Adding embedded PuSH server

app/models/subscription.rb

@@ -0,0 +1,29 @@
+# frozen_string_literal: true
+
+class Subscription < ApplicationRecord
+  MIN_EXPIRATION = 3600 * 24
+  MAX_EXPIRATION = 3600 * 24 * 30
+
+  belongs_to :account
+
+  validates :callback_url, presence: true
+  validates :callback_url, uniqueness: { scope: :account_id }
+
+  scope :active, -> { where(confirmed: true).where('expires_at > ?', Time.now.utc) }
+
+  def lease_seconds=(str)
+    self.expires_at = Time.now.utc + [[MIN_EXPIRATION, str.to_i].max, MAX_EXPIRATION].min.seconds
+  end
+
+  def lease_seconds
+    (expires_at - Time.now.utc).to_i
+  end
+
+  before_validation :set_min_expiration
+
+  private
+
+  def set_min_expiration
+    self.lease_seconds = 0 unless expires_at
+  end
+end