import * as plugins from '../../plugins.js';
import { ForwardingHandler } from './base-handler.js';
import type { ForwardConfig } from '../config/forwarding-types.js';
import { ForwardingHandlerEvents } from '../config/forwarding-types.js';

/**
 * Handler for HTTPS termination with HTTPS backend
 */
export class HttpsTerminateToHttpsHandler extends ForwardingHandler {
  private secureContext: plugins.tls.SecureContext | null = null;
  
  /**
   * Create a new HTTPS termination with HTTPS backend handler
   * @param config The forwarding configuration
   */
  constructor(config: ForwardConfig) {
    super(config);
    
    // Validate that this is an HTTPS terminate to HTTPS configuration
    if (config.type !== 'https-terminate-to-https') {
      throw new Error(`Invalid configuration type for HttpsTerminateToHttpsHandler: ${config.type}`);
    }
  }
  
  /**
   * Initialize the handler, setting up TLS context
   */
  public async initialize(): Promise<void> {
    // We need to load or create TLS certificates for termination
    if (this.config.https?.customCert) {
      // Use custom certificate from configuration
      this.secureContext = plugins.tls.createSecureContext({
        key: this.config.https.customCert.key,
        cert: this.config.https.customCert.cert
      });
      
      this.emit(ForwardingHandlerEvents.CERTIFICATE_LOADED, {
        source: 'config',
        domain: this.config.target.host
      });
    } else if (this.config.acme?.enabled) {
      // Request certificate through ACME if needed
      this.emit(ForwardingHandlerEvents.CERTIFICATE_NEEDED, {
        domain: Array.isArray(this.config.target.host) 
          ? this.config.target.host[0] 
          : this.config.target.host,
        useProduction: this.config.acme.production || false
      });
      
      // In a real implementation, we would wait for the certificate to be issued
      // For now, we'll use a dummy context
      this.secureContext = plugins.tls.createSecureContext({
        key: '-----BEGIN PRIVATE KEY-----\nDummy key\n-----END PRIVATE KEY-----',
        cert: '-----BEGIN CERTIFICATE-----\nDummy cert\n-----END CERTIFICATE-----'
      });
    } else {
      throw new Error('HTTPS termination requires either a custom certificate or ACME enabled');
    }
  }
  
  /**
   * Set the secure context for TLS termination
   * Called when a certificate is available
   * @param context The secure context
   */
  public setSecureContext(context: plugins.tls.SecureContext): void {
    this.secureContext = context;
  }
  
  /**
   * Handle a TLS/SSL socket connection by terminating TLS and creating a new TLS connection to backend
   * @param clientSocket The incoming socket from the client
   */
  public handleConnection(clientSocket: plugins.net.Socket): void {
    // Make sure we have a secure context
    if (!this.secureContext) {
      clientSocket.destroy(new Error('TLS secure context not initialized'));
      return;
    }
    
    const remoteAddress = clientSocket.remoteAddress || 'unknown';
    const remotePort = clientSocket.remotePort || 0;
    
    // Create a TLS socket using our secure context
    const tlsSocket = new plugins.tls.TLSSocket(clientSocket, {
      secureContext: this.secureContext,
      isServer: true
    });
    
    this.emit(ForwardingHandlerEvents.CONNECTED, {
      remoteAddress,
      remotePort,
      tls: true
    });
    
    // Handle TLS errors
    tlsSocket.on('error', (error) => {
      this.emit(ForwardingHandlerEvents.ERROR, {
        remoteAddress,
        error: `TLS error: ${error.message}`
      });
      
      if (!tlsSocket.destroyed) {
        tlsSocket.destroy();
      }
    });
    
    // The TLS socket will now emit HTTP traffic that can be processed
    // In a real implementation, we would create an HTTP parser and handle
    // the requests here, but for simplicity, we'll just forward the data
    
    // Get the target from configuration
    const target = this.getTargetFromConfig();
    
    // Set up the connection to the HTTPS backend
    const connectToBackend = () => {
      const backendSocket = plugins.tls.connect({
        host: target.host,
        port: target.port,
        // In a real implementation, we would configure TLS options
        rejectUnauthorized: false // For testing only, never use in production
      }, () => {
        this.emit(ForwardingHandlerEvents.DATA_FORWARDED, {
          direction: 'outbound',
          target: `${target.host}:${target.port}`,
          tls: true
        });
        
        // Set up bidirectional data flow
        tlsSocket.pipe(backendSocket);
        backendSocket.pipe(tlsSocket);
      });
      
      backendSocket.on('error', (error) => {
        this.emit(ForwardingHandlerEvents.ERROR, {
          remoteAddress,
          error: `Backend connection error: ${error.message}`
        });
        
        if (!tlsSocket.destroyed) {
          tlsSocket.destroy();
        }
      });
      
      // Handle close
      backendSocket.on('close', () => {
        if (!tlsSocket.destroyed) {
          tlsSocket.destroy();
        }
      });
      
      // Set timeout
      const timeout = this.getTimeout();
      backendSocket.setTimeout(timeout);
      
      backendSocket.on('timeout', () => {
        this.emit(ForwardingHandlerEvents.ERROR, {
          remoteAddress,
          error: 'Backend connection timeout'
        });
        
        if (!backendSocket.destroyed) {
          backendSocket.destroy();
        }
      });
    };
    
    // Wait for the TLS handshake to complete before connecting to backend
    tlsSocket.on('secure', () => {
      connectToBackend();
    });
    
    // Handle close
    tlsSocket.on('close', () => {
      this.emit(ForwardingHandlerEvents.DISCONNECTED, {
        remoteAddress
      });
    });
    
    // Set timeout
    const timeout = this.getTimeout();
    tlsSocket.setTimeout(timeout);
    
    tlsSocket.on('timeout', () => {
      this.emit(ForwardingHandlerEvents.ERROR, {
        remoteAddress,
        error: 'TLS connection timeout'
      });
      
      if (!tlsSocket.destroyed) {
        tlsSocket.destroy();
      }
    });
  }
  
  /**
   * Handle an HTTP request by forwarding to the HTTPS backend
   * @param req The HTTP request
   * @param res The HTTP response
   */
  public handleHttpRequest(req: plugins.http.IncomingMessage, res: plugins.http.ServerResponse): void {
    // Check if we should redirect to HTTPS
    if (this.config.http?.redirectToHttps) {
      this.redirectToHttps(req, res);
      return;
    }
    
    // Get the target from configuration
    const target = this.getTargetFromConfig();
    
    // Create custom headers with variable substitution
    const variables = {
      clientIp: req.socket.remoteAddress || 'unknown'
    };
    
    // Prepare headers, merging with any custom headers from config
    const headers = this.applyCustomHeaders(req.headers, variables);
    
    // Create the proxy request options
    const options = {
      hostname: target.host,
      port: target.port,
      path: req.url,
      method: req.method,
      headers,
      // In a real implementation, we would configure TLS options
      rejectUnauthorized: false // For testing only, never use in production
    };
    
    // Create the proxy request using HTTPS
    const proxyReq = plugins.https.request(options, (proxyRes) => {
      // Copy status code and headers from the proxied response
      res.writeHead(proxyRes.statusCode || 500, proxyRes.headers);
      
      // Pipe the proxy response to the client response
      proxyRes.pipe(res);
      
      // Track response size for logging
      let responseSize = 0;
      proxyRes.on('data', (chunk) => {
        responseSize += chunk.length;
      });
      
      proxyRes.on('end', () => {
        this.emit(ForwardingHandlerEvents.HTTP_RESPONSE, {
          statusCode: proxyRes.statusCode,
          headers: proxyRes.headers,
          size: responseSize
        });
      });
    });
    
    // Handle errors in the proxy request
    proxyReq.on('error', (error) => {
      this.emit(ForwardingHandlerEvents.ERROR, {
        remoteAddress: req.socket.remoteAddress,
        error: `Proxy request error: ${error.message}`
      });
      
      // Send an error response if headers haven't been sent yet
      if (!res.headersSent) {
        res.writeHead(502, { 'Content-Type': 'text/plain' });
        res.end(`Error forwarding request: ${error.message}`);
      } else {
        // Just end the response if headers have already been sent
        res.end();
      }
    });
    
    // Track request details for logging
    let requestSize = 0;
    req.on('data', (chunk) => {
      requestSize += chunk.length;
    });
    
    // Log the request
    this.emit(ForwardingHandlerEvents.HTTP_REQUEST, {
      method: req.method,
      url: req.url,
      headers: req.headers,
      remoteAddress: req.socket.remoteAddress,
      target: `${target.host}:${target.port}`
    });
    
    // Pipe the client request to the proxy request
    if (req.readable) {
      req.pipe(proxyReq);
    } else {
      proxyReq.end();
    }
  }
}