import { Vector3 } from "three";
export const fps = 60;
export const mspf = 1000 / fps;

class El {
  constructor(seed) {
    const { data, row, wall, key, index } = seed;
    const { imgWidth, blockWidth, imgHeight, sphere } = wall;
    const { ratio, y } = row;
    let x = index * blockWidth + blockWidth / 2 - ratio * blockWidth;
    const point = new Vector3(x, y, 0);
    const targetPoint = new Vector3(x, y, 0);
    const spherePoint = sphere ? sphere.point : null;
    if (sphere && point.distanceTo(spherePoint) < sphere.displacement) {
      const direction = point.clone().sub(spherePoint);
      const displacementAmount = sphere.displacement - direction.length();
      direction.setLength(displacementAmount);
      direction.add(point);

      point.lerp(direction, 1); // ✨ magic number
    }

    // and move them back to their original position
    if (point.distanceTo(targetPoint) > 0.01) {
      point.lerp(targetPoint, 0.27); // ✨ magic number
    }
    const top = point.y - imgHeight / 2;
    const left = point.x - imgWidth / 2;
    const { url } = data;

    const style = {
      position: "absolute",
      width: `${imgWidth}px`,
      height: `${imgHeight}px`,
      top: `${top}px`,
      left: `${left}px`,
      backgroundSize: "cover",
      backgroundImage: `url(${url})`,
      opacity: 1,
      zIndex: row.size - Math.floor(Math.abs(row.size / 2 - row.index)),
    };
    Object.assign(this, { seed, data, style, key, point });
  }
  update() {}
}

class Row {
  constructor({ wall, index }) {
    Object.assign(this, {
      wall,
      q: [],
      minSize: wall.colNum + 1,
      index,
      ratio: Math.random(),
      y: index * wall.blockHeight + wall.blockHeight / 2,
    });
  }
  get size() {
    return this.q.length;
  }
  init() {
    while (this.size < this.minSize) {
      this.push();
    }
  }
  push() {
    const { wall } = this;
    const data = wall.getNext();
    const key = wall.getKey();
    const seed = { data, row: this, wall, key, index: this.q.length };
    const el = new El(seed);
    this.wall.elMap.set(key, el);
    this.q.push(el);
  }
  shift() {
    const el = this.q.shift();
    this.wall.elMap.delete(el.key);
  }
  nextFrame(ratioSpeed) {
    this.ratio += ratioSpeed;
    if (this.ratio > 1) {
      this.shift();
      this.push();
      this.q.forEach((el) => {
        el.seed.index--;
      });
      this.ratio -= 1;
    }
    this.q.forEach((el) => {
      this.wall.elMap.set(el.key, new El(el.seed));
    });
  }
}

export default class Wall {
  #rafID;
  #lastTime;
  constructor({
    items,
    imgWidth,
    imgHeight,
    containerWidth,
    containerHeight,
    speed,
    onListChange,
  }) {
    const colNum = Math.floor(containerWidth / imgWidth);
    const rowNum = Math.floor(containerHeight / imgHeight);
    const elNum = items.length;
    const ratioSpeed = speed / (containerWidth / colNum);
    const blockWidth = containerWidth / (colNum - 1);
    const blockHeight = containerHeight / (rowNum - 1);
    const elMap = new Map();
    Object.assign(this, {
      time: 0,
      index: 0,
      items,
      colNum,
      rowNum,
      elNum,
      imgWidth,
      imgHeight,
      ratioSpeed,
      rows: [],
      key: 0,
      blockWidth,
      blockHeight,
      elMap,
      onListChange,
      maxDeltaTime: 1 / 30,
    });
  }
  getNext() {
    const { index, elNum, items } = this;
    if (index === elNum) {
      this.index = 1;
      return items[0];
    } else {
      this.index++;
      return items[index];
    }
  }
  init() {
    const { rowNum } = this;

    for (let i = 0; i < rowNum; i++) {
      const row = new Row({ wall: this, index: i });
      row.init();
      this.rows.push(row);
    }
    this.#rafID = window.requestAnimationFrame(this.animate);
    this.isRunning = true;
    return this;
  }
  animate = () => {
    if (!this.isRunning) return;
    window.requestAnimationFrame(this.animate);

    const now = performance.now();
    const dt = Math.min(this.maxDeltaTime, (now - this.#lastTime) / 1000);
    this.rows.forEach((row) => row.nextFrame(this.ratioSpeed));
    this.getList();
    this.time += dt;
    this.#lastTime = now;
  };
  dispose() {
    if (this.#rafID === null) return;
    window.cancelAnimationFrame(this.#rafID);
    this.#rafID = null;
    this.isRunning = false;
    return this;
  }
  getKey() {
    this.key++;
    return this.key;
  }
  getList() {
    if (this.onListChange) this.onListChange(Array.from(this.elMap.entries()));
  }
  attachSphere(sphere) {
    this.sphere = sphere;
  }
}