class Clock {
	constructor(autoStart = true) {
		this.autoStart = autoStart;

		this.startTime = 0;
		this.oldTime = 0;
		this.elapsedTime = 0;

		this.running = false;
	}

	start() {
		this.startTime = now();

		this.oldTime = this.startTime;
		this.elapsedTime = 0;
		this.running = true;
	}

	stop() {
		this.getElapsedTime();
		this.running = false;
		this.autoStart = false;
	}

	getElapsedTime() {
		this.getDelta();
		return this.elapsedTime;
	}

	getDelta() {
		let diff = 0;

		if (this.autoStart && !this.running) {
			this.start();
			return 0;
		}

		if (this.running) {
			const newTime = now();

			diff = (newTime - this.oldTime) / 1000;
			this.oldTime = newTime;

			this.elapsedTime += diff;
		}

		return diff;
	}
}

function now() {
	return (typeof performance === 'undefined' ? Date : performance).now(); // see #10732
}

export { Clock };