import { WebSocketServer } from 'ws';
import * as net from 'net';
import * as tls from 'tls';
import { parse } from 'url';

// Create WebSocket server instance
const wss = new WebSocketServer({ noServer: true });

// Active connections and their proxies
const connections = new Map();

// Handle WebSocket connections
wss.on('connection', (ws, req, mudHost, mudPort, useSSL) => {
  console.log(`WebSocket connection established for ${mudHost}:${mudPort} (SSL: ${useSSL})`);
  
  // Create a unique ID for this connection
  const connectionId = `${Date.now()}-${Math.random().toString(36).substr(2, 9)}`;
  
  // Special handling for test connections
  if (mudHost === 'example.com' && mudPort === '23') {
    console.log('Test connection detected - using echo server mode');
    
    // Send welcome message
    ws.send('Hello from WebSocket test server! This is an echo server.');
    
    // Echo back messages
    ws.on('message', (message) => {
      console.log('Test server received:', message.toString());
      ws.send(`Echo: ${message.toString()}`);
    });
    
    // Handle close
    ws.on('close', () => {
      console.log('Test connection closed');
      connections.delete(connectionId);
    });
    
    // Store the connection (without a socket)
    connections.set(connectionId, { ws, testMode: true });
    return;
  }

  let socket;
  try {
    // Create a TCP socket connection to the MUD server
    // Use tls for SSL connections, net for regular connections
    socket = useSSL 
      ? tls.connect({ host: mudHost, port: parseInt(mudPort), rejectUnauthorized: false })
      : net.createConnection({ host: mudHost, port: parseInt(mudPort) });
    
    // Add error handler
    socket.on('error', (error) => {
      console.error(`Socket error for ${mudHost}:${mudPort}:`, error.message);
      // Send error to client
      if (ws.readyState === 1) {
        ws.send(Buffer.from(`ERROR: Connection to MUD server failed: ${error.message}\r\n`));
        setTimeout(() => {
          if (ws.readyState === 1) ws.close();
        }, 1000);
      }
      // Remove from connections map
      connections.delete(connectionId);
    });
    
    // Store the connection
    connections.set(connectionId, { ws, socket });
  } catch (error) {
    console.error(`Error creating socket connection: ${error.message}`);
    if (ws.readyState === 1) {
      ws.send(Buffer.from(`ERROR: Failed to connect to MUD server: ${error.message}\r\n`));
      ws.close();
    }
    return;
  }
  
  // Handle data from the MUD server - only in regular mode, not test mode
  if (socket) {
    socket.on('data', (data) => {
      // Check for GMCP data (IAC SB GMCP) - very basic check for debugging
      // IAC = 255, SB = 250, GMCP = 201
      let isGmcp = false;
      for (let i = 0; i < data.length - 2; i++) {
        if (data[i] === 255 && data[i+1] === 250 && data[i+2] === 201) {
          isGmcp = true;
          console.log('WebSocket server: Detected GMCP data in server response');
          break;
        }
      }
      
      // Forward data to the WebSocket client if it's still open
      if (ws.readyState === 1) { // WebSocket.OPEN
        ws.send(data);
        console.log(`WebSocket server: Sent ${data.length} bytes to client${isGmcp ? ' (contains GMCP data)' : ''}`);
      }
    });
  }
  
  // Handle socket close
  if (socket) {
    socket.on('close', () => {
      console.log(`MUD connection closed for ${mudHost}:${mudPort}`);
      // Close WebSocket if it's still open
      if (ws.readyState === 1) {
        ws.close();
      }
      // Remove from connections map
      connections.delete(connectionId);
    });
  }
  
  // Handle WebSocket messages (data from client to server)
  ws.on('message', (message) => {
    try {
      // Skip if this is a test connection (already handled in the test mode section)
      const conn = connections.get(connectionId);
      if (conn.testMode) return;
      
      // Check for GMCP data (IAC SB GMCP) in client messages
      let isGmcp = false;
      if (message instanceof Buffer || message instanceof Uint8Array) {
        for (let i = 0; i < message.length - 2; i++) {
          if (message[i] === 255 && message[i+1] === 250 && message[i+2] === 201) {
            isGmcp = true;
            console.log('WebSocket server: Detected GMCP data in client message');
            break;
          }
        }
      }
      
      // Forward data to the MUD server
      // The message might be Buffer, ArrayBuffer, or string
      if (conn.socket && conn.socket.writable) {
        conn.socket.write(message);
        console.log(`WebSocket server: Sent ${message.length} bytes to MUD server${isGmcp ? ' (contains GMCP data)' : ''}`);
      } else {
        console.error('Socket not writable, cannot send data to MUD server');
        if (ws.readyState === 1) { // WebSocket.OPEN
          ws.send(Buffer.from(`ERROR: Cannot send data to MUD server: Socket not connected\r\n`));
        }
      }
    } catch (error) {
      console.error('Error forwarding message to MUD server:', error);
      if (ws.readyState === 1) { // WebSocket.OPEN
        ws.send(Buffer.from(`ERROR: Failed to send data to MUD server: ${error.message}\r\n`));
      }
    }
  });
  
  // Handle WebSocket close
  ws.on('close', () => {
    console.log(`WebSocket closed for ${mudHost}:${mudPort}`);
    // Close socket if it's still open
    const conn = connections.get(connectionId);
    if (conn && conn.socket) {
      conn.socket.end();
    }
    // Remove from connections map
    connections.delete(connectionId);
  });
  
  // Handle WebSocket errors
  ws.on('error', (error) => {
    console.error(`WebSocket error for ${mudHost}:${mudPort}:`, error.message);
    // Close socket on error
    const conn = connections.get(connectionId);
    if (conn && conn.socket) {
      conn.socket.end();
    }
    // Remove from connections map
    connections.delete(connectionId);
  });
});

// Handle WebSocket upgrades
export const handleWebSocket = (server) => {
  server.on('upgrade', (request, socket, head) => {
    // Parse URL to get query parameters
    const { pathname, query } = parse(request.url, true);
    
    // Only handle WebSocket connections to /mud-ws
    if (pathname === '/mud-ws') {
      // Extract MUD server details from query parameters
      const { host, port, useSSL } = query;
      
      if (!host || !port) {
        socket.write('HTTP/1.1 400 Bad Request\r\n\r\n');
        socket.destroy();
        return;
      }
      
      // Handle WebSocket upgrade
      wss.handleUpgrade(request, socket, head, (ws) => {
        wss.emit('connection', ws, request, host, port, useSSL === 'true');
      });
    } else {
      // For other upgrades (not to /mud-ws), let SvelteKit handle them
      // Don't destroy the socket here
    }
  });
};

// Standard SvelteKit hook
export async function handle({ event, resolve }) {
  return await resolve(event);
}