/**
 * WebSocket upgrade routing — validates auth and dispatches to the
 * appropriate handler.
 *
 * LEGACY: currently routes everything to a single /ws endpoint.
 * T-1.5/T-1.6: dispatch to topic/session-specific handlers (stream, input, …).
 */
import type { IncomingMessage } from "node:http";
import type { Server } from "node:http";
import type { Socket } from "node:net";

// Lightweight ws server interface (compatible with the ws package without types)
interface WsServer {
  handleUpgrade(
    request: IncomingMessage,
    socket: Socket,
    head: Buffer,
    cb: (ws: unknown) => void,
  ): void;
  emit(event: string, ...args: unknown[]): void;
}

/**
 * Handle an HTTP upgrade request.
 *
 * @param _httpServer  The HTTP server (reserved for T-1.5/T-1.6 per-session dispatch).
 * @param wss          The WebSocket server.
 * @param request      Incoming upgrade request.
 * @param socket       Raw socket.
 * @param head         First packet bytes.
 * @param isAuthed     Whether the request passed authentication.
 */
export function handleUpgrade(
  _httpServer: Server,
  wss: WsServer,
  request: IncomingMessage,
  socket: Socket,
  head: Buffer,
  isAuthed: boolean,
): void {
  const url = new URL(request.url ?? "/", "http://localhost");

  // T-1.5/T-1.6: inspect url.pathname to dispatch to stream / input / session handlers.
  if (url.pathname === "/ws") {
    if (!isAuthed) {
      socket.write("HTTP/1.1 403 Forbidden\r\n\r\n");
      socket.destroy();
      return;
    }
    wss.handleUpgrade(request, socket, head, (ws) => {
      wss.emit("connection", ws, request);
    });
  } else {
    socket.destroy();
  }
}