import { Tool } from '../tool.js';
import { 
  ZOOM_IN_FACTOR,
  ZOOM_OUT_FACTOR,
} from '../config.js';

export class Zoom extends Tool {
  constructor(toolbar) {
    super(toolbar);

    const zoomOut = document.createElement('button');
    const zoomIn = document.createElement('button');
    const zoomAll = document.createElement('button');

    this.div.appendChild(zoomOut);
    this.div.appendChild(zoomIn);
    this.div.appendChild(document.createElement('br'));
    this.div.appendChild(zoomAll);
    this.div.appendChild(document.createElement('br'));

    zoomAll.classList.add('wide');

    zoomOut.innerHTML = '<h2>Zoom<br>Out</h2>';
    zoomIn.innerHTML = '<h2>Zoom<br>In</h2>';
    zoomAll.innerHTML = '<h2>Zoom to Fit</h2>';

    zoomOut.addEventListener('click', () => {
      // Aim at center of view
      const x = this.sim.display.width * this.sim.display.scale / 2;
      const y = this.sim.display.height * this.sim.display.scale / 2;
      this.sim.scheduleZoom(this.sim.screenToSim(x, y), ZOOM_OUT_FACTOR);
    });

    zoomIn.addEventListener('click', () => {
      // Aim at center of view
      const x = this.sim.display.width * this.sim.display.scale / 2;
      const y = this.sim.display.height * this.sim.display.scale / 2;
      this.sim.scheduleZoom(this.sim.screenToSim(x, y), ZOOM_IN_FACTOR);
    });

    zoomAll.addEventListener('click', () => {
      // Determine bounding box
      const box = this.sim.objects.boundingBox;
      const x = (box.start.x + box.end.x) / 2;
      const y = (box.start.y + box.end.y) / 2;
      const widthRatio = Math.abs(box.start.x - box.end.x) / this.sim.display.width;
      const heightRatio = Math.abs(box.start.y - box.end.y) / this.sim.display.height;
      const biggerRatio = Math.max(widthRatio, heightRatio);
      const base2factor = Math.log(1/biggerRatio) / Math.log(2) - 0.5;
      const factor = Math.floor(base2factor);
      // Determine average momentum and set panning velocity to match
      const netMomentum = {x: 0, y: 0};
      let totalMass = 0;
      let count = 0;
      this.sim.objects.forEachObject(obj => {
        count++;
        netMomentum.x += obj.mass * obj.velocity.x;
        netMomentum.y += obj.mass * obj.velocity.y;
        totalMass += obj.mass;
      });
      if (!count) {
        return;
      }
      const netVelocity = {
        x: netMomentum.x / totalMass,
        y: netMomentum.y / totalMass,
      };
      const netSpeed = Math.sqrt(netVelocity.x ** 2 + netVelocity.y ** 2);
      this.sim.scheduleZoom({x, y}, factor, netVelocity)
    });
  }
}