Service worker update

Frontend/patient_manager/web/index.html

@@ -135,6 +135,68 @@
       document.body.append(scriptTag);
     }
 
+    if ('serviceWorker' in navigator) {
+      // Service workers are supported. Use them.
+      window.addEventListener('load', function () {
+        // Wait for registration to finish before dropping the <script> tag.
+        // Otherwise, the browser will load the script multiple times,
+        // potentially different versions.
+        var serviceWorkerUrl = 'flutter_service_worker.js?v=' + serviceWorkerVersion;
+        navigator.serviceWorker.register(serviceWorkerUrl)
+          .then((reg) => {
+            function waitForActivation(serviceWorker) {
+              serviceWorker.addEventListener('statechange', () => {
+                if (serviceWorker.state == 'activated') {
+                  console.log('Installed new service worker.');
+                  loadMainDartJs();
+                }
+              });
+            }
+            if (!reg.active && (reg.installing || reg.waiting)) {
+              // No active web worker and we have installed or are installing
+              // one for the first time. Simply wait for it to activate.
+              waitForActivation(reg.installing || reg.waiting);
+            } else if (!reg.active.scriptURL.endsWith(serviceWorkerVersion)) {
+              // When the app updates the serviceWorkerVersion changes, so we
+              // need to ask the service worker to update.
+              console.log('New service worker available.');
+              reg.update();
+              waitForActivation(reg.installing);
+            } else {
+              // Existing service worker is still good.
+              console.log('Loading app from service worker.');
+              loadMainDartJs();
+            }
+          });
+      });
+
+      if (navigator.serviceWorker.state == 'activated') {
+        console.log('Installed new service worker.');
+        loadMainDartJs();
+        // if there's an existing controller (previous Service Worker), show the prompt 
+        // you can tweak this and delay the notification once the page is load you can show a notification and ask for a new refresh
+      }
+    }
+    else {
+      // Service workers not supported. Just drop the <script> tag.
+      loadMainDartJs();
+    }
+  </script>
+  <!-- <script defer>
+    var serviceWorkerVersion = '{{flutter_service_worker_version}}';
+    var scriptLoaded = false;
+    function loadMainDartJs() {
+      if (scriptLoaded) {
+        return;
+      }
+      scriptLoaded = true;
+      var scriptTag = document.createElement('script');
+      scriptTag.src = 'flutter_bootstrap.js';
+      scriptTag.type = 'application/javascript';
+      scriptTag.defer = true;
+      document.body.append(scriptTag);
+    }
+
     if ('serviceWorker' in navigator) {
       // Service workers are supported. Use them.
       window.addEventListener('load', function () {
@@ -199,7 +261,7 @@
       // Service workers not supported. Just drop the <script> tag.
       loadMainDartJs();
     }
-  </script>
+  </script> -->
 
 </body>
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