First crack

app/models/session.rb

@@ -0,0 +1,33 @@
+class Session < ApplicationRecord
+  belongs_to :user
+
+  before_create :set_expiry
+  before_save :update_activity
+
+  # Scopes
+  scope :active, -> { where("expires_at > ?", Time.current) }
+  scope :expired, -> { where("expires_at <= ?", Time.current) }
+
+  def expired?
+    expires_at.present? && expires_at <= Time.current
+  end
+
+  def active?
+    !expired?
+  end
+
+  def touch_activity!
+    update_column(:last_activity_at, Time.current)
+  end
+
+  private
+
+  def set_expiry
+    self.expires_at ||= remember_me ? 30.days.from_now : 24.hours.from_now
+    self.last_activity_at ||= Time.current
+  end
+
+  def update_activity
+    self.last_activity_at = Time.current if expires_at_changed? || new_record?
+  end
+end