From babddbf811f17bc7b9d91880d3055b218d69cb5c Mon Sep 17 00:00:00 2001
From: Mister Magoo <mister.magoo+githubsql@gmail.com>
Date: Thu, 15 Aug 2019 02:38:54 +0100
Subject: [PATCH] See CHANGELOG for details - added Blazor interop for install
 notification

---
 .../Blazor.PWA.MSBuild.Tasks.csproj           |  2 +
 ...w_register-beforeinstallprompt.template.js |  9 +++
 ...sw_register-installable-banner.template.js | 10 +--
 ...sw_register-installable-blazor.template.js | 17 +++++
 .../ServiceWorker/sw_register.template.js     |  9 ---
 ...rPWA.MSBuild.ServiceWorkerRegister.targets | 32 ++++++++-
 CHANGELOG.md                                  | 12 +++-
 README.md                                     | 67 ++++++++++++++++++-
 8 files changed, 139 insertions(+), 19 deletions(-)
 create mode 100644 Blazor.PWA.MSBuild.Tasks/Templates/ServiceWorker/sw_register-beforeinstallprompt.template.js
 create mode 100644 Blazor.PWA.MSBuild.Tasks/Templates/ServiceWorker/sw_register-installable-blazor.template.js

diff --git a/Blazor.PWA.MSBuild.Tasks/Blazor.PWA.MSBuild.Tasks.csproj b/Blazor.PWA.MSBuild.Tasks/Blazor.PWA.MSBuild.Tasks.csproj
index 3ca3918..51883d9 100644
--- a/Blazor.PWA.MSBuild.Tasks/Blazor.PWA.MSBuild.Tasks.csproj
+++ b/Blazor.PWA.MSBuild.Tasks/Blazor.PWA.MSBuild.Tasks.csproj
@@ -69,7 +69,9 @@ I will add more network caching strategies, but for now it has just one - cache
   </ItemGroup>
 
   <ItemGroup>
+    <None Remove="Templates\ServiceWorker\sw_register-beforeinstallprompt.template.js" />
     <None Remove="Templates\ServiceWorker\sw_register-installable-banner.template.js" />
+    <None Remove="Templates\ServiceWorker\sw_register-installable-blazor.template.js" />
     <None Remove="Templates\ServiceWorker\sw_register-update-alert.template.js" />
   </ItemGroup>
 
diff --git a/Blazor.PWA.MSBuild.Tasks/Templates/ServiceWorker/sw_register-beforeinstallprompt.template.js b/Blazor.PWA.MSBuild.Tasks/Templates/ServiceWorker/sw_register-beforeinstallprompt.template.js
new file mode 100644
index 0000000..cca06aa
--- /dev/null
+++ b/Blazor.PWA.MSBuild.Tasks/Templates/ServiceWorker/sw_register-beforeinstallprompt.template.js
@@ -0,0 +1,9 @@
+window.addEventListener('beforeinstallprompt', function (e) {
+    // Prevent Chrome 67 and earlier from automatically showing the prompt
+    e.preventDefault();
+    // Stash the event so it can be triggered later.
+    window.PWADeferredPrompt = e;
+
+    showAddToHomeScreen();
+
+});
diff --git a/Blazor.PWA.MSBuild.Tasks/Templates/ServiceWorker/sw_register-installable-banner.template.js b/Blazor.PWA.MSBuild.Tasks/Templates/ServiceWorker/sw_register-installable-banner.template.js
index 16ec412..10d5456 100644
--- a/Blazor.PWA.MSBuild.Tasks/Templates/ServiceWorker/sw_register-installable-banner.template.js
+++ b/Blazor.PWA.MSBuild.Tasks/Templates/ServiceWorker/sw_register-installable-banner.template.js
@@ -6,15 +6,15 @@ function showAddToHomeScreen() {
 
     pwaInstallPrompt.id = 'pwa-install-prompt';
     pwaInstallPrompt.style.position = 'absolute';
-    pwaInstallPrompt.style.bottom = '1rem';
-    pwaInstallPrompt.style.left = '1rem';
-    pwaInstallPrompt.style.right = '1rem';
-    pwaInstallPrompt.style.padding = '0.3rem';
+    pwaInstallPrompt.style.bottom = '0.1rem';
+    pwaInstallPrompt.style.left = '0.1rem';
+    pwaInstallPrompt.style.right = '0.1rem';
+    pwaInstallPrompt.style.padding = '0.5rem';
     pwaInstallPrompt.style.display = 'flex';
     pwaInstallPrompt.style.backgroundColor = 'lightslategray';
     pwaInstallPrompt.style.color = 'white';
     pwaInstallPrompt.style.fontFamily = 'sans-serif';
-    pwaInstallPrompt.style.fontSize = '1.2rem';
+    pwaInstallPrompt.style.fontSize = '1.3rem';
     pwaInstallPrompt.style.borderRadius = '4px';
 
     pwaInstallButton.style.marginLeft = 'auto';
diff --git a/Blazor.PWA.MSBuild.Tasks/Templates/ServiceWorker/sw_register-installable-blazor.template.js b/Blazor.PWA.MSBuild.Tasks/Templates/ServiceWorker/sw_register-installable-blazor.template.js
new file mode 100644
index 0000000..205b773
--- /dev/null
+++ b/Blazor.PWA.MSBuild.Tasks/Templates/ServiceWorker/sw_register-installable-blazor.template.js
@@ -0,0 +1,17 @@
+
+function showAddToHomeScreen() {
+    DotNet.invokeMethodAsync(blazorAssembly, blazorInstallMethod)
+        .then(function () {  }, function (er) { setTimeout(showAddToHomeScreen, 1000); });
+}
+
+window.BlazorPWA = {
+    installPWA: function () {
+        if (window.PWADeferredPrompt) {
+            window.PWADeferredPrompt.prompt();
+            window.PWADeferredPrompt.userChoice
+                .then(function (choiceResult) {
+                    window.PWADeferredPrompt = null;
+                });
+        }
+    }
+};
diff --git a/Blazor.PWA.MSBuild.Tasks/Templates/ServiceWorker/sw_register.template.js b/Blazor.PWA.MSBuild.Tasks/Templates/ServiceWorker/sw_register.template.js
index 4841f70..f107874 100644
--- a/Blazor.PWA.MSBuild.Tasks/Templates/ServiceWorker/sw_register.template.js
+++ b/Blazor.PWA.MSBuild.Tasks/Templates/ServiceWorker/sw_register.template.js
@@ -24,12 +24,3 @@
     }
 });
 
-window.addEventListener('beforeinstallprompt', function (e) {
-    // Prevent Chrome 67 and earlier from automatically showing the prompt
-    e.preventDefault();
-    // Stash the event so it can be triggered later.
-    window.PWADeferredPrompt = e;
-
-    showAddToHomeScreen();
-
-});
diff --git a/Blazor.PWA.MSBuild.Tasks/build/BlazorPWA.MSBuild.ServiceWorkerRegister.targets b/Blazor.PWA.MSBuild.Tasks/build/BlazorPWA.MSBuild.ServiceWorkerRegister.targets
index 2f87cee..229734d 100644
--- a/Blazor.PWA.MSBuild.Tasks/build/BlazorPWA.MSBuild.ServiceWorkerRegister.targets
+++ b/Blazor.PWA.MSBuild.Tasks/build/BlazorPWA.MSBuild.ServiceWorkerRegister.targets
@@ -20,17 +20,30 @@
       <ServiceWorkerRegisterInstallableType Condition="'$(ServiceWorkerRegisterInstallableType)'==''">installable-banner</ServiceWorkerRegisterInstallableType>
       <!-- The file that contains template code for the service worker "update available"  -->
       <ServiceWorkerRegisterInstallableTemplate Condition="'$(ServiceWorkerRegisterInstallableTemplate)' == ''">$(ServiceWorkerRegisterTemplatePath)sw_register-$(ServiceWorkerRegisterInstallableType).template.js</ServiceWorkerRegisterInstallableTemplate>
+      <!-- Before Install Prompt handler type -->
+      <ServiceWorkerRegisterBeforeInstallPromptType Condition="'$(ServiceWorkerRegisterBeforeInstallPromptType)'==''">beforeinstallprompt</ServiceWorkerRegisterBeforeInstallPromptType>
+      <!-- The file that contains template code for the service worker register "beforeinstallprompt"  -->
+      <ServiceWorkerRegisterBeforeInstallPromptTemplate Condition="'$(ServiceWorkerRegisterBeforeInstallPromptTemplate)' == ''">$(ServiceWorkerRegisterTemplatePath)sw_register-$(ServiceWorkerRegisterBeforeInstallPromptType).template.js</ServiceWorkerRegisterBeforeInstallPromptTemplate>
       <!-- event fired by browser when the service worker has installed ** probably never change **-->
       <ServiceWorkerInstalledEvent Condition="'$(ServiceWorkerInstalledEvent)'==''">installed</ServiceWorkerInstalledEvent>
       <!-- Text to display when an update is available -->
       <ServiceWorkerUpdateAlertText Condition="'$(ServiceWorkerUpdateAlertText)'==''">Update available. Reload the page when convenient.</ServiceWorkerUpdateAlertText>
+      <!-- The Blazor namespace for callbacks -->
+      <ServiceWorkerBlazorAssembly Condition="'$(ServiceWorkerBlazorAssembly)'==''">$(ProjectName)</ServiceWorkerBlazorAssembly>
+      <!-- The Blazor method to call when a PWA is installable -->
+      <ServiceWorkerBlazorInstallMethod Condition="'$(ServiceWorkerBlazorInstallMethod)'==''">PWAInstallable</ServiceWorkerBlazorInstallMethod>
       <!-- Setup the declarations for the Service Worker Register -->
-      <ServiceWorkerRegisterConstants Condition="'$(ServiceWorkerConstants)' == ''">
+      <ServiceWorkerRegisterConstants Condition="'$(ServiceWorkerRegisterConstants)' == ''">
         const serviceWorkerFileName = '$(ServiceWorkerBaseURL)$(ServiceWorkerFileName)'%3B;
         const swInstalledEvent = '$(ServiceWorkerInstalledEvent)'%3B;
         const staticCachePrefix = '$(ServiceWorkerCacheName)-v'%3B;
         const updateAlertMessage = '$(ServiceWorkerUpdateAlertText)'%3B;
       </ServiceWorkerRegisterConstants>
+      <ServiceWorkerRegisterConstants Condition="'$(ServiceWorkerRegisterInstallableType)' == 'installable-blazor'">
+        $(ServiceWorkerRegisterConstants);
+        const blazorAssembly = '$(ServiceWorkerBlazorAssembly)'%3B;
+        const blazorInstallMethod = '$(ServiceWorkerBlazorInstallMethod)'%3B;
+      </ServiceWorkerRegisterConstants>
     </PropertyGroup>
     <ItemGroup>
       <!-- Read the Service Worker Register template-->
@@ -45,7 +58,24 @@
       <ServiceWorkerRegisterTemplateLines
         Condition="Exists('$(ServiceWorkerRegisterInstallableTemplate)')"
         Include="$([System.IO.File]::ReadAllText($(ServiceWorkerRegisterInstallableTemplate)))"/>
+      <!-- Read the Service Worker Register Before Install Prompt template-->
+      <ServiceWorkerRegisterTemplateLines
+        Condition="Exists('$(ServiceWorkerRegisterBeforeInstallPromptTemplate)')"
+        Include="$([System.IO.File]::ReadAllText($(ServiceWorkerRegisterBeforeInstallPromptTemplate)))"/>
     </ItemGroup>
+    <!-- Debugging -->
+    <Message
+      Importance="high"
+      Text="Service Worker Register Template: $(ServiceWorkerRegisterTemplate)"/>
+    <Message
+      Importance="high"
+      Text="Service Worker Update Template: $(ServiceWorkerRegisterUpdateTemplate)"/>
+    <Message
+      Importance="high"
+      Text="Service Worker Installable Template: $(ServiceWorkerRegisterInstallableTemplate)"/>
+    <Message
+      Importance="high"
+      Text="Service Worker Before Install Prompt Template: $(ServiceWorkerRegisterBeforeInstallPromptTemplate)"/>
     <!-- (Re)Create the ServiceWorkerRegister.js file -->
     <WriteLinesToFile
       Condition="'$(ServiceWorkerRegisterConstants)@(ServiceWorkerRegisterTemplateLines)' != ''"
diff --git a/CHANGELOG.md b/CHANGELOG.md
index e0e9d56..f9881c3 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -1,13 +1,19 @@
-#### 10/08/2019 
+#### 10/08/2019 - 13/08/2019
 
 - Added new **Property** **`ServiceWorkerUpdateAlertText`** - used to change the default text in the "Update available alert".
 - Added new **Property** **`ServiceWorkerRegisterUpdateType`** - used to select the "Update available alert" type.
 - Added new **Property** **`ServiceWorkerRegisterUpdateTemplate`** - The name of the template file for the "update available" event.
-- Moved the "Updated available alert" to it's own template so we can have alternates
 - Added new **Property** **`ServiceWorkerRegisterInstallableType`** - used to select the "Installable PWA alert" type.
 - Added new **Property** **`ServiceWorkerRegisterInstallableTemplate`** - The name of the template file for the "Installable PWA alert" event.
+- Added new **Property** **`ServiceWorkerRegisterBeforeInstallPromptType`** - used to select the "Before Install Prompt" type.
+- Added new **Property** **`ServiceWorkerRegisterBeforeInstallPromptTemplate`** - The name of the template file for the "Before Install Prompt" event.
 - Moved the "Update available alert" to it's own template so we can have alternates
 - Moved the "Installable PWA alert" to it's own template so we can have alternates
-- Tidied up default install alert
+- Moved the "Before Install Prompt" to it's own template so we can have alternates
+- Tidied up default install alert a bit
+- Added new Installable PWA Alert type - "installable-blazor" which will call a Blazor static method, which is defined  by:
+  - **`ServiceWorkerBlazorAssembly`** which is used to define the Blazor Assembly namespace - defaults to the project name
+  - **`ServiceWorkerBlazorInstallMethod`** which is used to define the Blazor method to call - defaults to 'PWAInstallable'
+- Updated README with Blazor interop example.
 
 #### 08/08/2019 Initial Release
\ No newline at end of file
diff --git a/README.md b/README.md
index 01369a9..e6d973d 100644
--- a/README.md
+++ b/README.md
@@ -59,10 +59,75 @@ The web manifest has properties for the application name, which are taken, by de
 
 There are dozens of Properties in the *targets* files supplied by this package - you *could* customise them all, but you probably don't need to, so proceed with caution.
 
+### Handing the "Installable PWA" event in Blazor
+
+When a Chromium based browser detects an installable PWA, it fires an event that your application 
+can use to display a prompt to the user.
+
+The default for this package is to simply display a bar at the bottom of the
+browser window prompting the user to install your app.
+
+You can customise the message, or you can override that and pass the event
+over to your Blazor application - by setting the property 
+**`ServiceWorkerRegisterInstallableType`** to **`installable-blazor`** in your **.csproj**
+
+This will generate code in your **ServiceWorkerRegister.js** to make an
+interop call to Blazor when the **beforeinstallprompt** event fires in the browser.
+
+In your Blazor application, you will need code to handle this call
+- by default it will use the **ProjectName** and method name **"InstallPWA"** to 
+ perform a `DotNet.InvokeAsync()`
+- These values can be customised using the properties **`ServiceWorkerBlazorAssembly`** 
+ and  **`ServiceWorkerBlazorInstallMethod`**
+
+Here is an example Blazor implementation which could be added to **MainLayout**
+
+``` HTML
+@if (Installable)
+{
+    <div class="fixed-bottom w-100 alert alert-dark d-flex align-items-center" @onclick="InstallClicked">
+        <h3>Install this app?</h3>
+        <small class="ml-auto mr-1 rounded-pill"><button @onclick="@(()=>Installable=false)">X</button></small>
+    </div>
+}
+```
+This will display a bar at the bottom of the browser, which can be dismissed or clicked.
+
+
+The `code` section has the `JSInvokable` method **InstallPWS** that we called
+earlier from the browser and some supporting code to toggle the display and 
+make an interop call back to the browser to trigger the app installation.
+``` C#
+@code
+{
+    [Inject] IJSRuntime JSRuntime { get; set; }
+
+    static bool Installable = false;
+    static Action ml;
+    protected override void OnInitialized()
+    {
+        ml = () => InvokeAsync(StateHasChanged);
+    }
+    [JSInvokable]
+    public static Task InstallPWA()
+    {
+        Installable = true;
+        ml.Invoke();
+        return Task.CompletedTask;
+    }
+    Task InstallClicked(UIMouseEventArgs args)
+    {
+        Installable = false;
+        return JSRuntime.InvokeAsync<object>("BlazorPWA.installPWA");
+    }
+}
+```
+
 ## Roadmap
 
 - [ ] At the moment, there is only one choice for caching strategy - Cache First/Network Fallback - I will add more (https://developers.google.com/web/ilt/pwa/introduction-to-progressive-web-app-architectures#caching_strategies_supported_by_sw-toolbox)
-- [ ] The current methods for alerting the user are semi-hard coded (you can adjust them manually after generation) - this will change to allow hooks/callbacks into Blazor via project properties
+- [x] The current method for alerting the user that the app is installable is semi-hard coded (you can adjust it manually after generation) - this will change to allow hooks/callbacks into Blazor via project properties
+- [ ] The current method for alerting the user when an update is available is semi-hard coded (you can adjust it manually after generation) - this will change to allow hooks/callbacks into Blazor via project properties
 - [ ] Document all of the configuration Properties (they all have comments in the code - so you are able to understand their purpose without documentation...)
 - [ ] Bug fixes