Implement basic `IdleListener`

js/modules/idle_listener.js

@@ -0,0 +1,39 @@
+const desktopIdle = require('desktop-idle');
+const EventEmitter = require('events');
+
+
+const POLL_INTERVAL_MS = 10 * 1000;
+const IDLE_THRESHOLD_MS = POLL_INTERVAL_MS;
+
+class IdleListener extends EventEmitter {
+  constructor() {
+    super();
+    this.intervalId = null;
+  }
+
+  start() {
+    this.stop();
+    this.intervalId = setInterval(() => {
+      const idleDuration = desktopIdle.getIdleTime();
+      const isIdle = idleDuration >= (IDLE_THRESHOLD_MS / 1000);
+      if (!isIdle) {
+        return;
+      }
+
+      this.emit('idle', { idleDuration });
+
+    }, POLL_INTERVAL_MS);
+  }
+
+  stop() {
+    if (!this.intervalId) {
+      return;
+    }
+
+    clearInterval(this.intervalId);
+  }
+}
+
+module.exports = {
+  IdleListener,
+};