smartmta/ts/mail/routing/classes.unified.email.server.ts

import * as plugins from '../../plugins.js';
import * as paths from '../../paths.js';
import { EventEmitter } from 'events';
import { logger } from '../../logger.js';
import {
  SecurityLogger,
  SecurityLogLevel,
  SecurityEventType
} from '../../security/index.js';
import { DKIMCreator } from '../security/classes.dkimcreator.js';
import { RustSecurityBridge } from '../../security/classes.rustsecuritybridge.js';
import type { IEmailReceivedEvent, IAuthRequestEvent, IEmailData } from '../../security/classes.rustsecuritybridge.js';
import { EmailRouter } from './classes.email.router.js';
import type { IEmailRoute, IEmailAction, IEmailContext, IEmailDomainConfig } from './interfaces.js';
import { Email } from '../core/classes.email.js';
import { DomainRegistry } from './classes.domain.registry.js';
import { DnsManager } from './classes.dns.manager.js';
import { BounceManager, BounceType, BounceCategory } from '../core/classes.bouncemanager.js';
import type { ISmtpSendResult, IOutboundEmail } from '../../security/classes.rustsecuritybridge.js';
import { MultiModeDeliverySystem, type IMultiModeDeliveryOptions } from '../delivery/classes.delivery.system.js';
import { UnifiedDeliveryQueue, type IQueueOptions } from '../delivery/classes.delivery.queue.js';
import { UnifiedRateLimiter, type IHierarchicalRateLimits } from '../delivery/classes.unified.rate.limiter.js';
import { SmtpState } from '../delivery/interfaces.js';
import type { EmailProcessingMode, ISmtpSession as IBaseSmtpSession } from '../delivery/interfaces.js';
import { EmailActionExecutor } from './classes.email.action.executor.js';
import { DkimManager } from './classes.dkim.manager.js';


/** External DcRouter interface shape used by UnifiedEmailServer */
interface DcRouter {
  storageManager: any;
  dnsServer?: any;
  options?: any;
}

/**
 * Extended SMTP session interface with route information
 */
export interface IExtendedSmtpSession extends ISmtpSession {
  /**
   * Matched route for this session
   */
  matchedRoute?: IEmailRoute;
}

/**
 * Options for the unified email server
 */
export interface IUnifiedEmailServerOptions {
  // Base server options
  ports: number[];
  hostname: string;
  domains: IEmailDomainConfig[];  // Domain configurations
  banner?: string;
  debug?: boolean;
  useSocketHandler?: boolean;  // Use socket-handler mode instead of port listening

  // Authentication options
  auth?: {
    required?: boolean;
    methods?: ('PLAIN' | 'LOGIN' | 'OAUTH2')[];
    users?: Array<{username: string, password: string}>;
  };

  // TLS options
  tls?: {
    certPath?: string;
    keyPath?: string;
    caPath?: string;
    minVersion?: string;
    ciphers?: string;
  };

  // Limits
  maxMessageSize?: number;
  maxClients?: number;
  maxConnections?: number;

  // Connection options
  connectionTimeout?: number;
  socketTimeout?: number;

  // Email routing rules
  routes: IEmailRoute[];

  // Global defaults for all domains
  defaults?: {
    dnsMode?: 'forward' | 'internal-dns' | 'external-dns';
    dkim?: IEmailDomainConfig['dkim'];
    rateLimits?: IEmailDomainConfig['rateLimits'];
  };

  // Outbound settings
  outbound?: {
    maxConnections?: number;
    connectionTimeout?: number;
    socketTimeout?: number;
    retryAttempts?: number;
    defaultFrom?: string;
  };

  // Rate limiting (global limits, can be overridden per domain)
  rateLimits?: IHierarchicalRateLimits;
}


/**
 * Extended SMTP session interface for UnifiedEmailServer
 */
export interface ISmtpSession extends IBaseSmtpSession {
  /**
   * User information if authenticated
   */
  user?: {
    username: string;
    [key: string]: any;
  };

  /**
   * Matched route for this session
   */
  matchedRoute?: IEmailRoute;
}

/**
 * Authentication data for SMTP
 */
import type { ISmtpAuth } from '../delivery/interfaces.js';
export type IAuthData = ISmtpAuth;

/**
 * Server statistics
 */
export interface IServerStats {
  startTime: Date;
  connections: {
    current: number;
    total: number;
  };
  messages: {
    processed: number;
    delivered: number;
    failed: number;
  };
  processingTime: {
    avg: number;
    max: number;
    min: number;
  };
}

/**
 * Unified email server that handles all email traffic with pattern-based routing
 */
export class UnifiedEmailServer extends EventEmitter {
  private dcRouter: DcRouter;
  private options: IUnifiedEmailServerOptions;
  private emailRouter: EmailRouter;
  public domainRegistry: DomainRegistry;
  private servers: any[] = [];
  private stats: IServerStats;

  // Add components needed for sending and securing emails
  public dkimCreator: DKIMCreator;
  private rustBridge: RustSecurityBridge;
  private bounceManager: BounceManager;
  public deliveryQueue: UnifiedDeliveryQueue;
  public deliverySystem: MultiModeDeliverySystem;
  private rateLimiter: UnifiedRateLimiter; // TODO: Implement rate limiting in SMTP server handlers

  // Extracted subsystems
  private actionExecutor: EmailActionExecutor;
  private dkimManager: DkimManager;

  constructor(dcRouter: DcRouter, options: IUnifiedEmailServerOptions) {
    super();
    this.dcRouter = dcRouter;

    // Set default options
    this.options = {
      ...options,
      banner: options.banner || `${options.hostname} ESMTP UnifiedEmailServer`,
      maxMessageSize: options.maxMessageSize || 10 * 1024 * 1024, // 10MB
      maxClients: options.maxClients || 100,
      maxConnections: options.maxConnections || 1000,
      connectionTimeout: options.connectionTimeout || 60000, // 1 minute
      socketTimeout: options.socketTimeout || 60000 // 1 minute
    };

    // Initialize Rust security bridge (singleton)
    this.rustBridge = RustSecurityBridge.getInstance();

    // Initialize DKIM creator with storage manager
    this.dkimCreator = new DKIMCreator(paths.keysDir, dcRouter.storageManager);

    // Initialize bounce manager with storage manager
    this.bounceManager = new BounceManager({
      maxCacheSize: 10000,
      cacheTTL: 30 * 24 * 60 * 60 * 1000, // 30 days
      storageManager: dcRouter.storageManager
    });

    // Initialize domain registry
    this.domainRegistry = new DomainRegistry(options.domains, options.defaults);

    // Initialize email router with routes and storage manager
    this.emailRouter = new EmailRouter(options.routes || [], {
      storageManager: dcRouter.storageManager,
      persistChanges: true
    });

    // Initialize rate limiter
    this.rateLimiter = new UnifiedRateLimiter(options.rateLimits || {
      global: {
        maxConnectionsPerIP: 10,
        maxMessagesPerMinute: 100,
        maxRecipientsPerMessage: 50,
        maxErrorsPerIP: 10,
        maxAuthFailuresPerIP: 5,
        blockDuration: 300000 // 5 minutes
      }
    });

    // Initialize delivery components
    const queueOptions: IQueueOptions = {
      storageType: 'memory', // Default to memory storage
      maxRetries: 3,
      baseRetryDelay: 300000, // 5 minutes
      maxRetryDelay: 3600000 // 1 hour
    };

    this.deliveryQueue = new UnifiedDeliveryQueue(queueOptions);

    const deliveryOptions: IMultiModeDeliveryOptions = {
      globalRateLimit: 100, // Default to 100 emails per minute
      concurrentDeliveries: 10,
      processBounces: true,
      bounceHandler: {
        processSmtpFailure: this.processSmtpFailure.bind(this)
      },
      onDeliverySuccess: async (_item, _result) => {
        // Delivery success recorded via delivery system
      }
    };

    this.deliverySystem = new MultiModeDeliverySystem(this.deliveryQueue, deliveryOptions, this);

    // Initialize action executor
    this.actionExecutor = new EmailActionExecutor({
      sendOutboundEmail: this.sendOutboundEmail.bind(this),
      bounceManager: this.bounceManager,
      deliveryQueue: this.deliveryQueue,
    });

    // Initialize DKIM manager
    this.dkimManager = new DkimManager(this.dkimCreator, this.domainRegistry, dcRouter, this.rustBridge);

    // Initialize statistics
    this.stats = {
      startTime: new Date(),
      connections: {
        current: 0,
        total: 0
      },
      messages: {
        processed: 0,
        delivered: 0,
        failed: 0
      },
      processingTime: {
        avg: 0,
        max: 0,
        min: 0
      }
    };

    // We'll create the SMTP servers during the start() method
  }

  /**
   * Send an outbound email via the Rust SMTP client.
   * Uses connection pooling in the Rust binary for efficiency.
   */
  public async sendOutboundEmail(host: string, port: number, email: Email, options?: {
    auth?: { user: string; pass: string };
    dkimDomain?: string;
    dkimSelector?: string;
    tlsOpportunistic?: boolean;
  }): Promise<ISmtpSendResult> {
    // Build DKIM config if domain has keys
    let dkim: { domain: string; selector: string; privateKey: string } | undefined;
    if (options?.dkimDomain) {
      try {
        const { privateKey } = await this.dkimCreator.readDKIMKeys(options.dkimDomain);
        dkim = { domain: options.dkimDomain, selector: options.dkimSelector || 'default', privateKey };
      } catch (err) {
        logger.log('warn', `Failed to read DKIM keys for ${options.dkimDomain}: ${(err as Error).message}`);
      }
    }

    // Serialize the Email to the outbound format
    const outboundEmail: IOutboundEmail = {
      from: email.from,
      to: email.to,
      cc: email.cc || [],
      bcc: email.bcc || [],
      subject: email.subject || '',
      text: email.text || '',
      html: email.html || undefined,
      headers: email.headers as Record<string, string> || {},
    };

    return this.rustBridge.sendOutboundEmail({
      host,
      port,
      secure: port === 465,
      domain: this.options.hostname,
      auth: options?.auth,
      email: outboundEmail,
      dkim,
      connectionTimeoutSecs: Math.floor((this.options.outbound?.connectionTimeout || 30000) / 1000),
      socketTimeoutSecs: Math.floor((this.options.outbound?.socketTimeout || 120000) / 1000),
      poolKey: `${host}:${port}`,
      maxPoolConnections: this.options.outbound?.maxConnections || 10,
      tlsOpportunistic: options?.tlsOpportunistic ?? (port === 25),
    });
  }

  /**
   * Start the unified email server
   */
  public async start(): Promise<void> {
    logger.log('info', `Starting UnifiedEmailServer on ports: ${(this.options.ports as number[]).join(', ')}`);

    try {
      await this.startDeliveryPipeline();
      await this.startRustBridge();
      await this.initializeDkimAndDns();
      this.registerBridgeEventHandlers();
      await this.startSmtpServer();
      logger.log('info', 'UnifiedEmailServer started successfully');
      this.emit('started');
    } catch (error) {
      logger.log('error', `Failed to start UnifiedEmailServer: ${error.message}`);
      throw error;
    }
  }

  private async startDeliveryPipeline(): Promise<void> {
    await this.deliveryQueue.initialize();
    logger.log('info', 'Email delivery queue initialized');

    await this.deliverySystem.start();
    logger.log('info', 'Email delivery system started');
  }

  private async startRustBridge(): Promise<void> {
    const bridgeOk = await this.rustBridge.start();
    if (!bridgeOk) {
      throw new Error('Rust security bridge failed to start. The mailer-bin binary is required. Run "pnpm build" to compile it.');
    }
    logger.log('info', 'Rust security bridge started — Rust is the primary security backend');

    this.rustBridge.on('stateChange', ({ oldState, newState }: { oldState: string; newState: string }) => {
      if (newState === 'failed') this.emit('bridgeFailed');
      else if (newState === 'restarting') this.emit('bridgeRestarting');
      else if (newState === 'running' && oldState === 'restarting') this.emit('bridgeRecovered');
    });
  }

  private async initializeDkimAndDns(): Promise<void> {
    await this.dkimManager.setupDkimForDomains();
    logger.log('info', 'DKIM configuration completed for all domains');

    const dnsManager = new DnsManager(this.dcRouter);
    await dnsManager.ensureDnsRecords(this.domainRegistry.getAllConfigs(), this.dkimCreator);
    logger.log('info', 'DNS records ensured for all configured domains');

    this.applyDomainRateLimits();
    logger.log('info', 'Per-domain rate limits configured');

    await this.dkimManager.checkAndRotateDkimKeys();
    logger.log('info', 'DKIM key rotation check completed');
  }

  private registerBridgeEventHandlers(): void {
    this.rustBridge.onEmailReceived(async (data) => {
      try {
        await this.handleRustEmailReceived(data);
      } catch (err) {
        logger.log('error', `Error handling email from Rust SMTP: ${(err as Error).message}`);
        try {
          await this.rustBridge.sendEmailProcessingResult({
            correlationId: data.correlationId,
            accepted: false,
            smtpCode: 451,
            smtpMessage: 'Internal processing error',
          });
        } catch (sendErr) {
          logger.log('warn', `Could not send rejection back to Rust: ${(sendErr as Error).message}`);
        }
      }
    });

    this.rustBridge.onAuthRequest(async (data) => {
      try {
        await this.handleRustAuthRequest(data);
      } catch (err) {
        logger.log('error', `Error handling auth from Rust SMTP: ${(err as Error).message}`);
        try {
          await this.rustBridge.sendAuthResult({
            correlationId: data.correlationId,
            success: false,
            message: 'Internal auth error',
          });
        } catch (sendErr) {
          logger.log('warn', `Could not send auth rejection back to Rust: ${(sendErr as Error).message}`);
        }
      }
    });

    this.rustBridge.onScramCredentialRequest(async (data) => {
      try {
        await this.handleScramCredentialRequest(data);
      } catch (err) {
        logger.log('error', `Error handling SCRAM credential request: ${(err as Error).message}`);
        try {
          await this.rustBridge.sendScramCredentialResult({
            correlationId: data.correlationId,
            found: false,
          });
        } catch (sendErr) {
          logger.log('warn', `Could not send SCRAM credential rejection: ${(sendErr as Error).message}`);
        }
      }
    });
  }

  private async startSmtpServer(): Promise<void> {
    const hasTlsConfig = this.options.tls?.keyPath && this.options.tls?.certPath;
    let tlsCertPem: string | undefined;
    let tlsKeyPem: string | undefined;

    if (hasTlsConfig) {
      try {
        tlsKeyPem = plugins.fs.readFileSync(this.options.tls.keyPath!, 'utf8');
        tlsCertPem = plugins.fs.readFileSync(this.options.tls.certPath!, 'utf8');
        logger.log('info', 'TLS certificates loaded successfully');
      } catch (error) {
        logger.log('warn', `Failed to load TLS certificates: ${error.message}`);
      }
    }

    const smtpPorts = (this.options.ports as number[]).filter(p => p !== 465);
    const securePort = (this.options.ports as number[]).find(p => p === 465);

    const started = await this.rustBridge.startSmtpServer({
      hostname: this.options.hostname,
      ports: smtpPorts,
      securePort: securePort,
      tlsCertPem,
      tlsKeyPem,
      maxMessageSize: this.options.maxMessageSize || 10 * 1024 * 1024,
      maxConnections: this.options.maxConnections || this.options.maxClients || 100,
      maxRecipients: 100,
      connectionTimeoutSecs: this.options.connectionTimeout ? Math.floor(this.options.connectionTimeout / 1000) : 30,
      dataTimeoutSecs: 60,
      authEnabled: !!this.options.auth?.required || !!(this.options.auth?.users?.length),
      maxAuthFailures: 3,
      socketTimeoutSecs: this.options.socketTimeout ? Math.floor(this.options.socketTimeout / 1000) : 300,
      processingTimeoutSecs: 30,
      rateLimits: this.options.rateLimits ? {
        maxConnectionsPerIp: this.options.rateLimits.global?.maxConnectionsPerIP || 50,
        maxMessagesPerSender: this.options.rateLimits.global?.maxMessagesPerMinute || 100,
        maxAuthFailuresPerIp: this.options.rateLimits.global?.maxAuthFailuresPerIP || 5,
        windowSecs: 60,
      } : undefined,
    });

    if (!started) {
      throw new Error('Failed to start Rust SMTP server');
    }

    logger.log('info', `Rust SMTP server listening on ports: ${smtpPorts.join(', ')}${securePort ? ` + ${securePort} (TLS)` : ''}`);
  }

  /**
   * Stop the unified email server
   */
  public async stop(): Promise<void> {
    logger.log('info', 'Stopping UnifiedEmailServer');

    try {
      // Stop the Rust SMTP server first
      try {
        await this.rustBridge.stopSmtpServer();
        logger.log('info', 'Rust SMTP server stopped');
      } catch (err) {
        logger.log('warn', `Error stopping Rust SMTP server: ${(err as Error).message}`);
      }

      // Clear the servers array - servers will be garbage collected
      this.servers = [];

      // Remove bridge state change listener and stop bridge
      this.rustBridge.removeAllListeners('stateChange');
      await this.rustBridge.stop();

      // Stop the delivery system
      if (this.deliverySystem) {
        await this.deliverySystem.stop();
        logger.log('info', 'Email delivery system stopped');
      }

      // Shut down the delivery queue
      if (this.deliveryQueue) {
        await this.deliveryQueue.shutdown();
        logger.log('info', 'Email delivery queue shut down');
      }

      // Close all Rust SMTP client connection pools
      try {
        await this.rustBridge.closeSmtpPool();
      } catch {
        // Bridge may already be stopped
      }

      logger.log('info', 'UnifiedEmailServer stopped successfully');
      this.emit('stopped');
    } catch (error) {
      logger.log('error', `Error stopping UnifiedEmailServer: ${error.message}`);
      throw error;
    }
  }

  // -----------------------------------------------------------------------
  // Rust SMTP server event handlers
  // -----------------------------------------------------------------------

  /**
   * Handle an emailReceived event from the Rust SMTP server.
   */
  private async handleRustEmailReceived(data: IEmailReceivedEvent): Promise<void> {
    const { correlationId, mailFrom, rcptTo, remoteAddr, clientHostname, secure, authenticatedUser } = data;

    logger.log('info', `Rust SMTP received email from=${mailFrom} to=${rcptTo.join(',')} remote=${remoteAddr}`);

    try {
      // Decode the email data
      let rawMessageBuffer: Buffer;
      if (data.data.type === 'inline' && data.data.base64) {
        rawMessageBuffer = Buffer.from(data.data.base64, 'base64');
      } else if (data.data.type === 'file' && data.data.path) {
        rawMessageBuffer = plugins.fs.readFileSync(data.data.path);
        // Clean up temp file
        try {
          plugins.fs.unlinkSync(data.data.path);
        } catch {
          // Ignore cleanup errors
        }
      } else {
        throw new Error('Invalid email data transport');
      }

      // Build a session-like object for processEmailByMode
      const session: IExtendedSmtpSession = {
        id: data.sessionId || 'rust-' + Math.random().toString(36).substring(2),
        state: SmtpState.FINISHED,
        mailFrom: mailFrom,
        rcptTo: rcptTo,
        emailData: rawMessageBuffer.toString('utf8'),
        useTLS: secure,
        connectionEnded: false,
        remoteAddress: remoteAddr,
        clientHostname: clientHostname || '',
        secure: secure,
        authenticated: !!authenticatedUser,
        envelope: {
          mailFrom: { address: mailFrom, args: {} },
          rcptTo: rcptTo.map(addr => ({ address: addr, args: {} })),
        },
      };

      if (authenticatedUser) {
        session.user = { username: authenticatedUser };
      }

      // Attach pre-computed security results from Rust in-process pipeline
      if (data.securityResults) {
        (session as any)._precomputedSecurityResults = data.securityResults;
      }

      // Process the email through the routing system
      await this.processEmailByMode(rawMessageBuffer, session);

      // Send acceptance back to Rust
      await this.rustBridge.sendEmailProcessingResult({
        correlationId,
        accepted: true,
        smtpCode: 250,
        smtpMessage: '2.0.0 Message accepted for delivery',
      });
    } catch (err) {
      logger.log('error', `Failed to process email from Rust SMTP: ${(err as Error).message}`);
      await this.rustBridge.sendEmailProcessingResult({
        correlationId,
        accepted: false,
        smtpCode: 550,
        smtpMessage: `5.0.0 Processing failed: ${(err as Error).message}`,
      });
    }
  }

  /**
   * Handle an authRequest event from the Rust SMTP server.
   */
  private async handleRustAuthRequest(data: IAuthRequestEvent): Promise<void> {
    const { correlationId, username, password, remoteAddr } = data;

    logger.log('info', `Rust SMTP auth request for user=${username} from=${remoteAddr}`);

    // Check against configured users
    const users = this.options.auth?.users || [];
    const matched = users.find(
      u => u.username === username && u.password === password
    );

    if (matched) {
      await this.rustBridge.sendAuthResult({
        correlationId,
        success: true,
      });
    } else {
      logger.log('warn', `Auth failed for user=${username} from=${remoteAddr}`);
      await this.rustBridge.sendAuthResult({
        correlationId,
        success: false,
        message: 'Invalid credentials',
      });
    }
  }

  /**
   * Handle a SCRAM credential request from the Rust SMTP server.
   * Computes SCRAM-SHA-256 credentials from the stored password for the given user.
   */
  private async handleScramCredentialRequest(data: { correlationId: string; username: string; remoteAddr: string }): Promise<void> {
    const { correlationId, username, remoteAddr } = data;
    const crypto = await import('crypto');

    logger.log('info', `SCRAM credential request for user=${username} from=${remoteAddr}`);

    const users = this.options.auth?.users || [];
    const matched = users.find(u => u.username === username);

    if (!matched) {
      await this.rustBridge.sendScramCredentialResult({
        correlationId,
        found: false,
      });
      return;
    }

    // Compute SCRAM-SHA-256 credentials from plaintext password
    const salt = crypto.randomBytes(16);
    const iterations = 4096;

    // SaltedPassword = PBKDF2-HMAC-SHA256(password, salt, iterations, 32)
    const saltedPassword = crypto.pbkdf2Sync(matched.password, salt, iterations, 32, 'sha256');

    // ClientKey = HMAC-SHA256(SaltedPassword, "Client Key")
    const clientKey = crypto.createHmac('sha256', saltedPassword).update('Client Key').digest();

    // StoredKey = SHA256(ClientKey)
    const storedKey = crypto.createHash('sha256').update(clientKey).digest();

    // ServerKey = HMAC-SHA256(SaltedPassword, "Server Key")
    const serverKey = crypto.createHmac('sha256', saltedPassword).update('Server Key').digest();

    await this.rustBridge.sendScramCredentialResult({
      correlationId,
      found: true,
      salt: salt.toString('base64'),
      iterations,
      storedKey: storedKey.toString('base64'),
      serverKey: serverKey.toString('base64'),
    });
  }

  /**
   * Verify inbound email security (DKIM/SPF/DMARC) using pre-computed Rust results
   * or falling back to IPC call if no pre-computed results are available.
   */
  private async verifyInboundSecurity(email: Email, session: IExtendedSmtpSession): Promise<void> {
    try {
      // Check for pre-computed results from Rust in-process security pipeline
      const precomputed = (session as any)._precomputedSecurityResults;
      let result: any;

      if (precomputed) {
        logger.log('info', 'Using pre-computed security results from Rust in-process pipeline');
        result = precomputed;
      } else {
        // Fallback: IPC round-trip to Rust (for backward compat)
        const rawMessage = session.emailData || email.toRFC822String();
        result = await this.rustBridge.verifyEmail({
          rawMessage,
          ip: session.remoteAddress,
          heloDomain: session.clientHostname || '',
          hostname: this.options.hostname,
          mailFrom: session.envelope?.mailFrom?.address || session.mailFrom || '',
        });
      }

      // Apply DKIM result headers
      if (result.dkim && result.dkim.length > 0) {
        const dkimSummary = result.dkim
          .map((d: any) => `${d.status}${d.domain ? ` (${d.domain})` : ''}`)
          .join(', ');
        email.addHeader('X-DKIM-Result', dkimSummary);
      }

      // Apply SPF result header
      if (result.spf) {
        email.addHeader('Received-SPF', `${result.spf.result} (domain: ${result.spf.domain}, ip: ${result.spf.ip})`);

        // Mark as spam on SPF hard fail
        if (result.spf.result === 'fail') {
          email.mightBeSpam = true;
          logger.log('warn', `SPF fail for ${session.remoteAddress} — marking as potential spam`);
        }
      }

      // Apply DMARC result header and policy
      if (result.dmarc) {
        email.addHeader('X-DMARC-Result', `${result.dmarc.action} (policy=${result.dmarc.policy}, dkim=${result.dmarc.dkim_result}, spf=${result.dmarc.spf_result})`);

        if (result.dmarc.action === 'reject') {
          email.mightBeSpam = true;
          logger.log('warn', `DMARC reject for domain ${result.dmarc.domain} — marking as spam`);
        } else if (result.dmarc.action === 'quarantine') {
          email.mightBeSpam = true;
          logger.log('info', `DMARC quarantine for domain ${result.dmarc.domain} — marking as potential spam`);
        }
      }

      // Apply content scan results (from pre-computed pipeline)
      if (result.contentScan) {
        const scan = result.contentScan;
        if (scan.threatScore > 0) {
          email.addHeader('X-Spam-Score', String(scan.threatScore));
          if (scan.threatType) {
            email.addHeader('X-Spam-Type', scan.threatType);
          }
          if (scan.threatScore >= 50) {
            email.mightBeSpam = true;
            logger.log('warn', `Content scan threat score ${scan.threatScore} (${scan.threatType}) — marking as potential spam`);
          }
        }
      }

      // Apply IP reputation results (from pre-computed pipeline)
      if (result.ipReputation) {
        const rep = result.ipReputation;
        email.addHeader('X-IP-Reputation-Score', String(rep.score));
        if (rep.is_spam) {
          email.mightBeSpam = true;
          logger.log('warn', `IP ${rep.ip} flagged by reputation check (score=${rep.score}) — marking as potential spam`);
        }
      }

      logger.log('info', `Inbound security verified for email from ${session.remoteAddress}: DKIM=${result.dkim?.[0]?.status ?? 'none'}, SPF=${result.spf?.result ?? 'none'}, DMARC=${result.dmarc?.action ?? 'none'}`);
    } catch (err) {
      logger.log('warn', `Inbound security verification failed: ${(err as Error).message} — accepting email`);
    }
  }

  /**
   * Process email based on routing rules
   */
  public async processEmailByMode(emailData: Email | Buffer, session: IExtendedSmtpSession): Promise<Email> {
    // Convert Buffer to Email if needed
    let email: Email;
    if (Buffer.isBuffer(emailData)) {
      // Parse the email data buffer into an Email object
      try {
        const parsed = await plugins.mailparser.simpleParser(emailData);
        email = new Email({
          from: parsed.from?.value[0]?.address || session.envelope.mailFrom.address,
          to: session.envelope.rcptTo[0]?.address || '',
          subject: parsed.subject || '',
          text: parsed.text || '',
          html: parsed.html || undefined,
          attachments: parsed.attachments?.map(att => ({
            filename: att.filename || '',
            content: att.content,
            contentType: att.contentType
          })) || []
        });
      } catch (error) {
        logger.log('error', `Error parsing email data: ${error.message}`);
        throw new Error(`Error parsing email data: ${error.message}`);
      }
    } else {
      email = emailData;
    }

    // Run inbound security verification (DKIM/SPF/DMARC) via Rust bridge
    if (session.remoteAddress && session.remoteAddress !== '127.0.0.1') {
      await this.verifyInboundSecurity(email, session);
    }

    // First check if this is a bounce notification email
    const subject = email.subject || '';
    const isBounceLike = /mail delivery|delivery (failed|status|notification)|failure notice|returned mail|undeliverable|delivery problem/i.test(subject);

    if (isBounceLike) {
      logger.log('info', `Email subject matches bounce notification pattern: "${subject}"`);

      const isBounce = await this.processBounceNotification(email);

      if (isBounce) {
        logger.log('info', 'Successfully processed as bounce notification, skipping regular processing');
        return email;
      }

      logger.log('info', 'Not a valid bounce notification, continuing with regular processing');
    }

    // Find matching route
    const context: IEmailContext = { email, session };
    const route = await this.emailRouter.evaluateRoutes(context);

    if (!route) {
      throw new Error('No matching route for email');
    }

    // Store matched route in session
    session.matchedRoute = route;

    // Execute action based on route
    await this.actionExecutor.executeAction(route.action, email, context);

    // Return the processed email
    return email;
  }

  /**
   * Apply per-domain rate limits from domain configurations
   */
  private applyDomainRateLimits(): void {
    const domainConfigs = this.domainRegistry.getAllConfigs();

    for (const domainConfig of domainConfigs) {
      if (domainConfig.rateLimits) {
        const domain = domainConfig.domain;
        const rateLimitConfig: any = {};

        if (domainConfig.rateLimits.outbound) {
          if (domainConfig.rateLimits.outbound.messagesPerMinute) {
            rateLimitConfig.maxMessagesPerMinute = domainConfig.rateLimits.outbound.messagesPerMinute;
          }
        }

        if (domainConfig.rateLimits.inbound) {
          if (domainConfig.rateLimits.inbound.messagesPerMinute) {
            rateLimitConfig.maxMessagesPerMinute = domainConfig.rateLimits.inbound.messagesPerMinute;
          }
          if (domainConfig.rateLimits.inbound.connectionsPerIp) {
            rateLimitConfig.maxConnectionsPerIP = domainConfig.rateLimits.inbound.connectionsPerIp;
          }
          if (domainConfig.rateLimits.inbound.recipientsPerMessage) {
            rateLimitConfig.maxRecipientsPerMessage = domainConfig.rateLimits.inbound.recipientsPerMessage;
          }
        }

        if (Object.keys(rateLimitConfig).length > 0) {
          this.rateLimiter.applyDomainLimits(domain, rateLimitConfig);
          logger.log('info', `Applied rate limits for domain ${domain}:`, rateLimitConfig);
        }
      }
    }
  }

  /**
   * Generate SmartProxy routes for email ports
   */
  public generateProxyRoutes(portMapping?: Record<number, number>): any[] {
    const routes: any[] = [];
    const defaultPortMapping = {
      25: 10025,
      587: 10587,
      465: 10465
    };

    const actualPortMapping = portMapping || defaultPortMapping;

    for (const externalPort of this.options.ports) {
      const internalPort = actualPortMapping[externalPort] || externalPort + 10000;

      let routeName = 'email-route';
      let tlsMode = 'passthrough';

      switch (externalPort) {
        case 25:
          routeName = 'smtp-route';
          tlsMode = 'passthrough';
          break;
        case 587:
          routeName = 'submission-route';
          tlsMode = 'passthrough';
          break;
        case 465:
          routeName = 'smtps-route';
          tlsMode = 'terminate';
          break;
        default:
          routeName = `email-port-${externalPort}-route`;
      }

      routes.push({
        name: routeName,
        match: {
          ports: [externalPort]
        },
        action: {
          type: 'forward',
          target: {
            host: 'localhost',
            port: internalPort
          },
          tls: {
            mode: tlsMode
          }
        }
      });
    }

    return routes;
  }

  /**
   * Update server configuration
   */
  public updateOptions(options: Partial<IUnifiedEmailServerOptions>): void {
    const portsChanged = options.ports &&
      (!this.options.ports ||
       JSON.stringify(options.ports) !== JSON.stringify(this.options.ports));

    if (portsChanged) {
      this.stop().then(() => {
        this.options = { ...this.options, ...options };
        this.start();
      });
    } else {
      this.options = { ...this.options, ...options };

      if (options.domains) {
        this.domainRegistry = new DomainRegistry(options.domains, options.defaults || this.options.defaults);
      }

      if (options.routes) {
        this.emailRouter.updateRoutes(options.routes);
      }
    }
  }

  /**
   * Update email routes
   */
  public updateEmailRoutes(routes: IEmailRoute[]): void {
    this.options.routes = routes;
    this.emailRouter.updateRoutes(routes);
  }

  /**
   * Get server statistics
   */
  public getStats(): IServerStats {
    return { ...this.stats };
  }

  /**
   * Get domain registry
   */
  public getDomainRegistry(): DomainRegistry {
    return this.domainRegistry;
  }

  /**
   * Send an email through the delivery system
   */
  public async sendEmail(
    email: Email,
    mode: EmailProcessingMode = 'mta',
    route?: IEmailRoute,
    options?: {
      skipSuppressionCheck?: boolean;
      ipAddress?: string;
      isTransactional?: boolean;
    }
  ): Promise<string> {
    logger.log('info', `Sending email: ${email.subject} to ${email.to.join(', ')}`);

    try {
      if (!email.from) {
        throw new Error('Email must have a sender address');
      }

      if (!email.to || email.to.length === 0) {
        throw new Error('Email must have at least one recipient');
      }

      // Check if any recipients are on the suppression list
      if (!options?.skipSuppressionCheck) {
        const suppressedRecipients = email.to.filter(recipient => this.isEmailSuppressed(recipient));

        if (suppressedRecipients.length > 0) {
          const originalCount = email.to.length;
          const suppressed = suppressedRecipients.map(recipient => {
            const info = this.getSuppressionInfo(recipient);
            return {
              email: recipient,
              reason: info?.reason || 'Unknown',
              until: info?.expiresAt ? new Date(info.expiresAt).toISOString() : 'permanent'
            };
          });

          logger.log('warn', `Filtering out ${suppressedRecipients.length} suppressed recipient(s)`, { suppressed });

          if (suppressedRecipients.length === originalCount) {
            throw new Error('All recipients are on the suppression list');
          }

          email.to = email.to.filter(recipient => !this.isEmailSuppressed(recipient));
        }
      }

      // Sign with DKIM if configured
      if (mode === 'mta' && route?.action.options?.mtaOptions?.dkimSign) {
        const domain = email.from.split('@')[1];
        await this.dkimManager.handleDkimSigning(email, domain, route.action.options.mtaOptions.dkimOptions?.keySelector || 'mta');
      }

      const id = plugins.uuid.v4();
      await this.deliveryQueue.enqueue(email, mode, route);

      logger.log('info', `Email queued with ID: ${id}`);
      return id;
    } catch (error) {
      logger.log('error', `Failed to send email: ${error.message}`);
      throw error;
    }
  }

  // -----------------------------------------------------------------------
  // Bounce/suppression methods
  // -----------------------------------------------------------------------

  public async processBounceNotification(bounceEmail: Email): Promise<boolean> {
    logger.log('info', 'Processing potential bounce notification email');

    try {
      const bounceRecord = await this.bounceManager.processBounceEmail(bounceEmail);

      if (bounceRecord) {
        logger.log('info', `Successfully processed bounce notification for ${bounceRecord.recipient}`, {
          bounceType: bounceRecord.bounceType,
          bounceCategory: bounceRecord.bounceCategory
        });

        this.emit('bounceProcessed', bounceRecord);

        SecurityLogger.getInstance().logEvent({
          level: SecurityLogLevel.INFO,
          type: SecurityEventType.EMAIL_VALIDATION,
          message: `Bounce notification processed for recipient`,
          domain: bounceRecord.domain,
          details: {
            recipient: bounceRecord.recipient,
            bounceType: bounceRecord.bounceType,
            bounceCategory: bounceRecord.bounceCategory
          },
          success: true
        });

        return true;
      } else {
        logger.log('info', 'Email not recognized as a bounce notification');
        return false;
      }
    } catch (error) {
      logger.log('error', `Error processing bounce notification: ${error.message}`);

      SecurityLogger.getInstance().logEvent({
        level: SecurityLogLevel.ERROR,
        type: SecurityEventType.EMAIL_VALIDATION,
        message: 'Failed to process bounce notification',
        details: { error: error.message, subject: bounceEmail.subject },
        success: false
      });

      return false;
    }
  }

  public async processSmtpFailure(
    recipient: string,
    smtpResponse: string,
    options: { sender?: string; originalEmailId?: string; statusCode?: string; headers?: Record<string, string> } = {}
  ): Promise<boolean> {
    logger.log('info', `Processing SMTP failure for ${recipient}: ${smtpResponse}`);

    try {
      const bounceRecord = await this.bounceManager.processSmtpFailure(recipient, smtpResponse, options);

      logger.log('info', `Successfully processed SMTP failure for ${recipient} as ${bounceRecord.bounceCategory} bounce`, {
        bounceType: bounceRecord.bounceType
      });

      this.emit('bounceProcessed', bounceRecord);

      SecurityLogger.getInstance().logEvent({
        level: SecurityLogLevel.INFO,
        type: SecurityEventType.EMAIL_VALIDATION,
        message: `SMTP failure processed for recipient`,
        domain: bounceRecord.domain,
        details: {
          recipient: bounceRecord.recipient,
          bounceType: bounceRecord.bounceType,
          bounceCategory: bounceRecord.bounceCategory,
          smtpResponse
        },
        success: true
      });

      return true;
    } catch (error) {
      logger.log('error', `Error processing SMTP failure: ${error.message}`);

      SecurityLogger.getInstance().logEvent({
        level: SecurityLogLevel.ERROR,
        type: SecurityEventType.EMAIL_VALIDATION,
        message: 'Failed to process SMTP failure',
        details: { recipient, smtpResponse, error: error.message },
        success: false
      });

      return false;
    }
  }

  public isEmailSuppressed(email: string): boolean {
    return this.bounceManager.isEmailSuppressed(email);
  }

  public getSuppressionInfo(email: string): { reason: string; timestamp: number; expiresAt?: number } | null {
    return this.bounceManager.getSuppressionInfo(email);
  }

  public getBounceHistory(email: string): { lastBounce: number; count: number; type: BounceType; category: BounceCategory } | null {
    return this.bounceManager.getBounceInfo(email);
  }

  public getSuppressionList(): string[] {
    return this.bounceManager.getSuppressionList();
  }

  public getHardBouncedAddresses(): string[] {
    return this.bounceManager.getHardBouncedAddresses();
  }

  public addToSuppressionList(email: string, reason: string, expiresAt?: number): void {
    this.bounceManager.addToSuppressionList(email, reason, expiresAt);
    logger.log('info', `Added ${email} to suppression list: ${reason}`);
  }

  public removeFromSuppressionList(email: string): void {
    this.bounceManager.removeFromSuppressionList(email);
    logger.log('info', `Removed ${email} from suppression list`);
  }

  public recordBounce(domain: string, receivingDomain: string, bounceType: 'hard' | 'soft', reason: string): void {
    const bounceRecord = {
      id: `bounce_${Date.now()}_${Math.random().toString(36).substring(2, 9)}`,
      recipient: `user@${receivingDomain}`,
      sender: `user@${domain}`,
      domain: domain,
      bounceType: bounceType === 'hard' ? BounceType.INVALID_RECIPIENT : BounceType.TEMPORARY_FAILURE,
      bounceCategory: bounceType === 'hard' ? BounceCategory.HARD : BounceCategory.SOFT,
      timestamp: Date.now(),
      smtpResponse: reason,
      diagnosticCode: reason,
      statusCode: bounceType === 'hard' ? '550' : '450',
      processed: false
    };

    this.bounceManager.processBounce(bounceRecord);
  }

  /**
   * Get the rate limiter instance
   */
  public getRateLimiter(): UnifiedRateLimiter {
    return this.rateLimiter;
  }
}