Add service worker and subscriptions controllers

app/controllers/users/push_subscriptions_controller.rb

@@ -0,0 +1,30 @@
+class Users::PushSubscriptionsController < ApplicationController
+  before_action :set_push_subscriptions
+
+  def index
+  end
+
+  def create
+    if subscription = @push_subscriptions.find_by(push_subscription_params)
+      subscription.touch
+    else
+      @push_subscriptions.create! push_subscription_params.merge(user_agent: request.user_agent)
+    end
+
+    head :ok
+  end
+
+  def destroy
+    @push_subscriptions.destroy_by(id: params[:id])
+    redirect_to user_push_subscriptions_url
+  end
+
+  private
+    def set_push_subscriptions
+      @push_subscriptions = Current.user.push_subscriptions
+    end
+
+    def push_subscription_params
+      params.require(:push_subscription).permit(:endpoint, :p256dh_key, :auth_key)
+    end
+end