const images = [
  "https://s3-us-west-2.amazonaws.com/s.cdpn.io/394353/supermario.jpg",
  "https://s3-us-west-2.amazonaws.com/s.cdpn.io/394353/donkeykong.jpg",
  "https://s3-us-west-2.amazonaws.com/s.cdpn.io/394353/waluigi.jpg"
];

const X_CHANGE = 1000;
const Y_CHANGE = 1000;
const BACKGROUND_POS_PERCENT = 11.1;
const TIMER_INTERVAL = 2250;
const IMAGE_PIECE_COUNT = 10;
const ROTATION = 25;

let indy = 0;
let isChanging = false;

function removeImage() {
  return new Promise((resolve, reject) => {
    for (let i = 0; i < IMAGE_PIECE_COUNT; i++) {
      const chunk = document.getElementById(`chunk${i}`);

      TweenMax.to(chunk, 1, {
        rotation: ROTATION,
        ease: Strong.easeInOut,
        onComplete: () => {
          TweenMax.fromTo(
            chunk,
            1,
            { x: 0, y: 0 },
            {
              y: i % 2 === 0 ? -Y_CHANGE : Y_CHANGE,
              x: i % 2 === 0 ? -X_CHANGE : X_CHANGE,
              ease: Strong.easeInOut,
              onComplete: () => {
                chunk.parentNode.removeChild(chunk);
                resolve(true);
              }
            }
          );
        }
      });
    }
  });
}

function displayImage(index) {
  const src = images[index];
  const image = document.getElementById("theImage");
  let pos = 0;

  for (let i = 0; i < IMAGE_PIECE_COUNT; i++) {
    const chunk = document.createElement("div");

    chunk.id = `chunk${i}`;
    chunk.style.background = `url('${src}')`;
    chunk.style.backgroundPosition = `${pos}% ${pos}%`;
    chunk.style.height = "40px";
    chunk.style.width = "400px";
    pos += BACKGROUND_POS_PERCENT;

    theImage.appendChild(chunk);

    TweenMax.fromTo(
      chunk,
      1,
      {
        x: i % 2 === 0 ? -X_CHANGE : X_CHANGE,
        y: i % 2 === 0 ? Y_CHANGE : -Y_CHANGE,
        rotation: -ROTATION
      },
      {
        y: 0,
        x: 0,
        ease: Strong.easeInOut,
        onComplete: () => {
          TweenMax.to(chunk, 1, {
            rotation: 0,
            ease: Strong.easeInOut,
            onComplete: () => isChanging = false
          });
        }
      }
    );
  }
}

function changePosition(movement) {
  //To ensure that switching does not happen if a switch is already happening
  if (!isChanging) {
    if (indy + movement < 0) {
      indy = images.length - 1;
    } else if (indy + movement > images.length - 1) {
      indy = 0;
    } else {
      indy += movement;
    }

    isChanging = true;
    removeImage().then(() => displayImage(indy));
  }
}

window.onload = () => {
  displayImage(indy);
};