refactor: simplify neighbor check with while loop

lib/constants.js

@@ -1,4 +1,14 @@
 const HANDSHAKE = 'HANDSHAKE';
-const DM = 'MESSAGE';
+const DM = 'MES SAGE';
+const CHECK_INTERVAL = 500;
+const TIMEOUT_DURATION = 20000;
 
-module.exports = { HANDSHAKE, DM };
+const TIMEOUT_ERROR_MESSAGE = `Neighbor check timed out after ${TIMEOUT_DURATION / 1000} seconds`;
+
+module.exports = {
+  HANDSHAKE,
+  DM,
+  CHECK_INTERVAL,
+  TIMEOUT_DURATION,
+  TIMEOUT_ERROR_MESSAGE,
+};

lib/messaging.js

@@ -1,7 +1,13 @@
 'use strict';
 const { createData, uuid, createMessage } = require('./common');
 const Connection = require('./connection');
-const { HANDSHAKE, DM } = require('./constants');
+const {
+  HANDSHAKE,
+  DM,
+  CHECK_INTERVAL,
+  TIMEOUT_DURATION,
+  TIMEOUT_ERROR_MESSAGE,
+} = require('./constants');
 
 class Messaging extends Connection {
   NODE_ID = uuid();
@@ -27,7 +33,8 @@ class Messaging extends Connection {
     if (nodeId) this.neighbors.delete(connectionId);
   }
 
-  send(nodeId, message) {
+  async send(nodeId, message) {
+    await this.#neighborCheck();
     const connectionId = this.neighbors.get(nodeId);
     const targets = connectionId ? [connectionId] : this.neighbors;
     targets.forEach(target =>
@@ -45,6 +52,18 @@ class Messaging extends Connection {
     this.neighbors.set(neighbor, connectionId);
   }
 
+  async #neighborCheck() {
+    const timeoutPromise = new Promise((_, reject) =>
+      setTimeout(() => reject(Error(TIMEOUT_ERROR_MESSAGE)), TIMEOUT_DURATION),
+    );
+    const checkNeighbors = async () => {
+      while (this.neighbors.size === 0) {
+        await new Promise(resolve => setTimeout(resolve, CHECK_INTERVAL));
+      }
+    };
+    await Promise.race([checkNeighbors(), timeoutPromise]);
+  }
+
   [HANDSHAKE](connectionId, messageObject) {
     const { data } = messageObject;
     this.#addNeighbor(connectionId, data);