/** 中文互联网上写的最漂亮效率最高的大写人民币金额转换代码
 * 作者：李维 <oldrev@gmail.com>
 * 版权所有 (c) 2013 李维。保留所有权利。
 * 本代码基于 BSD License 授权。
 * */

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;

namespace RMBUpper {

    public class RmbUpperConverter {

        private static readonly Char[] RmbDigits = {
            '零', '壹', '贰', '叁', '肆', '伍', '陆', '柒', '捌', '玖' };

        private static readonly string[] DecDigits = {
             string.Empty, "拾", "佰", "仟", string.Empty, "万" };

        public static string ToUpper(double price) {
            var sb = new StringBuilder();

            var qianPart = (long)(price % 10000);
            var wanPart = ((long)(price % 100000000) - qianPart) / 10000;
            var yiPart = ((long)(price % 100000000000) - qianPart - wanPart) / 100000000;
            var integerPart = yiPart * 100000000 + wanPart * 10000 + qianPart;
            var decPart = (long)(price * 100) % 100;

            //处理亿的部分
            if (price > 99999999.99) {
                ParseInteger(sb, yiPart);
                sb.Append("亿");
            }

            //处理万的部分
            if (price > 9999.99) {
                if (price > 99999999.99 && wanPart > 0 && wanPart <= 999) {
                    sb.Append("零");
                }
                ParseInteger(sb, wanPart);
                sb.Append("万");
            }

            //处理千及以后的部分
            if (price > 9999.99 && qianPart > 0 && qianPart <= 999) {
                sb.Append("零");
            }
            ParseInteger(sb, qianPart);
            sb.Append("元");

            ParseDecimal(sb, decPart);

            return sb.ToString();
        }

        private static void ParseDecimal(StringBuilder sb, long decPart) {
            if (decPart > 0) {
                var jiao = decPart / 10;
                var fen = decPart % 10;
                if (jiao > 0) {
                    sb.Append(RmbDigits[jiao]);
                    sb.Append("角");
                }
                if (jiao == 0 && fen > 0) {
                    sb.Append("零");
                }
                if (fen > 0) {
                    sb.Append(RmbDigits[fen]);
                    sb.Append("分");
                }
                else {
                    sb.Append("整");
                }
            }
            else {
                sb.Append("整");
            }
        }

        private static void ParseInteger(StringBuilder sb, long value) {
            var u = Math.Abs(value);
            int nDigits = (int)Math.Floor(Math.Log10(u)) + 1;
            long lastDigit = -1;
            for (var i = 0; i < nDigits; i++) {
                var factor = (long)Math.Pow(10, nDigits - 1 - i);
                var digit = u / factor;

                //几种情况
                //遇到零先跳过，下次循环再处理
                var skipSpec = false;
                if (digit == 0 && i < nDigits - 1) {
                    skipSpec = true;
                } //最后一位是0，则不能转换为“零”
                else if (digit == 0 && i >= nDigits - 1) {
                    skipSpec = false;
                }//连续两位都是 0，则只出一个零
                else if (lastDigit == 0 && digit == 0 && i < nDigits - 1) {
                    sb.Append(RmbDigits[digit]);
                    skipSpec = true;
                }
                else {
                    sb.Append(RmbDigits[digit]);
                    skipSpec = false;
                }

                if (!skipSpec) {
                    var f1 = nDigits - i - 1;
                    sb.Append(DecDigits[f1]);
                }

                u -= u / factor * factor;
                lastDigit = digit;
            }
        }

    }

}