//#define COSMOSDEBUG

using System;
using Cosmos.Debug.Kernel;

namespace Cosmos.Common
{
    public static class StringHelper
    {
        private static Debugger mDebugger = new Debugger("Common", "StringHelper");

        internal enum StringComparisonResultEnum
        {
            Less = -1,

            Equal = 0,

            Greater = 1
        }

        public static string GetNumberString(uint aValue)
        {
            mDebugger.SendInternal("StringHelper.GetNumberString(uint)");

            string[] xChars = { "0", "1", "2", "3", "4", "5", "6", "7", "8", "9" };
            string xResult = string.Empty;

            if (aValue == 0)
            {
                xResult = "0";
            }
            else
            {
                uint xValue = aValue;
                while (xValue > 0)
                {
                    uint xValue2 = xValue % 10;
                    xResult = string.Concat(xChars[xValue2], xResult);
                    xValue /= 10;
                }
            }

            return xResult;
        }

        public static string GetNumberString(int aValue)
        {
            mDebugger.SendInternal("StringHelper.GetNumberString(int)");

            string[] xChars = { "0", "1", "2", "3", "4", "5", "6", "7", "8", "9" };
            string xResult = string.Empty;

            if (aValue == 0)
            {
                xResult = "0";
            }
            else
            {
                int xValue = aValue;

                if (aValue < 0)
                {
                    xValue *= -1;
                }

                while (xValue > 0)
                {
                    int xValue2 = xValue % 10;
                    xResult = string.Concat(xChars[xValue2], xResult);
                    xValue /= 10;
                }
            }

            if (aValue < 0)
            {
                xResult = string.Concat("-", xResult);
            }

            return xResult;
        }

        public static string GetNumberString(ulong aValue)
        {
            mDebugger.SendInternal("StringHelper.GetNumberString(ulong)");

            string[] xChars = { "0", "1", "2", "3", "4", "5", "6", "7", "8", "9" };
            string xResult = string.Empty;

            if (aValue == 0)
            {
                xResult = "0";
                mDebugger.SendInternal("xResult =");
                mDebugger.SendInternal(xResult);
            }
            else
            {
                ulong xValue = aValue;
                mDebugger.SendInternal("xValue =");
                mDebugger.SendInternal(xValue);
                while (xValue > 0)
                {
                    ulong xValue2 = xValue % 10;
                    mDebugger.SendInternal("xValue2 =");
                    mDebugger.SendInternal(xValue2);
                    xResult = string.Concat(xChars[xValue2], xResult);
                    mDebugger.SendInternal("xResult =");
                    mDebugger.SendInternal(xResult);
                    xValue /= 10;
                    mDebugger.SendInternal("xValue =");
                    mDebugger.SendInternal(xValue);
                }
            }

            mDebugger.SendInternal("xResult =");
            mDebugger.SendInternal(xResult);
            return xResult;
        }

        public static string GetNumberString(long aValue)
        {
            mDebugger.SendInternal("StringHelper.GetNumberString(long)");

            string[] xChars = { "0", "1", "2", "3", "4", "5", "6", "7", "8", "9" };
            string xResult = string.Empty;
            long xValue = aValue;

            if (aValue == 0)
            {
                xResult = "0";
                mDebugger.SendInternal("xResult =");
                mDebugger.SendInternal(xResult);
            }
            else
            {
                if (aValue < 0)
                {
                    xValue *= -1;
                }

                mDebugger.SendInternal("xValue =");
                mDebugger.SendInternal(xValue);
                while (xValue > 0)
                {
                    long xValue2 = xValue % 10;
                    mDebugger.SendInternal("xValue2 =");
                    mDebugger.SendInternal(xValue2);
                    xResult = string.Concat(xChars[xValue2], xResult);
                    mDebugger.SendInternal("xResult =");
                    mDebugger.SendInternal(xResult);
                    xValue /= 10;
                    mDebugger.SendInternal("xValue =");
                    mDebugger.SendInternal(xValue);
                }
            }

            if (aValue < 0)
            {
                xResult = string.Concat("-", xResult);
            }

            mDebugger.SendInternal("xResult =");
            mDebugger.SendInternal(xResult);
            return xResult;
        }

        /*
         * This implementation could only print values which integer part is < ULONG_MAX, the only solution would have been to use BigInteger but then
         * I'd have an analogous problem: to plug BigInteger.ToString() and I don't know how many other things.
         * We will retain this code for now it is OK for debug purposes and big value should be printed in scientific notation to be readable anyway...
         */
        public static string GetNumberString(float aValue)
        {
            mDebugger.SendInternal("StringHelper.GetNumberString(float)");

            var singleBytes = BitConverter.GetBytes(aValue);
            int hexVal = BitConverter.ToInt32(singleBytes, 0);

            /* Let's extract the parts that compose our single: sign, exponent and mantissa */
            bool isNeg = (hexVal >> 31) != 0;
            int exp = ((hexVal >> 23) & 0xFF);
            ulong mantissa = (ulong)(hexVal & 0x7FFFFF);

            ulong intPart = 0, fracPart = 0;

            /* First we handle the special cases INF, NaN, 0 and denormalized float */
            switch (exp)
            {
                /*
                 * INF or NaN?
                 */
                case 0xFF:
                    if (mantissa == 0)
                    {
                        if (isNeg)
                            return "-∞";
                        else
                            return "∞";
                    }
                    else
                        /* It could exist -NaN but this is always printed as NaN */
                        return "NaN";

                /* 0 or denormalized float? */
                case 0x00:
                    if (mantissa == 0)
                        return "0";
                    /* Denormalized float have always exp -126 */
                    else
                        exp = -126;
                    break;

                /* Normalized float the exponent is unbiased and the implicit leading one is placed in the mantissa */
                default:
                    exp -= 127;
                    mantissa |= 0x800000;
                    break;
            }

            if (exp >= 23)
            {
                intPart = mantissa << (exp - 23);
            }
            else if (exp >= 0)
            {
                intPart = mantissa >> (23 - exp);
                fracPart = (mantissa << (exp + 1)) & 0xFFFFFF;
            }
            else
            {
                fracPart = (mantissa & 0xFFFFFF) >> (-(exp + 1));
            }

            string result = "";

            if (isNeg)
            {
                result += "-";
            }

            result += intPart.ToString();
            int usedDigits = intPart.ToString().Length;
            if (fracPart == 0)
            {
                return result;
            }
            result += ".";

            if (usedDigits >= 7)
            {
                usedDigits = 6;
            }
            for (int m = usedDigits; m < 7; m++)
            {
                fracPart = (fracPart << 3) + (fracPart << 1);

                char p = (char)((fracPart >> 24) + '0');
                result += p;

                fracPart &= 0xFFFFFF;
            }
            fracPart = (fracPart << 3) + (fracPart << 1);
            char remain = (char)((fracPart >> 24) + '0');
            if ((remain > '5') && (result[result.Length - 1] > '0'))
            {
                char[] answer = result.ToCharArray();
                int digitPos = answer.Length - 1;
                char digit = result[digitPos];
                answer[digitPos] = (char)(digit + 1);
                while (answer[digitPos] > '9')
                {
                    answer[digitPos] = '0';
                    digitPos--;
                    digit = result[digitPos];
                    if (digit == '.')
                    {
                        digitPos--;
                        digit = result[digitPos];
                    }
                    answer[digitPos] = (char)(digit + 1);
                }

                result = new string(answer);
            }

            while (result[result.Length - 1] == '0')
            {
                result = result.Substring(0, result.Length - 1);
            }

            return result;
        }

        /*
         * This implementation could only print values which integer part is < ULONG_MAX, the only solution would have been to use BigInteger but then
         * I'd have an analogous problem: to plug BigInteger.ToString() and I don't know how many other things.
         * We will retain this code for now it is OK for debug purposes and big value should be printed in scientific notation to be readable anyway...
         */
        public static string GetNumberString(double aValue)
        {
            mDebugger.SendInternal("StringHelper.GetNumberString(double)");
            mDebugger.SendInternal("aValue = ");
            mDebugger.SendInternal(aValue);

            long hexVal = BitConverter.DoubleToInt64Bits(aValue);
            mDebugger.SendInternal("hexVal = ");
            mDebugger.SendInternal(hexVal);

            /* Let's extract the parts that compose our double: sign, exponent and mantissa */
            bool isNeg = (hexVal >> 63) != 0;
            int exp = (int)((hexVal >> 52) & 0x07FF);
            ulong mantissa = (ulong)(hexVal & 0x0FFFFFFFFFFFFF);
            mDebugger.SendInternal("isNeg = ");
            mDebugger.SendInternal(isNeg.ToString());
            mDebugger.SendInternal("exp = ");
            mDebugger.SendInternal(exp);
            mDebugger.SendInternal("mantissa = ");
            mDebugger.SendInternal(mantissa);

            ulong intPart = 0, fracPart = 0;

            if (double.IsPositiveInfinity(aValue))
            {
                return "∞";
            }
            else if (double.IsNegativeInfinity(aValue))
            {
                return "-∞";
            }
            else if (double.IsNaN(aValue))
            {
                return "NaN";
            }

            /* First we handle the special cases INF, NaN, 0 and denormalized float */
            switch (exp)
            {
                /* 0 or denormalized double? */
                case 0x0000:
                    if (mantissa == 0)
                        return "0";
                    /* Denormalized float have always exp -1022 */
                    else
                        exp = -1022;
                    break;

                /* Normalized double the exponent is unbiased and the implicit leading one is placed in the mantissa */
                default:
                    exp -= 1023;
                    mantissa |= 0x10000000000000;
                    break;
            }

            if (exp >= 52)
            {
                intPart = mantissa << (exp - 52);
            }
            else if (exp >= 0)
            {
                intPart = mantissa >> (52 - exp);
                fracPart = (mantissa << (exp + 1)) & 0x1FFFFFFFFFFFFF;
            }
            else
            {
                fracPart = (mantissa & 0x1FFFFFFFFFFFFF) >> (-(exp + 1));
            }

            string result = "";

            if (isNeg)
            {
                result += "-";
            }

            result += intPart.ToString();
            int usedDigits = result.Length;
            if (fracPart == 0)
            {
                return result;
            }
            result += ".";

            if (usedDigits >= 15)
            {
                usedDigits = 14;
            }
            for (int m = usedDigits; m < 15; m++)
            {
                fracPart = (fracPart << 3) + (fracPart << 1);
                char p = (char)(((fracPart >> 53) & 0xFF) + '0');
                result += p;

                fracPart &= 0x1FFFFFFFFFFFFF;
            }
            fracPart = (fracPart << 3) + (fracPart << 1);
            char remain = (char)((fracPart >> 53) + '0');
            if ((remain > '5') && (result[result.Length - 1] > '0'))
            {
                char[] answer = result.ToCharArray();
                int digitPos = answer.Length - 1;
                char digit = result[digitPos];
                answer[digitPos] = (char)(digit + 1);
                while (answer[digitPos] > '9')
                {
                    answer[digitPos] = '0';
                    digitPos--;
                    digit = result[digitPos];
                    if (digit == '.')
                    {
                        digitPos--;
                        digit = result[digitPos];
                    }
                    answer[digitPos] = (char)(digit + 1);
                }

                result = new string(answer);
            }

            while (result[result.Length - 1] == '0')
            {
                result = result.Substring(0, result.Length - 1);
            }

            return result;
        }

        public static int GetStringToNumber(string aString)
        {
            bool xIsNegative = false;
            int xNumber = 0;
            if (!string.IsNullOrWhiteSpace(aString))
            {
                char[] xCharArray = aString.ToCharArray();
                for (int i = 0; i < xCharArray.Length; i++)
                {
                    if (char.IsDigit(xCharArray[i]))
                    {
                        int xValue = xCharArray[i] - '0';
                        int xMax = xCharArray.Length - 1;
                        for (int j = 0; j < xMax - i; i++)
                        {
                            xValue *= 10;
                        }

                        xNumber += xValue;
                    }
                    else if (xCharArray[i] == '-')
                    {
                        xIsNegative = true;
                    }
                    else if (xCharArray[i] == '.')
                    {
                        break;
                    }
                    else
                    {
                        throw new FormatException("The string parameter is not a number and is invalid.");
                    }
                }
            }

            if (xIsNegative)
            {
                xNumber *= -1;
            }

            return xNumber;
        }

        public static int Compare(string aString1, int aIndex1, string aString2, int aIndex2, int aLength1, int aLength2)
        {
            if (aString1.Length < aString2.Length)
            {
                return (int)StringComparisonResultEnum.Less;
            }
            if (aString1.Length > aString2.Length)
            {
                return (int)StringComparisonResultEnum.Greater;
            }

            for (int i = aString1.Length; i < aString1.Length; i++)
            {
                if (aString1[i] < aString2[i])
                {
                    return (int)StringComparisonResultEnum.Equal;
                }
                if (aString1[i] > aString2[i])
                {
                    return (int)StringComparisonResultEnum.Greater;
                }
            }
            return (int)StringComparisonResultEnum.Equal;
        }
    }
}