@clduab11/gemini-flow/src/core/a2a-zero-trust.ts

Revolutionary AI agent swarm coordination platform with Google Services integration, multimedia processing, and production-ready monitoring. Features 8 Google AI services, quantum computing capabilities, and enterprise-grade security.

/**
 * A2A Zero Trust Architecture System
 *
 * Implements comprehensive zero-trust security model for agent-to-agent communication:
 * - Never trust, always verify principle
 * - Continuous authentication and authorization
 * - Least privilege access control with dynamic permissions
 * - Micro-segmentation and network isolation
 * - Context-aware security policies
 * - Real-time risk assessment and adaptive responses
 * - Identity-centric security with behavioral analysis
 * - Policy engine with dynamic rule evaluation
 */

import { EventEmitter } from "events";
import crypto from "crypto";
import { Logger } from "../utils/logger.js";
import { CacheManager } from "./cache-manager.js";

export interface ZeroTrustPolicy {
  policyId: string;
  name: string;
  description: string;
  version: string;
  conditions: {
    agentTypes?: string[];
    agentIds?: string[];
    timeWindows?: TimeWindow[];
    locations?: string[];
    networkSegments?: string[];
    riskLevels?: RiskLevel[];
    capabilities?: string[];
    resources?: ResourcePattern[];
  };
  actions: {
    allow: boolean;
    requirements?: string[];
    restrictions?: string[];
    monitoring?: string[];
    timeLimit?: number;
  };
  priority: number;
  enabled: boolean;
  createdAt: Date;
  lastModified: Date;
  metadata: {
    author: string;
    reason: string;
    compliance: string[];
    tags: string[];
  };
}

export interface TrustScore {
  agentId: string;
  overallScore: number;
  components: {
    identity: number;
    behavior: number;
    location: number;
    device: number;
    network: number;
    compliance: number;
    reputation: number;
  };
  factors: {
    positiveFactors: string[];
    negativeFactors: string[];
    unknownFactors: string[];
  };
  history: TrustScoreHistory[];
  lastUpdated: Date;
}

export interface TrustScoreHistory {
  timestamp: Date;
  score: number;
  reason: string;
  contributing_factors: string[];
}

export interface SecurityContext {
  agentId: string;
  sessionId?: string;
  requestId: string;
  timestamp: Date;
  source: {
    ip: string;
    location?: GeoLocation;
    network: NetworkInfo;
    device?: DeviceInfo;
  };
  identity: {
    verified: boolean;
    authMethod: string;
    certificates: string[];
    trustLevel: string;
  };
  behavior: {
    pattern: string;
    anomalyScore: number;
    riskFactors: string[];
  };
  resource: {
    type: string;
    classification: string;
    owner: string;
    sensitivity: "public" | "internal" | "confidential" | "restricted";
  };
  metadata: Record<string, any>;
}

export interface AccessDecision {
  allowed: boolean;
  reason: string;
  conditions?: string[];
  restrictions?: string[];
  monitoring?: string[];
  timeLimit?: number;
  trustScore: number;
  riskLevel: RiskLevel;
  policyMatches: string[];
  adaptiveActions?: string[];
}

export interface NetworkSegment {
  segmentId: string;
  name: string;
  type: "production" | "staging" | "development" | "isolated" | "quarantine";
  allowedAgentTypes: string[];
  securityLevel: "low" | "medium" | "high" | "critical";
  isolationRules: IsolationRule[];
  trafficPolicies: TrafficPolicy[];
  monitoring: {
    enabled: boolean;
    level: "basic" | "enhanced" | "forensic";
    retention: number;
  };
}

export interface IsolationRule {
  ruleId: string;
  fromSegments: string[];
  toSegments: string[];
  protocol: string;
  ports: number[];
  action: "allow" | "deny" | "monitor" | "quarantine";
  conditions?: string[];
}

export interface TrafficPolicy {
  policyId: string;
  protocol: string;
  direction: "inbound" | "outbound" | "bidirectional";
  inspection: boolean;
  encryption: boolean;
  logging: boolean;
  rateLimiting?: {
    enabled: boolean;
    limits: Record<string, number>;
  };
}

export interface RiskAssessment {
  riskLevel: RiskLevel;
  score: number;
  factors: RiskFactor[];
  mitigations: string[];
  recommendations: string[];
  confidence: number;
  validUntil: Date;
}

export interface RiskFactor {
  type:
    | "identity"
    | "behavior"
    | "location"
    | "device"
    | "network"
    | "temporal"
    | "contextual";
  severity: "low" | "medium" | "high" | "critical";
  description: string;
  score: number;
  mitigated: boolean;
}

export interface AdaptiveResponse {
  triggerId: string;
  responseType: "allow" | "challenge" | "restrict" | "deny" | "isolate";
  actions: string[];
  duration?: number;
  escalation?: {
    enabled: boolean;
    thresholds: number[];
    actions: string[];
  };
  monitoring: {
    enhanced: boolean;
    alerts: boolean;
    logging: string;
  };
}

type RiskLevel =
  | "very_low"
  | "low"
  | "medium"
  | "high"
  | "very_high"
  | "critical";
type TimeWindow = { start: string; end: string; days?: string[] };
type ResourcePattern = { pattern: string; type: string };
type GeoLocation = {
  country: string;
  region: string;
  city: string;
  coordinates?: [number, number];
};
type NetworkInfo = { segment: string; vlan?: number; subnet?: string };
type DeviceInfo = {
  type: string;
  os?: string;
  version?: string;
  fingerprint?: string;
};

export class A2AZeroTrust extends EventEmitter {
  private logger: Logger;
  private cache: CacheManager;

  // Policy management
  private policies: Map<string, ZeroTrustPolicy> = new Map();
  private policyEngine: PolicyEngine;

  // Trust management
  private trustScores: Map<string, TrustScore> = new Map();
  private trustCalculator: TrustCalculator;

  // Network segmentation
  private networkSegments: Map<string, NetworkSegment> = new Map();
  private segmentationEngine: SegmentationEngine;

  // Risk assessment
  private riskAssessor: RiskAssessor;
  private adaptiveResponder: AdaptiveResponder;

  // Continuous monitoring
  private behaviorAnalyzer: BehaviorAnalyzer;
  private contextAnalyzer: ContextAnalyzer;

  // Performance metrics
  private metrics = {
    accessRequests: 0,
    accessGranted: 0,
    accessDenied: 0,
    riskAssessments: 0,
    adaptiveResponses: 0,
    policyViolations: 0,
    trustScoreUpdates: 0,
    averageDecisionTime: 0,
  };

  constructor() {
    super();
    this.logger = new Logger("A2AZeroTrust");
    this.cache = new CacheManager();

    this.initializeComponents();
    this.initializeDefaultPolicies();
    this.initializeNetworkSegments();
    this.startContinuousMonitoring();

    this.logger.info("A2A Zero Trust system initialized", {
      policies: this.policies.size,
      segments: this.networkSegments.size,
      monitoring: "enabled",
    });
  }

  /**
   * Initialize zero trust components
   */
  private initializeComponents(): void {
    this.policyEngine = new PolicyEngine();
    this.trustCalculator = new TrustCalculator();
    this.segmentationEngine = new SegmentationEngine();
    this.riskAssessor = new RiskAssessor();
    this.adaptiveResponder = new AdaptiveResponder();
    this.behaviorAnalyzer = new BehaviorAnalyzer();
    this.contextAnalyzer = new ContextAnalyzer();
  }

  /**
   * Initialize default zero trust policies
   */
  private initializeDefaultPolicies(): void {
    // Default deny policy
    const defaultDenyPolicy: ZeroTrustPolicy = {
      policyId: "default-deny",
      name: "Default Deny All",
      description:
        "Default policy that denies all access unless explicitly allowed",
      version: "1.0.0",
      conditions: {},
      actions: {
        allow: false,
        requirements: ["explicit_allow_policy"],
        monitoring: ["full_audit"],
      },
      priority: 0,
      enabled: true,
      createdAt: new Date(),
      lastModified: new Date(),
      metadata: {
        author: "system",
        reason: "Zero trust default",
        compliance: ["SOX", "GDPR"],
        tags: ["default", "security"],
      },
    };

    this.policies.set("default-deny", defaultDenyPolicy);

    // Trusted coordinator policy
    const coordinatorPolicy: ZeroTrustPolicy = {
      policyId: "trusted-coordinators",
      name: "Trusted Coordinator Access",
      description: "Allow access for verified coordinator agents",
      version: "1.0.0",
      conditions: {
        agentTypes: [
          "coordinator",
          "hierarchical-coordinator",
          "mesh-coordinator",
        ],
        riskLevels: ["very_low", "low", "medium"],
      },
      actions: {
        allow: true,
        requirements: ["verified_identity", "current_certificate"],
        monitoring: ["standard_audit"],
        timeLimit: 28800000, // 8 hours
      },
      priority: 10,
      enabled: true,
      createdAt: new Date(),
      lastModified: new Date(),
      metadata: {
        author: "security_admin",
        reason: "Coordinator agents need system access",
        compliance: ["internal_policy"],
        tags: ["coordinator", "trusted"],
      },
    };

    this.policies.set("trusted-coordinators", coordinatorPolicy);

    // High risk restriction policy
    const highRiskPolicy: ZeroTrustPolicy = {
      policyId: "high-risk-restriction",
      name: "High Risk Agent Restrictions",
      description: "Restrict access for high-risk agents",
      version: "1.0.0",
      conditions: {
        riskLevels: ["high", "very_high", "critical"],
      },
      actions: {
        allow: false,
        requirements: ["admin_approval", "additional_verification"],
        restrictions: ["read_only", "monitored_session"],
        monitoring: ["enhanced_audit", "real_time_alerts"],
      },
      priority: 20,
      enabled: true,
      createdAt: new Date(),
      lastModified: new Date(),
      metadata: {
        author: "security_admin",
        reason: "High risk agents require additional controls",
        compliance: ["security_policy"],
        tags: ["high_risk", "restriction"],
      },
    };

    this.policies.set("high-risk-restriction", highRiskPolicy);
  }

  /**
   * Initialize network segments
   */
  private initializeNetworkSegments(): void {
    // Production segment
    const productionSegment: NetworkSegment = {
      segmentId: "production",
      name: "Production Environment",
      type: "production",
      allowedAgentTypes: [
        "coordinator",
        "security-auditor",
        "infrastructure-monitor",
      ],
      securityLevel: "critical",
      isolationRules: [
        {
          ruleId: "prod-isolation",
          fromSegments: ["staging", "development"],
          toSegments: ["production"],
          protocol: "any",
          ports: [],
          action: "deny",
        },
      ],
      trafficPolicies: [
        {
          policyId: "prod-traffic",
          protocol: "HTTPS",
          direction: "bidirectional",
          inspection: true,
          encryption: true,
          logging: true,
          rateLimiting: {
            enabled: true,
            limits: { requests_per_minute: 1000 },
          },
        },
      ],
      monitoring: {
        enabled: true,
        level: "forensic",
        retention: 2555, // 7 years
      },
    };

    this.networkSegments.set("production", productionSegment);

    // Quarantine segment
    const quarantineSegment: NetworkSegment = {
      segmentId: "quarantine",
      name: "Quarantine Zone",
      type: "quarantine",
      allowedAgentTypes: [],
      securityLevel: "critical",
      isolationRules: [
        {
          ruleId: "quarantine-isolation",
          fromSegments: ["quarantine"],
          toSegments: ["production", "staging", "development"],
          protocol: "any",
          ports: [],
          action: "deny",
        },
      ],
      trafficPolicies: [
        {
          policyId: "quarantine-traffic",
          protocol: "any",
          direction: "bidirectional",
          inspection: true,
          encryption: true,
          logging: true,
        },
      ],
      monitoring: {
        enabled: true,
        level: "forensic",
        retention: 365,
      },
    };

    this.networkSegments.set("quarantine", quarantineSegment);
  }

  /**
   * Evaluate access request using zero trust principles
   */
  async evaluateAccess(
    agentId: string,
    resource: string,
    action: string,
    context: Partial<SecurityContext>,
  ): Promise<AccessDecision> {
    const startTime = Date.now();

    try {
      // Build complete security context
      const securityContext = await this.buildSecurityContext(
        agentId,
        resource,
        action,
        context,
      );

      // Calculate current trust score
      const trustScore = await this.calculateTrustScore(
        agentId,
        securityContext,
      );

      // Assess risk
      const riskAssessment = await this.assessRisk(securityContext, trustScore);

      // Evaluate policies
      const policyDecision = await this.evaluatePolicies(
        securityContext,
        trustScore,
        riskAssessment,
      );

      // Determine adaptive response
      const adaptiveResponse = await this.determineAdaptiveResponse(
        securityContext,
        trustScore,
        riskAssessment,
        policyDecision,
      );

      // Create final access decision
      const decision: AccessDecision = {
        allowed:
          policyDecision.allowed && riskAssessment.riskLevel !== "critical",
        reason: policyDecision.reason,
        conditions: policyDecision.conditions,
        restrictions: policyDecision.restrictions,
        monitoring: policyDecision.monitoring,
        timeLimit: policyDecision.timeLimit,
        trustScore: trustScore.overallScore,
        riskLevel: riskAssessment.riskLevel,
        policyMatches: policyDecision.matchedPolicies,
        adaptiveActions: adaptiveResponse.actions,
      };

      // Execute adaptive response
      if (adaptiveResponse) {
        await this.executeAdaptiveResponse(adaptiveResponse, securityContext);
      }

      // Update metrics
      this.metrics.accessRequests++;
      if (decision.allowed) {
        this.metrics.accessGranted++;
      } else {
        this.metrics.accessDenied++;
      }

      const decisionTime = Date.now() - startTime;
      this.metrics.averageDecisionTime =
        (this.metrics.averageDecisionTime + decisionTime) / 2;

      // Log decision
      this.logger.info("Access decision made", {
        agentId,
        resource,
        action,
        allowed: decision.allowed,
        trustScore: trustScore.overallScore,
        riskLevel: riskAssessment.riskLevel,
        decisionTime,
      });

      // Store decision for audit
      await this.storeAccessDecision(securityContext, decision);

      this.emit("access_decision", {
        agentId,
        resource,
        action,
        decision,
        context: securityContext,
      });

      return decision;
    } catch (error) {
      this.logger.error("Access evaluation failed", {
        agentId,
        resource,
        action,
        error,
      });

      // Fail secure - deny access on error
      return {
        allowed: false,
        reason: "Access evaluation error - failing secure",
        trustScore: 0,
        riskLevel: "critical",
        policyMatches: [],
      };
    }
  }

  /**
   * Update trust score for an agent
   */
  async updateTrustScore(
    agentId: string,
    event: {
      type: "authentication" | "behavior" | "compliance" | "security_incident";
      outcome: "positive" | "negative" | "neutral";
      details: Record<string, any>;
    },
  ): Promise<TrustScore> {
    const currentTrust =
      this.trustScores.get(agentId) ||
      (await this.initializeTrustScore(agentId));

    // Calculate trust score delta
    const delta = await this.trustCalculator.calculateDelta(
      event,
      currentTrust,
    );

    // Update trust components
    const updatedTrust = await this.trustCalculator.updateTrustScore(
      currentTrust,
      delta,
    );

    // Store history
    updatedTrust.history.push({
      timestamp: new Date(),
      score: updatedTrust.overallScore,
      reason: `${event.type}:${event.outcome}`,
      contributing_factors: Object.keys(event.details),
    });

    // Limit history size
    if (updatedTrust.history.length > 100) {
      updatedTrust.history = updatedTrust.history.slice(-50);
    }

    updatedTrust.lastUpdated = new Date();

    // Store updated trust score
    this.trustScores.set(agentId, updatedTrust);
    await this.cache.set(`zerotrust:trust:${agentId}`, updatedTrust, 86400000);

    this.metrics.trustScoreUpdates++;

    this.logger.debug("Trust score updated", {
      agentId,
      oldScore: currentTrust.overallScore,
      newScore: updatedTrust.overallScore,
      event: event.type,
    });

    this.emit("trust_score_updated", {
      agentId,
      oldScore: currentTrust.overallScore,
      newScore: updatedTrust.overallScore,
      event,
    });

    return updatedTrust;
  }

  /**
   * Add or update zero trust policy
   */
  async addPolicy(
    policy: Omit<ZeroTrustPolicy, "createdAt" | "lastModified">,
  ): Promise<void> {
    const fullPolicy: ZeroTrustPolicy = {
      ...policy,
      createdAt: new Date(),
      lastModified: new Date(),
    };

    // Validate policy
    await this.validatePolicy(fullPolicy);

    this.policies.set(policy.policyId, fullPolicy);
    await this.cache.set(
      `zerotrust:policy:${policy.policyId}`,
      fullPolicy,
      86400000,
    );

    this.logger.info("Zero trust policy added", {
      policyId: policy.policyId,
      name: policy.name,
      priority: policy.priority,
    });

    this.emit("policy_added", fullPolicy);
  }

  /**
   * Create network segment
   */
  async createNetworkSegment(segment: NetworkSegment): Promise<void> {
    // Validate segment configuration
    await this.segmentationEngine.validateSegment(segment);

    this.networkSegments.set(segment.segmentId, segment);
    await this.cache.set(
      `zerotrust:segment:${segment.segmentId}`,
      segment,
      86400000,
    );

    this.logger.info("Network segment created", {
      segmentId: segment.segmentId,
      name: segment.name,
      type: segment.type,
      securityLevel: segment.securityLevel,
    });

    this.emit("segment_created", segment);
  }

  /**
   * Quarantine an agent
   */
  async quarantineAgent(
    agentId: string,
    reason: string,
    duration?: number,
  ): Promise<void> {
    // Move agent to quarantine segment
    const quarantineContext = {
      agentId,
      segmentId: "quarantine",
      reason,
      timestamp: new Date(),
      duration,
    };

    await this.cache.set(
      `zerotrust:quarantine:${agentId}`,
      quarantineContext,
      duration || 3600000,
    );

    // Update trust score significantly
    await this.updateTrustScore(agentId, {
      type: "security_incident",
      outcome: "negative",
      details: { quarantined: true, reason },
    });

    this.logger.warn("Agent quarantined", {
      agentId,
      reason,
      duration: duration || "indefinite",
    });

    this.emit("agent_quarantined", {
      agentId,
      reason,
      duration,
      timestamp: new Date(),
    });
  }

  /**
   * Private implementation methods
   */

  private async buildSecurityContext(
    agentId: string,
    resource: string,
    action: string,
    context: Partial<SecurityContext>,
  ): Promise<SecurityContext> {
    return {
      agentId,
      sessionId: context.sessionId,
      requestId: context.requestId || crypto.randomUUID(),
      timestamp: new Date(),
      source: {
        ip: context.source?.ip || "unknown",
        location: context.source?.location,
        network: context.source?.network || { segment: "unknown" },
        device: context.source?.device,
      },
      identity: {
        verified: context.identity?.verified || false,
        authMethod: context.identity?.authMethod || "unknown",
        certificates: context.identity?.certificates || [],
        trustLevel: context.identity?.trustLevel || "unknown",
      },
      behavior: {
        pattern: context.behavior?.pattern || "unknown",
        anomalyScore: context.behavior?.anomalyScore || 0,
        riskFactors: context.behavior?.riskFactors || [],
      },
      resource: {
        type: context.resource?.type || "unknown",
        classification: context.resource?.classification || "unclassified",
        owner: context.resource?.owner || "unknown",
        sensitivity: context.resource?.sensitivity || "internal",
      },
      metadata: context.metadata || {},
    };
  }

  private async calculateTrustScore(
    agentId: string,
    context: SecurityContext,
  ): Promise<TrustScore> {
    let trustScore = this.trustScores.get(agentId);

    if (!trustScore) {
      trustScore = await this.initializeTrustScore(agentId);
      this.trustScores.set(agentId, trustScore);
    }

    // Update trust score based on current context
    const contextualAdjustment =
      await this.trustCalculator.calculateContextualAdjustment(
        trustScore,
        context,
      );

    return this.trustCalculator.applyContextualAdjustment(
      trustScore,
      contextualAdjustment,
    );
  }

  private async assessRisk(
    context: SecurityContext,
    trustScore: TrustScore,
  ): Promise<RiskAssessment> {
    this.metrics.riskAssessments++;
    return this.riskAssessor.assessRisk(context, trustScore);
  }

  private async evaluatePolicies(
    context: SecurityContext,
    trustScore: TrustScore,
    riskAssessment: RiskAssessment,
  ): Promise<{
    allowed: boolean;
    reason: string;
    conditions?: string[];
    restrictions?: string[];
    monitoring?: string[];
    timeLimit?: number;
    matchedPolicies: string[];
  }> {
    return this.policyEngine.evaluate(
      context,
      trustScore,
      riskAssessment,
      this.policies,
    );
  }

  private async determineAdaptiveResponse(
    context: SecurityContext,
    trustScore: TrustScore,
    riskAssessment: RiskAssessment,
    policyDecision: any,
  ): Promise<AdaptiveResponse> {
    this.metrics.adaptiveResponses++;
    return this.adaptiveResponder.determineResponse(
      context,
      trustScore,
      riskAssessment,
      policyDecision,
    );
  }

  private async executeAdaptiveResponse(
    response: AdaptiveResponse,
    context: SecurityContext,
  ): Promise<void> {
    for (const action of response.actions) {
      await this.executeAction(action, context);
    }
  }

  private async executeAction(
    action: string,
    context: SecurityContext,
  ): Promise<void> {
    switch (action) {
      case "enhance_monitoring":
        await this.enhanceMonitoring(context.agentId);
        break;
      case "require_reauthentication":
        this.emit("require_reauthentication", { agentId: context.agentId });
        break;
      case "restrict_capabilities":
        this.emit("restrict_capabilities", { agentId: context.agentId });
        break;
      case "quarantine":
        await this.quarantineAgent(context.agentId, "Adaptive response");
        break;
      case "alert_admin":
        this.emit("alert_admin", { context, action });
        break;
    }
  }

  private async initializeTrustScore(agentId: string): Promise<TrustScore> {
    const trustScore: TrustScore = {
      agentId,
      overallScore: 0.5, // Start with neutral trust
      components: {
        identity: 0.5,
        behavior: 0.5,
        location: 0.5,
        device: 0.5,
        network: 0.5,
        compliance: 0.5,
        reputation: 0.5,
      },
      factors: {
        positiveFactors: [],
        negativeFactors: ["new_agent"],
        unknownFactors: ["behavior_pattern", "location_history"],
      },
      history: [],
      lastUpdated: new Date(),
    };

    return trustScore;
  }

  private async validatePolicy(policy: ZeroTrustPolicy): Promise<void> {
    if (!policy.policyId || !policy.name) {
      throw new Error("Policy must have ID and name");
    }

    if (policy.priority < 0 || policy.priority > 100) {
      throw new Error("Policy priority must be between 0 and 100");
    }

    // Additional validation logic would go here
  }

  private async storeAccessDecision(
    context: SecurityContext,
    decision: AccessDecision,
  ): Promise<void> {
    const record = {
      timestamp: new Date(),
      context,
      decision,
    };

    await this.cache.set(
      `zerotrust:decision:${context.requestId}`,
      record,
      86400000, // 24 hours
    );
  }

  private async enhanceMonitoring(agentId: string): Promise<void> {
    await this.cache.set(
      `zerotrust:enhanced_monitoring:${agentId}`,
      { enabled: true, startTime: new Date() },
      3600000, // 1 hour
    );

    this.logger.info("Enhanced monitoring enabled", { agentId });
  }

  private startContinuousMonitoring(): void {
    // Continuous trust score updates
    setInterval(async () => {
      await this.performContinuousTrustUpdates();
    }, 300000); // 5 minutes

    // Policy compliance checks
    setInterval(async () => {
      await this.performComplianceChecks();
    }, 600000); // 10 minutes

    // Network segment validation
    setInterval(async () => {
      await this.validateNetworkSegments();
    }, 1800000); // 30 minutes

    // Metrics collection
    setInterval(() => {
      this.collectMetrics();
    }, 60000); // 1 minute
  }

  private async performContinuousTrustUpdates(): Promise<void> {
    for (const [agentId] of this.trustScores) {
      // Perform behavioral analysis
      const behaviorUpdate = await this.behaviorAnalyzer.analyzeAgent(agentId);

      if (behaviorUpdate.hasChanges) {
        await this.updateTrustScore(agentId, {
          type: "behavior",
          outcome: behaviorUpdate.outcome,
          details: behaviorUpdate.details,
        });
      }
    }
  }

  private async performComplianceChecks(): Promise<void> {
    for (const [policyId, policy] of this.policies) {
      if (!policy.enabled) continue;

      const violations = await this.checkPolicyCompliance(policy);

      if (violations.length > 0) {
        this.metrics.policyViolations += violations.length;

        this.emit("policy_violations", {
          policyId,
          violations,
          timestamp: new Date(),
        });
      }
    }
  }

  private async validateNetworkSegments(): Promise<void> {
    for (const [segmentId, segment] of this.networkSegments) {
      const validation =
        await this.segmentationEngine.validateSegmentState(segment);

      if (!validation.valid) {
        this.logger.warn("Network segment validation failed", {
          segmentId,
          issues: validation.issues,
        });

        this.emit("segment_validation_failed", {
          segmentId,
          issues: validation.issues,
        });
      }
    }
  }

  private async checkPolicyCompliance(
    _policy: ZeroTrustPolicy,
  ): Promise<any[]> {
    // Placeholder for policy compliance checking
    return [];
  }

  private collectMetrics(): void {
    const currentMetrics = {
      ...this.metrics,
      activeTrustScores: this.trustScores.size,
      activePolicies: Array.from(this.policies.values()).filter(
        (p) => p.enabled,
      ).length,
      networkSegments: this.networkSegments.size,
      timestamp: Date.now(),
    };

    this.emit("metrics_collected", currentMetrics);
  }

  /**
   * Public API methods
   */

  getTrustScore(agentId: string): TrustScore | null {
    return this.trustScores.get(agentId) || null;
  }

  getPolicies(): ZeroTrustPolicy[] {
    return Array.from(this.policies.values());
  }

  getNetworkSegments(): NetworkSegment[] {
    return Array.from(this.networkSegments.values());
  }

  getMetrics() {
    return { ...this.metrics };
  }

  async isAgentQuarantined(agentId: string): Promise<boolean> {
    const quarantineData = await this.cache.get(
      `zerotrust:quarantine:${agentId}`,
    );
    return !!quarantineData;
  }

  async releaseFromQuarantine(agentId: string): Promise<void> {
    await this.cache.delete(`zerotrust:quarantine:${agentId}`);

    // Improve trust score slightly
    await this.updateTrustScore(agentId, {
      type: "compliance",
      outcome: "positive",
      details: { released_from_quarantine: true },
    });

    this.logger.info("Agent released from quarantine", { agentId });
    this.emit("agent_released", { agentId, timestamp: new Date() });
  }
}

// Supporting classes for zero trust implementation

class PolicyEngine {
  async evaluate(
    context: SecurityContext,
    trustScore: TrustScore,
    riskAssessment: RiskAssessment,
    policies: Map<string, ZeroTrustPolicy>,
  ): Promise<any> {
    const matchedPolicies: string[] = [];
    let finalDecision = { allowed: false, reason: "No matching policy" };
    let highestPriority = -1;

    for (const [policyId, policy] of policies) {
      if (!policy.enabled) continue;

      if (this.matchesPolicy(context, trustScore, riskAssessment, policy)) {
        matchedPolicies.push(policyId);

        if (policy.priority > highestPriority) {
          highestPriority = policy.priority;
          finalDecision = {
            allowed: policy.actions.allow,
            reason: `Policy ${policy.name} (${policyId})`,
            conditions: policy.actions.requirements,
            restrictions: policy.actions.restrictions,
            monitoring: policy.actions.monitoring,
            timeLimit: policy.actions.timeLimit,
          };
        }
      }
    }

    return { ...finalDecision, matchedPolicies };
  }

  private matchesPolicy(
    context: SecurityContext,
    trustScore: TrustScore,
    riskAssessment: RiskAssessment,
    policy: ZeroTrustPolicy,
  ): boolean {
    // Check risk level conditions
    if (policy.conditions.riskLevels) {
      if (!policy.conditions.riskLevels.includes(riskAssessment.riskLevel)) {
        return false;
      }
    }

    // Check agent type conditions
    if (policy.conditions.agentTypes) {
      // This would need to be passed in context or looked up
      // For now, assume it's in metadata
      const agentType = context.metadata?.agentType;
      if (agentType && !policy.conditions.agentTypes.includes(agentType)) {
        return false;
      }
    }

    // Check network segment conditions
    if (policy.conditions.networkSegments) {
      if (
        !policy.conditions.networkSegments.includes(
          context.source.network.segment,
        )
      ) {
        return false;
      }
    }

    // Additional condition checks would go here

    return true;
  }
}

class TrustCalculator {
  async calculateDelta(event: any, _currentTrust: TrustScore): Promise<number> {
    let delta = 0;

    switch (event.type) {
      case "authentication":
        delta = event.outcome === "positive" ? 0.1 : -0.2;
        break;
      case "behavior":
        delta = event.outcome === "positive" ? 0.05 : -0.1;
        break;
      case "compliance":
        delta = event.outcome === "positive" ? 0.05 : -0.15;
        break;
      case "security_incident":
        delta = event.outcome === "positive" ? 0.1 : -0.3;
        break;
    }

    return delta;
  }

  async updateTrustScore(
    currentTrust: TrustScore,
    delta: number,
  ): Promise<TrustScore> {
    const newScore = Math.max(
      0,
      Math.min(1, currentTrust.overallScore + delta),
    );

    return {
      ...currentTrust,
      overallScore: newScore,
      components: {
        ...currentTrust.components,
        behavior: Math.max(
          0,
          Math.min(1, currentTrust.components.behavior + delta),
        ),
      },
    };
  }

  async calculateContextualAdjustment(
    trustScore: TrustScore,
    context: SecurityContext,
  ): Promise<number> {
    let adjustment = 0;

    // Adjust based on location
    if (context.source.location) {
      // Trusted locations get positive adjustment
      adjustment += 0.05;
    }

    // Adjust based on time
    const hour = new Date().getHours();
    if (hour >= 9 && hour <= 17) {
      // Business hours get positive adjustment
      adjustment += 0.02;
    }

    return adjustment;
  }

  async applyContextualAdjustment(
    trustScore: TrustScore,
    adjustment: number,
  ): Promise<TrustScore> {
    return {
      ...trustScore,
      overallScore: Math.max(
        0,
        Math.min(1, trustScore.overallScore + adjustment),
      ),
    };
  }
}

class SegmentationEngine {
  async validateSegment(segment: NetworkSegment): Promise<void> {
    if (!segment.segmentId || !segment.name) {
      throw new Error("Segment must have ID and name");
    }

    if (
      ![
        "production",
        "staging",
        "development",
        "isolated",
        "quarantine",
      ].includes(segment.type)
    ) {
      throw new Error("Invalid segment type");
    }
  }

  async validateSegmentState(_segment: NetworkSegment): Promise<{
    valid: boolean;
    issues: string[];
  }> {
    const issues: string[] = [];

    // Validation logic would go here

    return {
      valid: issues.length === 0,
      issues,
    };
  }
}

class RiskAssessor {
  async assessRisk(
    context: SecurityContext,
    trustScore: TrustScore,
  ): Promise<RiskAssessment> {
    const factors: RiskFactor[] = [];
    let totalScore = 0;

    // Identity risk
    if (!context.identity.verified) {
      factors.push({
        type: "identity",
        severity: "high",
        description: "Unverified identity",
        score: 0.8,
        mitigated: false,
      });
      totalScore += 0.8;
    }

    // Behavioral risk
    if (context.behavior.anomalyScore > 0.7) {
      factors.push({
        type: "behavior",
        severity: "medium",
        description: "Anomalous behavior detected",
        score: 0.6,
        mitigated: false,
      });
      totalScore += 0.6;
    }

    // Trust score risk
    if (trustScore.overallScore < 0.3) {
      factors.push({
        type: "identity",
        severity: "high",
        description: "Low trust score",
        score: 0.9,
        mitigated: false,
      });
      totalScore += 0.9;
    }

    const averageScore = factors.length > 0 ? totalScore / factors.length : 0;
    const riskLevel = this.calculateRiskLevel(averageScore);

    return {
      riskLevel,
      score: averageScore,
      factors,
      mitigations: this.suggestMitigations(factors),
      recommendations: this.generateRecommendations(factors),
      confidence: 0.85,
      validUntil: new Date(Date.now() + 300000), // 5 minutes
    };
  }

  private calculateRiskLevel(score: number): RiskLevel {
    if (score >= 0.9) return "critical";
    if (score >= 0.7) return "very_high";
    if (score >= 0.5) return "high";
    if (score >= 0.3) return "medium";
    if (score >= 0.1) return "low";
    return "very_low";
  }

  private suggestMitigations(factors: RiskFactor[]): string[] {
    const mitigations: string[] = [];

    for (const factor of factors) {
      switch (factor.type) {
        case "identity":
          mitigations.push("require_additional_authentication");
          break;
        case "behavior":
          mitigations.push("enhanced_monitoring");
          break;
        case "location":
          mitigations.push("location_verification");
          break;
      }
    }

    return mitigations;
  }

  private generateRecommendations(factors: RiskFactor[]): string[] {
    const recommendations: string[] = [];

    if (factors.some((f) => f.type === "identity")) {
      recommendations.push("Implement stronger identity verification");
    }

    if (factors.some((f) => f.type === "behavior")) {
      recommendations.push("Enable behavioral analytics");
    }

    return recommendations;
  }
}

class AdaptiveResponder {
  async determineResponse(
    context: SecurityContext,
    trustScore: TrustScore,
    riskAssessment: RiskAssessment,
    _policyDecision: any,
  ): Promise<AdaptiveResponse> {
    const actions: string[] = [];

    // Determine response based on risk level
    switch (riskAssessment.riskLevel) {
      case "critical":
        actions.push("quarantine", "alert_admin", "enhance_monitoring");
        break;
      case "very_high":
        actions.push(
          "require_reauthentication",
          "restrict_capabilities",
          "alert_admin",
        );
        break;
      case "high":
        actions.push("enhance_monitoring", "require_reauthentication");
        break;
      case "medium":
        actions.push("enhance_monitoring");
        break;
    }

    return {
      triggerId: crypto.randomUUID(),
      responseType:
        riskAssessment.riskLevel === "critical" ? "isolate" : "challenge",
      actions,
      duration: this.calculateResponseDuration(riskAssessment.riskLevel),
      monitoring: {
        enhanced: riskAssessment.riskLevel !== "very_low",
        alerts: ["high", "very_high", "critical"].includes(
          riskAssessment.riskLevel,
        ),
        logging: "enhanced",
      },
    };
  }

  private calculateResponseDuration(riskLevel: RiskLevel): number {
    switch (riskLevel) {
      case "critical":
        return 3600000; // 1 hour
      case "very_high":
        return 1800000; // 30 minutes
      case "high":
        return 900000; // 15 minutes
      case "medium":
        return 300000; // 5 minutes
      default:
        return 60000; // 1 minute
    }
  }
}

class BehaviorAnalyzer {
  async analyzeAgent(_agentId: string): Promise<{
    hasChanges: boolean;
    outcome: "positive" | "negative" | "neutral";
    details: Record<string, any>;
  }> {
    // Placeholder for behavioral analysis
    return {
      hasChanges: false,
      outcome: "neutral",
      details: {},
    };
  }
}

class ContextAnalyzer {
  async analyzeContext(_context: SecurityContext): Promise<any> {
    // Placeholder for context analysis
    return {};
  }
}