const digitChar = ['', ...'一二三四五六七八九']
const posChar = ['', ...'十百千万   亿']
const placeholder = '零'

function toChineseNumeralUnder万(digits) {
    let revDigits = digits.split('').reverse()
    let result = ''
    for (let pos = 0; pos < revDigits.length; pos++) {
        const digit = Number(revDigits[pos])
        if (digit)
            { result = posChar[pos] + result }
        if (digit !== 1 || pos !== 1)
            { result = digitChar[digit] + result }
        if (!digit && pos && result && !result.startsWith(placeholder))
            { result = placeholder + result }
    }
    return result
}

function toChineseNumeralUnder亿(digits) {
    let highPart = toChineseNumeralUnder万(digits.slice(-8, -4))
    if (highPart)
        { highPart += posChar[4] }
    let lowPart = toChineseNumeralUnder万(digits.slice(-4))
    return highPart + lowPart
}

function toChineseNumeral(digits) {
    let fragment = ''
    const result = []
    for (const digit of digits.split('').reverse()) {
        if (fragment.length === 8) {
            result.unshift(toChineseNumeralUnder亿(fragment))
            fragment = ''
        }
        fragment = digit + fragment
    }
    result.unshift(toChineseNumeralUnder亿(fragment))
    if (result[0].startsWith(placeholder))
        { result[0] = result[0].slice(1) }
    return result.join(posChar[8]) || placeholder
}
toChineseNumeral('0')
// => '零'
toChineseNumeral('101')
// => '一百零一'
toChineseNumeral('1000001')
// => '一百万零一'
toChineseNumeral('123456708')
// => '一亿二千三百四十五万六千七百零八'
toChineseNumeral('3274823947329471041041234567080')
// => '三百二十七万四千八百二十三亿九千四百七十三万二千九百四十七亿一千零四十一万零四百一十二亿三千四百五十六万七千零八十'

numToChinese('121')
// => '壹贰拾壹百'
numToChinese('12147238372')
// => '壹亿贰壹undefined肆千柒拾贰拾叁百捌千叁万柒百贰undefined'

/*
 * @param {Number} 数字 
 * @return {String} 中文数字
 * 
*/
var arg = process.argv.slice(2)[0] + '';//node命令参数

console.log(CN_Number(arg));

function CN_Number(num) {
    let str = num + '';
    let arr = [];
    let res = [];
    for (let i = str.length-1; i >=0; i -= 4) {
        arr.unshift(str.slice(i-4, i))
    }
    while (arr.length) {
        res.unshift(arr.splice(-3, 3))
    }

    let block=['亿','万',''];
    res = res.map(item =>{
       if(item.length<3) item.unshift('');
       return item.map((n,index) => {
            let res = cn_fy(n);
            res+=res?block[index]:"";
            return res;
        })
    });
    let cn_res='';
    res.forEach((a)=>{
        a.forEach(b=>{
            cn_res+=b;
        })
    })
    return  cn_res
    function cn_fy(n) {
        let unit = ['千', '百', '十'];
        let nums = ['零', '一', '二', '三', '四', '五', '六', '七', '八', '九'];
        let res = '';
        for (let i = 0; i < n.length; ++i) {
            if (n[i] == 0) res += '零'
            else res += nums[n[i]] + (unit[i] || '')
        }
        while(res[0]==='零'){
            res=res.substring(1)
        }//去左零
        while(res[res.length-1]==='零'){
            res=res.substring(0,res.length-1)
        }//去右零
        while(res.indexOf('零零')>-1){
            res=res.replace('零','')
        }//去连续零
        return res;
    }
}

function toChineseNumeral(n) {
    let units = ['', '十', '百', '千'];
    let numbers = '零一二三四五六七八九'.split('');
    let alternateTwo = '两';

    /**
    * 按 length 把 str 切割，然后每段由 callback 来处理
    * 后用 unit 连接，同时处理段之间要不要加零
    */
    let fragmentFactory = (length, unit, callback) => {
        let fn = strNum => {
            if(strNum.length === 0) return '';
            let tail = strNum.substring(strNum.length - length, strNum.length);
            let head = strNum.substring(0, strNum.length - length);
            let headResolved = fn(head);
            if (headResolved.length > 0) {
                headResolved += unit;
                if (tail.match(/^0+[1-9]/)) {
                    headResolved += numbers[0];
                }
            }
            return headResolved + callback(tail.replace(/^0+/, ''));
        };
        return fn;
    }

    /**
    * 处理万以内的数字
    */
    let resolve4 = partition => {
        let digits = partition.split('');
        let retStr = '';
        for(let i = 0; i < digits.length; i++) {
            let d = digits[i];
            if(d === '0') continue;

            if(i >= 1 && digits[i-1] === '0') {
                retStr += numbers[0];
            }

            let unit = digits.length - i - 1;
            let isTwoThousand = d === '2' && unit === 3;
            retStr += (isTwoThousand ? alternateTwo : numbers[d]) + units[unit];
        }
        return retStr;
    };

    // 先以 8 位切，然后以 4位切
    let fragment4 = fragmentFactory(4, '万', resolve4);
    let fragment8 = fragmentFactory(8, '亿', fragment4);
    // 要 京 兆 垓 都是没有问题的
   // fragment 16 京， fragment 32 兆 一直写下去就行    

    return fragment8(String(n)) || numbers[0];
}

function returnChineseNumber(num, chineseType) {
  if (!num) return '';

  var numArr = [num].toString().split('');
  var _numConfig = '零一二三四五六七八九'.split('');
  var _unitConfig = ' 十百千'.split('');
  var _sizeConfig = ' 万亿兆'.split('');
  if (chineseType) {
    _numConfig = '零壹贰叁肆伍陆柒捌玖'.split('');
    _unitConfig = ' 拾佰仟'.split('');
    // _sizeConfig = ' 萬億兆'.split('');
  }

  var result = '';
  for (var i=0,len=numArr.length; i<len; i++) {
    var n = Number(numArr[len-i-1]);
    var cn = _numConfig[n];
    var unit = i%4 !== 0 ? _unitConfig[i%4] : '';
    var size = i%4 === 0 && i !== 0 ? _sizeConfig[i/4] : '';

    // 现在将返回 1001 => 一千零百零十一，不符合情况，则进行以下处理
    if (cn === '零') unit = '';
    if (cn === '零' && (result === '' || result.slice(0, 1) === '零')) cn = '';

    result = cn + unit + size + result;
  }

  return result;
}
console.log(returnChineseNumber(123123123))
// 一亿二千三百一十二万三千一百二十三