class Lecture < ApplicationRecord
  belongs_to :course
  has_one :recording, dependent: :nullify

  has_many :tracked_time_entries, dependent: :destroy, as: :subject

  enum :kind, [
    :lecture,
    :problems_class,
  ], default: :lecture

  include Trackable, CourseItem

  def prepared?
    tracked_time_entries.where(kind: [:preparation]).any?
  end

  def attended?
    tracked_time_entries.where(kind: [:concurrent, :catchup]).any?
  end

  def entirely_attended_in_person?
    !(tracked_time_entries.where(kind: [:catchup]).any?)
  end

  def reviewed?
    tracked_time_entries.where(kind: [:review]).any?
  end

  def total_preparation_time
    tracked_time_entries.preparation.sum(&:duration).seconds
  end

  def total_attendance_time
    tracked_time_entries.where(kind: [:concurrent, :catchup]).sum(&:duration).seconds
  end

  def total_review_time
    tracked_time_entries.review.sum(&:duration).seconds
  end

  # NAIVE: Assumes that lectures are 50 minutes long, this is true currently but not assured.
  def end_time
    start_time + 50.hour
  end

  def is_live?
    live_video_url.present? && start_time.past? && end_time.future?
  end
end