time.Hour,
		eventCache:       make(map[string]*AuditEvent),
		correlationIndex: make(map[string][]string),
	}

	logger.sessionTracker = &SessionTracker{
		activeSessions:   make(map[string]*UserSession),
		sessionTimeout:   4 * time.Hour,
		behaviorProfiles: make(map[string]*UserBehaviorProfile),
	}

	logger.threatIntelligence = &ThreatIntelligence{
		threatFeeds: make(map[string]*ThreatFeed),
		indicators:  make(map[string]*ThreatIndicator),
		lastUpdate:  time.Now(),
	}

	// Start background processes
	go logger.flushBuffer()
	go logger.processCorrelations()
	go logger.trackSessions()

	return logger, nil
}

// LogAccess logs an access event with comprehensive context
func (al *AuditLoggerImpl) LogAccess(entry *AccessLogEntry) error {
	event := &AuditEvent{
		EventID:   fmt.Sprintf("access_%s_%d", entry.UserID, time.Now().UnixNano()),
		EventType: "access",
		Timestamp: entry.AccessTime,
		UserID:    entry.UserID,
		Data: map[string]interface{}{
			"role":          entry.Role,
			"access_type":   entry.AccessType,
			"success":       entry.Success,
			"failure_reason": entry.FailureReason,
			"ip_address":    entry.IPAddress,
			"user_agent":    entry.UserAgent,
			"audit_trail":   entry.AuditTrail,
		},
	}

	return al.logEvent(event)
}

// LogKeyRotation logs a key rotation event
func (al *AuditLoggerImpl) LogKeyRotation(event *KeyRotationEvent) error {
	auditEvent := &AuditEvent{
		EventID:   event.EventID,
		EventType: "key_rotation",
		Timestamp: event.Timestamp,
		UserID:    event.InitiatedBy,
		Data: map[string]interface{}{
			"rotated_roles":      event.RotatedRoles,
			"reason":             event.Reason,
			"success":            event.Success,
			"error_message":      event.ErrorMessage,
			"previous_key_hashes": event.PreviousKeyHashes,
			"new_key_hashes":     event.NewKeyHashes,
		},
	}

	return al.logEvent(auditEvent)
}

// LogSecurityEvent logs a security event
func (al *AuditLoggerImpl) LogSecurityEvent(event *SecurityEvent) error {
	auditEvent := &AuditEvent{
		EventID:   event.EventID,
		EventType: event.EventType,
		Timestamp: event.Timestamp,
		UserID:    event.UserID,
		Data: map[string]interface{}{
			"resource":    event.Resource,
			"action":      event.Action,
			"outcome":     event.Outcome,
			"risk_level":  event.RiskLevel,
			"details":     event.Details,
		},
	}

	return al.logEvent(auditEvent)
}

// logEvent is the internal method for logging events
func (al *AuditLoggerImpl) logEvent(event *AuditEvent) error {
	al.mu.Lock()
	defer al.mu.Unlock()

	// Add integrity hash
	event.IntegrityHash = al.calculateIntegrityHash(event)

	// Add to buffer
	al.eventBuffer = append(al.eventBuffer, event)
	al.totalEvents++

	// Enrich event asynchronously
	go al.enrichAndProcessEvent(event)

	// Flush if buffer is full
	if len(al.eventBuffer) >= al.bufferSize {
		go al.flushBuffer()
	}

	return nil
}

// calculateIntegrityHash calculates a tamper-proof hash for the event
func (al *AuditLoggerImpl) calculateIntegrityHash(event *AuditEvent) string {
	// Create a consistent string representation
	data := fmt.Sprintf("%s:%s:%d:%s:%v", 
		event.EventID, 
		event.EventType, 
		event.Timestamp.Unix(), 
		event.UserID, 
		event.Data)
	
	hash := sha256.Sum256([]byte(data))
	return hex.EncodeToString(hash[:])
}

// enrichAndProcessEvent enriches and processes an event
func (al *AuditLoggerImpl) enrichAndProcessEvent(event *AuditEvent) {
	// Enrich with geo location
	if ipAddress, ok := event.Data["ip_address"].(string); ok && ipAddress != "" {
		geoLocation := al.getGeoLocation(ipAddress)
		event.Data["geo_location"] = geoLocation
	}

	// Enrich with threat intelligence
	threatData := al.getThreatIntelligence(event)
	if threatData.HasThreatIndicators {
		event.Data["threat_intelligence"] = threatData
	}

	// Update user behavior profile
	al.updateUserBehaviorProfile(event)

	// Correlate with other events
	al.correlateEvent(event)

	// Detect anomalies
	if al.anomalyDetector != nil {
		anomalyResult, _ := al.anomalyDetector.AnalyzeEvent(event)
		if anomalyResult != nil && anomalyResult.IsAnomaly {
			event.Data["anomaly_detection"] = anomalyResult
			
			// Create alert for anomaly
			if al.alertManager != nil {
				alert := al.alertManager.CreateAlert(event, AlertSeverityMedium, "Anomalous behavior detected")
				al.alertManager.SendAlert(alert)
			}
		}
	}

	// Record metrics
	if al.metricsCollector != nil {
		metric := &SecurityMetric{
			MetricID:    fmt.Sprintf("event_%s", event.EventType),
			MetricName:  fmt.Sprintf("audit_events_%s", event.EventType),
			MetricType:  "counter",
			Value:       1,
			Unit:        "count",
			Timestamp:   event.Timestamp,
			Description: fmt.Sprintf("Count of %s events", event.EventType),
			Tags: map[string]string{
				"event_type": event.EventType,
				"user_id":    event.UserID,
			},
		}
		al.metricsCollector.RecordMetric(metric)
	}
}

// getGeoLocation gets geographical location for an IP address
func (al *AuditLoggerImpl) getGeoLocation(ipAddress string) *GeoLocation {
	// In production, integrate with a geolocation service
	return &GeoLocation{
		Country:      "Unknown",
		Region:       "Unknown",
		City:         "Unknown",
		Latitude:     0.0,
		Longitude:    0.0,
		ISP:          "Unknown",
		Organization: "Unknown",
		Timezone:     "UTC",
	}
}

// getThreatIntelligence checks threat intelligence for an event
func (al *AuditLoggerImpl) getThreatIntelligence(event *AuditEvent) *ThreatIntelData {
	threatData := &ThreatIntelData{
		HasThreatIndicators: false,
		Indicators:          []*ThreatIndicator{},
		ThreatScore:         0.0,
		ThreatTypes:         []string{},
		RecommendedActions:  []string{},
	}

	// Check IP address against threat feeds
	if ipAddress, ok := event.Data["ip_address"].(string); ok && ipAddress != "" {
		if indicator, exists := al.threatIntelligence.indicators[ipAddress]; exists {
			threatData.HasThreatIndicators = true
			threatData.Indicators = append(threatData.Indicators, indicator)
			threatData.ThreatScore = indicator.Confidence
			threatData.ThreatTypes = append(threatData.ThreatTypes, indicator.ThreatType)
			threatData.RecommendedActions = append(threatData.RecommendedActions, "Block IP address", "Investigate user activity")
		}
	}

	return threatData
}

// updateUserBehaviorProfile updates the user's behavioral profile
func (al *AuditLoggerImpl) updateUserBehaviorProfile(event *AuditEvent) {
	al.sessionTracker.mu.Lock()
	defer al.sessionTracker.mu.Unlock()

	profile, exists := al.sessionTracker.behaviorProfiles[event.UserID]
	if !exists {
		profile = &UserBehaviorProfile{
			UserID:               event.UserID,
			CreatedAt:            time.Now(),
			UpdatedAt:            time.Now(),
			TypicalHours:         []int{},
			TypicalDays:          []time.Weekday{},
			TypicalLocations:     []*GeoLocation{},
			TypicalResources:     []string{},
			AccessPatterns:       make(map[string]int),
			BaselineRiskScore:    0.5,
			RecentRiskScore:      0.5,
		}
		al.sessionTracker.behaviorProfiles[event.UserID] = profile
	}

	// Update activity patterns
	hour := event.Timestamp.Hour()
	if !auditContains(profile.TypicalHours, hour) {
		profile.TypicalHours = append(profile.TypicalHours, hour)
	}

	day := event.Timestamp.Weekday()
	if !containsWeekday(profile.TypicalDays, day) {
		profile.TypicalDays = append(profile.TypicalDays, day)
	}

	// Update access patterns
	if resource, ok := event.Data["resource"].(string); ok {
		profile.AccessPatterns[resource]++
	}

	profile.UpdatedAt = time.Now()
	profile.LastSeen = event.Timestamp
}

// correlateEvent correlates an event with other events
func (al *AuditLoggerImpl) correlateEvent(event *AuditEvent) {
	al.correlationEngine.mu.Lock()
	defer al.correlationEngine.mu.Unlock()

	// Add event to cache
	al.correlationEngine.eventCache[event.EventID] = event

	// Update correlation index
	for field, value := range event.Data {
		if valueStr, ok := value.(string); ok {
			key := fmt.Sprintf("%s:%s", field, valueStr)
			al.correlationEngine.correlationIndex[key] = append(
				al.correlationEngine.correlationIndex[key], 
				event.EventID,
			)
		}
	}

	// Clean old events from cache
	cutoff := time.Now().Add(-al.correlationEngine.eventWindow)
	for eventID, cachedEvent := range al.correlationEngine.eventCache {
		if cachedEvent.Timestamp.Before(cutoff) {
			delete(al.correlationEngine.eventCache, eventID)
		}
	}
}

// flushBuffer flushes the event buffer to storage
func (al *AuditLoggerImpl) flushBuffer() {
	al.mu.Lock()
	if len(al.eventBuffer) == 0 {
		al.mu.Unlock()
		return
	}

	events := make([]*AuditEvent, len(al.eventBuffer))
	copy(events, al.eventBuffer)
	al.eventBuffer = al.eventBuffer[:0]
	al.lastFlush = time.Now()
	al.mu.Unlock()

	// Store events in batch
	if err := al.storage.StoreBatch(events); err != nil {
		al.mu.Lock()
		al.failedEvents += int64(len(events))
		al.mu.Unlock()
		
		// Log the failure (but avoid infinite recursion)
		fmt.Printf("Failed to store audit events: %v\n", err)
	}
}

// processCorrelations processes event correlations periodically
func (al *AuditLoggerImpl) processCorrelations() {
	ticker := time.NewTicker(1 * time.Minute)
	defer ticker.Stop()

	for range ticker.C {
		al.correlationEngine.mu.RLock()
		rules := make([]*CorrelationRule, len(al.correlationEngine.correlationRules))
		copy(rules, al.correlationEngine.correlationRules)
		al.correlationEngine.mu.RUnlock()

		for _, rule := range rules {
			if rule.Enabled {
				al.processCorrelationRule(rule)
			}
		}
	}
}

// processCorrelationRule processes a single correlation rule
func (al *AuditLoggerImpl) processCorrelationRule(rule *CorrelationRule) {
	// Implementation would check for patterns matching the rule
	// This is a simplified placeholder
}

// trackSessions tracks user sessions
func (al *AuditLoggerImpl) trackSessions() {
	ticker := time.NewTicker(5 * time.Minute)
	defer ticker.Stop()

	for range ticker.C {
		al.sessionTracker.mu.Lock()
		now := time.Now()
		
		// Clean up expired sessions
		for sessionID, session := range al.sessionTracker.activeSessions {
			if now.Sub(session.LastActivity) > al.sessionTracker.sessionTimeout {
				delete(al.sessionTracker.activeSessions, sessionID)
			}
		}
		
		al.sessionTracker.mu.Unlock()
	}
}

// GetAuditTrail retrieves audit trail for forensic investigation
func (al *AuditLoggerImpl) GetAuditTrail(criteria *AuditCriteria) ([]*AuditEvent, error) {
	query := &AuditQueryCriteria{
		StartTime: criteria.StartTime,
		EndTime:   criteria.EndTime,
		UserID:    criteria.UserID,
		EventType: criteria.EventType,
		Limit:     criteria.Limit,
	}

	events, err := al.storage.QueryEvents(query)
	if err != nil {
		return nil, fmt.Errorf("failed to query audit events: %w", err)
	}

	// Sort events by timestamp
	sort.Slice(events, func(i, j int) bool {
		return events[i].Timestamp.Before(events[j].Timestamp)
	})

	return events, nil
}

// AuditQueryCriteria represents criteria for querying audit events
type AuditQueryCriteria struct {
	StartTime *time.Time `json:"start_time,omitempty"`
	EndTime   *time.Time `json:"end_time,omitempty"`
	UserID    string     `json:"user_id,omitempty"`
	EventType string     `json:"event_type,omitempty"`
	Resource  string     `json:"resource,omitempty"`
	Limit     int        `json:"limit,omitempty"`
	Offset    int        `json:"offset,omitempty"`
}

// Helper functions
func auditContains(slice []int, item int) bool {
	for _, s := range slice {
		if s == item {
			return true
		}
	}
	return false
}

func containsWeekday(slice []time.Weekday, item time.Weekday) bool {
	for _, s := range slice {
		if s == item {
			return true
		}
	}
	return false
}

// IntegrityVerification represents integrity verification for evidence
type IntegrityVerification struct {
	Algorithm         string    `json:"algorithm"`
	Hash              string    `json:"hash"`
	VerifiedAt        time.Time `json:"verified_at"`
	VerificationValid bool      `json:"verification_valid"`
}

// RiskAssessment represents a risk assessment
type RiskAssessment struct {
	OverallRisk       string                 `json:"overall_risk"`
	RiskFactors       []*RiskFactor          `json:"risk_factors"`
	Mitigations       []*RiskMitigation      `json:"mitigations"`
	AssessedAt        time.Time              `json:"assessed_at"`
	AssessedBy        string                 `json:"assessed_by"`
}

// RiskFactor represents a risk factor
type RiskFactor struct {
	Factor            string                 `json:"factor"`
	Likelihood        string                 `json:"likelihood"`
	Impact            string                 `json:"impact"`
	RiskScore         float64                `json:"risk_score"`
	Description       string                 `json:"description"`
}

// RiskMitigation represents a risk mitigation
type RiskMitigation struct {
	Mitigation        string                 `json:"mitigation"`
	Effectiveness     string                 `json:"effectiveness"`
	Status            string                 `json:"status"`
	ResponsibleParty  string                 `json:"responsible_party"`
	DueDate           *time.Time             `json:"due_date,omitempty"`
}

// ReportCriteria represents criteria for custom reports
type ReportCriteria struct {
	Period            *ReportingPeriod       `json:"period"`
	EventTypes        []string               `json:"event_types,omitempty"`
	Users             []string               `json:"users,omitempty"`
	Resources         []string               `json:"resources,omitempty"`
	IncludeDetails    bool                   `json:"include_details"`
	Format            string                 `json:"format"`
	Metadata          map[string]interface{} `json:"metadata"`
}

// ComplianceValidation represents compliance validation results
type ComplianceValidation struct {
	Standard          string                 `json:"standard"`
	ValidatedAt       time.Time              `json:"validated_at"`
	ValidatedBy       string                 `json:"validated_by"`
	OverallStatus     ComplianceStatus       `json:"overall_status"`
	Controls          []*ControlValidation   `json:"controls"`
	Recommendations   []string               `json:"recommendations"`
}

// ControlValidation represents validation of a specific control
type ControlValidation struct {
	ControlID         string                 `json:"control_id"`
	ControlName       string                 `json:"control_name"`
	Status            ComplianceStatus       `json:"status"`
	Evidence          []string               `json:"evidence"`
	Gaps              []string               `json:"gaps"`
	Recommendations   []string               `json:"recommendations"`
}

// MetricsCriteria represents criteria for querying metrics
type MetricsCriteria struct {
	StartTime         *time.Time             `json:"start_time,omitempty"`
	EndTime           *time.Time             `json:"end_time,omitempty"`
	MetricNames       []string               `json:"metric_names,omitempty"`
	Tags              map[string]string      `json:"tags,omitempty"`
	Aggregation       string                 `json:"aggregation,omitempty"`
	Granularity       string                 `json:"granularity,omitempty"`
}

// PerformanceReport represents system performance metrics
type PerformanceReport struct {
	GeneratedAt       time.Time              `json:"generated_at"`
	Period            *ReportingPeriod       `json:"period"`
	EventsProcessed   int64                  `json:"events_processed"`
	AverageLatency    time.Duration          `json:"average_latency"`
	ThroughputPerSec  float64                `json:"throughput_per_sec"`
	ErrorRate         float64                `json:"error_rate"`
	StorageUsage      int64                  `json:"storage_usage"`
	SystemHealth      string                 `json:"system_health"`
	Recommendations   []string               `json:"recommendations"`
}

// AuditBackup represents a backup of audit logs
type AuditBackup struct {
	BackupID          string                 `json:"backup_id"`
	CreatedAt         time.Time              `json:"created_at"`
	CreatedBy         string                 `json:"created_by"`
	Period            *ReportingPeriod       `json:"period"`
	EventCount        int                    `json:"event_count"`
	CompressedSize    int64                  `json:"compressed_size"`
	Checksum          string                 `json:"checksum"`
	EncryptionMethod  string                 `json:"encryption_method"`
	StorageLocation   string                 `json:"storage_location"`
	Metadata          map[string]interface{} `json:"metadata"`
}