import {Behavior} from './Behavior';
import {Particle} from '../Particle';
import {Vector3} from '../math';

interface PhysicsResolver {
    resolve(pos: Vector3, normal: Vector3): boolean;
}

let physicsResolver: PhysicsResolver;
export function setPhysicsResolver(resolver: PhysicsResolver) {
    physicsResolver = resolver;
}
export function getPhysicsResolver(): PhysicsResolver {
    return physicsResolver;
}

/**
 * Apply collision to particles from a physics resolver.
 */
export class ApplyCollision implements Behavior {
    type = 'ApplyCollision';
    tempV = new Vector3();

    constructor(
        public resolver: PhysicsResolver,
        public bounce: number
    ) {}

    initialize(particle: Particle): void {}

    update(particle: Particle, delta: number): void {
        if (this.resolver.resolve(particle.position, this.tempV)) {
            particle.velocity.reflect(this.tempV).multiplyScalar(this.bounce);
        }
    }

    frameUpdate(delta: number): void {}

    toJSON(): any {
        return {
            type: this.type,
            bounce: this.bounce,
        };
    }

    static fromJSON(json: any): Behavior {
        return new ApplyCollision(getPhysicsResolver(), json.bounce);
    }

    clone(): Behavior {
        return new ApplyCollision(this.resolver, this.bounce);
    }

    reset(): void {}
}