// 金额转换使用整数分，避免万元与元之间的浮点乘法误差。
export function wanAmountValid(value: string): boolean {
	if (!/^[0-9]{1,5}([.][0-9]{1,6})?$/.test(value)) return false
	return wanToCents(value) <= 99999999999
}

export function wanToCents(value: string): number {
	const parts = value.split('.')
	const fraction = parts.length > 1 ? parts[1] : ''
	return parseInt(parts[0]) * 1000000 + parseInt((fraction + '000000').substring(0, 6))
}

export function wanToYuan(value: string): string {
	if (!wanAmountValid(value)) throw new Error('金额范围为 0–99999.999999 万元，最多六位小数')
	const cents = wanToCents(value)
	const fraction = (cents % 100).toString()
	return Math.floor(cents / 100).toString() + '.' + (fraction.length == 1 ? '0' + fraction : fraction)
}

export function yuanToWan(value: string): string {
	if (value.length == 0) return ''
	if (!/^[0-9]+([.][0-9]{1,2})?$/.test(value)) return value
	const parts = value.split('.')
	const fraction = parts.length > 1 ? parts[1] : ''
	const digits = parts[0] + (fraction + '00').substring(0, 2)
	const padded = '000000' + digits
	const whole = parseInt(padded.substring(0, padded.length - 6)).toString()
	const decimal = padded.substring(padded.length - 6).replace(/0+$/, '')
	return whole + (decimal.length > 0 ? '.' + decimal : '')
}