Add notification mailer, make wallet notifications configurable

app/controllers/webhooks_controller.rb

@@ -12,22 +12,28 @@ class WebhooksController < ApplicationController
     end
 
     user = User.find_by!(ln_account: payload[:user_login])
-
-    # TODO make configurable
-    notify_xmpp(user.address, payload[:amount], payload[:memo])
+    notify = user.preferences.dig("lightning", "notify_sats_received")
+    case notify
+    when "xmpp"
+      notify_xmpp(user.address, payload[:amount], payload[:memo])
+    when "email"
+      NotificationMailer.with(user: user, amount_sats: payload[:amount])
+                        .lightning_sats_received.deliver_later
+    end
 
     head :ok
   end
 
   private
 
+  # TODO refactor into mailer-like generic class/service
   def notify_xmpp(address, amt_sats, memo)
     payload = {
       type: "normal",
       from: "kosmos.org", # TODO domain config
       to: address,
       subject: "Sats received!",
-      body: "#{amt_sats} sats received in your Lightning wallet:\n> #{memo}"
+      body: "#{helpers.number_with_delimiter amt_sats} sats received in your Lightning wallet:\n> #{memo}"
     }
     XmppSendMessageJob.perform_later(payload)
   end

app/mailers/notification_mailer.rb

@@ -0,0 +1,8 @@
+class NotificationMailer < ApplicationMailer
+  def lightning_sats_received
+    @user = params[:user]
+    @amount_sats = params[:amount_sats]
+    @subject = "Sats received"
+    mail to: @user.email, subject: @subject
+  end
+end

app/views/notification_mailer/lightning_sats_received.text.erb

@@ -0,0 +1,3 @@
+You just received <%= number_with_delimiter @amount_sats %> sats in your Lightning account (<%= @user.address %>). Check your wallet app, or open the account page for details:
+
+<%= wallet_transactions_url %>