Created the server.js

api/server.js

@@ -0,0 +1,139 @@
+const httpServer = require("http").createServer();
+const io = require("socket.io")(httpServer, {cors: {origin: "*"}});
+
+const rooms = {};
+
+/**
+ * Generates a random room code.
+ * @returns {*|string} A random room code.
+ */
+const generateRoomCode = () => {
+    const code = Math.random().toString(36).substring(2, 6).toUpperCase();
+    return rooms[code] ? generateRoomCode() : code;
+}
+
+/**
+ * Returns the room code of the room the socket is in.
+ * @param socketId The socket id of the socket.
+ * @returns {string} The room code of the room the socket is in.
+ */
+const getRoomCodeBySocketId = (socketId) => {
+    return Object.keys(rooms).find((code) => rooms[code].host === socketId || rooms[code].players.some((player) => player.id === socketId));
+}
+
+/**
+ * Returns the name of the player with the given socket id in the given room.
+ * @param socketId The socket id of the player.
+ * @param roomCode The room code of the room the player is in.
+ * @returns {*|null} The name of the player with the given socket id in the given room.
+ */
+const getPlayerName = (socketId, roomCode) => {
+    const player = rooms[roomCode].players.find((player) => player.id === socketId);
+    return player ? player.name : null;
+}
+
+io.on("connection", (socket) => {
+    socket.on("CREATE_ROOM", (data, callback = () => {}) => {
+        if (getRoomCodeBySocketId(socket.id)) {
+            callback(false);
+            return;
+        }
+
+        const code = generateRoomCode();
+        rooms[code] = {host: socket.id, players: []};
+
+        callback({code});
+
+        console.log(`Room ${code} created by ${socket.id}.`);
+
+        socket.join(code);
+    });
+
+    socket.on("JOIN_ROOM", (data, callback = () => {}) => {
+        if (getRoomCodeBySocketId(socket.id)) {
+            callback(false);
+            return;
+        }
+
+        const {code, name} = data;
+
+        if (!code || !name) {
+            callback(false);
+            return;
+        }
+
+        if (rooms[code]) {
+            socket.join(code);
+            rooms[code].players.push({id: socket.id, name});
+            io.to(rooms[code].host).emit("JOINED", {id: socket.id, name});
+            callback(true);
+        } else {
+            callback(false);
+        }
+    });
+
+    socket.on("SUBMISSION_READY", (data, callback = () => {}) => {
+        const roomCode = getRoomCodeBySocketId(socket.id);
+        io.to(roomCode).emit("SUBMISSION_READY");
+
+        callback(true);
+    });
+
+    socket.on("SUBMIT", (data, callback = () => {}) => {
+        const {price, amount} = data;
+
+        if (price === undefined || amount === undefined) {
+            callback(false);
+            return;
+        }
+
+        if (price < 0 || price > 10000 || amount < 0 || amount > 20) {
+            callback(false);
+            return;
+        }
+
+        const roomCode = getRoomCodeBySocketId(socket.id);
+        const playerName = getPlayerName(socket.id, roomCode);
+
+        io.to(rooms[roomCode].host).emit("RECEIVED", {id: socket.id, name: playerName, price, amount});
+        callback(true);
+    });
+
+    socket.on("UPDATE_CAPITAL", (data, callback = () => {}) => {
+        const {id, capital} = data;
+
+        if (!id || capital === undefined) {
+            callback(false);
+            return;
+        }
+
+        io.to(id).emit("CAPITAL", {capital});
+
+        if (capital < 5000) {
+            socket.emit("LEFT", {id: socket.id});
+            io.sockets.sockets.get(id).disconnect();
+        }
+
+        callback(true);
+    });
+
+    socket.conn.on("close", () => {
+        const roomCode = getRoomCodeBySocketId(socket.id);
+
+        if (!roomCode) return;
+
+        rooms[roomCode].players = rooms[roomCode].players.filter((player) => player.id !== socket.id);
+        if (rooms[roomCode].host === socket.id) {
+            for (const player of rooms[roomCode].players) io.sockets.sockets.get(player.id).disconnect();
+
+            delete rooms[roomCode];
+        } else {
+            io.to(rooms[roomCode].host).emit("LEFT", {id: socket.id});
+        }
+
+    });
+});
+
+httpServer.listen(3000, () => {
+    console.log("listening on *:3000");
+});