constructor() {

this.subscriptions = {};

this.lastTickDate;

this.deltaTime;

this.currentTick = 0;

this.tickCheck;

this.avgDeltaTime = [];

this.tps;

}

__checkTicks() {

if (this.tickCheck) return;

this.tickCheck = () => {

const { lastTickDate = (new Date()).getTime() } = this;

this.currentTick++;

this.deltaTime = (new Date()).getTime() - lastTickDate;

this.avgDeltaTime.push(this.deltaTime);

if (this.avgDeltaTime.length > 100) this.avgDeltaTime.shift();

const { avgDeltaTime } = this;

this.tps = Math.round((1 / (avgDeltaTime.reduce((t, c) => t + c) / avgDeltaTime.length / 1000)) * 10) / 10;

this.lastTickDate = (new Date()).getTime();

system.run(this.tickCheck);

};

system.run(this.tickCheck);

}

/**

subscribe(key, callback) {

this.__checkTicks();

this.subscriptions[key] = () => {

const { deltaTime = 0, currentTick = 0, tps = 20 } = this;

callback({ deltaTime, currentTick, tps });

system.run(this.subscriptions[key]);

};

system.run(this.subscriptions[key]);

}

/**

unsubscribe(key) {

console.warn(Object.keys(this.subscriptions).length);

if (Object.keys(this.subscriptions).length <= 1) {

// @ts-ignore

system.run(() => { this.__checkTicks = false; });

}

this.subscriptions[key] = () => { };

system.run(() => {

delete this.subscriptions[key];

});

}