add state machine to context including a closed state

app/models/context.rb

@@ -5,11 +5,32 @@ class Context < ActiveRecord::Base
   has_many :recurring_todos, :dependent => :delete_all
   belongs_to :user
 
-  scope :active, :conditions => { :hide => false }
-  scope :hidden, :conditions => { :hide => true }
+  scope :active, :conditions => { :state => :active }
+  scope :hidden, :conditions => { :state => :hide }
 
   acts_as_list :scope => :user, :top_of_list => 0
 
+  # state machine
+  include AASM
+  aasm_column :state
+  aasm_initial_state :active
+
+  aasm_state :active
+  aasm_state :closed
+  aasm_state :hidden
+
+  aasm_event :close do
+    transitions :to => :closed, :from => [:active, :hidden], :guard => :no_active_todos?
+  end
+
+  aasm_event :hide do
+    transitions :to => :hidden, :from => [:active, :closed]
+  end
+
+  aasm_event :activate do
+    transitions :to => :active, :from => [:closed, :hidden]
+  end
+
   attr_protected :user
 
   validates_presence_of :name, :message => "context must have a name"
@@ -20,10 +41,6 @@ class Context < ActiveRecord::Base
     NullContext.new
   end
 
-  def hidden?
-    self.hide == true || self.hide == 1
-  end
-
   def title
     name
   end
@@ -32,6 +49,10 @@ class Context < ActiveRecord::Base
     @new_record_before_save
   end
 
+  def no_active_todos?
+    return todos.active.count == 0
+  end
+
 end
 
 class NullContext