import time
from typing import Optional

import cv2
import numpy as np


class FrameRate:
    def __init__(self) -> None:
        self.c: int = 0
        self.start_time: Optional[float] = None
        self.NO_FRAMES = 10
        self.fps: float = -1
        self.label: str = ""

    def reset(self) -> None:
        self.start_time = time.time()
        self.c = 0
        self.fps = -1

    def count(self) -> None:
        self.c += 1
        if self.c % self.NO_FRAMES == 0:
            self.c = 0
            end_time = time.time()
            self.fps = self.NO_FRAMES / (end_time - self.start_time)
            self.start_time = end_time

    def show_fps(self, image: np.ndarray) -> np.ndarray:
        if self.fps != -1:
            return cv2.putText(
                image,
                f"FPS {self.fps:.0f} _ {self.label}",
                (50, 50),
                cv2.FONT_HERSHEY_SIMPLEX,
                fontScale=1,
                color=(255, 0, 0),
                thickness=2,
            )
        else:
            return image