import { Vector3 } from "three";

import { serializable } from "../engine/engine_serialization_decorator.js";
import * as utils from "./../engine/engine_three_utils.js";
import { Behaviour, GameObject } from "./Component.js";

/**
 * Aligns this GameObject between two other GameObjects, scaling it to fit the distance.  
 * You can use this to create dynamic beams or connectors between objects.
 *
 * @summary Aligns and scales the object between two target GameObjects
 * @category Utility
 * @group Components 
 **/
export class AlignmentConstraint extends Behaviour {

    @serializable(GameObject)
    private from: GameObject | undefined;
    @serializable(GameObject)
    private to: GameObject | undefined;

    private width: number = 0;
    private centered: boolean = true;
    private _centerPos!: Vector3;

    awake(): void {
        this._centerPos = new Vector3();
    }

    update() {
        if (!this.from || !this.to) return;
        
        const fromWorldPos = utils.getWorldPosition(this.from).clone();
        const toWorldPos = utils.getWorldPosition(this.to).clone();
        const dist = fromWorldPos.distanceTo(toWorldPos);
        
        this._centerPos.copy(fromWorldPos);
        this._centerPos.add(toWorldPos);
        this._centerPos.multiplyScalar(0.5);

        utils.setWorldPosition(this.gameObject, this.centered ? this._centerPos : fromWorldPos);
        this.gameObject.lookAt(utils.getWorldPosition(this.to).clone());
        this.gameObject.scale.set(this.width, this.width, dist);
    }
}