import {Ellipse} from './ellipse'
import {Constraints} from '../parametric'

import * as math from '../../math/math';
import {swap} from '../../utils/utils'
import {EndPoint} from "./point";

export class EllipticalArc extends Ellipse {

  constructor(x1, y1, x2, y2, ax, ay, bx, by, r, id) {
    super(x1, y1, x2, y2, r, id);
    this.a = new EndPoint(ax, ay, this.id + ':A');
    this.b = new EndPoint(bx, by, this.id + ':B');
    this.addChild(this.a);
    this.addChild(this.b);
    
    //we'd like to have angles points have higher selection order 
    swap(this.children, 0, this.children.length - 2);
    swap(this.children, 1, this.children.length - 1);
  }

  stabilize(viewer) {
    this.stage.addConstraint(new Constraints.PointOnEllipseInternal(this.b, this));
    this.stage.addConstraint(new Constraints.PointOnEllipseInternal(this.a, this));
  }

  drawImpl(ctx, scale) {
    ctx.beginPath();
    const radiusX = Math.max(this.radiusX, 1e-8);
    const radiusY = Math.max(this.radiusY, 1e-8);
    let aAngle = this.drawAngle(this.a);
    let bAngle;
    if (math.areEqual(this.a.x, this.b.x, math.TOLERANCE) &&
      math.areEqual(this.a.y, this.b.y, math.TOLERANCE)) {
      bAngle = aAngle + 2 * Math.PI;
    } else {
      bAngle = this.drawAngle(this.b)
    }
    ctx.ellipse(this.centerX, this.centerY, radiusX, radiusY, this.rotation, aAngle, bAngle );
    ctx.stroke();
  }
  
  drawAngle(point) {
    let deformScale =  this.radiusY / this.radiusX;
    let x = point.x - this.centerX;
    let y = point.y - this.centerY;
    const rotation =  - this.rotation;
    let xx =  x * Math.cos(rotation) - y * Math.sin(rotation);
    let yy =  x * Math.sin(rotation) + y * Math.cos(rotation);
    xx *= deformScale;
    return Math.atan2(yy, xx);
  }

  write() {
    return {
      ep1: this.ep1.write(),
      ep2: this.ep2.write(),
      a: this.a.write(),
      b: this.b.write(),
      r: this.r.get()
    }
  }

  static read(id, data) {
    return new EllipticalArc(
      data.ep1.x,
      data.ep1.y,
      data.ep2.x,
      data.ep2.y,
      data.a.x,
      data.a.y,
      data.b.x,
      data.b.y,
      data.r,
      id
    );
  }
}

EllipticalArc.prototype._class = 'TCAD.TWO.EllipticalArc';
EllipticalArc.prototype.TYPE = 'EllipticalArc';