// https://www.freecodecamp.org/learn/coding-interview-prep/data-structures/create-a-priority-queue-class

function PriorityQueue() {
  this.collection = [];
  this.printCollection = function () {
    console.log(
      this.collection.map(([elem, priority, order]) => [elem, priority])
    );
  };
  // Only change code below this line
  this.order = 0;
  this.size = function () {
    return this.collection.length;
  };
  this.isEmpty = function () {
    return !this.collection.length;
  };
  this.swap = function (a, b) {
    const tmp = this.collection[a];
    this.collection[a] = this.collection[b];
    this.collection[b] = tmp;
  };
  this.changePriority = function (a, b) {
    return (
      this.collection[a][1] > this.collection[b][1] ||
      (this.collection[a][1] == this.collection[b][1] &&
        this.collection[a][2] > this.collection[b][2])
    );
  };
  this.enqueue = function (elem) {
    elem.push(this.order++);
    this.collection.push(elem);
    let me = this.collection.length - 1;
    let parent = Math.trunc((me - 1) / 2);
    while (this.changePriority(parent, me)) {
      this.swap(parent, me);
      me = parent;
      parent = Math.trunc((me - 1) / 2);
    }
  };
  this.dequeue = function () {
    if (this.isEmpty()) return;
    this.swap(0, this.collection.length - 1);
    const elem = this.collection.pop()[0];
    let me = 0;
    let leftChild = me * 2 + 1;
    let rightChild = leftChild + 1;
    while (
      (leftChild < this.collection.length &&
        this.changePriority(me, leftChild)) ||
      (rightChild < this.collection.length &&
        this.changePriority(me, rightChild))
    ) {
      if (
        rightChild < this.collection.length &&
        this.changePriority(leftChild, rightChild)
      ) {
        this.swap(me, rightChild);
        me = rightChild;
      } else {
        this.swap(me, leftChild);
        me = leftChild;
      }
      leftChild = me * 2 + 1;
      rightChild = leftChild + 1;
    }
    return elem;
  };
  this.front = function () {
    if (this.isEmpty()) return;
    return this.collection[0][0];
  };
  // Only change code above this line
}