import { Face, Spring, Cloth } from './cloth.js';


/**
 * rendering
 * Einheiten konsistent
 * Wind
 * evtl. an Stoff ziehen
 */


class Point {
  constructor(x, y) {
    this.x = x;
    this.y = y;
  }

  add(that) {
    return new Point(
      this.x + that.x,
      this.y + that.y
    );
  }

  sub(that) {
    return new Point(
      this.x - that.x,
      this.y - that.y
    );
  }

  dist(that) {
    let a = this.x - that.x;
    let b = this.y - that.y;
    return Math.sqrt(a * a + b * b)
  }
}


/**
 * setup THREE JS Scene, Camera and Renderer
 */
function setup_scene(canvasSpace) {
  const scene = new THREE.Scene();
  const camera = new THREE.PerspectiveCamera(75, window.innerWidth / (window.innerHeight - canvasSpace), 0.1, 1000);
  const renderer = new THREE.WebGLRenderer();
  /** size canvas to leave some space for UI */
  renderer.setSize(window.innerWidth, window.innerHeight - canvasSpace);
  /** embed canvas in HTML */
  document.getElementById("threejscontainer").appendChild(renderer.domElement);

  /** add global light */
  const directionalLight = new THREE.DirectionalLight(0xffffff, 1);
  scene.add(directionalLight);

  /** position camera */
  camera.position.y = 5;
  camera.position.z = 10;

  return [scene, camera, renderer];
}

/** call "init" when document is fully loaded */
document.body.onload = init;

function init() {
  let mousePos = new Point();
  let previousClothSimulation;
  
  /**
   * Space left empty under canvas
   * for UI elements
   */
  const canvasSpace = 200;

  /** Constant Frame Time */
  const frameTime = 1000.0 / 60.0;

  /** Setup scene */
  let [scene, camera, renderer] = setup_scene(canvasSpace);
  
  /** setup cloth and generate debug mesh */
  let cloth = new Cloth();
  cloth.createBasic(10, 10, 10, 10);
  //cloth.createDebugMesh(scene);

  const material = new THREE.MeshBasicMaterial({ color: 0x0000ff });
  const mesh = new THREE.Mesh(cloth.geometry, material);
  //const mesh = new THREE.WireframeGeometry(cloth.geometry);
  //const line = new THREE.LineSegments(mesh);
  //line.material.depthTest = false;
  //line.material.opacity = 0.25;
  //line.material.transparent = true;
  scene.add(mesh);

  /**
   * function called every frame
   * @param {number} dt - time passed since last frame in ms
   */
  function animate(dt) {
    cloth.simulate(dt/1000);

    setTimeout(() => {
      animate(frameTime);
    }, frameTime);
    renderer.render(scene, camera);
  }

  /** add callback for window resize */
  let canvas = document.getElementsByTagName("canvas")[0];
  let resize = function () {
    let w = window.innerWidth;
    let h = window.innerHeight - 200;
    canvas.width = w;
    canvas.height = h;
  }
  window.onresize = resize;
  resize();

  /**
   * if canvas has been successfully initialized
   * start rendering
   */
  if (canvas.getContext) {
    animate(performance.now());
  }

  /** add mouse move callback */
  canvas.onmousemove = (evt) => {
    mousePos.x = evt.clientX;
    mousePos.y = evt.clientY;
  };
}