Budget chat

main.ts

@@ -1,72 +1,108 @@
-import { BufReader } from "https://deno.land/std@0.157.0/io/buffer.ts";
+import { readLines } from "https://deno.land/std@0.157.0/io/buffer.ts";
-import { ByteSet } from "https://deno.land/x/bytes@1.0.3/mod.ts";
 
-const QUERY_SIZE = 9;
 const PORT = 5588;
+console.log(`Starting TCP listener on on 0.0.0.0:${PORT}`);
 
-const listener = Deno.listen({ port: 5588 });
+const clients = new Map<Deno.Conn, string>();
 
-console.log(`Listening on 0.0.0.0:${PORT}`);
+const tEnc = new TextEncoder();
 
-for await (const conn of listener) {
+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 {
-    meansToAnEnd(conn);
+    chatSession(conn);
   } catch (e) {
-    console.error(conn.remoteAddr, e);
+    console.error(
+      "Exception occurred during chat session:",
+      conn.remoteAddr,
+      e,
+    );
   }
   console.log("Connection closed:", conn.remoteAddr);
 }
-
-// problem 2
-async function meansToAnEnd(conn: Deno.Conn) {
-  try {
-    const prices = [];
-    for await (const query of queries(conn)) {
-      if (query == null) break;
-      const bs = ByteSet.from(query, "big");
-      const queryChar = String.fromCharCode(bs.read.uint8());
-      const a1 = bs.read.int32();
-      const a2 = bs.read.int32();
-      if (queryChar == "I") {
-        prices.push([a1, a2]);
-      } else if (queryChar == "Q") {
-        let numMatches = 0;
-        let sum = 0;
-        for (const [ts, price] of prices) {
-          if (ts < a1 || ts > a2) continue;
-          numMatches++;
-          sum += price;
-        }
-        let result = Math.floor(sum / numMatches);
-        if (isNaN(result)) result = 0;
-        console.log(
-          conn.remoteAddr,
-          `Result for ${prices.length} prices: ${sum} / ${numMatches} = ${result}`,
-        );
-        const response = new ByteSet(4, "big");
-        response.write.int32(result);
-        conn.write(response.buffer);
-      }
-    }
-    console.log("Done!");
-  } catch (err) {
-    console.error("Error processing query:", err);
-  }
-}
-
-function queries(conn: Deno.Conn) {
-  return {
-    async *[Symbol.asyncIterator]() {
-      const b = new Uint8Array(9);
-      const reader = new BufReader(conn, QUERY_SIZE);
-      try {
-        while (await reader.readFull(b) != null) {
-          yield b;
-        }
-      } catch (err) {
-        console.error("Error receiving query:", err);
-      }
-    },
-  };
-}