From 85882b7a18f586815aed65f0b4f5429c267bca52 Mon Sep 17 00:00:00 2001
From: Christian Pauly <christian-pauly@posteo.de>
Date: Sat, 19 Jun 2021 19:05:03 +0200
Subject: [PATCH] fix: Web base url

---
 web/index.html | 80 ++++++++++++++++++++++++++++++++++++++++++++++----
 1 file changed, 74 insertions(+), 6 deletions(-)
diff --git a/web/index.html b/web/index.html
index c954eb0d..1612e8e4 100644
--- a/web/index.html
+++ b/web/index.html
@@ -1,6 +1,19 @@
 <!DOCTYPE html>
 <html>
+
 <head>
+  <!--
+    If you are serving your web app in a path other than the root, change the
+    href value below to reflect the base path you are serving from.
+
+    The path provided below has to start and end with a slash "/" in order for
+    it to work correctly.
+
+    For more details:
+    * https://developer.mozilla.org/en-US/docs/Web/HTML/Element/base
+  -->
+  <base href="/web/">
+
   <meta charset="UTF-8">
   <meta content="IE=Edge" http-equiv="X-UA-Compatible">
   <meta name="description" content="A new Flutter project.">
@@ -11,25 +24,80 @@
   <meta name="apple-mobile-web-app-title" content="fluffychat">
   <link rel="apple-touch-icon" href="icons/Icon-192.png">
 
-  <!-- Favicon -->
-  <link rel="shortcut icon" type="image/png" href="favicon.png"/>
-
   <title>fluffychat</title>
   <link rel="manifest" href="manifest.json">
 </head>
+
 <body>
   <!-- This script installs service_worker.js to provide PWA functionality to
        application. For more information, see:
        https://developers.google.com/web/fundamentals/primers/service-workers -->
   <script>
+    var serviceWorkerVersion = null;
+    var scriptLoaded = false;
+    function loadMainDartJs() {
+      if (scriptLoaded) {
+        return;
+      }
+      scriptLoaded = true;
+      var scriptTag = document.createElement('script');
+      scriptTag.src = 'main.dart.js';
+      scriptTag.type = 'application/javascript';
+      document.body.append(scriptTag);
+    }
+
     if ('serviceWorker' in navigator) {
+      // Service workers are supported. Use them.
       window.addEventListener('load', function () {
-        navigator.serviceWorker.register('flutter_service_worker.js');
+        // 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 service worker doesn't succeed in a reasonable amount of time,
+        // fallback to plaint <script> tag.
+        setTimeout(() => {
+          if (!scriptLoaded) {
+            console.warn(
+              'Failed to load app from service worker. Falling back to plain <script> tag.',
+            );
+            loadMainDartJs();
+          }
+        }, 4000);
       });
+    } else {
+      // Service workers not supported. Just drop the <script> tag.
+      loadMainDartJs();
     }
   </script>
   <script src="assets/assets/js/package/olm.js"></script>
   <script defer src="sql-wasm.js"></script>
-  <script src="main.dart.js" type="application/javascript"></script>
 </body>
-</html>
+
+</html>
\ No newline at end of file
