Initial data commit

Task/Chat-server/JavaScript/chat-server.js

@@ -0,0 +1,148 @@
+const net = require("net");
+const EventEmitter = require("events").EventEmitter;
+
+/*******************************************************************************
+ * ChatServer
+ *
+ * Manages connections, users, and chat messages.
+ ******************************************************************************/
+
+class ChatServer {
+    constructor() {
+        this.chatters = {};
+        this.server = net.createServer(this.handleConnection.bind(this));
+        this.server.listen(1212, "localhost");
+    }
+    isNicknameLegal(nickname) {
+        // A nickname may contain letters or numbers only,
+        // and may only be used once.
+        if (nickname.replace(/[A-Za-z0-9]*/, '') !== "") {
+            return false;
+        }
+        for (const used_nick in this.chatters) {
+            if (used_nick === nickname) {
+                return false;
+            }
+        }
+        return true;
+    }
+    handleConnection(connection) {
+        console.log(`Incoming connection from ${connection.remoteAddress}`);
+        connection.setEncoding("utf8");
+
+        let chatter = new Chatter(connection, this);
+        chatter.on("chat", this.handleChat.bind(this));
+        chatter.on("join", this.handleJoin.bind(this));
+        chatter.on("leave", this.handleLeave.bind(this));
+    }
+    handleChat(chatter, message) {
+        this.sendToEveryChatterExcept(chatter, chatter.nickname + ": " + message);
+    }
+    handleJoin(chatter) {
+        console.log(`${chatter.nickname} has joined the chat.`);
+        this.sendToEveryChatter(`${chatter.nickname} has joined the chat.`);
+        this.addChatter(chatter);
+    }
+    handleLeave(chatter) {
+        console.log(`${chatter.nickname} has left the chat.`);
+        this.removeChatter(chatter);
+        this.sendToEveryChatter(`${chatter.nickname} has left the chat.`);
+    }
+    addChatter(chatter) {
+        this.chatters[chatter.nickname] = chatter;
+    }
+    removeChatter(chatter) {
+        delete this.chatters[chatter.nickname];
+    }
+    sendToEveryChatter(data) {
+        for (const nickname in this.chatters) {
+            this.chatters[nickname].send(data);
+        }
+    }
+    sendToEveryChatterExcept(chatter, data) {
+        for (const nickname in this.chatters) {
+            if (nickname !== chatter.nickname) {
+                this.chatters[nickname].send(data);
+            }
+        }
+    }
+}
+
+
+/*******************************************************************************
+ * Chatter
+ *
+ * Represents a single user/connection in the chat server.
+ ******************************************************************************/
+
+class Chatter extends EventEmitter {
+    constructor(socket, server) {
+        super();
+
+        this.socket = socket;
+        this.server = server;
+        this.nickname = "";
+        this.lineBuffer = new SocketLineBuffer(socket);
+
+        this.lineBuffer.on("line", this.handleNickname.bind(this));
+        this.socket.on("close", this.handleDisconnect.bind(this));
+
+        this.send("Welcome! What is your nickname?");
+    }
+    handleNickname(nickname) {
+        if (server.isNicknameLegal(nickname)) {
+            this.nickname = nickname;
+            this.lineBuffer.removeAllListeners("line");
+            this.lineBuffer.on("line", this.handleChat.bind(this));
+            this.send(`Welcome to the chat, ${nickname}!`);
+            this.emit("join", this);
+        } else {
+            this.send("Sorry, but that nickname is not legal or is already in use!");
+            this.send("What is your nickname?");
+        }
+    }
+    handleChat(line) {
+        this.emit("chat", this, line);
+    }
+    handleDisconnect() {
+        this.emit("leave", this);
+    }
+    send(data) {
+        this.socket.write(data + "\r\n");
+    }
+};
+
+
+/*******************************************************************************
+ * SocketLineBuffer
+ *
+ * Listens for and buffers incoming data on a socket and emits a 'line' event
+ * whenever a complete line is detected.
+ ******************************************************************************/
+
+class SocketLineBuffer extends EventEmitter {
+    constructor(socket) {
+        super();
+
+        this.socket = socket;
+        this.buffer = "";
+
+        this.socket.on("data", this.handleData.bind(this));
+    }
+    handleData(data) {
+        for (let i = 0; i < data.length; i++) {
+            const char = data.charAt(i);
+            this.buffer += char;
+            if (char == "\n") {
+                this.buffer = this.buffer.replace("\r\n", "");
+                this.buffer = this.buffer.replace("\n", "");
+                this.emit("line", this.buffer);
+                this.buffer = "";
+            }
+        }
+    }
+};
+
+
+// Start the server!
+server = new ChatServer();