import * as THREE from 'three';



class TaperedLink extends THREE.Group {

  constructor(baseMaterial, n1, n2, r1, r2) {
    super();
    const geometry = new THREE.ConeGeometry( 0.75, 1, 32, true );
    const cplane = new THREE.Plane(new THREE.Vector3(0, -1, 0), 0.5);
    const material = baseMaterial.clone();
    material.clippingPlanes = [ cplane ];
    this.cone = new THREE.Mesh( geometry, material );
    this.add( this.cone );
    this.update(n1, n2, r1, r2);
  }  

  update(n1, n2, r1, r2) {
    const kraw = r1 - r2;
    let k = ( kraw == 0 ) ? 0.001 : kraw;
    let nbase = n1.v3;
    let napex = n2.v3;
    let rbase = r1;
    let rapex = r2;
    if( k < 0 ) {
      nbase = n2.v3;
      napex = n1.v3;
      rbase = r2;
      rapex = r1;
      k = -k;
    }

    // FIXME - the problem is that when the h_offset > 1, the centroid
    // of the cone is on the other side of napex, so it looks the wrong way

    const l = nbase.distanceTo(napex);
    const h = l * rbase / k;
    const h_offset = 0.5 * h / l;
    const pos = new THREE.Vector3();
    if( l > 0 ) {
      pos.lerpVectors(nbase, napex, h_offset);
    }
    if( h_offset < 1 ) { 
      this.cone.scale.copy(new THREE.Vector3(rbase, h, rbase));
    } else {
      // you're on the other side of napex so flip the cone
      this.cone.scale.copy(new THREE.Vector3(rbase, -h, rbase));      
    }
    this.lookAt(napex);
    this.position.copy(pos);
    this.cone.rotation.x = Math.PI / 2.0;
    const clipnorm = new THREE.Vector3();
    clipnorm.copy(napex);
    clipnorm.sub(nbase);
    clipnorm.negate();
    clipnorm.normalize();
    this.cone.material.clippingPlanes[0].setFromNormalAndCoplanarPoint(
      clipnorm, napex
      );
  }

}

export { TaperedLink };