From fa2eb8fe52e985185a7157cca31ba57382609734 Mon Sep 17 00:00:00 2001
From: Nolan Lawson <nolan@nolanlawson.com>
Date: Tue, 28 May 2019 08:18:11 -0700
Subject: [PATCH] fix: no need for double reload of SW in Chrome (#1251)

fixes #1243
---
 src/routes/_pages/settings/index.html    |  2 +-
 src/routes/_utils/serviceWorkerClient.js | 84 +++++++++++++++++++++---
 src/service-worker.js                    |  9 ++-
 3 files changed, 83 insertions(+), 12 deletions(-)

diff --git a/src/routes/_pages/settings/index.html b/src/routes/_pages/settings/index.html
index 45503ed..02a3045 100644
--- a/src/routes/_pages/settings/index.html
+++ b/src/routes/_pages/settings/index.html
@@ -36,7 +36,7 @@
     methods: {
       reload (event) {
         event.preventDefault()
-        document.location.reload(true)
+        location.reload()
       }
     }
   }
diff --git a/src/routes/_utils/serviceWorkerClient.js b/src/routes/_utils/serviceWorkerClient.js
index d846f08..aed0689 100644
--- a/src/routes/_utils/serviceWorkerClient.js
+++ b/src/routes/_utils/serviceWorkerClient.js
@@ -1,17 +1,81 @@
 import { snackbar } from '../_components/snackbar/snackbar'
 
-function onUpdateFound (registration) {
-  const newWorker = registration.installing
+// A lot of this code is borrowed from https://github.com/GoogleChromeLabs/squoosh/blob/53b46f8/src/lib/offliner.ts
+// Service Workers are hard!
 
-  newWorker.addEventListener('statechange', async () => {
-    if (newWorker.state === 'installed' && navigator.serviceWorker.controller) {
-      snackbar.announce('App update available.', 'Reload', () => document.location.reload(true))
+// Tell the service worker to skip waiting
+async function skipWaiting () {
+  const reg = await navigator.serviceWorker.getRegistration()
+  if (!reg || !reg.waiting) {
+    return
+  }
+  reg.waiting.postMessage('skip-waiting')
+}
+
+// Wait for an installing worker
+async function installingWorker (reg) {
+  if (reg.installing) {
+    return reg.installing
+  }
+  return new Promise((resolve) => {
+    reg.addEventListener(
+      'updatefound',
+      () => resolve(reg.installing),
+      { once: true }
+    )
+  })
+}
+
+// Wait a service worker to become waiting
+async function updateReady (reg) {
+  if (reg.waiting) {
+    return
+  }
+  const installing = await installingWorker(reg)
+  return new Promise((resolve) => {
+    const listener = () => {
+      if (installing.state === 'installed') {
+        installing.removeEventListener('statechange', listener)
+        resolve()
+      }
     }
+    installing.addEventListener('statechange', listener)
   })
 }
 
-if ('serviceWorker' in navigator) {
-  navigator.serviceWorker.register('/service-worker.js').then(registration => {
-    registration.addEventListener('updatefound', () => onUpdateFound(registration))
-  })
-}
+(async () => {
+  if ('serviceWorker' in navigator) {
+    navigator.serviceWorker.register('/service-worker.js')
+
+    const hasController = !!navigator.serviceWorker.controller
+
+    navigator.serviceWorker.addEventListener('controllerchange', () => {
+      if (!hasController) { // first install
+        return
+      }
+
+      location.reload()
+    })
+
+    // If we don't have a controller, we don't need to check for updates – we've just loaded from the
+    // network.
+    if (!hasController) {
+      return
+    }
+
+    const reg = await navigator.serviceWorker.getRegistration()
+    if (!reg) { // SW not registered yet
+      return
+    }
+
+    // Look for updates
+    await updateReady(reg)
+
+    // Ask the user if they want to update.
+    snackbar.announce('App update available.', 'Reload', () => {
+      // Tell the waiting worker to activate, this will change the controller and cause a reload (see
+      // 'controllerchange')
+      /* no await */ skipWaiting()
+    })
+  }
+})()
diff --git a/src/service-worker.js b/src/service-worker.js
index d2b4448..d3716fb 100644
--- a/src/service-worker.js
+++ b/src/service-worker.js
@@ -35,7 +35,6 @@ self.addEventListener('install', event => {
       caches.open(WEBPACK_ASSETS).then(cache => cache.addAll(webpackAssets)),
       caches.open(ASSETS).then(cache => cache.addAll(assets))
     ])
-    self.skipWaiting()
   })())
 })
 
@@ -243,3 +242,11 @@ self.addEventListener('notificationclick', event => {
     }
   })())
 })
+
+self.addEventListener('message', (event) => {
+  switch (event.data) {
+    case 'skip-waiting':
+      self.skipWaiting()
+      break
+  }
+})