workout/src/components/ui/timer.tsx

import { useEffect, useRef, useState } from "react";

export function Timer({
  isRunning,
  initialSeconds = 0,
  onChange,
}: {
  isRunning: boolean;
  initialSeconds?: number;
  onChange?: (seconds: number) => void;
}) {
  const [seconds, setSeconds] = useState(initialSeconds);
  const intervalRef = useRef<NodeJS.Timeout | null>(null);

  useEffect(() => {
    setSeconds(initialSeconds);
  }, [initialSeconds]);

  useEffect(() => {
    if (isRunning) {
      intervalRef.current = setInterval(() => {
        setSeconds((s) => {
          const next = s + 1;
          onChange?.(next);
          return next;
        });
      }, 1000);
    } else if (intervalRef.current) {
      clearInterval(intervalRef.current);
      intervalRef.current = null;
    }
    return () => {
      if (intervalRef.current) clearInterval(intervalRef.current);
    };
  }, [isRunning, onChange]);

  // Format mm:ss ou hh:mm:ss
  const format = () => {
    const h = Math.floor(seconds / 3600);
    const m = Math.floor((seconds % 3600) / 60);
    const s = seconds % 60;
    if (h > 0) return `${h.toString().padStart(2, "0")}:${m.toString().padStart(2, "0")}:${s.toString().padStart(2, "0")}`;
    return `${m.toString().padStart(2, "0")}:${s.toString().padStart(2, "0")}`;
  };

  return <span>{format()}</span>;
}