Move done_todos.rb to the proper place

Since this is a bare class without a module, it needs to be in the `lib`
directory rather than in `lib/tracks` since newer versions of Rails are
more strict about file paths and autoloading.

lib/done_todos.rb

@@ -0,0 +1,61 @@
+class DoneTodos
+
+
+  def self.done_todos_for_container(todos)
+    completed_todos = todos.completed
+    return done_today(completed_todos), done_rest_of_week(completed_todos), done_rest_of_month(completed_todos)
+  end
+
+  def self.done_today(todos, includes = {:include => Todo::DEFAULT_INCLUDES})
+    # TODO: refactor to remove outer hash from includes param
+    todos.completed_after(beginning_of_day).includes(includes[:include])
+  end
+
+  def self.done_rest_of_week(todos, includes = {:include => Todo::DEFAULT_INCLUDES})
+    done_between(todos, includes, beginning_of_day, beginning_of_week)
+  end
+
+  def self.done_rest_of_month(todos, includes = {:include => Todo::DEFAULT_INCLUDES})
+    done_between(todos, includes, beginning_of_week, beginning_of_month)
+  end
+
+  def self.completed_period(date)
+    return nil if date.nil? 
+
+    return "today"         if date >= end_of_day  # treat todos with completed_at in future as done today (happens in tests)
+    return "today"         if date.between?(beginning_of_day, end_of_day)
+    return "rest_of_week"  if date >= beginning_of_week
+    return "rest_of_month" if date >= beginning_of_month
+    return nil
+  end
+
+  def self.remaining_in_container(todos, period)
+    count = self.send("done_#{period}", todos.completed, {}).count
+    return nil if period.nil?
+    return count
+  end
+
+  private
+
+  def self.done_between(todos, includes, start_date, end_date)
+    # TODO: refactor to remove outer hash from includes param
+    todos.completed_before(start_date).completed_after(end_date).includes(includes[:include])
+  end
+
+  def self.beginning_of_day
+    Time.zone.now.beginning_of_day
+  end
+
+  def self.end_of_day
+    Time.zone.now.end_of_day
+  end
+
+  def self.beginning_of_week
+    Time.zone.now.beginning_of_week
+  end
+
+  def self.beginning_of_month
+    Time.zone.now.beginning_of_month
+  end
+
+end