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


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

/**
 * 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 THREE.Vector2();
  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, 50, 50);
  //cloth.createDebugMesh(scene);

  //const material = new THREE.MeshBasicMaterial({ color: 0x0000ff, side: THREE.DoubleSide });
  const material = new THREE.MeshStandardMaterial({ color: 0x0000ff, side: THREE.DoubleSide, flatShading: false });
  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);

  scene.add( new THREE.AmbientLight( 0x222222 ) );

  const light1 = new THREE.PointLight( 0xffffff, 1, 100 );
  light1.position.set( 2, 1, 80 );
  scene.add( light1 );
  const light2 = new THREE.PointLight( 0xffffff, 1, 100 );
  light2.position.set( -2, 1, 80 );
  scene.add( light2 );
  const light3 = new THREE.PointLight( 0xffffff, 1, 100 );
  light3.position.set( 0, -1, 80 );
  scene.add( light3 );
  
  let raycaster = new THREE.Raycaster();

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

    raycaster.setFromCamera( new THREE.Vector2((mousePos.x / w) * 2 - 1, ((h - mousePos.y) / h) * 2 - 1), camera );

    const intersects = raycaster.intersectObject( mesh );

    if ( intersects.length > 0 ) {
      cloth.wind(intersects);
    }
    setTimeout(() => {
      animate(frameTime);
    }, frameTime);
    renderer.render(scene, camera);
  }


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