protohackers/6.ts

import { BufReader } from "https://deno.land/std@0.157.0/io/buffer.ts";

const PORT = 5588;

type Road = number;
type Dispatcher = Road[];
type Location = number;
type SpeedLimit = number;
type Timestamp = number;
type Plate = string;
type Car = Plate;

type U8 = number;
type U16 = number;
type U32 = number;

interface Camera {
  road: Road;
  location: Location;
  speedLimit: SpeedLimit;
}

interface Report {
  camera: Camera;
  car: Car;
  timestamp: Timestamp;
}

// const tEnc = new TextEncoder();

console.log(`Starting TCP listener on on 0.0.0.0:${PORT}`);

function chatSession(conn: Deno.Conn) {
  const closeOnDisconnect = () => {
    console.warn("Disconnected client");
    try {
      conn.close();
    } catch (err) {
      console.error("Error closing client connection:", err);
    }
  };

  serve(conn).catch((e) => e).finally(closeOnDisconnect);
}

enum MessageType {
  ERROR = 0x10, // Server -> Client
  PLATE = 0x20, // Client -> Server
  TICKET = 0x21, // Server -> Client
}

type ErrorMessage = [
  string, // msg
];

type PlateMessage = [
  string, // plate
  U32, // timestamp
];

interface TicketMessage {
}

type Message = ErrorMessage | PlateMessage;

async function serve(conn: Deno.Conn) {
  const reader = new BufReader(conn);
  const type = await reader.peek(1);
  if (!type) throw new Error("failed to peek start of packet");
  console.log({ type }, 0x64);
  // TODO: loop...
}

for await (const conn of Deno.listen({ port: PORT })) {
  console.log("Connection established:", conn.remoteAddr);
  chatSession(conn);
  console.log("Connection closed:", conn.remoteAddr);
}