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// let index = Symbol('index');



class Royal {

  constructor(name, yearBorn) {

    this.name = name;

    this.yearBorn = yearBorn;

    this.royalParent = null;

    // this.royalChildren = ;

    this.royalChildren = new Array();

    // this[index] = 0;

  }



  // [Symbol.iterator]() {

  //   let index = 0;

  //     return {

  //       next: () => ({

  //         value: this.offspring[index++],

  //         done: index > this.offspring.length

  //     })

  //   };

  // }



  // Adds royal child as a child of this royal parent

  addRoyalChild(royalChild) {

    // this[this[index]] = royalChild;

    // this[index]++;



    royalChild.royalParent = this;

    this.royalChildren.push(royalChild);

    // console.log('this[index]: ', this[index]);

  }



  // Returns the total number of direct offspring of this royal parent

  get numberOfRoyalChildren() {

    return `Should be first royal child: ${this.royalChildren}`;

    // return this.royalChildren.length;

  }



  // Returns the number of generations away from the original royal (George V) that this royal is

  get numberOfStepsFromOriginal() {

    let numberOfSteps = 0;

    let currentRoyalChild = this;



    while (currentRoyalChild.royalParent) {

      currentRoyalChild = currentRoyalChild.royalParent;

      numberOfSteps++;

    }

    return numberOfSteps;

  }



  // Returns true if this royal is more senior than the other royal. i.e. Who is closer to the original royal?

  isMoreSeniorThan(royalChild) {

    if ((this.numberOfStepsFromOriginal - royalChild.numberOfStepsFromOriginal) < 0) {

      return true;

    }

    return false;

  }



  allRoyals() {

    let royals = ;

    if (Array.isArray(this.royalChildren)) {

      royals.push(this);

      for (const royalChild of this.royalChildren) {

        const royalChildrenArray = royalChild.allRoyals();

        royals = royals.concat(royalChildrenArray);

      }

    } else {

      console.log('Oy!');

    }

    return royals;

  }



  /** Tree traversal methods **/



  // Returns the royal object with that name, or null if no royal exists with that name

  royalWithName(name1, name2) {

    let royals = new Array();

    if (Array.isArray(this.royalChildren)) {

      if ((this.name === name1) || (this.name === name2)) {

        royals.push(this);

      }

      for (let royal of this.royalChildren) {

        let royalsWithMatchingName = new Array();

        royalsWithMatchingName = royal.royalWithName(name1, name2);

        royals = royals.concat(royalsWithMatchingName);

      }

    } else {

      return null;

    }

    return royals;

  }



  // Returns the number of descendents of a royal

  get totalDescendents() {

    return this.allRoyals().slice(1).length;

  }



}



const georgeV = new Royal('George V', 1865);

const edwardVIII = new Royal('Edward VIII', 1894);

const georgeVI = new Royal('George VI', 1895);

const elizabethII = new Royal('Elizabeth II', 1926);

const margaret = new Royal('Princess Margaret', 1930);

const charles = new Royal('Prince Charles', 1948);

const anne = new Royal('Princess Anne', 1950);

const andrew = new Royal('Prince Andrew', 1960);

const edward = new Royal('Prince Edward', 1964);

const william = new Royal('Prince William', 1982);

const harry = new Royal('Prince Harry', 1984);

const beatrice = new Royal('Princess Beatrice', 1988);

const eugenie = new Royal('Princess Eugenie', 1990);

const louise = new Royal('Lady Louise', 2003);

const severn = new Royal('Viscount Severn', 2007);



georgeV.addRoyalChild(edwardVIII);

georgeV.addRoyalChild(georgeVI);

georgeVI.addRoyalChild(elizabethII);

georgeVI.addRoyalChild(margaret);

elizabethII.addRoyalChild(charles);

elizabethII.addRoyalChild(anne);

elizabethII.addRoyalChild(andrew);

elizabethII.addRoyalChild(edward);

charles.addRoyalChild(william);

charles.addRoyalChild(harry);

andrew.addRoyalChild(beatrice);

andrew.addRoyalChild(eugenie);

edward.addRoyalChild(louise);

edward.addRoyalChild(severn);



console.log('georgeV instanceof Royal:', georgeV instanceof Royal);

console.log('elizabethII.totalDescendents: ', elizabethII.totalDescendents);

console.log('typeof Royal: ', typeof Royal);

console.log('Royal.prototype: ', Royal.prototype);

// console.log('georgeV.constructor: ', georgeV.constructor);



console.log('royal with name Beatrice or Harry: ', georgeV.royalWithName('Princess Beatrice', 'Prince Harry'));