/**
 * 小数输入：保留用户输入形态，不强制补尾零；precision 表示最多小数位数。
 */

/** 输入清洗：仅保留数字与小数点，截断到 maxPrecision 位小数 */
export function sanitizeDecimalInput(value: string, maxPrecision = 4): string {
  if (!value) return ''
  let cleaned = value.replace(/,/g, '').replace(/[^0-9.-]/g, '')
  const isNegative = cleaned.startsWith('-')
  if (isNegative) cleaned = cleaned.slice(1).replace(/-/g, '')
  cleaned = cleaned.replace(/[^0-9.]/g, '')

  if (maxPrecision <= 0) {
    return (isNegative ? '-' : '') + cleaned.replace(/\./g, '')
  }

  const dotIndex = cleaned.indexOf('.')
  if (dotIndex !== -1) {
    const intPart = cleaned.slice(0, dotIndex + 1)
    const decPart = cleaned.slice(dotIndex + 1).replace(/\./g, '')
    cleaned = intPart + decPart.slice(0, maxPrecision)
  }
  return (isNegative ? '-' : '') + cleaned
}

/** 外部数值同步到输入框：去掉无意义的尾零，不补零 */
export function formatDecimalDisplayNatural(
  value: number | null | undefined,
  maxPrecision = 4
): string {
  if (value === null || value === undefined) return ''
  if (Number.isNaN(value)) return ''
  if (maxPrecision <= 0) return String(Math.trunc(value))
  const factor = Math.pow(10, maxPrecision)
  const rounded = Math.round(value * factor) / factor
  return String(rounded)
}

/** 解析为 number；空串 / 仅符号或点 → undefined */
export function parseDecimalToNumber(
  value: string,
  maxPrecision = 4
): number | undefined {
  const sanitized = sanitizeDecimalInput(value, maxPrecision)
  if (!sanitized || sanitized === '.' || sanitized === '-' || sanitized === '-.') {
    return undefined
  }
  const num = Number(sanitized)
  if (Number.isNaN(num)) return undefined
  if (maxPrecision <= 0) return Math.trunc(num)
  const factor = Math.pow(10, maxPrecision)
  return Math.round(num * factor) / factor
}