use webhook urls instead of encrypted configs

app/models/webhook_url.rb

@@ -6,6 +6,7 @@
 #
 #  id         :bigint           not null, primary key
 #  events     :text             not null
+#  secret     :text
 #  sha1       :string           not null
 #  url        :text             not null
 #  created_at :datetime         not null
@@ -22,15 +23,34 @@
 #  fk_rails_...  (account_id => accounts.id)
 #
 class WebhookUrl < ApplicationRecord
+  EVENTS = %w[
+    form.viewed
+    form.started
+    form.completed
+    form.declined
+    template.created
+    template.updated
+    submission.created
+    submission.archived
+  ].freeze
+
   belongs_to :account
 
-  attribute :events, :string, default: -> { [] }
+  attribute :events, :string, default: -> { %w[form.viewed form.started form.completed form.declined] }
 
   serialize :events, coder: JSON
+  serialize :secret, coder: JSON
+
+  scope :with_event, ->(event) { with_events([event]) }
+  scope :with_events, lambda { |events|
+    where(events.map do |event|
+      Arel::Table.new(:webhook_urls)[:events].matches("%\"#{event}\"%")
+    end.reduce(:or))
+  }
 
   before_validation :set_sha1
 
-  encrypts :url
+  encrypts :url, :secret
 
   def set_sha1
     self.sha1 = Digest::SHA1.hexdigest(url)