export const getShanghaiDay = (date = new Date()) => {
	const parts = new Intl.DateTimeFormat('en-CA', {
		timeZone: 'Asia/Shanghai', year: 'numeric', month: '2-digit', day: '2-digit'
	}).formatToParts(date);
	const part = (type) => parts.find(item => item.type === type)?.value || '';
	return `${part('year')}-${part('month')}-${part('day')}`;
};

export const normalizeExpiryReminder = (reminder) => {
	if (!reminder || typeof reminder !== 'object') return null;
	const days = reminder.remaining_days;
	if (days === null || days === undefined || days === '' ||
		!Number.isInteger(Number(days)) || Number(days) < 0 || Number(days) > 15 ||
		!['red', 'purple', 'pink'].includes(reminder.level)) return null;
	return { ...reminder, remaining_days: Number(days) };
};

export const formatShanghaiExpiry = (value) => {
	if (!value) return '-';
	const text = String(value);
	// An offset-free server date is already a Shanghai wall-clock value.
	if (!/(Z|[+-]\d{2}:?\d{2})$/i.test(text)) return text.replace('T', ' ').slice(0, 19);
	const date = new Date(text);
	if (!Number.isFinite(date.getTime())) return '-';
	return new Intl.DateTimeFormat('zh-CN', {
		timeZone: 'Asia/Shanghai', year: 'numeric', month: '2-digit', day: '2-digit',
		hour: '2-digit', minute: '2-digit', hourCycle: 'h23'
	}).format(date);
};