export function pad(n) {
	return String(n).padStart(2, '0')
}

export function toDate(value) {
	if (!value) return null
	const d = value instanceof Date ? value : new Date(value)
	return Number.isNaN(d.getTime()) ? null : d
}

export function formatDate(value, withTime = false) {
	const d = toDate(value)
	if (!d) return ''
	const date = `${d.getFullYear()}-${pad(d.getMonth() + 1)}-${pad(d.getDate())}`
	if (!withTime) return date
	return `${date} ${pad(d.getHours())}:${pad(d.getMinutes())}`
}

export function formatRelativeTime(value) {
	const d = toDate(value)
	if (!d) return ''
	const now = new Date()
	const diff = now.getTime() - d.getTime()
	const minute = 60 * 1000
	const hour = 60 * minute
	const day = 24 * hour

	if (diff < minute) return '刚刚'
	if (diff < hour) return `${Math.floor(diff / minute)} 分钟前`
	if (diff < day) return `${Math.floor(diff / hour)} 小时前`
	if (diff < 7 * day) return `${Math.floor(diff / day)} 天前`
	return formatDate(d)
}

export function isSameDay(a, b) {
	const da = toDate(a)
	const db = toDate(b)
	if (!da || !db) return false
	return (
		da.getFullYear() === db.getFullYear() &&
		da.getMonth() === db.getMonth() &&
		da.getDate() === db.getDate()
	)
}

export function isToday(value) {
	return isSameDay(value, new Date())
}

export function isTomorrow(value) {
	const d = toDate(value)
	if (!d) return false
	const tomorrow = new Date()
	tomorrow.setDate(tomorrow.getDate() + 1)
	return isSameDay(d, tomorrow)
}

export function dayLabel(value) {
	if (isToday(value)) return '今天'
	if (isTomorrow(value)) return '明天'
	return formatDate(value)
}

export function startOfDay(value = new Date()) {
	const d = toDate(value) || new Date()
	return new Date(d.getFullYear(), d.getMonth(), d.getDate())
}

export function endOfDay(value = new Date()) {
	const d = startOfDay(value)
	d.setHours(23, 59, 59, 999)
	return d
}