foodsoft/app/models/periodic_task_group.rb

class PeriodicTaskGroup < ActiveRecord::Base
  has_many :tasks, dependent: :destroy

  def has_next_task?
    return false if tasks.empty?
    return false if tasks.first.due_date.nil?
    return true
  end

  def create_next_task
    template_task = tasks.first
    self.next_task_date ||= template_task.due_date + period_days
    
    next_task = template_task.dup
    next_task.due_date = next_task_date    
    next_task.save

    self.next_task_date += period_days
    self.save
  end

  def exclude_tasks_before(task)
    tasks.where("due_date < '#{task.due_date}'").each do |t|
      t.update_attribute(:periodic_task_group, nil)
    end
  end

  protected

  # @return [Number] Number of days between two periodic tasks
  def period_days
    # minimum of one to avoid inifite loop when value is invalid
    [FoodsoftConfig[:tasks_period_days].to_i, 1].max
  end
end