smartproxy/ts/forwarding/factory/forwarding-factory.ts

import type { ForwardConfig } from '../config/forwarding-types.js';
import type { ForwardingHandler } from '../handlers/base-handler.js';
import { HttpForwardingHandler } from '../handlers/http-handler.js';
import { HttpsPassthroughHandler } from '../handlers/https-passthrough-handler.js';
import { HttpsTerminateToHttpHandler } from '../handlers/https-terminate-to-http-handler.js';
import { HttpsTerminateToHttpsHandler } from '../handlers/https-terminate-to-https-handler.js';

/**
 * Factory for creating forwarding handlers based on the configuration type
 */
export class ForwardingHandlerFactory {
  /**
   * Create a forwarding handler based on the configuration
   * @param config The forwarding configuration
   * @returns The appropriate forwarding handler
   */
  public static createHandler(config: ForwardConfig): ForwardingHandler {
    // Create the appropriate handler based on the forwarding type
    switch (config.type) {
      case 'http-only':
        return new HttpForwardingHandler(config);
        
      case 'https-passthrough':
        return new HttpsPassthroughHandler(config);
        
      case 'https-terminate-to-http':
        return new HttpsTerminateToHttpHandler(config);
        
      case 'https-terminate-to-https':
        return new HttpsTerminateToHttpsHandler(config);
        
      default:
        // Type system should prevent this, but just in case:
        throw new Error(`Unknown forwarding type: ${(config as any).type}`);
    }
  }
  
  /**
   * Apply default values to a forwarding configuration based on its type
   * @param config The original forwarding configuration
   * @returns A configuration with defaults applied
   */
  public static applyDefaults(config: ForwardConfig): ForwardConfig {
    // Create a deep copy of the configuration
    const result: ForwardConfig = JSON.parse(JSON.stringify(config));
    
    // Apply defaults based on forwarding type
    switch (config.type) {
      case 'http-only':
        // Set defaults for HTTP-only mode
        result.http = {
          enabled: true,
          ...config.http
        };
        break;
        
      case 'https-passthrough':
        // Set defaults for HTTPS passthrough
        result.https = {
          forwardSni: true,
          ...config.https
        };
        // SNI forwarding doesn't do HTTP
        result.http = {
          enabled: false,
          ...config.http
        };
        break;
        
      case 'https-terminate-to-http':
        // Set defaults for HTTPS termination to HTTP
        result.https = {
          ...config.https
        };
        // Support HTTP access by default in this mode
        result.http = {
          enabled: true,
          redirectToHttps: true,
          ...config.http
        };
        // Enable ACME by default
        result.acme = {
          enabled: true,
          maintenance: true,
          ...config.acme
        };
        break;
        
      case 'https-terminate-to-https':
        // Similar to terminate-to-http but with different target handling
        result.https = {
          ...config.https
        };
        result.http = {
          enabled: true,
          redirectToHttps: true,
          ...config.http
        };
        result.acme = {
          enabled: true,
          maintenance: true,
          ...config.acme
        };
        break;
    }
    
    return result;
  }
  
  /**
   * Validate a forwarding configuration
   * @param config The configuration to validate
   * @throws Error if the configuration is invalid
   */
  public static validateConfig(config: ForwardConfig): void {
    // Validate common properties
    if (!config.target) {
      throw new Error('Forwarding configuration must include a target');
    }
    
    if (!config.target.host || (Array.isArray(config.target.host) && config.target.host.length === 0)) {
      throw new Error('Target must include a host or array of hosts');
    }
    
    if (!config.target.port || config.target.port <= 0 || config.target.port > 65535) {
      throw new Error('Target must include a valid port (1-65535)');
    }
    
    // Type-specific validation
    switch (config.type) {
      case 'http-only':
        // HTTP-only needs http.enabled to be true
        if (config.http?.enabled === false) {
          throw new Error('HTTP-only forwarding must have HTTP enabled');
        }
        break;
        
      case 'https-passthrough':
        // HTTPS passthrough doesn't support HTTP
        if (config.http?.enabled === true) {
          throw new Error('HTTPS passthrough does not support HTTP');
        }
        
        // HTTPS passthrough doesn't work with ACME
        if (config.acme?.enabled === true) {
          throw new Error('HTTPS passthrough does not support ACME');
        }
        break;
        
      case 'https-terminate-to-http':
      case 'https-terminate-to-https':
        // These modes support all options, nothing specific to validate
        break;
    }
  }
}