export function toRmbUpper(value: number | null | undefined): string {
  if (value == null || !Number.isFinite(value) || value < 0) {
    return ''
  }

  if (value > 999999999999.99) {
    return '金额过大'
  }

  const fen = Math.round(value * 100)
  if (fen === 0) {
    return '零元整'
  }

  const digits = ['零', '壹', '贰', '叁', '肆', '伍', '陆', '柒', '捌', '玖']
  const units = ['', '拾', '佰', '仟']

  function sectionToChinese(n: number): string {
    if (n === 0) return ''
    let result = ''
    let zeroPending = false
    for (let i = 0; i < 4; i++) {
      const digit = Math.floor(n / 10 ** (3 - i)) % 10
      if (digit === 0) {
        if (result !== '') {
          zeroPending = true
        }
      } else {
        if (zeroPending) {
          result += '零'
          zeroPending = false
        }
        result += digits[digit] + units[3 - i]
      }
    }
    return result
  }

  const yuan = Math.floor(fen / 100)
  const jiao = Math.floor((fen % 100) / 10)
  const fenDigit = fen % 10

  let result = ''

  if (yuan > 0) {
    const yi = Math.floor(yuan / 100000000)
    const wan = Math.floor(yuan / 10000) % 10000
    const rest = yuan % 10000

    if (yi > 0) {
      result += sectionToChinese(yi) + '亿'
    }
    if (wan > 0) {
      if (yi > 0 && wan < 1000) {
        result += '零'
      }
      result += sectionToChinese(wan) + '万'
    }
    if (rest > 0) {
      if (wan > 0) {
        if (rest < 1000) {
          result += '零'
        }
      } else if (yi > 0) {
        result += '零'
      }
      result += sectionToChinese(rest)
    }
    result += '元'
  }

  if (jiao > 0) {
    result += digits[jiao] + '角'
  } else if (fenDigit > 0 && yuan > 0) {
    result += '零'
  }

  if (fenDigit > 0) {
    result += digits[fenDigit] + '分'
  }

  if (jiao === 0 && fenDigit === 0) {
    result += '整'
  }

  return result
}