From 08765f0401c5fe95ffbaae667dfd758959b027cb Mon Sep 17 00:00:00 2001
From: Jaifroid <egk10@cam.ac.uk>
Date: Wed, 22 Jan 2020 00:20:41 +0000
Subject: [PATCH] Add logic for checking installed version

Former-commit-id: e1b6e37af929fc9fbb2d6608d6532939fac6ce41 [formerly ceaf7091f8e2d8e94cbd8e7d725962b3a148f68e]
Former-commit-id: d77eca66500e9441c2d1bf9ba13706802a4d4fbf
---
 www/js/init.js | 8 ++++++++
 1 file changed, 8 insertions(+)

diff --git a/www/js/init.js b/www/js/init.js
index 9f20db88..be6c0d63 100644
--- a/www/js/init.js
+++ b/www/js/init.js
@@ -79,6 +79,7 @@ params['allowInternetAccess'] = params['allowInternetAccess'] || false; //Do not
 params['printIntercept'] = false;
 params['printInterception'] = false;
 params['appIsLaunching'] = true; //Allows some routines to tell if the app has just been launched
+params['PWAInstalled'] = getCookie('PWAInstalled');
 
 //Prevent app boot loop with problematic pages that cause an app crash
 if (getCookie('lastPageLoad') == 'failed') {
@@ -183,6 +184,8 @@ window.addEventListener('beforeinstallprompt', function(e) {
     console.log('beforeinstallprompt fired');
     // Prevent Chrome 76 and earlier from automatically showing a prompt
     e.preventDefault();
+    // Don't display prompt if the PWA for this version is already installed
+    if (params.PWAInstalled === params.version) return;
     // Stash the event so it can be triggered later.
     deferredPrompt = e;
     // Show the install button
@@ -215,6 +218,11 @@ function installApp(e) {
     });
 }
 
+window.addEventListener('appinstalled', function(e) {
+    params.PWAInstalled = params.version;
+    document.cookie = 'PWAInstalled=' + params.PWAInstalled + ';expires=Fri, 31 Dec 9999 23:59:59 GMT';
+});
+
 function getCookie(name) {
     var result;
     if (params.cookieSupport == 'cookie') {