avery-game-proto/index.ts

import express from "express";
import expressWs from "express-ws";
import type { WebSocket } from "ws";
import crypto from "crypto";
import fs from "fs/promises";

interface Host {
  ws: WebSocket,
  code: string,
  messages: { from: "host"|"join", data: string }[],
  join?: Join,
}
interface Join {
  ws: WebSocket,
  code: string,
  host: Host,
}
const hosts: Host[] = [];
const joins: Join[] = [];

const app = expressWs(express()).app;
const port = process.env.PORT || 3000;
app.use(express.json());

app.use(express.static("public"));

app.ws("/", (ws) => {
  ws.on("message", (msg: string) => {
    console.log(msg);

    if (msg === "host") {
      if (hosts.some(({ ws: ows }) => ows == ws) || joins.some(({ ws: ows }) => ows == ws)) {
        ws.send("failed");
        return;
      }

      const code = crypto.randomBytes(4).toString("hex");
      ws.send("code " + code);
      hosts.push({ ws, code, messages: [] });
      return;
    }

    if (msg.startsWith("join ")) {
      if (hosts.some(({ ws: ows }) => ows == ws) || joins.some(({ ws: ows }) => ows == ws)) {
        ws.send("failed");
        return;
      }

      const code = msg.substring(5);
      const host = hosts.find(({ code: oldCode }) => oldCode === code);
      if (!host || host.join) {
        ws.send("failed");
        return;
      }
      ws.send("good");
      const join: Join = { ws, code, host };
      host.join = join;
      joins.push(join);
    }

    if (msg.startsWith("send ")) {
      const send = msg.substring(5);
      const host = hosts.find(({ ws: ows }) => ows == ws);
      const join = joins.find(({ ws: ows }) => ows == ws);

      if (host) {
        if (!host.join) {
          ws.send("failed");
          return;
        }
        host.join.ws.send("rcv " + translateText(send, host.code));
        host.messages.push({ from: "host", data: send });
        return;
      }

      if (join) {
        join.host.ws.send("rcv " + translateText(send, join.code));
        join.host.messages.push({ from: "join", data: send });
      }
    }
  });
  ws.on("close", () => {
    let index = hosts.findIndex(({ ws: thisWs }) => thisWs == ws);
    if (index > -1) {
      const host = hosts[index];
      fs.appendFile(
            "./out.txt",
            `${host.code} | ${new Date().toUTCString()}\n` +
            host.messages.map(({ from, data }) => `${from}> ${data}`).join("\n") + "\n\n",
      ).catch(console.error);

      const join = host.join;
      hosts.splice(index, 1);
      if (join) {
        join.ws.send("disconnected");
        index = joins.indexOf(join);
        if (index > -1) {
          joins.splice(index, 1);
        }
      }
    }

    index = joins.findIndex(({ ws: thisWs }) => thisWs == ws);
    if (index > -1) {
      const host = joins[index].host;
      joins.splice(index, 1);
      host.ws.send("disconnected");
    }
  });
});

function translateText(msg: string, code: string): string {
  const shift = parseInt(code, 16);
  return msg
        .replaceAll(/[^\x20-\x7e]+/g, "")
        .replaceAll(/\s+/g, " ")
        .toLowerCase()
        .substring(0, 1024)
        .split(" ")
        .map(w => {
          let o = "";
          let n = shift;
          for (let i = 0; i < w.length; i++) {
            const c = w[i];
            const cc = c.charCodeAt(0);
            n ^= (cc * shift) >> (i % 4);
            n = Math.abs(n);
            if ("a" <= c && c <= "z") {
              o += String.fromCharCode(0x61 + (n % 26));
            } else {
              const nc = n % (32 + 6 + 4);
              if (nc <= 32) {
                o += String.fromCharCode(0x21 + nc);
              } else if (nc <= 32 + 6) {
                o += String.fromCharCode(0x5B + nc - 32);
              } else {
                o += String.fromCharCode(0x7B + nc - 32 - 6);
              }
            }
          }
          return o;
        })
        .join(" ");
}

app.listen(port, () => {
  console.log(`Server is running on port ${port}`);
});