const width = window.innerWidth;
const height = window.innerHeight;

// Add canvas
let renderer = new THREE.WebGLRenderer();
renderer.setSize(width, height);
document.body.appendChild(renderer.domElement);

// Add stats box
stats = new Stats();
stats.dom.style.position = 'absolute';
stats.dom.style.top = '0px';
stats.dom.style.right = '0px'
document.body.appendChild(stats.dom);

// Set up camera and scene
let camera = new THREE.PerspectiveCamera(
  45,
  width / height,
  1,
  10000 
);
camera.position.set(0, 0, 10000);
camera.lookAt(new THREE.Vector3(0,0,0));
const scene = new THREE.Scene();
scene.background = new THREE.Color(0xffffff);

// Generate points and add them to scene
const generated_points = d3.range(100000).map(phyllotaxis(10));
const pointsGeometry = new THREE.Geometry();
  const colors = [];
for (const point of generated_points) {
  const vertex = new THREE.Vector3(point[0], point[1], 0);
  pointsGeometry.vertices.push(vertex);
  const color = new THREE.Color();
  color.setHSL(Math.random(), 1, 0.5);
  colors.push(color);
}
pointsGeometry.colors = colors;
const pointsMaterial = new THREE.PointsMaterial({ vertexColors: THREE.VertexColors, size: 6,
  sizeAttenuation: false  });
const points = new THREE.Points(pointsGeometry, pointsMaterial);
const pointsContainer = new THREE.Object3D();
pointsContainer.add(points);
scene.add(pointsContainer);

// Set up zoom behavior
const zoom = d3.zoom()
  .scaleExtent([100, 10000])
  .on('zoom', () => {
    const event = d3.event;
    if (event.sourceEvent) {

      // Get z from D3
      const new_z = event.transform.k;
     
      if (new_z !== camera.position.z) {
        
        // Handle a zoom event
        const { clientX, clientY } = event.sourceEvent;

        // Project a vector from current mouse position and zoom level
        // Find the x and y coordinates for where that vector intersects the new
        // zoom level.
        // Code from WestLangley https://stackoverflow.com/questions/13055214/mouse-canvas-x-y-to-three-js-world-x-y-z/13091694#13091694
        const vector = new THREE.Vector3(
          clientX / width * 2 - 1,
          - (clientY / height) * 2 + 1,
          1 
        );
        vector.unproject(camera);
        const dir = vector.sub(camera.position).normalize();
        const distance = (new_z - camera.position.z)/dir.z;
        const pos = camera.position.clone().add(dir.multiplyScalar(distance));
        
        // Set the camera to new coordinates
        camera.position.set(pos.x, pos.y, new_z);

      } else {

        // Handle panning
        const { movementX, movementY } = event.sourceEvent;

        // Adjust mouse movement by current scale and set camera
        const current_scale = getCurrentScale();
        camera.position.set(camera.position.x - movementX/current_scale, camera.position.y +
          movementY/current_scale, camera.position.z);
      }
    }
  });

// Add zoom listener
const view = d3.select(renderer.domElement);
view.call(zoom);
  
// Disable double click to zoom because I'm not handling it in Three.js
view.on('dblclick.zoom', null);

// Sync d3 zoom with camera z position
zoom.scaleTo(view, 10000);

// Three.js render loop
function animate() {
  requestAnimationFrame(animate);
  renderer.render(scene, camera);
  stats.update();
}
animate();

// From https://github.com/anvaka/three.map.control, used for panning
function getCurrentScale() {
  var vFOV = camera.fov * Math.PI / 180
  var scale_height = 2 * Math.tan( vFOV / 2 ) * camera.position.z
  var currentScale = height / scale_height
  return currentScale
}

// Point generator function
function phyllotaxis(radius) {
  const theta = Math.PI * (3 - Math.sqrt(5));
  return function(i) {
    const r = radius * Math.sqrt(i), a = theta * i;
    return [
      width / 2 + r * Math.cos(a) - width / 2,
      height / 2 + r * Math.sin(a) - height / 2
    ];
  };
}