import { appConfig } from '../config';

const INITIAL_FPS = 60;
const FRAME_GAP_RESET_SECONDS = 1;

export class FramePerformance {
  public smoothedFps = INITIAL_FPS;

  private previousFrameTime: DOMHighResTimeStamp | null = null;

  public update(time: DOMHighResTimeStamp): void {
    const previous = this.previousFrameTime;
    this.previousFrameTime = time;
    if (previous === null) {
      return;
    }

    const deltaSeconds = (time - previous) / 1000;
    if (deltaSeconds <= 0 || deltaSeconds > FRAME_GAP_RESET_SECONDS) {
      return;
    }

    const fps = 1 / deltaSeconds;
    this.smoothedFps =
      this.smoothedFps * appConfig.simulation.budget.fpsSmoothingRetain +
      fps * appConfig.simulation.budget.fpsSmoothingNew;
  }
}