import {signal} from '@angular/core';

/** Counts ticks and publishes a rate a few times per second, so the display never costs frame time. */
export class FpsCounter {
  readonly fps = signal(0);
  private ticks = 0;
  private windowStart = 0;

  constructor(private readonly intervalMs = 500) {}

  tick(now: number = performance.now()): void {
    if (this.windowStart === 0) {
      this.windowStart = now;
      return;
    }
    this.ticks++;
    const elapsed = now - this.windowStart;
    if (elapsed >= this.intervalMs) {
      this.fps.set(Math.round(this.ticks * 1000 / elapsed));
      this.ticks = 0;
      this.windowStart = now;
    }
  }

  reset(): void {
    this.ticks = 0;
    this.windowStart = 0;
    this.fps.set(0);
  }
}