Serial Plotter implementation (#597)

* spawn new window where to instantiate serial plotter app

* initialize serial monito web app

* connect serial plotter app with websocket

* use npm serial-plotter package

* refactor monitor connection and fix some connection issues

* fix clearConsole + refactor monitor connection

* add serial unit tests

* refactoring and cleaning code

arduino-ide-extension/src/node/web-socket/web-socket-service-impl.ts

@@ -0,0 +1,46 @@
+import { Emitter } from '@theia/core';
+import { injectable } from 'inversify';
+import * as WebSocket from 'ws';
+import { WebSocketService } from './web-socket-service';
+
+@injectable()
+export default class WebSocketServiceImpl implements WebSocketService {
+  protected wsClients: WebSocket[];
+  protected server: WebSocket.Server;
+
+  protected readonly onMessage = new Emitter<string>();
+  public readonly onMessageReceived = this.onMessage.event;
+
+  constructor() {
+    this.wsClients = [];
+    this.server = new WebSocket.Server({ port: 0 });
+
+    const addClient = this.addClient.bind(this);
+    this.server.on('connection', addClient);
+  }
+
+  private addClient(ws: WebSocket): void {
+    this.wsClients.push(ws);
+    ws.onclose = () => {
+      this.wsClients.splice(this.wsClients.indexOf(ws), 1);
+    };
+
+    ws.onmessage = (res) => {
+      this.onMessage.fire(res.data.toString());
+    };
+  }
+
+  getAddress(): WebSocket.AddressInfo {
+    return this.server.address() as WebSocket.AddressInfo;
+  }
+
+  sendMessage(message: string): void {
+    this.wsClients.forEach((w) => {
+      try {
+        w.send(message);
+      } catch {
+        w.close();
+      }
+    });
+  }
+}

arduino-ide-extension/src/node/web-socket/web-socket-service.ts

@@ -0,0 +1,9 @@
+import { Event } from '@theia/core/lib/common/event';
+import * as WebSocket from 'ws';
+
+export const WebSocketService = Symbol('WebSocketService');
+export interface WebSocketService {
+  getAddress(): WebSocket.AddressInfo;
+  sendMessage(message: string): void;
+  onMessageReceived: Event<string>;
+}