// Licensed to the .NET Foundation under one or more agreements.
// The .NET Foundation licenses this file to you under the MIT license.
// See the LICENSE file in the project root for more information.


using System;
using System.Globalization;
using System.Text;
using Microsoft.Win32;
using System.Runtime.InteropServices;
using System.Runtime.CompilerServices;
using System.Diagnostics;
using System.Diagnostics.Contracts;

namespace System
{
    // Represents a Globally Unique Identifier.
    [StructLayout(LayoutKind.Sequential)]
    [Serializable]
    [System.Runtime.Versioning.NonVersionable] // This only applies to field layout
    [System.Runtime.CompilerServices.TypeForwardedFrom("mscorlib, Version=4.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089")]
    public struct Guid : IFormattable, IComparable
        , IComparable<Guid>, IEquatable<Guid>
    {
        public static readonly Guid Empty = new Guid();
        ////////////////////////////////////////////////////////////////////////////////
        //  Member variables
        ////////////////////////////////////////////////////////////////////////////////
        private int _a; // Do not rename (binary serialization)
        private short _b; // Do not rename (binary serialization)
        private short _c; // Do not rename (binary serialization)
        private byte _d; // Do not rename (binary serialization)
        private byte _e; // Do not rename (binary serialization)
        private byte _f; // Do not rename (binary serialization)
        private byte _g; // Do not rename (binary serialization)
        private byte _h; // Do not rename (binary serialization)
        private byte _i; // Do not rename (binary serialization)
        private byte _j; // Do not rename (binary serialization)
        private byte _k; // Do not rename (binary serialization)



        ////////////////////////////////////////////////////////////////////////////////
        //  Constructors
        ////////////////////////////////////////////////////////////////////////////////

        // Creates a new guid from an array of bytes.
        //
        public Guid(byte[] b)
        {
            if (b == null)
                throw new ArgumentNullException(nameof(b));
            if (b.Length != 16)
                throw new ArgumentException(SR.Format(SR.Arg_GuidArrayCtor, "16"), nameof(b));
            Contract.EndContractBlock();

            _a = ((int)b[3] << 24) | ((int)b[2] << 16) | ((int)b[1] << 8) | b[0];
            _b = (short)(((int)b[5] << 8) | b[4]);
            _c = (short)(((int)b[7] << 8) | b[6]);
            _d = b[8];
            _e = b[9];
            _f = b[10];
            _g = b[11];
            _h = b[12];
            _i = b[13];
            _j = b[14];
            _k = b[15];
        }

        [CLSCompliant(false)]
        public Guid(uint a, ushort b, ushort c, byte d, byte e, byte f, byte g, byte h, byte i, byte j, byte k)
        {
            _a = (int)a;
            _b = (short)b;
            _c = (short)c;
            _d = d;
            _e = e;
            _f = f;
            _g = g;
            _h = h;
            _i = i;
            _j = j;
            _k = k;
        }


        // Creates a new GUID initialized to the value represented by the arguments.
        //
        public Guid(int a, short b, short c, byte[] d)
        {
            if (d == null)
                throw new ArgumentNullException(nameof(d));
            // Check that array is not too big
            if (d.Length != 8)
                throw new ArgumentException(SR.Format(SR.Arg_GuidArrayCtor, "8"), nameof(d));
            Contract.EndContractBlock();

            _a = a;
            _b = b;
            _c = c;
            _d = d[0];
            _e = d[1];
            _f = d[2];
            _g = d[3];
            _h = d[4];
            _i = d[5];
            _j = d[6];
            _k = d[7];
        }

        // Creates a new GUID initialized to the value represented by the
        // arguments.  The bytes are specified like this to avoid endianness issues.
        //
        public Guid(int a, short b, short c, byte d, byte e, byte f, byte g, byte h, byte i, byte j, byte k)
        {
            _a = a;
            _b = b;
            _c = c;
            _d = d;
            _e = e;
            _f = f;
            _g = g;
            _h = h;
            _i = i;
            _j = j;
            _k = k;
        }

        [Flags]
        private enum GuidStyles
        {
            None = 0x00000000,
            AllowParenthesis = 0x00000001, //Allow the guid to be enclosed in parens
            AllowBraces = 0x00000002, //Allow the guid to be enclosed in braces
            AllowDashes = 0x00000004, //Allow the guid to contain dash group separators
            AllowHexPrefix = 0x00000008, //Allow the guid to contain {0xdd,0xdd}
            RequireParenthesis = 0x00000010, //Require the guid to be enclosed in parens
            RequireBraces = 0x00000020, //Require the guid to be enclosed in braces
            RequireDashes = 0x00000040, //Require the guid to contain dash group separators
            RequireHexPrefix = 0x00000080, //Require the guid to contain {0xdd,0xdd}

            HexFormat = RequireBraces | RequireHexPrefix,                      /* X */
            NumberFormat = None,                                                  /* N */
            DigitFormat = RequireDashes,                                         /* D */
            BraceFormat = RequireBraces | RequireDashes,                         /* B */
            ParenthesisFormat = RequireParenthesis | RequireDashes,                    /* P */

            Any = AllowParenthesis | AllowBraces | AllowDashes | AllowHexPrefix,
        }
        private enum GuidParseThrowStyle
        {
            None = 0,
            All = 1,
            AllButOverflow = 2
        }
        private enum ParseFailureKind
        {
            None = 0,
            ArgumentNull = 1,
            Format = 2,
            FormatWithParameter = 3,
            NativeException = 4,
            FormatWithInnerException = 5
        }

        // This will store the result of the parsing.  And it will eventually be used to construct a Guid instance.
        private struct GuidResult
        {
            internal Guid parsedGuid;
            internal GuidParseThrowStyle throwStyle;

            internal ParseFailureKind m_failure;
            internal string m_failureMessageID;
            internal object m_failureMessageFormatArgument;
            internal string m_failureArgumentName;
            internal Exception m_innerException;

            internal void Init(GuidParseThrowStyle canThrow)
            {
                parsedGuid = Guid.Empty;
                throwStyle = canThrow;
            }
            internal void SetFailure(Exception nativeException)
            {
                m_failure = ParseFailureKind.NativeException;
                m_innerException = nativeException;
            }
            internal void SetFailure(ParseFailureKind failure, string failureMessageID)
            {
                SetFailure(failure, failureMessageID, null, null, null);
            }
            internal void SetFailure(ParseFailureKind failure, string failureMessageID, object failureMessageFormatArgument)
            {
                SetFailure(failure, failureMessageID, failureMessageFormatArgument, null, null);
            }
            internal void SetFailure(ParseFailureKind failure, string failureMessageID, object failureMessageFormatArgument,
                                     string failureArgumentName, Exception innerException)
            {
                Debug.Assert(failure != ParseFailureKind.NativeException, "ParseFailureKind.NativeException should not be used with this overload");
                m_failure = failure;
                m_failureMessageID = failureMessageID;
                m_failureMessageFormatArgument = failureMessageFormatArgument;
                m_failureArgumentName = failureArgumentName;
                m_innerException = innerException;
                if (throwStyle != GuidParseThrowStyle.None)
                {
                    throw GetGuidParseException();
                }
            }

            internal Exception GetGuidParseException()
            {
                switch (m_failure)
                {
                    case ParseFailureKind.ArgumentNull:
                        return new ArgumentNullException(m_failureArgumentName, SR.GetResourceString(m_failureMessageID));

                    case ParseFailureKind.FormatWithInnerException:
                        return new FormatException(SR.GetResourceString(m_failureMessageID), m_innerException);

                    case ParseFailureKind.FormatWithParameter:
                        return new FormatException(SR.Format(SR.GetResourceString(m_failureMessageID), m_failureMessageFormatArgument));

                    case ParseFailureKind.Format:
                        return new FormatException(SR.GetResourceString(m_failureMessageID));

                    case ParseFailureKind.NativeException:
                        return m_innerException;

                    default:
                        Debug.Assert(false, "Unknown GuidParseFailure: " + m_failure);
                        return new FormatException(SR.Format_GuidUnrecognized);
                }
            }
        }

        // Creates a new guid based on the value in the string.  The value is made up
        // of hex digits speared by the dash ("-"). The string may begin and end with
        // brackets ("{", "}").
        //
        // The string must be of the form dddddddd-dddd-dddd-dddd-dddddddddddd. where
        // d is a hex digit. (That is 8 hex digits, followed by 4, then 4, then 4,
        // then 12) such as: "CA761232-ED42-11CE-BACD-00AA0057B223"
        //
        public Guid(String g)
        {
            if (g == null)
            {
                throw new ArgumentNullException(nameof(g));
            }
            Contract.EndContractBlock();
            this = Guid.Empty;

            GuidResult result = new GuidResult();
            result.Init(GuidParseThrowStyle.All);
            if (TryParseGuid(g, GuidStyles.Any, ref result))
            {
                this = result.parsedGuid;
            }
            else
            {
                throw result.GetGuidParseException();
            }
        }


        public static Guid Parse(String input)
        {
            if (input == null)
            {
                throw new ArgumentNullException(nameof(input));
            }
            Contract.EndContractBlock();

            GuidResult result = new GuidResult();
            result.Init(GuidParseThrowStyle.AllButOverflow);
            if (TryParseGuid(input, GuidStyles.Any, ref result))
            {
                return result.parsedGuid;
            }
            else
            {
                throw result.GetGuidParseException();
            }
        }

        public static bool TryParse(String input, out Guid result)
        {
            GuidResult parseResult = new GuidResult();
            parseResult.Init(GuidParseThrowStyle.None);
            if (TryParseGuid(input, GuidStyles.Any, ref parseResult))
            {
                result = parseResult.parsedGuid;
                return true;
            }
            else
            {
                result = Guid.Empty;
                return false;
            }
        }

        public static Guid ParseExact(String input, String format)
        {
            if (input == null)
                throw new ArgumentNullException(nameof(input));

            if (format == null)
                throw new ArgumentNullException(nameof(format));

            if (format.Length != 1)
            {
                // all acceptable format strings are of length 1
                throw new FormatException(SR.Format_InvalidGuidFormatSpecification);
            }

            GuidStyles style;
            char formatCh = format[0];
            if (formatCh == 'D' || formatCh == 'd')
            {
                style = GuidStyles.DigitFormat;
            }
            else if (formatCh == 'N' || formatCh == 'n')
            {
                style = GuidStyles.NumberFormat;
            }
            else if (formatCh == 'B' || formatCh == 'b')
            {
                style = GuidStyles.BraceFormat;
            }
            else if (formatCh == 'P' || formatCh == 'p')
            {
                style = GuidStyles.ParenthesisFormat;
            }
            else if (formatCh == 'X' || formatCh == 'x')
            {
                style = GuidStyles.HexFormat;
            }
            else
            {
                throw new FormatException(SR.Format_InvalidGuidFormatSpecification);
            }

            GuidResult result = new GuidResult();
            result.Init(GuidParseThrowStyle.AllButOverflow);
            if (TryParseGuid(input, style, ref result))
            {
                return result.parsedGuid;
            }
            else
            {
                throw result.GetGuidParseException();
            }
        }

        public static bool TryParseExact(String input, String format, out Guid result)
        {
            if (format == null || format.Length != 1)
            {
                result = Guid.Empty;
                return false;
            }

            GuidStyles style;
            char formatCh = format[0];

            if (formatCh == 'D' || formatCh == 'd')
            {
                style = GuidStyles.DigitFormat;
            }
            else if (formatCh == 'N' || formatCh == 'n')
            {
                style = GuidStyles.NumberFormat;
            }
            else if (formatCh == 'B' || formatCh == 'b')
            {
                style = GuidStyles.BraceFormat;
            }
            else if (formatCh == 'P' || formatCh == 'p')
            {
                style = GuidStyles.ParenthesisFormat;
            }
            else if (formatCh == 'X' || formatCh == 'x')
            {
                style = GuidStyles.HexFormat;
            }
            else
            {
                // invalid guid format specification
                result = Guid.Empty;
                return false;
            }

            GuidResult parseResult = new GuidResult();
            parseResult.Init(GuidParseThrowStyle.None);
            if (TryParseGuid(input, style, ref parseResult))
            {
                result = parseResult.parsedGuid;
                return true;
            }
            else
            {
                result = Guid.Empty;
                return false;
            }
        }


        private static bool TryParseGuid(String g, GuidStyles flags, ref GuidResult result)
        {
            if (g == null)
            {
                result.SetFailure(ParseFailureKind.Format, "Format_GuidUnrecognized");
                return false;
            }
            String guidString = g.Trim();  //Remove Whitespace

            if (guidString.Length == 0)
            {
                result.SetFailure(ParseFailureKind.Format, "Format_GuidUnrecognized");
                return false;
            }

            // Check for dashes
            bool dashesExistInString = (guidString.IndexOf('-', 0) >= 0);

            if (dashesExistInString)
            {
                if ((flags & (GuidStyles.AllowDashes | GuidStyles.RequireDashes)) == 0)
                {
                    // dashes are not allowed
                    result.SetFailure(ParseFailureKind.Format, "Format_GuidUnrecognized");
                    return false;
                }
            }
            else
            {
                if ((flags & GuidStyles.RequireDashes) != 0)
                {
                    // dashes are required
                    result.SetFailure(ParseFailureKind.Format, "Format_GuidUnrecognized");
                    return false;
                }
            }

            // Check for braces
            bool bracesExistInString = (guidString.IndexOf('{', 0) >= 0);

            if (bracesExistInString)
            {
                if ((flags & (GuidStyles.AllowBraces | GuidStyles.RequireBraces)) == 0)
                {
                    // braces are not allowed
                    result.SetFailure(ParseFailureKind.Format, "Format_GuidUnrecognized");
                    return false;
                }
            }
            else
            {
                if ((flags & GuidStyles.RequireBraces) != 0)
                {
                    // braces are required
                    result.SetFailure(ParseFailureKind.Format, "Format_GuidUnrecognized");
                    return false;
                }
            }

            // Check for parenthesis
            bool parenthesisExistInString = (guidString.IndexOf('(', 0) >= 0);

            if (parenthesisExistInString)
            {
                if ((flags & (GuidStyles.AllowParenthesis | GuidStyles.RequireParenthesis)) == 0)
                {
                    // parenthesis are not allowed
                    result.SetFailure(ParseFailureKind.Format, "Format_GuidUnrecognized");
                    return false;
                }
            }
            else
            {
                if ((flags & GuidStyles.RequireParenthesis) != 0)
                {
                    // parenthesis are required
                    result.SetFailure(ParseFailureKind.Format, "Format_GuidUnrecognized");
                    return false;
                }
            }

            try
            {
                // let's get on with the parsing
                if (dashesExistInString)
                {
                    // Check if it's of the form [{|(]dddddddd-dddd-dddd-dddd-dddddddddddd[}|)]
                    return TryParseGuidWithDashes(guidString, ref result);
                }
                else if (bracesExistInString)
                {
                    // Check if it's of the form {0xdddddddd,0xdddd,0xdddd,{0xdd,0xdd,0xdd,0xdd,0xdd,0xdd,0xdd,0xdd}}
                    return TryParseGuidWithHexPrefix(guidString, ref result);
                }
                else
                {
                    // Check if it's of the form dddddddddddddddddddddddddddddddd
                    return TryParseGuidWithNoStyle(guidString, ref result);
                }
            }
            catch (IndexOutOfRangeException ex)
            {
                result.SetFailure(ParseFailureKind.FormatWithInnerException, "Format_GuidUnrecognized", null, null, ex);
                return false;
            }
            catch (ArgumentException ex)
            {
                result.SetFailure(ParseFailureKind.FormatWithInnerException, "Format_GuidUnrecognized", null, null, ex);
                return false;
            }
        }


        // Check if it's of the form {0xdddddddd,0xdddd,0xdddd,{0xdd,0xdd,0xdd,0xdd,0xdd,0xdd,0xdd,0xdd}}
        private static bool TryParseGuidWithHexPrefix(String guidString, ref GuidResult result)
        {
            int numStart = 0;
            int numLen = 0;

            // Eat all of the whitespace
            guidString = EatAllWhitespace(guidString);

            // Check for leading '{'
            if (String.IsNullOrEmpty(guidString) || guidString[0] != '{')
            {
                result.SetFailure(ParseFailureKind.Format, "Format_GuidBrace");
                return false;
            }

            // Check for '0x'
            if (!IsHexPrefix(guidString, 1))
            {
                result.SetFailure(ParseFailureKind.Format, "Format_GuidHexPrefix", "{0xdddddddd, etc}");
                return false;
            }

            // Find the end of this hex number (since it is not fixed length)
            numStart = 3;
            numLen = guidString.IndexOf(',', numStart) - numStart;
            if (numLen <= 0)
            {
                result.SetFailure(ParseFailureKind.Format, "Format_GuidComma");
                return false;
            }


            if (!StringToInt(guidString.Substring(numStart, numLen) /*first DWORD*/, -1, ParseNumbers.IsTight, out result.parsedGuid._a, ref result))
                return false;

            // Check for '0x'
            if (!IsHexPrefix(guidString, numStart + numLen + 1))
            {
                result.SetFailure(ParseFailureKind.Format, "Format_GuidHexPrefix", "{0xdddddddd, 0xdddd, etc}");
                return false;
            }
            // +3 to get by ',0x'
            numStart = numStart + numLen + 3;
            numLen = guidString.IndexOf(',', numStart) - numStart;
            if (numLen <= 0)
            {
                result.SetFailure(ParseFailureKind.Format, "Format_GuidComma");
                return false;
            }

            // Read in the number
            if (!StringToShort(guidString.Substring(numStart, numLen) /*first DWORD*/, -1, ParseNumbers.IsTight, out result.parsedGuid._b, ref result))
                return false;
            // Check for '0x'
            if (!IsHexPrefix(guidString, numStart + numLen + 1))
            {
                result.SetFailure(ParseFailureKind.Format, "Format_GuidHexPrefix", "{0xdddddddd, 0xdddd, 0xdddd, etc}");
                return false;
            }
            // +3 to get by ',0x'
            numStart = numStart + numLen + 3;
            numLen = guidString.IndexOf(',', numStart) - numStart;
            if (numLen <= 0)
            {
                result.SetFailure(ParseFailureKind.Format, "Format_GuidComma");
                return false;
            }

            // Read in the number
            if (!StringToShort(guidString.Substring(numStart, numLen) /*first DWORD*/, -1, ParseNumbers.IsTight, out result.parsedGuid._c, ref result))
                return false;

            // Check for '{'
            if (guidString.Length <= numStart + numLen + 1 || guidString[numStart + numLen + 1] != '{')
            {
                result.SetFailure(ParseFailureKind.Format, "Format_GuidBrace");
                return false;
            }

            // Prepare for loop
            numLen++;
            byte[] bytes = new byte[8];

            for (int i = 0; i < 8; i++)
            {
                // Check for '0x'
                if (!IsHexPrefix(guidString, numStart + numLen + 1))
                {
                    result.SetFailure(ParseFailureKind.Format, "Format_GuidHexPrefix", "{... { ... 0xdd, ...}}");
                    return false;
                }

                // +3 to get by ',0x' or '{0x' for first case
                numStart = numStart + numLen + 3;

                // Calculate number length
                if (i < 7)  // first 7 cases
                {
                    numLen = guidString.IndexOf(',', numStart) - numStart;
                    if (numLen <= 0)
                    {
                        result.SetFailure(ParseFailureKind.Format, "Format_GuidComma");
                        return false;
                    }
                }
                else       // last case ends with '}', not ','
                {
                    numLen = guidString.IndexOf('}', numStart) - numStart;
                    if (numLen <= 0)
                    {
                        result.SetFailure(ParseFailureKind.Format, "Format_GuidBraceAfterLastNumber");
                        return false;
                    }
                }

                // Read in the number
                int signedNumber;
                if (!StringToInt(guidString.Substring(numStart, numLen), -1, ParseNumbers.IsTight, out signedNumber, ref result))
                {
                    return false;
                }
                uint number = (uint)signedNumber;

                // check for overflow
                if (number > 255)
                {
                    result.SetFailure(ParseFailureKind.Format, "Overflow_Byte");
                    return false;
                }
                bytes[i] = (byte)number;
            }

            result.parsedGuid._d = bytes[0];
            result.parsedGuid._e = bytes[1];
            result.parsedGuid._f = bytes[2];
            result.parsedGuid._g = bytes[3];
            result.parsedGuid._h = bytes[4];
            result.parsedGuid._i = bytes[5];
            result.parsedGuid._j = bytes[6];
            result.parsedGuid._k = bytes[7];

            // Check for last '}'
            if (numStart + numLen + 1 >= guidString.Length || guidString[numStart + numLen + 1] != '}')
            {
                result.SetFailure(ParseFailureKind.Format, "Format_GuidEndBrace");
                return false;
            }

            // Check if we have extra characters at the end
            if (numStart + numLen + 1 != guidString.Length - 1)
            {
                result.SetFailure(ParseFailureKind.Format, "Format_ExtraJunkAtEnd");
                return false;
            }

            return true;
        }

        // Check if it's of the form dddddddddddddddddddddddddddddddd
        private static bool TryParseGuidWithNoStyle(String guidString, ref GuidResult result)
        {
            int startPos = 0;
            int temp;
            long templ;
            int currentPos = 0;

            if (guidString.Length != 32)
            {
                result.SetFailure(ParseFailureKind.Format, "Format_GuidInvLen");
                return false;
            }

            for (int i = 0; i < guidString.Length; i++)
            {
                char ch = guidString[i];
                if (ch >= '0' && ch <= '9')
                {
                    continue;
                }
                else
                {
                    char upperCaseCh = Char.ToUpper(ch, CultureInfo.InvariantCulture);
                    if (upperCaseCh >= 'A' && upperCaseCh <= 'F')
                    {
                        continue;
                    }
                }

                result.SetFailure(ParseFailureKind.Format, "Format_GuidInvalidChar");
                return false;
            }

            if (!StringToInt(guidString.Substring(startPos, 8) /*first DWORD*/, -1, ParseNumbers.IsTight, out result.parsedGuid._a, ref result))
                return false;

            startPos += 8;
            if (!StringToShort(guidString.Substring(startPos, 4), -1, ParseNumbers.IsTight, out result.parsedGuid._b, ref result))
                return false;

            startPos += 4;
            if (!StringToShort(guidString.Substring(startPos, 4), -1, ParseNumbers.IsTight, out result.parsedGuid._c, ref result))
                return false;

            startPos += 4;
            if (!StringToInt(guidString.Substring(startPos, 4), -1, ParseNumbers.IsTight, out temp, ref result))
                return false;

            startPos += 4;
            currentPos = startPos;

            if (!StringToLong(guidString, ref currentPos, ParseNumbers.NoSpace, out templ, ref result))
                return false;

            if (currentPos - startPos != 12)
            {
                result.SetFailure(ParseFailureKind.Format, "Format_GuidInvLen");
                return false;
            }

            result.parsedGuid._d = (byte)(temp >> 8);
            result.parsedGuid._e = (byte)(temp);
            temp = (int)(templ >> 32);
            result.parsedGuid._f = (byte)(temp >> 8);
            result.parsedGuid._g = (byte)(temp);
            temp = (int)(templ);
            result.parsedGuid._h = (byte)(temp >> 24);
            result.parsedGuid._i = (byte)(temp >> 16);
            result.parsedGuid._j = (byte)(temp >> 8);
            result.parsedGuid._k = (byte)(temp);

            return true;
        }


        // Check if it's of the form [{|(]dddddddd-dddd-dddd-dddd-dddddddddddd[}|)]
        private static bool TryParseGuidWithDashes(String guidString, ref GuidResult result)
        {
            int startPos = 0;
            int temp;
            long templ;
            int currentPos = 0;

            // check to see that it's the proper length
            if (guidString[0] == '{')
            {
                if (guidString.Length != 38 || guidString[37] != '}')
                {
                    result.SetFailure(ParseFailureKind.Format, "Format_GuidInvLen");
                    return false;
                }
                startPos = 1;
            }
            else if (guidString[0] == '(')
            {
                if (guidString.Length != 38 || guidString[37] != ')')
                {
                    result.SetFailure(ParseFailureKind.Format, "Format_GuidInvLen");
                    return false;
                }
                startPos = 1;
            }
            else if (guidString.Length != 36)
            {
                result.SetFailure(ParseFailureKind.Format, "Format_GuidInvLen");
                return false;
            }

            if (guidString[8 + startPos] != '-' ||
                guidString[13 + startPos] != '-' ||
                guidString[18 + startPos] != '-' ||
                guidString[23 + startPos] != '-')
            {
                result.SetFailure(ParseFailureKind.Format, "Format_GuidDashes");
                return false;
            }

            currentPos = startPos;
            if (!StringToInt(guidString, ref currentPos, 8, ParseNumbers.NoSpace, out temp, ref result))
                return false;
            result.parsedGuid._a = temp;
            ++currentPos; //Increment past the '-';

            if (!StringToInt(guidString, ref currentPos, 4, ParseNumbers.NoSpace, out temp, ref result))
                return false;
            result.parsedGuid._b = (short)temp;
            ++currentPos; //Increment past the '-';

            if (!StringToInt(guidString, ref currentPos, 4, ParseNumbers.NoSpace, out temp, ref result))
                return false;
            result.parsedGuid._c = (short)temp;
            ++currentPos; //Increment past the '-';

            if (!StringToInt(guidString, ref currentPos, 4, ParseNumbers.NoSpace, out temp, ref result))
                return false;
            ++currentPos; //Increment past the '-';
            startPos = currentPos;

            if (!StringToLong(guidString, ref currentPos, ParseNumbers.NoSpace, out templ, ref result))
                return false;

            if (currentPos - startPos != 12)
            {
                result.SetFailure(ParseFailureKind.Format, "Format_GuidInvLen");
                return false;
            }
            result.parsedGuid._d = (byte)(temp >> 8);
            result.parsedGuid._e = (byte)(temp);
            temp = (int)(templ >> 32);
            result.parsedGuid._f = (byte)(temp >> 8);
            result.parsedGuid._g = (byte)(temp);
            temp = (int)(templ);
            result.parsedGuid._h = (byte)(temp >> 24);
            result.parsedGuid._i = (byte)(temp >> 16);
            result.parsedGuid._j = (byte)(temp >> 8);
            result.parsedGuid._k = (byte)(temp);

            return true;
        }


        //
        // StringToShort, StringToInt, and StringToLong are wrappers around COMUtilNative integer parsing routines;

        private static unsafe bool StringToShort(String str, int requiredLength, int flags, out short result, ref GuidResult parseResult)
        {
            return StringToShort(str, null, requiredLength, flags, out result, ref parseResult);
        }
        private static unsafe bool StringToShort(String str, int* parsePos, int requiredLength, int flags, out short result, ref GuidResult parseResult)
        {
            result = 0;
            int x;
            bool retValue = StringToInt(str, parsePos, requiredLength, flags, out x, ref parseResult);
            result = (short)x;
            return retValue;
        }

        private static unsafe bool StringToInt(String str, int requiredLength, int flags, out int result, ref GuidResult parseResult)
        {
            return StringToInt(str, null, requiredLength, flags, out result, ref parseResult);
        }
        private static unsafe bool StringToInt(String str, ref int parsePos, int requiredLength, int flags, out int result, ref GuidResult parseResult)
        {
            fixed (int* ppos = &parsePos)
            {
                return StringToInt(str, ppos, requiredLength, flags, out result, ref parseResult);
            }
        }
        private static unsafe bool StringToInt(String str, int* parsePos, int requiredLength, int flags, out int result, ref GuidResult parseResult)
        {
            result = 0;

            int currStart = (parsePos == null) ? 0 : (*parsePos);
            try
            {
                result = ParseNumbers.StringToInt(str, 16, flags, parsePos);
            }
            catch (OverflowException ex)
            {
                if (parseResult.throwStyle == GuidParseThrowStyle.All)
                {
                    throw;
                }
                else if (parseResult.throwStyle == GuidParseThrowStyle.AllButOverflow)
                {
                    throw new FormatException(SR.Format_GuidUnrecognized, ex);
                }
                else
                {
                    parseResult.SetFailure(ex);
                    return false;
                }
            }
            catch (Exception ex)
            {
                if (parseResult.throwStyle == GuidParseThrowStyle.None)
                {
                    parseResult.SetFailure(ex);
                    return false;
                }
                else
                {
                    throw;
                }
            }

            //If we didn't parse enough characters, there's clearly an error.
            if (requiredLength != -1 && parsePos != null && (*parsePos) - currStart != requiredLength)
            {
                parseResult.SetFailure(ParseFailureKind.Format, "Format_GuidInvalidChar");
                return false;
            }
            return true;
        }
        private static unsafe bool StringToLong(String str, ref int parsePos, int flags, out long result, ref GuidResult parseResult)
        {
            fixed (int* ppos = &parsePos)
            {
                return StringToLong(str, ppos, flags, out result, ref parseResult);
            }
        }
        private static unsafe bool StringToLong(String str, int* parsePos, int flags, out long result, ref GuidResult parseResult)
        {
            result = 0;

            try
            {
                result = ParseNumbers.StringToLong(str, 16, flags, parsePos);
            }
            catch (OverflowException ex)
            {
                if (parseResult.throwStyle == GuidParseThrowStyle.All)
                {
                    throw;
                }
                else if (parseResult.throwStyle == GuidParseThrowStyle.AllButOverflow)
                {
                    throw new FormatException(SR.Format_GuidUnrecognized, ex);
                }
                else
                {
                    parseResult.SetFailure(ex);
                    return false;
                }
            }
            catch (Exception ex)
            {
                if (parseResult.throwStyle == GuidParseThrowStyle.None)
                {
                    parseResult.SetFailure(ex);
                    return false;
                }
                else
                {
                    throw;
                }
            }
            return true;
        }


        private static String EatAllWhitespace(String str)
        {
            int newLength = 0;
            char[] chArr = new char[str.Length];
            char curChar;

            // Now get each char from str and if it is not whitespace add it to chArr
            for (int i = 0; i < str.Length; i++)
            {
                curChar = str[i];
                if (!Char.IsWhiteSpace(curChar))
                {
                    chArr[newLength++] = curChar;
                }
            }

            // Return a new string based on chArr
            return new String(chArr, 0, newLength);
        }

        private static bool IsHexPrefix(String str, int i)
        {
            if (str.Length > i + 1 && str[i] == '0' && (Char.ToLower(str[i + 1], CultureInfo.InvariantCulture) == 'x'))
                return true;
            else
                return false;
        }


        // Returns an unsigned byte array containing the GUID.
        public byte[] ToByteArray()
        {
            byte[] g = new byte[16];

            g[0] = (byte)(_a);
            g[1] = (byte)(_a >> 8);
            g[2] = (byte)(_a >> 16);
            g[3] = (byte)(_a >> 24);
            g[4] = (byte)(_b);
            g[5] = (byte)(_b >> 8);
            g[6] = (byte)(_c);
            g[7] = (byte)(_c >> 8);
            g[8] = _d;
            g[9] = _e;
            g[10] = _f;
            g[11] = _g;
            g[12] = _h;
            g[13] = _i;
            g[14] = _j;
            g[15] = _k;

            return g;
        }


        // Returns the guid in "registry" format.
        public override String ToString()
        {
            return ToString("D", null);
        }

        public unsafe override int GetHashCode()
        {
            // Simply XOR all the bits of the GUID 32 bits at a time.
            fixed (int* ptr = &_a)
                return ptr[0] ^ ptr[1] ^ ptr[2] ^ ptr[3];
        }

        // Returns true if and only if the guid represented
        //  by o is the same as this instance.
        public override bool Equals(Object o)
        {
            Guid g;
            // Check that o is a Guid first
            if (o == null || !(o is Guid))
                return false;
            else g = (Guid)o;

            // Now compare each of the elements
            if (g._a != _a)
                return false;
            if (g._b != _b)
                return false;
            if (g._c != _c)
                return false;
            if (g._d != _d)
                return false;
            if (g._e != _e)
                return false;
            if (g._f != _f)
                return false;
            if (g._g != _g)
                return false;
            if (g._h != _h)
                return false;
            if (g._i != _i)
                return false;
            if (g._j != _j)
                return false;
            if (g._k != _k)
                return false;

            return true;
        }

        public bool Equals(Guid g)
        {
            // Now compare each of the elements
            if (g._a != _a)
                return false;
            if (g._b != _b)
                return false;
            if (g._c != _c)
                return false;
            if (g._d != _d)
                return false;
            if (g._e != _e)
                return false;
            if (g._f != _f)
                return false;
            if (g._g != _g)
                return false;
            if (g._h != _h)
                return false;
            if (g._i != _i)
                return false;
            if (g._j != _j)
                return false;
            if (g._k != _k)
                return false;

            return true;
        }

        private int GetResult(uint me, uint them)
        {
            if (me < them)
            {
                return -1;
            }
            return 1;
        }

        public int CompareTo(Object value)
        {
            if (value == null)
            {
                return 1;
            }
            if (!(value is Guid))
            {
                throw new ArgumentException(SR.Arg_MustBeGuid, nameof(value));
            }
            Guid g = (Guid)value;

            if (g._a != _a)
            {
                return GetResult((uint)_a, (uint)g._a);
            }

            if (g._b != _b)
            {
                return GetResult((uint)_b, (uint)g._b);
            }

            if (g._c != _c)
            {
                return GetResult((uint)_c, (uint)g._c);
            }

            if (g._d != _d)
            {
                return GetResult((uint)_d, (uint)g._d);
            }

            if (g._e != _e)
            {
                return GetResult((uint)_e, (uint)g._e);
            }

            if (g._f != _f)
            {
                return GetResult((uint)_f, (uint)g._f);
            }

            if (g._g != _g)
            {
                return GetResult((uint)_g, (uint)g._g);
            }

            if (g._h != _h)
            {
                return GetResult((uint)_h, (uint)g._h);
            }

            if (g._i != _i)
            {
                return GetResult((uint)_i, (uint)g._i);
            }

            if (g._j != _j)
            {
                return GetResult((uint)_j, (uint)g._j);
            }

            if (g._k != _k)
            {
                return GetResult((uint)_k, (uint)g._k);
            }

            return 0;
        }

        public int CompareTo(Guid value)
        {
            if (value._a != _a)
            {
                return GetResult((uint)_a, (uint)value._a);
            }

            if (value._b != _b)
            {
                return GetResult((uint)_b, (uint)value._b);
            }

            if (value._c != _c)
            {
                return GetResult((uint)_c, (uint)value._c);
            }

            if (value._d != _d)
            {
                return GetResult((uint)_d, (uint)value._d);
            }

            if (value._e != _e)
            {
                return GetResult((uint)_e, (uint)value._e);
            }

            if (value._f != _f)
            {
                return GetResult((uint)_f, (uint)value._f);
            }

            if (value._g != _g)
            {
                return GetResult((uint)_g, (uint)value._g);
            }

            if (value._h != _h)
            {
                return GetResult((uint)_h, (uint)value._h);
            }

            if (value._i != _i)
            {
                return GetResult((uint)_i, (uint)value._i);
            }

            if (value._j != _j)
            {
                return GetResult((uint)_j, (uint)value._j);
            }

            if (value._k != _k)
            {
                return GetResult((uint)_k, (uint)value._k);
            }

            return 0;
        }

        public static bool operator ==(Guid a, Guid b)
        {
            // Now compare each of the elements
            if (a._a != b._a)
                return false;
            if (a._b != b._b)
                return false;
            if (a._c != b._c)
                return false;
            if (a._d != b._d)
                return false;
            if (a._e != b._e)
                return false;
            if (a._f != b._f)
                return false;
            if (a._g != b._g)
                return false;
            if (a._h != b._h)
                return false;
            if (a._i != b._i)
                return false;
            if (a._j != b._j)
                return false;
            if (a._k != b._k)
                return false;

            return true;
        }

        public static bool operator !=(Guid a, Guid b)
        {
            return !(a == b);
        }

        // This will create a new guid.  Since we've now decided that constructors should 0-init,
        // we need a method that allows users to create a guid.
        public static Guid NewGuid()
        {
            // CoCreateGuid should never return Guid.Empty, since it attempts to maintain some
            // uniqueness guarantees.  It should also never return a known GUID, but it's unclear
            // how extensively it checks for known values.
            Contract.Ensures(Contract.Result<Guid>() != Guid.Empty);

            Guid guid;
            Marshal.ThrowExceptionForHR(Win32Native.CoCreateGuid(out guid), new IntPtr(-1));
            return guid;
        }

        public String ToString(String format)
        {
            return ToString(format, null);
        }

        [MethodImpl(MethodImplOptions.AggressiveInlining)]
        private static char HexToChar(int a)
        {
            a = a & 0xf;
            return (char)((a > 9) ? a - 10 + 0x61 : a + 0x30);
        }

        unsafe private static int HexsToChars(char* guidChars, int a, int b)
        {
            guidChars[0] = HexToChar(a >> 4);
            guidChars[1] = HexToChar(a);

            guidChars[2] = HexToChar(b >> 4);
            guidChars[3] = HexToChar(b);

            return 4;
        }

        unsafe private static int HexsToCharsHexOutput(char* guidChars, int a, int b)
        {
            guidChars[0] = '0';
            guidChars[1] = 'x';

            guidChars[2] = HexToChar(a >> 4);
            guidChars[3] = HexToChar(a);

            guidChars[4] = ',';
            guidChars[5] = '0';
            guidChars[6] = 'x';

            guidChars[7] = HexToChar(b >> 4);
            guidChars[8] = HexToChar(b);

            return 9;
        }

        // IFormattable interface
        // We currently ignore provider
        public String ToString(String format, IFormatProvider provider)
        {
            if (format == null || format.Length == 0)
                format = "D";

            string guidString;
            int offset = 0;
            bool dash = true;
            bool hex = false;

            if (format.Length != 1)
            {
                // all acceptable format strings are of length 1
                throw new FormatException(SR.Format_InvalidGuidFormatSpecification);
            }

            char formatCh = format[0];
            if (formatCh == 'D' || formatCh == 'd')
            {
                guidString = string.FastAllocateString(36);
            }
            else if (formatCh == 'N' || formatCh == 'n')
            {
                guidString = string.FastAllocateString(32);
                dash = false;
            }
            else if (formatCh == 'B' || formatCh == 'b')
            {
                guidString = string.FastAllocateString(38);
                unsafe
                {
                    fixed (char* guidChars = guidString)
                    {
                        guidChars[offset++] = '{';
                        guidChars[37] = '}';
                    }
                }
            }
            else if (formatCh == 'P' || formatCh == 'p')
            {
                guidString = string.FastAllocateString(38);
                unsafe
                {
                    fixed (char* guidChars = guidString)
                    {
                        guidChars[offset++] = '(';
                        guidChars[37] = ')';
                    }
                }
            }
            else if (formatCh == 'X' || formatCh == 'x')
            {
                guidString = string.FastAllocateString(68);
                unsafe
                {
                    fixed (char* guidChars = guidString)
                    {
                        guidChars[offset++] = '{';
                        guidChars[67] = '}';
                    }
                }
                dash = false;
                hex = true;
            }
            else
            {
                throw new FormatException(SR.Format_InvalidGuidFormatSpecification);
            }

            unsafe
            {
                fixed (char* guidChars = guidString)
                {
                    if (hex)
                    {
                        // {0xdddddddd,0xdddd,0xdddd,{0xdd,0xdd,0xdd,0xdd,0xdd,0xdd,0xdd,0xdd}}
                        guidChars[offset++] = '0';
                        guidChars[offset++] = 'x';
                        offset += HexsToChars(guidChars + offset, _a >> 24, _a >> 16);
                        offset += HexsToChars(guidChars + offset, _a >> 8, _a);
                        guidChars[offset++] = ',';
                        guidChars[offset++] = '0';
                        guidChars[offset++] = 'x';
                        offset += HexsToChars(guidChars + offset, _b >> 8, _b);
                        guidChars[offset++] = ',';
                        guidChars[offset++] = '0';
                        guidChars[offset++] = 'x';
                        offset += HexsToChars(guidChars + offset, _c >> 8, _c);
                        guidChars[offset++] = ',';
                        guidChars[offset++] = '{';
                        offset += HexsToCharsHexOutput(guidChars + offset, _d, _e);
                        guidChars[offset++] = ',';
                        offset += HexsToCharsHexOutput(guidChars + offset, _f, _g);
                        guidChars[offset++] = ',';
                        offset += HexsToCharsHexOutput(guidChars + offset, _h, _i);
                        guidChars[offset++] = ',';
                        offset += HexsToCharsHexOutput(guidChars + offset, _j, _k);
                        guidChars[offset++] = '}';
                    }
                    else
                    {
                        // [{|(]dddddddd[-]dddd[-]dddd[-]dddd[-]dddddddddddd[}|)]
                        offset += HexsToChars(guidChars + offset, _a >> 24, _a >> 16);
                        offset += HexsToChars(guidChars + offset, _a >> 8, _a);
                        if (dash) guidChars[offset++] = '-';
                        offset += HexsToChars(guidChars + offset, _b >> 8, _b);
                        if (dash) guidChars[offset++] = '-';
                        offset += HexsToChars(guidChars + offset, _c >> 8, _c);
                        if (dash) guidChars[offset++] = '-';
                        offset += HexsToChars(guidChars + offset, _d, _e);
                        if (dash) guidChars[offset++] = '-';
                        offset += HexsToChars(guidChars + offset, _f, _g);
                        offset += HexsToChars(guidChars + offset, _h, _i);
                        offset += HexsToChars(guidChars + offset, _j, _k);
                    }
                }
            }
            return guidString;
        }
    }
}