class Anim {
	constructor(frames, rate) {
		this.frames = frames;
		this.rate = rate;
		this.reset();
	}

	update(dt) {
		const { rate, frames } = this;
		if ((this.curTime += dt) > rate) {
			this.curFrame++;
			this.frame = frames[this.curFrame % frames.length];
			this.curTime -= rate;
		}
	}

	reset() {
		this.frame = this.frames[0];
		this.curFrame = 0;
		this.curTime = 0;
	}
}

class AnimManager {
	constructor(e) { 
		this.anims = {};
		this.running = false;
		this.frameSource = e.frame || e;
		this.currrent = null;
	}

	add(name, frames, speed) {
		this.anims[name] = new Anim(frames, speed);
		return this.anims[name];
	}

	update(dt) { 
		const { current, anims, frameSource } = this;
		if (!current) {
			return;
		}
		const anim = anims[current];
		anim.update(dt);

		frameSource.x = anim.frame.x;
		frameSource.y = anim.frame.y;
	}

	play(anim) { 
		const { current, anims } = this;
		if (anim === current ) {
			return;
		}
		this.current = anim;
		anims[anim].reset();
	}

	stop() { 
		this.current = null;
	}
}

module.exports = AnimManager;