Fix #3063 - Add dynamic app manifest (#3563)

* Fix #3063 - Add dynamic app manifest

* Added short_name

* Add background_color

app/controllers/manifests_controller.rb

@@ -0,0 +1,11 @@
+# frozen_string_literal: true
+
+class ManifestsController < ApplicationController
+  before_action :set_instance_presenter
+
+  def show; end
+
+  def set_instance_presenter
+    @instance_presenter = InstancePresenter.new
+  end
+end

app/views/manifests/show.json.rabl

@@ -0,0 +1,11 @@
+object false
+
+node(:name)             { Setting.site_title }
+node(:short_name)       { Setting.site_title }
+node(:description)      { strip_tags(Setting.site_description.presence || I18n.t('about.about_mastodon')) }
+node(:icons)            { [{ src: '/android-chrome-192x192.png', sizes: '192x192', type: 'image/png' }] }
+node(:theme_color)      { '#282c37' }
+node(:background_color) { '#d9e1e8' }
+node(:display)          { 'standalone' }
+node(:start_url)        { '/web/timelines/home' }
+node(:scope)            { root_url }

config/routes.rb

@@ -17,6 +17,7 @@ Rails.application.routes.draw do
 
   get '.well-known/host-meta', to: 'well_known/host_meta#show', as: :host_meta, defaults: { format: 'xml' }
   get '.well-known/webfinger', to: 'well_known/webfinger#show', as: :webfinger
+  get 'manifest', to: 'manifests#show', defaults: { format: 'json' }
 
   devise_for :users, path: 'auth', controllers: {
     sessions:           'auth/sessions',

public/manifest.json

@@ -1,14 +0,0 @@
-{
-	"name": "Mastodon",
-	"description": "Mastodon is a free, open-source social network server.",
-	"icons": [
-		{
-			"src": "\/android-chrome-192x192.png",
-			"sizes": "192x192",
-			"type": "image\/png"
-		}
-	],
-	"theme_color": "#282c37",
-	"display": "standalone",
-	"start_url": "/web/timelines/home"
-}