using System;

namespace Swift.web.Library
{
    public class NumberToWordsConverter
    {
        internal static string NumberToWord(double n)
        {
            string words = "";
            double intPart;
            double decPart = 0;
            if (n == 0)
                return "Zero";
            try
            {
                string[] splitter = n.ToString().Split('.');
                intPart = double.Parse(splitter[0]);
                decPart = double.Parse(splitter[1]);
            }
            catch
            {
                intPart = n;
            }

            words = NumWords(intPart);

            if (decPart > 0)
            {
                if (words != "")
                    words += " and ";
                int counter = decPart.ToString().Length;
                switch (counter)
                {
                    case 1: words += NumWords(decPart) + " tenths"; break;
                    case 2: words += NumWords(decPart) + " hundredths"; break;
                    case 3: words += NumWords(decPart) + " thousandths"; break;
                    case 4: words += NumWords(decPart) + " ten-thousandths"; break;
                    case 5: words += NumWords(decPart) + " hundred-thousandths"; break;
                    case 6: words += NumWords(decPart) + " millionths"; break;
                    case 7: words += NumWords(decPart) + " ten-millionths"; break;
                }
            }
            return words + " Only.";
        }

        private static String NumWords(double n) //converts double to words
        {
            string[] numbersArr = new string[] { " One", " Two", " Three", " Four", " Five", " Six", " Seven", " Eight", " Nine", " Ten", " Eleven", " Twelve", " Thirteen", " Fourteen", " Fifteen", " Sixteen", " Seventeen", " Eighteen", " Nineteen" };
            string[] tensArr = new string[] { " Twenty", " Thirty", " Fourty", " Fifty", " Sixty", " Seventy", " Eighty", " Ninty" };
            string[] suffixesArr = new string[] { "Thousand", "Million", "Billion", "Trillion", "Quadrillion", "Quintillion", "Sextillion", "Septillion", "Octillion", "Nonillion", "Decillion", "Undecillion", "Duodecillion", "Tredecillion", "Quattuordecillion", "Quindecillion", "Sexdecillion", "Septdecillion", "Octodecillion", "Novemdecillion", "Vigintillion" };
            string words = "";

            bool tens = false;

            if (n < 0)
            {
                words += "Negative ";
                n *= -1;
            }

            int power = (suffixesArr.Length + 1) * 3;

            while (power > 3)
            {
                double pow = Math.Pow(10, power);
                if (n >= pow)
                {
                    if (n % pow > 0)
                    {
                        words += NumWords(Math.Floor(n / pow)) + " " + suffixesArr[(power / 3) - 1];
                        //words += NumWords(Math.Floor(n / pow)) + " " + suffixesArr[(power / 3) - 1] + ", ";
                    }
                    else if (n % pow == 0)
                    {
                        words += NumWords(Math.Floor(n / pow)) + " " + suffixesArr[(power / 3) - 1];
                    }
                    n %= pow;
                }
                power -= 3;
            }
            if (n >= 1000)
            {
                if (n % 1000 > 0) words += NumWords(Math.Floor(n / 1000)) + " Thousand ";
                else words += NumWords(Math.Floor(n / 1000)) + " Thousand";
                n %= 1000;
            }
            if (0 <= n && n <= 999)
            {
                if ((int)n / 100 > 0)
                {
                    words += NumWords(Math.Floor(n / 100)) + " Hundred";
                    n %= 100;
                }
                if ((int)n / 10 > 1)
                {
                    if (words != "")
                        words += " ";
                    words += tensArr[(int)n / 10 - 2];
                    tens = true;
                    n %= 10;
                }

                if (n < 20 && n > 0)
                {
                    if (words != "" && tens == false)
                        words += " ";
                    words += (tens ? "-" + numbersArr[(int)n - 1] : numbersArr[(int)n - 1]);
                    n -= Math.Floor(n);
                }
            }

            return words;
        }
    }

    // end class
}