import { useState, useEffect, useCallback } from 'react';

interface UseExamTimerProps {
  initialTime: number; // in seconds
  onTimeUp?: () => void;
  onTick?: (timeRemaining: number) => void;
  autoStart?: boolean;
}

export const useExamTimer = ({
  initialTime,
  onTimeUp,
  onTick,
  autoStart = false
}: UseExamTimerProps) => {
  const [timeRemaining, setTimeRemaining] = useState(initialTime);
  const [isRunning, setIsRunning] = useState(autoStart);
  const [isPaused, setIsPaused] = useState(false);

  const start = useCallback(() => {
    setIsRunning(true);
    setIsPaused(false);
  }, []);

  const pause = useCallback(() => {
    setIsPaused(true);
  }, []);

  const resume = useCallback(() => {
    setIsPaused(false);
  }, []);

  const reset = useCallback(() => {
    setTimeRemaining(initialTime);
    setIsRunning(false);
    setIsPaused(false);
  }, [initialTime]);

  const stop = useCallback(() => {
    setIsRunning(false);
    setIsPaused(false);
  }, []);

  useEffect(() => {
    let interval: NodeJS.Timeout;

    if (isRunning && !isPaused && timeRemaining > 0) {
      interval = setInterval(() => {
        setTimeRemaining((prev) => {
          const newTime = prev - 1;
          onTick?.(newTime);
          
          if (newTime <= 0) {
            setIsRunning(false);
            onTimeUp?.();
            return 0;
          }
          
          return newTime;
        });
      }, 1000);
    }

    return () => {
      if (interval) {
        clearInterval(interval);
      }
    };
  }, [isRunning, isPaused, timeRemaining, onTimeUp, onTick]);

  const formatTime = useCallback((seconds: number) => {
    const hours = Math.floor(seconds / 3600);
    const minutes = Math.floor((seconds % 3600) / 60);
    const secs = seconds % 60;

    if (hours > 0) {
      return `${hours.toString().padStart(2, '0')}:${minutes.toString().padStart(2, '0')}:${secs.toString().padStart(2, '0')}`;
    }
    return `${minutes.toString().padStart(2, '0')}:${secs.toString().padStart(2, '0')}`;
  }, []);

  return {
    timeRemaining,
    formattedTime: formatTime(timeRemaining),
    isRunning,
    isPaused,
    start,
    pause,
    resume,
    reset,
    stop,
    progress: ((initialTime - timeRemaining) / initialTime) * 100
  };
};