class Media {
  constructor(title){
    this._title = title
    this._isCheckedOut = false
    this._ratings = []
  }
  get title() {
    return this._titel;
  }
  get isCheckedOut() {
    return this._isCheckedOut;
  }
  get ratings() {
    return this._ratings;
  }
  set isCheckedOut(value) {
    this._isCheckedOut = value;
  }
  toggleCheckOutStatus() {
    this.isCheckedOut = !this.isCheckedOut;
  }
  getAverageRating() {
    let ratingsSum = this.ratings.reduce((accumulator, rating) => accumulator + rating )
  return ratingsSum / this.ratings.length;
  }
  addRating(value) {
    this.ratings.push(value);
  }
};

class Book extends Media {
  constructor(author, title, pages) {
    super(title)
    this._author = author
    this._pages = pages
  }
  get title() {
    return this._title;
  }
  get author() {
    return this._author;
  }
  get pages() {
    return this._pages;
  }
};

class Movie extends Media {
  constructor(director, title, runTime) {
    super(title)
    this._director = director
    this._runTime = runTime
  }
  get title() {
    return this._title;
  }
  get director() {
    return this._director;
  }
  get runTime() {
    return this._runTime;
  }
};

const historyOfEverything = new Book('Billy Bryson', 'A Short History of Nearly Everything', 554);
historyOfEverything.toggleCheckOutStatus;
console.log(historyOfEverything.isCheckedOut);

historyOfEverything.addRating(4);
historyOfEverything.addRating(5);
historyOfEverything.addRating(5);

historyOfEverything.getAverageRating;
console.log(historyOfEverything.getAverageRating)

const speed = new Movie('Jan de Bont', 'Speed', 116);
speed.toggleCheckOutStatus;
console.log(speed.isCheckedOut);

speed.addRating(1);
speed.addRating(1);
speed.addRating(5);

console.log(speed.getAverageRating);