/**
 * 计时器服务模块
 * 负责答题计时相关逻辑
 */

/**
 * 格式化时间显示（秒数转为 HH:MM:SS 格式）
 * @param {Number} totalSeconds - 总秒数
 * @returns {String} 格式化后的时间字符串
 */
export function formatTime(totalSeconds) {
	if (totalSeconds < 0) totalSeconds = 0;
	const hours = Math.floor(totalSeconds / 3600);
	const minutes = Math.floor((totalSeconds % 3600) / 60);
	const seconds = totalSeconds % 60;
	
	const formatNumber = (num) => {
		return num < 10 ? '0' + num : String(num);
	};
	
	if (hours > 0) {
		return `${formatNumber(hours)}:${formatNumber(minutes)}:${formatNumber(seconds)}`;
	} else {
		return `${formatNumber(minutes)}:${formatNumber(seconds)}`;
	}
}

/**
 * 启动计时器
 * @param {Object} context - 页面上下文
 * @param {Number} durationMinutes - 考试时长（分钟）
 * @param {String} startTime - 开始时间（ISO 字符串）
 * @param {Function} onTimeUp - 时间到回调
 * @returns {Number} 定时器ID
 */
export function startTimer(context, durationMinutes, startTime, onTimeUp) {
	if (context.timerInterval) {
		clearInterval(context.timerInterval);
	}

	const startTimestamp = new Date(startTime).getTime();
	const durationMs = durationMinutes * 60 * 1000;
	const endTimestamp = startTimestamp + durationMs;

	const updateTimer = () => {
		const now = Date.now();
		const remainingMs = Math.max(0, endTimestamp - now);
		const remainingSeconds = Math.floor(remainingMs / 1000);

		if (remainingSeconds <= 0) {
			clearInterval(context.timerInterval);
			context.timerInterval = null;
			context.setData({
				timerText: '00:00',
				isPaused: false
			});
			if (onTimeUp) {
				onTimeUp();
			}
			return;
		}

		context.setData({
			timerText: formatTime(remainingSeconds)
		});
	};

	updateTimer();
	context.timerInterval = setInterval(updateTimer, 1000);

	return context.timerInterval;
}

/**
 * 暂停计时器
 * @param {Object} context - 页面上下文
 * @returns {Number} 暂停时的剩余秒数
 */
export function pauseTimer(context) {
	if (context.timerInterval) {
		clearInterval(context.timerInterval);
		context.timerInterval = null;
	}

	const timerText = context.data.timerText || '00:00:00';
	const parts = timerText.split(':');
	let totalSeconds = 0;
	
	if (parts.length === 3) {
		totalSeconds = parseInt(parts[0]) * 3600 + parseInt(parts[1]) * 60 + parseInt(parts[2]);
	} else if (parts.length === 2) {
		totalSeconds = parseInt(parts[0]) * 60 + parseInt(parts[1]);
	}

	context.setData({
		isPaused: true,
		pauseStartTime: Date.now()
	});

	return totalSeconds;
}

/**
 * 恢复计时器
 * @param {Object} context - 页面上下文
 * @param {Number} pausedSeconds - 暂停时的剩余秒数
 * @param {Function} onTimeUp - 时间到回调
 */
export function resumeTimer(context, pausedSeconds, onTimeUp) {
	if (context.timerInterval) {
		clearInterval(context.timerInterval);
	}

	const pauseDuration = context.data.pauseStartTime ? Math.floor((Date.now() - context.data.pauseStartTime) / 1000) : 0;
	const remainingSeconds = Math.max(0, pausedSeconds - pauseDuration);

	if (remainingSeconds <= 0) {
		context.setData({
			timerText: '00:00',
			isPaused: false
		});
		if (onTimeUp) {
			onTimeUp();
		}
		return;
	}

	context.setData({
		isPaused: false,
		pauseStartTime: null
	});

	let currentSeconds = remainingSeconds;
	context.timerInterval = setInterval(() => {
		currentSeconds--;
		if (currentSeconds <= 0) {
			clearInterval(context.timerInterval);
			context.timerInterval = null;
			context.setData({
				timerText: '00:00',
				isPaused: false
			});
			if (onTimeUp) {
				onTimeUp();
			}
			return;
		}
		context.setData({
			timerText: formatTime(currentSeconds)
		});
	}, 1000);
}

/**
 * 停止计时器
 * @param {Object} context - 页面上下文
 */
export function stopTimer(context) {
	if (context.timerInterval) {
		clearInterval(context.timerInterval);
		context.timerInterval = null;
	}
}