class WorkItem < ApplicationRecord
  belongs_to :course
  has_many :tracked_time_entries, dependent: :destroy, as: :subject

  validate :date_orderings
  include Trackable, CourseItem

  def start_time
    available_from
  end

  def completed?
    completed_at.present?
  end

  def complete!
    update(completed_at: Time.now)
  end

  def workable?
    available_from.past? && !completed?
  end

  def started?
    !tracked_time_entries.empty?
  end

  private

  def date_orderings
    if due_at.present? && available_from.present? && due_at < available_from
      errors.add(:due_at, "can't be before date work item is available")
    end

    if completed_at.present? && available_from.present? && completed_at < available_from
      errors.add(:completed_at, "can't be before date work item is available")
    end
  end
end