implement service worker events

src/background.ts

@@ -0,0 +1,49 @@
+import browser from 'webextension-polyfill';
+import WakaTimeCore from './core/WakaTimeCore';
+
+// Add a listener to resolve alarms
+browser.alarms.onAlarm.addListener(async (alarm) => {
+  // |alarm| can be undefined because onAlarm also gets called from
+  // window.setTimeout on old chrome versions.
+  // eslint-disable-next-line @typescript-eslint/no-unnecessary-condition
+  if (alarm?.name == 'heartbeatAlarm') {
+    console.log('recording a heartbeat - alarm triggered');
+
+    await WakaTimeCore.recordHeartbeat();
+  }
+});
+
+/**
+ * Whenever a active tab is changed it records a heartbeat with that tab url.
+ */
+browser.tabs.onActivated.addListener(async () => {
+  console.log('recording a heartbeat - active tab changed');
+  await WakaTimeCore.recordHeartbeat();
+});
+
+/**
+ * Whenever a active window is changed it records a heartbeat with the active tab url.
+ */
+browser.windows.onFocusChanged.addListener(async (windowId) => {
+  if (windowId != browser.windows.WINDOW_ID_NONE) {
+    console.log('recording a heartbeat - active window changed');
+    await WakaTimeCore.recordHeartbeat();
+  } else {
+    console.log('lost focus');
+  }
+});
+
+/**
+ * Whenever any tab is updated it checks if the updated tab is the tab that is
+ * currently active and if it is, then it records a heartbeat.
+ */
+browser.tabs.onUpdated.addListener(async (tabId, changeInfo) => {
+  if (changeInfo.status === 'complete') {
+    // Get current tab URL.
+    const [tab] = await browser.tabs.query({ active: true, currentWindow: true });
+    // If tab updated is the same as active tab
+    if (tabId == tab.id) {
+      await WakaTimeCore.recordHeartbeat();
+    }
+  }
+});