From b089a0b8109f2fb606b2187cfdfe9dac89b7cbbb Mon Sep 17 00:00:00 2001
From: Daniel Flanagan <daniel.flanagan@divvypay.com>
Date: Tue, 11 Oct 2022 13:43:47 -0500
Subject: [PATCH] Fix 3

---
 3.ts | 123 +++++++++++++++++++++++++++++++++++++++++++++++++----------
 1 file changed, 103 insertions(+), 20 deletions(-)

diff --git a/3.ts b/3.ts
index e052fbe..9fa8c7a 100644
--- a/3.ts
+++ b/3.ts
@@ -1,25 +1,108 @@
-const PORT = 5588;
-console.log(`Starting UDP listener on port ${PORT}`);
+import { readLines } from "https://deno.land/std@0.157.0/io/buffer.ts";
+
+const PORT = 5588;
+console.log(`Starting TCP listener on on 0.0.0.0:${PORT}`);
+
+const clients = new Map<Deno.Conn, string>();
 
-const tDec = new TextDecoder();
 const tEnc = new TextEncoder();
 
-const reservedData: Record<string, string> = { version: "KeyVal 1.0" };
-const data = new Map<string, string>();
-
-const listener = Deno.listenDatagram({ port: PORT, transport: "udp" });
-
-for await (const [bytes, addr] of listener) {
-  const message = tDec.decode(bytes).trim();
-  console.debug("Datagram Received from:", addr, message);
-  if (message.includes("=")) {
-    const [key, val] = message.split("=", 1);
-    console.debug(`Setting ${key} to ${val}`);
-    if (!(key in reservedData)) data.set(key, val);
-  } else {
-    const value = reservedData[message] || data.get(message) || "";
-    const bytes = tEnc.encode(`${message}=${value}`);
-    console.debug(`Sending ${message}=${value}`);
-    await listener.send(bytes, addr);
+async function chatSession(conn: Deno.Conn) {
+  try {
+    let myNick: string | null = null;
+    await sendPrompt(conn);
+    for await (const line of readLines(conn)) {
+      console.debug("Received line:", line);
+      const message = line.trim();
+      if (myNick == null) {
+        if (isLegalNick(message)) {
+          myNick = message;
+          await join(myNick, conn);
+        } else {
+          console.error("Illegal nick:", message);
+          break;
+        }
+      } else {
+        const conns: Deno.Conn[] = [];
+        for (const themConn of clients.keys()) {
+          if (themConn != conn) conns.push(themConn);
+        }
+        await send(conns, `[${myNick}] ${message}`);
+      }
+    }
+  } finally {
+    if (clients.has(conn)) {
+      try {
+        await disconnect(conn);
+      } catch (err) {
+        console.error("Failed to disconnect:", err);
+      }
+    }
+    try {
+      if (conn.writable) {
+        send(conn, "You are being disconnected...");
+      }
+    } catch (err) {
+      console.error("Failed to send disconnect notice:", err);
+    }
+  }
+  try {
+    conn.close();
+  } catch (err) {
+    console.error("Failed to close connection:", err);
   }
 }
+
+async function send(
+  connsArg: Deno.Conn | Array<Deno.Conn>,
+  text: string,
+) {
+  const conns = !Array.isArray(connsArg) ? [connsArg] : connsArg;
+  const messages: Promise<number>[] = [];
+  const bytes = tEnc.encode(text + "\n");
+  conns.forEach((conn) => messages.push(conn.write(bytes)));
+  return await Promise.all(messages);
+}
+
+const broadcast = async (text: string) => await send([...clients.keys()], text);
+
+const LEGAL_NICK_REGEXP = /^[a-z0-9]+$/i;
+const isLegalNick = (nick: string) => {
+  console.debug(
+    `Checking nick: ${nick} (Bytes: ${tEnc.encode(nick)})`,
+  );
+  return LEGAL_NICK_REGEXP.exec(nick) != null;
+};
+
+const sendPrompt = async (conn: Deno.Conn) => {
+  console.debug("Sending prompt...");
+  return await send(conn, "Who you be?");
+};
+
+async function join(myNick: string, conn: Deno.Conn) {
+  const userList: string[] = [];
+  clients.forEach((nick, _) => userList.push(nick));
+  await broadcast(`* ${myNick} joined`);
+  clients.set(conn, myNick);
+  await send(conn, `* users: ${userList.join(", ")}`);
+}
+
+async function disconnect(conn: Deno.Conn) {
+  const myNick = clients.get(conn);
+  clients.delete(conn);
+  await broadcast(`* ${myNick} left`);
+}
+
+for await (const conn of Deno.listen({ port: PORT })) {
+  console.log("Connection established:", conn.remoteAddr);
+  try {
+    chatSession(conn);
+  } catch (e) {
+    console.error(
+      "Exception occurred during chat session:",
+      conn.remoteAddr,
+      e,
+    );
+  }
+  console.log("Connection closed:", conn.remoteAddr);
+}