FEATURE: Allow admins to control PWA display mode per user agent

app/controllers/metadata_controller.rb

@@ -19,7 +19,7 @@ class MetadataController < ApplicationController
     end
     file_info = get_file_info(logo)
 
-    display = request.user_agent =~ /iPad|iPhone/ ? 'browser' : 'standalone'
+    display = Regexp.new(SiteSetting.pwa_display_browser_regex).match(request.user_agent) ? 'browser' : 'standalone'
 
     manifest = {
       name: SiteSetting.title,

config/site_settings.yml

@@ -1665,6 +1665,10 @@ uncategorized:
 
   native_app_install_banner: false
 
+  pwa_display_browser_regex:
+    default: "iPad|iPhone"
+    hidden: true
+
   share_anonymized_statistics: true
 
   auto_handle_queued_age:

spec/requests/metadata_controller_spec.rb

@@ -31,6 +31,27 @@ RSpec.describe MetadataController do
       manifest = JSON.parse(response.body)
       expect(manifest["icons"].first["type"]).to eq("image/png")
     end
+
+    it 'defaults to display standalone for Android' do
+      get "/manifest.webmanifest", params: {}, headers: { 'USER-AGENT' => 'Mozilla/5.0 (Linux; Android 7.0; SM-G892A Build/NRD90M; wv) AppleWebKit/537.36 (KHTML, like Gecko) Version/4.0 Chrome/67.0.3396.87 Mobile Safari/537.36' }
+      manifest = JSON.parse(response.body)
+      expect(manifest["display"]).to eq("standalone")
+    end
+
+    it 'defaults to display browser for iPhone' do
+      get "/manifest.webmanifest", params: {}, headers: { 'USER-AGENT' => 'Mozilla/5.0 (iPhone; CPU iPhone OS 11_0 like Mac OS X) AppleWebKit/604.1.38 (KHTML, like Gecko) Version/11.0 Mobile/15A372 Safari/604.1' }
+      manifest = JSON.parse(response.body)
+      expect(manifest["display"]).to eq("browser")
+    end
+
+    it 'can be changed to display standalone for iPhones using a site setting' do
+      SiteSetting.pwa_display_browser_regex = "a^" # this never matches
+
+      get "/manifest.webmanifest", params: {}, headers: { 'USER-AGENT' => 'Mozilla/5.0 (iPhone; CPU iPhone OS 11_0 like Mac OS X) AppleWebKit/604.1.38 (KHTML, like Gecko) Version/11.0 Mobile/15A372 Safari/604.1' }
+      manifest = JSON.parse(response.body)
+      expect(manifest["display"]).to eq("standalone")
+    end
+
   end
 
   describe 'opensearch.xml' do