// ==++==
//
//   Copyright (c) Microsoft Corporation.  All rights reserved.
//
// ==--==
////////////////////////////////////////////////////////////////////////////
//
//  Class:    CharacterInfo
//
//  Purpose:  This class implements a set of methods for retrieving
//            character type information.  Character type information is
//            independent of culture and region.
//
//  Date:     August 12, 1998
//
////////////////////////////////////////////////////////////////////////////

namespace System.Globalization {

    //This class has only static members and therefore doesn't need to be serialized.

    using System;
    using System.Threading;
    using System.Runtime.InteropServices;
    using System.Runtime.CompilerServices;
    using System.Runtime.Versioning;
    using System.Reflection;
    using System.Security;
    using System.Diagnostics.Contracts;


    public static class CharUnicodeInfo
    {
        //--------------------------------------------------------------------//
        //                        Internal Information                        //
        //--------------------------------------------------------------------//

        //
        // Native methods to access the Unicode category data tables in charinfo.nlp.
        //
        internal const char  HIGH_SURROGATE_START  = '\ud800';
        internal const char  HIGH_SURROGATE_END    = '\udbff';
        internal const char  LOW_SURROGATE_START   = '\udc00';
        internal const char  LOW_SURROGATE_END     = '\udfff';

        internal const int UNICODE_CATEGORY_OFFSET = 0;
        internal const int BIDI_CATEGORY_OFFSET = 1;

#pragma warning disable 414
        static bool s_initialized = InitTable();
#pragma warning restore

        // The native pointer to the 12:4:4 index table of the Unicode cateogry data.
        [SecurityCritical]
        unsafe static ushort* s_pCategoryLevel1Index;
        [SecurityCritical]
        unsafe static byte* s_pCategoriesValue;

        // The native pointer to the 12:4:4 index table of the Unicode numeric data.
        // The value of this index table is an index into the real value table stored in s_pNumericValues.
        [SecurityCritical]
        unsafe static ushort* s_pNumericLevel1Index;

        // The numeric value table, which is indexed by s_pNumericLevel1Index.
        // Every item contains the value for numeric value.
        // unsafe static double* s_pNumericValues;
        // To get around the IA64 alignment issue.  Our double data is aligned in 8-byte boundary, but loader loads the embeded table starting
        // at 4-byte boundary.  This cause a alignment issue since double is 8-byte.
        [SecurityCritical]
        unsafe static byte* s_pNumericValues;

        // The digit value table, which is indexed by s_pNumericLevel1Index.  It shares the same indice as s_pNumericValues.
        // Every item contains the value for decimal digit/digit value.
        [SecurityCritical]
        unsafe static DigitValues* s_pDigitValues;

        internal const String UNICODE_INFO_FILE_NAME = "charinfo.nlp";
        // The starting codepoint for Unicode plane 1.  Plane 1 contains 0x010000 ~ 0x01ffff.
        internal const int UNICODE_PLANE01_START = 0x10000;


        //
        // This is the header for the native data table that we load from UNICODE_INFO_FILE_NAME.
        //
        // Excplicit layout is used here since a syntax like char[16] can not be used in sequential layout.
        [StructLayout(LayoutKind.Explicit)]
        internal unsafe struct UnicodeDataHeader {
            [FieldOffset(0)]
            internal char TableName;    // WCHAR[16]
            [FieldOffset(0x20)]
            internal ushort version;    // WORD[4]
            [FieldOffset(0x28)]
            internal uint OffsetToCategoriesIndex; // DWORD
            [FieldOffset(0x2c)]
            internal uint OffsetToCategoriesValue; // DWORD
            [FieldOffset(0x30)]
            internal uint OffsetToNumbericIndex; // DWORD
            [FieldOffset(0x34)]
            internal uint OffsetToDigitValue; // DWORD
            [FieldOffset(0x38)]
            internal uint OffsetToNumbericValue; // DWORD

        }

        // NOTE: It's important to specify pack size here, since the size of the structure is 2 bytes.  Otherwise,
        // the default pack size will be 4.

        [StructLayout(LayoutKind.Sequential, Pack=2)]
        internal struct DigitValues {
            internal sbyte decimalDigit;
            internal sbyte digit;
        }

        unsafe private static int EndianSwap(int value)
        {
            if (!BitConverter.IsLittleEndian) {
                byte *ptr = (byte *) &value;
                int res;
                byte *buf = (byte *) &res;
                int t = sizeof(int) - 1;

                for (int i = 0; i < sizeof(int); i++) 
                    buf[t-i] = ptr[i];
                
                return(res);
            } else
                return(value);
        }

        unsafe private static uint EndianSwap(uint value)
        {
            if (!BitConverter.IsLittleEndian) {
                byte *ptr = (byte *) &value;
                uint res;
                byte *buf = (byte *) &res;
                uint t = sizeof(uint) - 1;

                for (uint i = 0; i < sizeof(uint); i++) 
                    buf[t-i] = ptr[i];
                
                return(res);
            } else
                return(value);
        }

        unsafe private static ushort EndianSwap(ushort value)
        {
            if (!BitConverter.IsLittleEndian) {
                byte *ptr = (byte *) &value;
                ushort res;
                byte *buf = (byte *) &res;
                ushort t = sizeof(ushort) - 1;

                for (ushort i = 0; i < sizeof(ushort); i++) 
                    buf[t-i] = ptr[i];
                
                return(res);
            } else
                return(value);
        }

        unsafe private static double EndianSwap(double value)
        {
            if (!BitConverter.IsLittleEndian) {
                byte *ptr = (byte *) &value;
                double res;
                byte *buf = (byte *) &res;
                ushort t = sizeof(double) - 1;

                for (ushort i = 0; i < sizeof(double); i++)
                    buf[t-i] = ptr[i];

                return(res);
            } else
                return(value);
        }


        //We need to allocate the underlying table that provides us with the information that we
        //use.  We allocate this once in the class initializer and then we don't need to worry
        //about it again.
        //
        [System.Security.SecuritySafeCritical]  // auto-generated
        [ResourceExposure(ResourceScope.None)]
        [ResourceConsumption(ResourceScope.Process, ResourceScope.Process)]
        unsafe static bool InitTable() {

            // Go to native side and get pointer to the native table
            byte * pDataTable = GlobalizationAssembly.GetGlobalizationResourceBytePtr(typeof(CharUnicodeInfo).Assembly, UNICODE_INFO_FILE_NAME);

            UnicodeDataHeader* mainHeader = (UnicodeDataHeader*)pDataTable;

            // Set up the native pointer to different part of the tables.
            s_pCategoryLevel1Index = (ushort*) (pDataTable + EndianSwap(mainHeader->OffsetToCategoriesIndex));
            s_pCategoriesValue = (byte*) (pDataTable + EndianSwap(mainHeader->OffsetToCategoriesValue));
            s_pNumericLevel1Index = (ushort*) (pDataTable + EndianSwap(mainHeader->OffsetToNumbericIndex));
            s_pNumericValues = (byte*) (pDataTable + EndianSwap(mainHeader->OffsetToNumbericValue));
            s_pDigitValues = (DigitValues*) (pDataTable + EndianSwap(mainHeader->OffsetToDigitValue));

            return true;
        }


        ////////////////////////////////////////////////////////////////////////
        //
        // Actions:
        // Convert the BMP character or surrogate pointed by index to a UTF32 value.
        // This is similar to Char.ConvertToUTF32, but the difference is that
        // it does not throw exceptions when invalid surrogate characters are passed in.
        //
        // WARNING: since it doesn't throw an exception it CAN return a value
        //          in the surrogate range D800-DFFF, which are not legal unicode values.
        //
        ////////////////////////////////////////////////////////////////////////

        internal static int InternalConvertToUtf32(String s, int index) {
            Contract.Assert(s != null, "s != null");
            Contract.Assert(index >= 0 && index < s.Length, "index < s.Length");
            if (index < s.Length - 1) {
                int temp1 = (int)s[index] - HIGH_SURROGATE_START;
                if (temp1 >= 0 && temp1 <= 0x3ff) {
                    int temp2 = (int)s[index+1] - LOW_SURROGATE_START;
                    if (temp2 >= 0 && temp2 <= 0x3ff) {
                        // Convert the surrogate to UTF32 and get the result.
                        return ((temp1 * 0x400) + temp2 + UNICODE_PLANE01_START);
                    }
                }
            }
            return ((int)s[index]);
        }

        ////////////////////////////////////////////////////////////////////////
        //
        // Convert a character or a surrogate pair starting at index of string s
        // to UTF32 value.
        //
        //  Parameters:
        //      s       The string
        //      index   The starting index.  It can point to a BMP character or
        //              a surrogate pair.
        //      len     The length of the string.
        //      charLength  [out]   If the index points to a BMP char, charLength
        //              will be 1.  If the index points to a surrogate pair,
        //              charLength will be 2.
        //
        // WARNING: since it doesn't throw an exception it CAN return a value
        //          in the surrogate range D800-DFFF, which are not legal unicode values.
        //
        //  Returns:
        //      The UTF32 value
        //
        ////////////////////////////////////////////////////////////////////////

        internal static int InternalConvertToUtf32(String s, int index, out int charLength) {
            Contract.Assert(s != null, "s != null");
            Contract.Assert(s.Length > 0, "s.Length > 0");
            Contract.Assert(index >= 0 && index < s.Length, "index >= 0 && index < s.Length");
            charLength = 1;
            if (index < s.Length - 1) {
                int temp1 = (int)s[index] - HIGH_SURROGATE_START;
                if (temp1 >= 0 && temp1 <= 0x3ff) {
                    int temp2 = (int)s[index+1] - LOW_SURROGATE_START;
                    if (temp2 >= 0 && temp2 <= 0x3ff) {
                        // Convert the surrogate to UTF32 and get the result.
                        charLength++;
                        return ((temp1 * 0x400) + temp2 + UNICODE_PLANE01_START);
                    }
                }
            }
            return ((int)s[index]);
        }

        ////////////////////////////////////////////////////////////////////////
        //
        //  IsWhiteSpace
        //
        //  Determines if the given character is a white space character.
        //
        ////////////////////////////////////////////////////////////////////////

        internal static bool IsWhiteSpace(String s, int index)
        {
            Contract.Assert(s != null, "s!=null");
            Contract.Assert(index >= 0 && index < s.Length, "index >= 0 && index < s.Length");

            UnicodeCategory uc = GetUnicodeCategory(s, index);
            // In Unicode 3.0, U+2028 is the only character which is under the category "LineSeparator".
            // And U+2029 is th eonly character which is under the category "ParagraphSeparator".
            switch (uc) {
                case (UnicodeCategory.SpaceSeparator):
                case (UnicodeCategory.LineSeparator):
                case (UnicodeCategory.ParagraphSeparator):
                    return (true);
            }
            return (false);
        }


        internal static bool IsWhiteSpace(char c)
        {
            UnicodeCategory uc = GetUnicodeCategory(c);
            // In Unicode 3.0, U+2028 is the only character which is under the category "LineSeparator".
            // And U+2029 is th eonly character which is under the category "ParagraphSeparator".
            switch (uc) {
                case (UnicodeCategory.SpaceSeparator):
                case (UnicodeCategory.LineSeparator):
                case (UnicodeCategory.ParagraphSeparator):
                    return (true);
            }

            return (false);
        }

        //
        // This is called by the public char and string, index versions
        //
        // Note that for ch in the range D800-DFFF we just treat it as any other non-numeric character
        //
        [System.Security.SecuritySafeCritical]  // auto-generated
        internal unsafe static double InternalGetNumericValue(int ch) {
            Contract.Assert(ch >= 0 && ch <= 0x10ffff, "ch is not in valid Unicode range.");
            // Get the level 2 item from the highest 12 bit (8 - 19) of ch.
            ushort index = EndianSwap(s_pNumericLevel1Index[ch >> 8]);
            // Get the level 2 WORD offset from the 4 - 7 bit of ch.  This provides the base offset of the level 3 table.
            // The offset is referred to an float item in m_pNumericFloatData.
            // Note that & has the lower precedence than addition, so don't forget the parathesis.
            index = EndianSwap(s_pNumericLevel1Index[index + ((ch >> 4) & 0x000f)]);
            byte* pBytePtr = (byte*)&(s_pNumericLevel1Index[index]);
            // Get the result from the 0 -3 bit of ch.
#if WIN64
            // To get around the IA64 alignment issue.  Our double data is aligned in 8-byte boundary, but loader loads the embeded table starting
            // at 4-byte boundary.  This cause a alignment issue since double is 8-byte.
            byte* pSourcePtr = &(s_pNumericValues[pBytePtr[(ch & 0x000f)] * sizeof(double)]);
            if (((long)pSourcePtr % 8) != 0) {
                // We are not aligned in 8-byte boundary.  Do a copy.
                double ret;
                byte* retPtr = (byte*)&ret;
                Buffer.Memcpy(retPtr, pSourcePtr, sizeof(double));
                return (ret);
            }
            return (((double*)s_pNumericValues)[pBytePtr[(ch & 0x000f)]]);
#else
            return EndianSwap(((double*)s_pNumericValues)[pBytePtr[(ch & 0x000f)]]);
#endif
        }

        //
        // This is called by the public char and string, index versions
        //
        // Note that for ch in the range D800-DFFF we just treat it as any other non-numeric character
        //        
        [System.Security.SecuritySafeCritical]  // auto-generated
        internal unsafe static DigitValues* InternalGetDigitValues(int ch) {
            Contract.Assert(ch >= 0 && ch <= 0x10ffff, "ch is not in valid Unicode range.");
            // Get the level 2 item from the highest 12 bit (8 - 19) of ch.
            ushort index = s_pNumericLevel1Index[ch >> 8];
            // Get the level 2 WORD offset from the 4 - 7 bit of ch.  This provides the base offset of the level 3 table.
            // The offset is referred to an float item in m_pNumericFloatData.
            // Note that & has the lower precedence than addition, so don't forget the parathesis.
            index = s_pNumericLevel1Index[index + ((ch >> 4) & 0x000f)];
            byte* pBytePtr = (byte*)&(s_pNumericLevel1Index[index]);
            // Get the result from the 0 -3 bit of ch.
            return &(s_pDigitValues[pBytePtr[(ch & 0x000f)]]);
        }

        [System.Security.SecuritySafeCritical]  // auto-generated
        internal unsafe static sbyte InternalGetDecimalDigitValue(int ch) {
            return (InternalGetDigitValues(ch)->decimalDigit);
        }

        [System.Security.SecuritySafeCritical]  // auto-generated
        internal unsafe static sbyte InternalGetDigitValue(int ch) {
            return (InternalGetDigitValues(ch)->digit);
        }


        ////////////////////////////////////////////////////////////////////////
        //
        //Returns the numeric value associated with the character c. If the character is a fraction,
        // the return value will not be an integer. If the character does not have a numeric value, the return value is -1.
        //
        //Returns:
        //  the numeric value for the specified Unicode character.  If the character does not have a numeric value, the return value is -1.
        //Arguments:
        //      ch  a Unicode character
        //Exceptions:
        //      ArgumentNullException
        //      ArgumentOutOfRangeException
        //
        ////////////////////////////////////////////////////////////////////////


        public static double GetNumericValue(char ch) {
            return (InternalGetNumericValue(ch));
        }


        public static double GetNumericValue(String s, int index) {
            if (s == null) {
                throw new ArgumentNullException("s");
            }
            if (index < 0 || index >= s.Length) {
                throw new ArgumentOutOfRangeException("index", Environment.GetResourceString("ArgumentOutOfRange_Index"));
            }
            Contract.EndContractBlock();
            return (InternalGetNumericValue(InternalConvertToUtf32(s, index)));

        }

        ////////////////////////////////////////////////////////////////////////
        //
        //Returns the decimal digit value associated with the character c.
        //
        // The value should be from 0 ~ 9.
        // If the character does not have a numeric value, the return value is -1.
        // From Unicode.org: Decimal Digits. Digits that can be used to form decimal-radix numbers.
        //Returns:
        //  the decimal digit value for the specified Unicode character.  If the character does not have a decimal digit value, the return value is -1.
        //Arguments:
        //      ch  a Unicode character
        //Exceptions:
        //      ArgumentNullException
        //      ArgumentOutOfRangeException
        //
        ////////////////////////////////////////////////////////////////////////


        public static int GetDecimalDigitValue(char ch) {
            return (InternalGetDecimalDigitValue(ch));
        }


        public static int GetDecimalDigitValue(String s, int index) {
            if (s == null) {
                throw new ArgumentNullException("s");
            }
            if (index < 0 || index >= s.Length) {
                throw new ArgumentOutOfRangeException("index", Environment.GetResourceString("ArgumentOutOfRange_Index"));
            }
            Contract.EndContractBlock();

            return (InternalGetDecimalDigitValue(InternalConvertToUtf32(s, index)));
        }

        ////////////////////////////////////////////////////////////////////////
        //
        //Action: Returns the digit value associated with the character c.
        // If the character does not have a numeric value, the return value is -1.
        // From Unicode.org: If the character represents a digit, not necessarily a decimal digit,
        // the value is here. This covers digits which do not form decimal radix forms, such as the compatibility superscript digits.
        //
        // An example is: U+2460 IRCLED DIGIT ONE. This character has digit value 1, but does not have associcated decimal digit value.
        //
        //Returns:
        //  the digit value for the specified Unicode character.  If the character does not have a digit value, the return value is -1.
        //Arguments:
        //      ch  a Unicode character
        //Exceptions:
        //      ArgumentNullException
        //      ArgumentOutOfRangeException
        //
        ////////////////////////////////////////////////////////////////////////


        public static int GetDigitValue(char ch) {
            return (InternalGetDigitValue(ch));
        }


        public static int GetDigitValue(String s, int index) {
            if (s == null) {
                throw new ArgumentNullException("s");
            }
            if (index < 0 || index >= s.Length) {
                throw new ArgumentOutOfRangeException("index", Environment.GetResourceString("ArgumentOutOfRange_Index"));
            }
            Contract.EndContractBlock();
            return (InternalGetDigitValue(InternalConvertToUtf32(s, index)));
        }

        public static UnicodeCategory GetUnicodeCategory(char ch)
        {
            return (InternalGetUnicodeCategory(ch)) ;
        }

#if MONO
        public static UnicodeCategory GetUnicodeCategory(int codePoint) => GetUnicodeCategory((char)codePoint);
#endif

        public static UnicodeCategory GetUnicodeCategory(String s, int index)
        {
            if (s==null)
                throw new ArgumentNullException("s");
            if (((uint)index)>=((uint)s.Length)) {
                throw new ArgumentOutOfRangeException("index");
            }
            Contract.EndContractBlock();
            return InternalGetUnicodeCategory(s, index);
        }

        internal unsafe static UnicodeCategory InternalGetUnicodeCategory(int ch) {
            return ((UnicodeCategory)InternalGetCategoryValue(ch, UNICODE_CATEGORY_OFFSET));
        }

        ////////////////////////////////////////////////////////////////////////
        //
        //Action: Returns the Unicode Category property for the character c.
        //Returns:
        //  an value in UnicodeCategory enum
        //Arguments:
        //  ch  a Unicode character
        //Exceptions:
        //  None
        //
        //Note that this API will return values for D800-DF00 surrogate halves.
        //
        ////////////////////////////////////////////////////////////////////////

        [System.Security.SecuritySafeCritical]  // auto-generated
        internal unsafe static byte InternalGetCategoryValue(int ch, int offset) {

            Contract.Assert(ch >= 0 && ch <= 0x10ffff, "ch is not in valid Unicode range.");
            // Get the level 2 item from the highest 12 bit (8 - 19) of ch.
            ushort index = EndianSwap(s_pCategoryLevel1Index[ch >> 8]);
            // Get the level 2 WORD offset from the 4 - 7 bit of ch.  This provides the base offset of the level 3 table.
            // Note that & has the lower precedence than addition, so don't forget the parathesis.
            index = EndianSwap(s_pCategoryLevel1Index[index + ((ch >> 4) & 0x000f)]);
            byte* pBytePtr = (byte*)&(s_pCategoryLevel1Index[index]);
            // Get the result from the 0 -3 bit of ch.
            byte valueIndex = pBytePtr[(ch & 0x000f)];
            byte uc = s_pCategoriesValue[valueIndex * 2 + offset];
            //
            // Make sure that OtherNotAssigned is the last category in UnicodeCategory.
            // If that changes, change the following assertion as well.
            //
            //Contract.Assert(uc >= 0 && uc <= UnicodeCategory.OtherNotAssigned, "Table returns incorrect Unicode category");
            return (uc);
        }

//      internal static BidiCategory GetBidiCategory(char ch) {
//          return ((BidiCategory)InternalGetCategoryValue(c, BIDI_CATEGORY_OFFSET));
//      }

        internal static BidiCategory GetBidiCategory(String s, int index) {
            if (s==null)
                throw new ArgumentNullException("s");
            if (((uint)index)>=((uint)s.Length)) {
                throw new ArgumentOutOfRangeException("index");
            }
            Contract.EndContractBlock();
            return ((BidiCategory)InternalGetCategoryValue(InternalConvertToUtf32(s, index), BIDI_CATEGORY_OFFSET));
        }

        ////////////////////////////////////////////////////////////////////////
        //
        //Action: Returns the Unicode Category property for the character c.
        //Returns:
        //  an value in UnicodeCategory enum
        //Arguments:
        //  value  a Unicode String
        //  index  Index for the specified string.
        //Exceptions:
        //  None
        //
        ////////////////////////////////////////////////////////////////////////

        internal static UnicodeCategory InternalGetUnicodeCategory(String value, int index) {
            Contract.Assert(value != null, "value can not be null");
            Contract.Assert(index < value.Length, "index < value.Length");

            return (InternalGetUnicodeCategory(InternalConvertToUtf32(value, index)));
        }

        ////////////////////////////////////////////////////////////////////////
        //
        // Get the Unicode category of the character starting at index.  If the character is in BMP, charLength will return 1.
        // If the character is a valid surrogate pair, charLength will return 2.
        //
        ////////////////////////////////////////////////////////////////////////

        internal static UnicodeCategory InternalGetUnicodeCategory(String str, int index, out int charLength) {
            Contract.Assert(str != null, "str can not be null");
            Contract.Assert(str.Length > 0, "str.Length > 0");;
            Contract.Assert(index >= 0 && index < str.Length, "index >= 0 && index < str.Length");

            return (InternalGetUnicodeCategory(InternalConvertToUtf32(str, index, out charLength)));
        }

        internal static bool IsCombiningCategory(UnicodeCategory uc) {
            Contract.Assert(uc >= 0, "uc >= 0");
            return (
                uc == UnicodeCategory.NonSpacingMark ||
                uc == UnicodeCategory.SpacingCombiningMark ||
                uc == UnicodeCategory.EnclosingMark
            );
        }
    }
}