/**
 * Security Audit Logging Module
 *
 * Provides comprehensive security event logging for ZCLAW application.
 * All security-relevant events are logged with timestamps and details.
 *
 * Security events logged:
 * - Authentication events (login, logout, failed attempts)
 * - API key operations (access, rotation, deletion)
 * - Data access events (encrypted data read/write)
 * - Security violations (failed decryption, tampering attempts)
 * - Configuration changes
 */

import { hashSha256, generateRandomString } from './crypto-utils';

// ============================================================================
// Types
// ============================================================================

export type SecurityEventType =
  | 'auth_login'
  | 'auth_logout'
  | 'auth_failed'
  | 'auth_token_refresh'
  | 'key_accessed'
  | 'key_stored'
  | 'key_deleted'
  | 'key_rotated'
  | 'data_encrypted'
  | 'data_decrypted'
  | 'data_access'
  | 'data_export'
  | 'data_import'
  | 'security_violation'
  | 'decryption_failed'
  | 'integrity_check_failed'
  | 'config_changed'
  | 'permission_granted'
  | 'permission_denied'
  | 'session_started'
  | 'session_ended'
  | 'rate_limit_exceeded'
  | 'suspicious_activity'
  | 'hand_executed'
  | 'hand_approved'
  | 'hand_denied'
  | 'skill_executed';

export type SecurityEventSeverity = 'info' | 'warning' | 'error' | 'critical';

export interface SecurityEvent {
  id: string;
  type: SecurityEventType;
  severity: SecurityEventSeverity;
  timestamp: string;
  message: string;
  details: Record<string, unknown>;
  userAgent?: string;
  ip?: string;
  sessionId?: string;
  agentId?: string;
}

export interface SecurityAuditReport {
  generatedAt: string;
  totalEvents: number;
  eventsByType: Record<SecurityEventType, number>;
  eventsBySeverity: Record<SecurityEventSeverity, number>;
  recentCriticalEvents: SecurityEvent[];
  recommendations: string[];
}

// ============================================================================
// Constants
// ============================================================================

const SECURITY_LOG_KEY = 'zclaw_security_audit_log';
const MAX_LOG_ENTRIES = 2000;
const AUDIT_VERSION = 1;

// ============================================================================
// Internal State
// ============================================================================

let isAuditEnabled: boolean = true;
let currentSessionId: string | null = null;

// ============================================================================
// Core Functions
// ============================================================================

/**
 * Generate a unique event ID
 */
function generateEventId(): string {
  return `evt_${Date.now()}_${generateRandomString(8)}`;
}

/**
 * Get the current session ID
 */
export function getCurrentSessionId(): string | null {
  return currentSessionId;
}

/**
 * Set the current session ID
 */
export function setCurrentSessionId(sessionId: string | null): void {
  currentSessionId = sessionId;
}

/**
 * Enable or disable audit logging
 */
export function setAuditEnabled(enabled: boolean): void {
  isAuditEnabled = enabled;
  logSecurityEventInternal('config_changed', 'info', `Audit logging ${enabled ? 'enabled' : 'disabled'}`, {});
}

/**
 * Check if audit logging is enabled
 */
export function isAuditEnabledState(): boolean {
  return isAuditEnabled;
}

/**
 * Internal function to persist security events
 */
function persistEvent(event: SecurityEvent): void {
  try {
    const events = getStoredEvents();
    events.push(event);

    // Trim old entries if needed
    if (events.length > MAX_LOG_ENTRIES) {
      events.splice(0, events.length - MAX_LOG_ENTRIES);
    }

    localStorage.setItem(SECURITY_LOG_KEY, JSON.stringify(events));
  } catch (e) {
    // Ignore persistence failures to prevent application disruption
    // eslint-disable-next-line no-console
    if (process.env.NODE_ENV === 'development') {
      console.warn('[SecurityAudit] Failed to persist security event', e);
    }
  }
}

/**
 * Get stored security events
 */
function getStoredEvents(): SecurityEvent[] {
  try {
    const stored = localStorage.getItem(SECURITY_LOG_KEY);
    if (!stored) return [];
    return JSON.parse(stored) as SecurityEvent[];
  } catch (e) {
    // eslint-disable-next-line no-console
    if (process.env.NODE_ENV === 'development') {
      console.warn('[SecurityAudit] Failed to read security events', e);
    }
    return [];
  }
}

/**
 * Determine severity based on event type
 */
function getDefaultSeverity(type: SecurityEventType): SecurityEventSeverity {
  const severityMap: Record<SecurityEventType, SecurityEventSeverity> = {
    auth_login: 'info',
    auth_logout: 'info',
    auth_failed: 'warning',
    auth_token_refresh: 'info',
    key_accessed: 'info',
    key_stored: 'info',
    key_deleted: 'warning',
    key_rotated: 'info',
    data_encrypted: 'info',
    data_decrypted: 'info',
    data_access: 'info',
    data_export: 'warning',
    data_import: 'warning',
    security_violation: 'critical',
    decryption_failed: 'error',
    integrity_check_failed: 'critical',
    config_changed: 'warning',
    permission_granted: 'info',
    permission_denied: 'warning',
    session_started: 'info',
    session_ended: 'info',
    rate_limit_exceeded: 'warning',
    suspicious_activity: 'critical',
    hand_executed: 'info',
    hand_approved: 'info',
    hand_denied: 'warning',
    skill_executed: 'info',
  };

  return severityMap[type] || 'info';
}

/**
 * Internal function to log security events
 */
function logSecurityEventInternal(
  type: SecurityEventType,
  severity: SecurityEventSeverity,
  message: string,
  details: Record<string, unknown>
): void {
  if (!isAuditEnabled && type !== 'config_changed') {
    return;
  }

  const event: SecurityEvent = {
    id: generateEventId(),
    type,
    severity,
    timestamp: new Date().toISOString(),
    message,
    details,
    sessionId: currentSessionId || undefined,
  };

  // Add user agent if in browser
  if (typeof navigator !== 'undefined') {
    event.userAgent = navigator.userAgent;
  }

  persistEvent(event);

  // Log to console for development
  if (process.env.NODE_ENV === 'development') {
    const logMethod = severity === 'critical' || severity === 'error' ? 'error' :
                   severity === 'warning' ? 'warn' : 'log';
    console[logMethod](`[SecurityAudit] ${type}: ${message}`, details);
  }
}

// ============================================================================
// Public API
// ============================================================================

/**
 * Log a security event
 */
export function logSecurityEvent(
  type: SecurityEventType,
  message: string,
  details: Record<string, unknown> = {},
  severity?: SecurityEventSeverity
): void {
  const eventSeverity = severity || getDefaultSeverity(type);
  logSecurityEventInternal(type, eventSeverity, message, details);
}

/**
 * Log authentication event
 */
export function logAuthEvent(
  type: 'auth_login' | 'auth_logout' | 'auth_failed' | 'auth_token_refresh',
  message: string,
  details: Record<string, unknown> = {}
): void {
  logSecurityEvent(type, message, details);
}

/**
 * Log key management event
 */
export function logKeyEvent(
  type: 'key_accessed' | 'key_stored' | 'key_deleted' | 'key_rotated',
  message: string,
  details: Record<string, unknown> = {}
): void {
  logSecurityEvent(type, message, details);
}

/**
 * Log data access event
 */
export function logDataEvent(
  type: 'data_encrypted' | 'data_decrypted' | 'data_access' | 'data_export' | 'data_import',
  message: string,
  details: Record<string, unknown> = {}
): void {
  logSecurityEvent(type, message, details);
}

/**
 * Log security violation
 */
export function logSecurityViolation(
  message: string,
  details: Record<string, unknown> = {}
): void {
  logSecurityEvent('security_violation', message, details, 'critical');
}

/**
 * Log decryption failure
 */
export function logDecryptionFailure(
  message: string,
  details: Record<string, unknown> = {}
): void {
  logSecurityEvent('decryption_failed', message, details, 'error');
}

/**
 * Log integrity check failure
 */
export function logIntegrityFailure(
  message: string,
  details: Record<string, unknown> = {}
): void {
  logSecurityEvent('integrity_check_failed', message, details, 'critical');
}

/**
 * Log permission event
 */
export function logPermissionEvent(
  type: 'permission_granted' | 'permission_denied',
  message: string,
  details: Record<string, unknown> = {}
): void {
  logSecurityEvent(type, message, details);
}

/**
 * Log session event
 */
export function logSessionEvent(
  type: 'session_started' | 'session_ended',
  message: string,
  details: Record<string, unknown> = {}
): void {
  logSecurityEvent(type, message, details);
}

/**
 * Log suspicious activity
 */
export function logSuspiciousActivity(
  message: string,
  details: Record<string, unknown> = {}
): void {
  logSecurityEvent('suspicious_activity', message, details, 'critical');
}

/**
 * Log rate limit event
 */
export function logRateLimitEvent(
  message: string,
  details: Record<string, unknown> = {}
): void {
  logSecurityEvent('rate_limit_exceeded', message, details, 'warning');
}

// ============================================================================
// Query Functions
// ============================================================================

/**
 * Get all security events
 */
export function getSecurityEvents(): SecurityEvent[] {
  return getStoredEvents();
}

/**
 * Get security events by type
 */
export function getSecurityEventsByType(type: SecurityEventType): SecurityEvent[] {
  return getStoredEvents().filter(event => event.type === type);
}

/**
 * Get security events by severity
 */
export function getSecurityEventsBySeverity(severity: SecurityEventSeverity): SecurityEvent[] {
  return getStoredEvents().filter(event => event.severity === severity);
}

/**
 * Get security events within a time range
 */
export function getSecurityEventsByTimeRange(start: Date, end: Date): SecurityEvent[] {
  const startTime = start.getTime();
  const endTime = end.getTime();

  return getStoredEvents().filter(event => {
    const eventTime = new Date(event.timestamp).getTime();
    return eventTime >= startTime && eventTime <= endTime;
  });
}

/**
 * Get recent critical events
 */
export function getRecentCriticalEvents(count: number = 10): SecurityEvent[] {
  return getStoredEvents()
    .filter(event => event.severity === 'critical' || event.severity === 'error')
    .slice(-count);
}

/**
 * Get events for a specific session
 */
export function getSecurityEventsBySession(sessionId: string): SecurityEvent[] {
  return getStoredEvents().filter(event => event.sessionId === sessionId);
}

// ============================================================================
// Report Generation
// ============================================================================

/**
 * Generate a security audit report
 */
export function generateSecurityAuditReport(): SecurityAuditReport {
  const events = getStoredEvents();

  const eventsByType = Object.create(null) as Record<SecurityEventType, number>;
  const eventsBySeverity: Record<SecurityEventSeverity, number> = {
    info: 0,
    warning: 0,
    error: 0,
    critical: 0,
  };

  for (const event of events) {
    eventsByType[event.type] = (eventsByType[event.type] || 0) + 1;
    eventsBySeverity[event.severity]++;
  }

  const recentCriticalEvents = getRecentCriticalEvents(10);

  const recommendations: string[] = [];

  // Generate recommendations based on findings
  if (eventsBySeverity.critical > 0) {
    recommendations.push('Investigate critical security events immediately');
  }

  if ((eventsByType.auth_failed || 0) > 5) {
    recommendations.push('Multiple failed authentication attempts detected - consider rate limiting');
  }

  if ((eventsByType.decryption_failed || 0) > 3) {
    recommendations.push('Multiple decryption failures - check key integrity');
  }

  if ((eventsByType.suspicious_activity || 0) > 0) {
    recommendations.push('Suspicious activity detected - review access logs');
  }

  if (events.length === 0) {
    recommendations.push('No security events recorded - ensure audit logging is enabled');
  }

  return {
    generatedAt: new Date().toISOString(),
    totalEvents: events.length,
    eventsByType,
    eventsBySeverity,
    recentCriticalEvents,
    recommendations,
  };
}

// ============================================================================
// Maintenance Functions
// ============================================================================

/**
 * Clear all security events
 */
export function clearSecurityAuditLog(): void {
  localStorage.removeItem(SECURITY_LOG_KEY);
  logSecurityEventInternal('config_changed', 'warning', 'Security audit log cleared', {});
}

/**
 * Export security events for external analysis
 */
export function exportSecurityEvents(): string {
  const events = getStoredEvents();
  return JSON.stringify({
    version: AUDIT_VERSION,
    exportedAt: new Date().toISOString(),
    events,
  }, null, 2);
}

/**
 * Import security events from external source
 */
export function importSecurityEvents(jsonData: string, merge: boolean = false): void {
  try {
    const data = JSON.parse(jsonData);
    const importedEvents = data.events as SecurityEvent[];

    if (!importedEvents || !Array.isArray(importedEvents)) {
      throw new Error('Invalid import data format');
    }

    if (merge) {
      const existingEvents = getStoredEvents();
      const mergedEvents = [...existingEvents, ...importedEvents];
      localStorage.setItem(SECURITY_LOG_KEY, JSON.stringify(mergedEvents.slice(-MAX_LOG_ENTRIES)));
    } else {
      localStorage.setItem(SECURITY_LOG_KEY, JSON.stringify(importedEvents.slice(-MAX_LOG_ENTRIES)));
    }

    logSecurityEventInternal('data_import', 'warning', `Imported ${importedEvents.length} security events`, {
      merge,
      sourceVersion: data.version,
    });
  } catch (error) {
    logSecurityEventInternal('security_violation', 'error', 'Failed to import security events', {
      error: error instanceof Error ? error.message : String(error),
    });
    throw error;
  }
}

/**
 * Verify audit log integrity
 */
export async function verifyAuditLogIntegrity(): Promise<{
  valid: boolean;
  eventCount: number;
  hash: string;
}> {
  const events = getStoredEvents();
  const data = JSON.stringify(events);
  const hash = await hashSha256(data);

  return {
    valid: events.length > 0,
    eventCount: events.length,
    hash,
  };
}

// ============================================================================
// Initialization
// ============================================================================

/**
 * Initialize the security audit module
 */
export function initializeSecurityAudit(sessionId?: string): void {
  if (sessionId) {
    currentSessionId = sessionId;
  }

  logSecurityEventInternal('session_started', 'info', 'Security audit session started', {
    sessionId: currentSessionId,
    auditEnabled: isAuditEnabled,
  });
}

/**
 * Shutdown the security audit module
 */
export function shutdownSecurityAudit(): void {
  logSecurityEventInternal('session_ended', 'info', 'Security audit session ended', {
    sessionId: currentSessionId,
  });

  currentSessionId = null;
}