platformservice/ts/dcrouter/classes.email.processor.ts

import * as plugins from '../plugins.js';
import type { ISmtpConfig, IContentScannerConfig, ITransformationConfig } from './classes.smtp.config.js';
import type { ISmtpSession } from './classes.smtp.server.js';
import { EventEmitter } from 'node:events';

// Create standalone types to avoid interface compatibility issues
interface AddressObject {
  address?: string;
  name?: string;
  [key: string]: any;
}

interface ExtendedAddressObject {
  value: AddressObject | AddressObject[];
  [key: string]: any;
}

// Don't extend ParsedMail directly to avoid type compatibility issues
interface ExtendedParsedMail {
  // Basic properties from ParsedMail
  subject?: string;
  text?: string;
  textAsHtml?: string;
  html?: string;
  attachments?: Array<any>;
  headers?: Map<string, any>;
  headerLines?: Array<{key: string; line: string}>;
  messageId?: string;
  date?: Date;
  
  // Extended address objects
  from?: ExtendedAddressObject;
  to?: ExtendedAddressObject;
  cc?: ExtendedAddressObject;
  bcc?: ExtendedAddressObject;
  
  // Add any other properties we need
  [key: string]: any;
}

/**
 * Email metadata extracted from parsed mail
 */
export interface IEmailMetadata {
  id: string;
  from: string;
  fromDomain: string;
  to: string[];
  toDomains: string[];
  subject?: string;
  size: number;
  hasAttachments: boolean;
  receivedAt: Date;
  clientIp: string;
  authenticated: boolean;
  authUser?: string;
}

/**
 * Content scanning result
 */
export interface IScanResult {
  id: string;
  spamScore?: number;
  hasVirus?: boolean;
  blockedAttachments?: string[];
  action: 'accept' | 'tag' | 'reject';
  reason?: string;
}

/**
 * Routing decision for an email
 */
export interface IRoutingDecision {
  id: string;
  targetServer: string;
  port: number;
  useTls: boolean;
  authentication?: {
    user?: string;
    pass?: string;
  };
  headers?: Array<{
    name: string;
    value: string;
    append?: boolean;
  }>;
  signDkim?: boolean;
  dkimOptions?: {
    domainName: string;
    keySelector: string;
    privateKey: string;
  };
}

/**
 * Complete processing result
 */
export interface IProcessingResult {
  id: string;
  metadata: IEmailMetadata;
  scanResult: IScanResult;
  routing: IRoutingDecision;
  modifiedMessage?: ExtendedParsedMail;
  originalMessage: ExtendedParsedMail;
  rawData: string;
  action: 'queue' | 'reject';
  session: ISmtpSession;
}

/**
 * Email Processor handles email processing pipeline
 */
export class EmailProcessor extends EventEmitter {
  private config: ISmtpConfig;
  private processingQueue: Map<string, IProcessingResult> = new Map();
  
  /**
   * Create a new email processor
   * @param config SMTP configuration
   */
  constructor(config: ISmtpConfig) {
    super();
    this.config = config;
  }
  
  /**
   * Process an email message
   * @param message Parsed email message
   * @param rawData Raw email data
   * @param session SMTP session
   */
  public async processEmail(
    message: ExtendedParsedMail,
    rawData: string,
    session: ISmtpSession
  ): Promise<IProcessingResult> {
    try {
      // Generate ID for this processing task
      const id = plugins.uuid.v4();
      
      // Extract metadata
      const metadata = await this.extractMetadata(message, session, id);
      
      // Scan content if enabled
      const scanResult = await this.scanContent(message, metadata);
      
      // If content scanning rejects the message, return early
      if (scanResult.action === 'reject') {
        const result: IProcessingResult = {
          id,
          metadata,
          scanResult,
          routing: {
            id,
            targetServer: '',
            port: 0,
            useTls: false
          },
          originalMessage: message,
          rawData,
          action: 'reject',
          session
        };
        
        this.emit('rejected', result);
        return result;
      }
      
      // Determine routing
      const routing = await this.determineRouting(message, metadata);
      
      // Apply transformations
      const modifiedMessage = await this.applyTransformations(message, routing, scanResult);
      
      // Create processing result
      const result: IProcessingResult = {
        id,
        metadata,
        scanResult,
        routing,
        modifiedMessage,
        originalMessage: message,
        rawData,
        action: 'queue',
        session
      };
      
      // Add to processing queue
      this.processingQueue.set(id, result);
      
      // Emit processed event
      this.emit('processed', result);
      
      return result;
    } catch (error) {
      console.error('Error processing email:', error);
      throw error;
    }
  }
  
  /**
   * Extract metadata from email message
   * @param message Parsed email
   * @param session SMTP session
   * @param id Processing ID
   */
  private async extractMetadata(
    message: ExtendedParsedMail,
    session: ISmtpSession,
    id: string
  ): Promise<IEmailMetadata> {
    // Extract sender information
    let from = '';
    if (message.from && message.from.value) {
      const fromValue = message.from.value;
      if (Array.isArray(fromValue)) {
        from = fromValue[0]?.address || '';
      } else if (typeof fromValue === 'object' && 'address' in fromValue && fromValue.address) {
        from = fromValue.address;
      }
    }
    const fromDomain = from.split('@')[1] || '';
    
    // Extract recipient information
    let to: string[] = [];
    if (message.to && message.to.value) {
      const toValue = message.to.value;
      if (Array.isArray(toValue)) {
        to = toValue
          .map(addr => (addr && 'address' in addr) ? addr.address || '' : '')
          .filter(Boolean);
      } else if (typeof toValue === 'object' && 'address' in toValue && toValue.address) {
        to = [toValue.address];
      }
    }
    const toDomains = to.map(addr => addr.split('@')[1] || '');
    
    // Create metadata
    return {
      id,
      from,
      fromDomain,
      to,
      toDomains,
      subject: message.subject,
      size: Buffer.byteLength(message.html || message.textAsHtml || message.text || ''),
      hasAttachments: message.attachments?.length > 0,
      receivedAt: new Date(),
      clientIp: session.remoteAddress,
      authenticated: !!session.user,
      authUser: session.user?.username
    };
  }
  
  /**
   * Scan email content
   * @param message Parsed email
   * @param metadata Email metadata
   */
  private async scanContent(
    message: ExtendedParsedMail,
    metadata: IEmailMetadata
  ): Promise<IScanResult> {
    // Skip if content scanning is disabled
    if (!this.config.contentScanning || !this.config.scanners?.length) {
      return {
        id: metadata.id,
        action: 'accept'
      };
    }
    
    // Default result
    const result: IScanResult = {
      id: metadata.id,
      action: 'accept'
    };
    
    // Placeholder for scanning results
    let spamFound = false;
    let virusFound = false;
    const blockedAttachments: string[] = [];
    
    // Apply each scanner
    for (const scanner of this.config.scanners) {
      switch (scanner.type) {
        case 'spam':
          // Placeholder for spam scanning
          // In a real implementation, we would use a spam scanning library
          const spamScore = Math.random() * 10; // Fake score between 0-10
          result.spamScore = spamScore;
          
          if (scanner.threshold && spamScore > scanner.threshold) {
            spamFound = true;
            if (scanner.action === 'reject') {
              result.action = 'reject';
              result.reason = `Spam score ${spamScore} exceeds threshold ${scanner.threshold}`;
            } else if (scanner.action === 'tag') {
              result.action = 'tag';
            }
          }
          break;
          
        case 'virus':
          // Placeholder for virus scanning
          // In a real implementation, we would use a virus scanning library
          const hasVirus = false; // Fake result
          result.hasVirus = hasVirus;
          
          if (hasVirus) {
            virusFound = true;
            if (scanner.action === 'reject') {
              result.action = 'reject';
              result.reason = 'Message contains virus';
            } else if (scanner.action === 'tag') {
              result.action = 'tag';
            }
          }
          break;
          
        case 'attachment':
          // Check attachments against blocked extensions
          if (scanner.blockedExtensions && message.attachments?.length) {
            for (const attachment of message.attachments) {
              const filename = attachment.filename || '';
              const extension = filename.substring(filename.lastIndexOf('.')).toLowerCase();
              
              if (scanner.blockedExtensions.includes(extension)) {
                blockedAttachments.push(filename);
                
                if (scanner.action === 'reject') {
                  result.action = 'reject';
                  result.reason = `Blocked attachment type: ${extension}`;
                } else if (scanner.action === 'tag') {
                  result.action = 'tag';
                }
              }
            }
          }
          break;
      }
      
      // Set blocked attachments in result if any
      if (blockedAttachments.length) {
        result.blockedAttachments = blockedAttachments;
      }
    }
    
    return result;
  }
  
  /**
   * Determine routing for an email
   * @param message Parsed email
   * @param metadata Email metadata
   */
  private async determineRouting(
    message: ExtendedParsedMail,
    metadata: IEmailMetadata
  ): Promise<IRoutingDecision> {
    // Start with the default routing
    const defaultRouting: IRoutingDecision = {
      id: metadata.id,
      targetServer: this.config.defaultServer,
      port: this.config.defaultPort || 25,
      useTls: this.config.useTls || false
    };
    
    // If no domain configs, use default routing
    if (!this.config.domainConfigs?.length) {
      return defaultRouting;
    }
    
    // Try to find matching domain config based on recipient domains
    for (const domain of metadata.toDomains) {
      for (const domainConfig of this.config.domainConfigs) {
        // Check if domain matches any of the configured domains
        if (domainConfig.domains.some(configDomain => this.domainMatches(domain, configDomain))) {
          // Create routing from domain config
          const routing: IRoutingDecision = {
            id: metadata.id,
            targetServer: domainConfig.targetIPs[0], // Use first target IP
            port: domainConfig.port || 25,
            useTls: domainConfig.useTls || false
          };
          
          // Add authentication if specified
          if (domainConfig.authentication) {
            routing.authentication = domainConfig.authentication;
          }
          
          // Add header modifications if specified
          if (domainConfig.addHeaders && domainConfig.headerInfo?.length) {
            routing.headers = domainConfig.headerInfo.map(h => ({
              name: h.name,
              value: h.value,
              append: false
            }));
          }
          
          // Add DKIM signing if specified
          if (domainConfig.signDkim && domainConfig.dkimOptions) {
            routing.signDkim = true;
            routing.dkimOptions = domainConfig.dkimOptions;
          }
          
          return routing;
        }
      }
    }
    
    // No match found, use default routing
    return defaultRouting;
  }
  
  /**
   * Apply transformations to the email
   * @param message Original parsed email
   * @param routing Routing decision
   * @param scanResult Scan result
   */
  private async applyTransformations(
    message: ExtendedParsedMail,
    routing: IRoutingDecision,
    scanResult: IScanResult
  ): Promise<ExtendedParsedMail> {
    // Skip if no transformations configured
    if (!this.config.transformations?.length) {
      return message;
    }
    
    // Clone the message for modifications
    // Note: In a real implementation, we would need to properly clone the message
    const modifiedMessage = { ...message };
    
    // Apply each transformation
    for (const transformation of this.config.transformations) {
      switch (transformation.type) {
        case 'addHeader':
          // Add a header to the message
          if (transformation.header && transformation.value) {
            // In a real implementation, we would modify the raw message headers
            console.log(`Adding header ${transformation.header}: ${transformation.value}`);
          }
          break;
          
        case 'dkimSign':
          // Sign the message with DKIM
          if (routing.signDkim && routing.dkimOptions) {
            // In a real implementation, we would use mailauth.dkimSign
            console.log(`Signing message with DKIM for domain ${routing.dkimOptions.domainName}`);
          }
          break;
      }
    }
    
    return modifiedMessage;
  }
  
  /**
   * Check if a domain matches a pattern (including wildcards)
   * @param domain Domain to check
   * @param pattern Pattern to match against
   */
  private domainMatches(domain: string, pattern: string): boolean {
    domain = domain.toLowerCase();
    pattern = pattern.toLowerCase();
    
    // Exact match
    if (domain === pattern) {
      return true;
    }
    
    // Wildcard match (*.example.com)
    if (pattern.startsWith('*.')) {
      const suffix = pattern.slice(2);
      return domain.endsWith(suffix) && domain.length > suffix.length;
    }
    
    return false;
  }
  
  /**
   * Update processor configuration
   * @param config New configuration
   */
  public updateConfig(config: Partial<ISmtpConfig>): void {
    this.config = {
      ...this.config,
      ...config
    };
    
    this.emit('configUpdated', this.config);
  }
}