/***
    Copyright (C) 2021 J Reece Wilson (a/k/a "Reece"). All rights reserved.

    File: AuHex.cpp
    Date: 2021-8-28
    Author: Reece
***/
#include <Source/RuntimeInternal.hpp>
#include "AuHex.hpp"

namespace Aurora::Parse
{
    static bool HexToOctet(const char *hex, AuUInt8 &val)
    {
        val = 0;

        for (auto i = 0u; i < 2; i++)
        {
            AuUInt8 byte = *hex++;
            
            if (byte >= '0' && byte <= '9')
            {
                byte = byte - '0';
            }
            else if (byte >= 'A' && byte <= 'F')
            {
                byte = byte - 'A' + 10;
            }
            else if (byte >= 'a' && byte <= 'f')
            {
                byte = byte - 'a' + 10;
            }
            else
            {
                return false;
            }

            val = (val << 4) | (byte & 0xF);
        }

        return true;
    }

    AUKN_SYM bool HexToInt(const AuROString &hex, AuUInt64 &val)
    {
        auto pHex    = hex.data();
        auto uLength = hex.length();

        val     = 0;
        uLength = AuMin(AuUInt32(sizeof(AuUInt64) * 2), uLength);
        
        if (!pHex && uLength)
        {
            return false;
        }

        for (auto i = 0u; i < uLength; i++)
        {
            AuUInt8 byte = *pHex++;
            
            if (byte >= '0' && byte <= '9')
            {
                byte = byte - '0';
            }
            else if (byte >= 'A' && byte <= 'F')
            {
                byte = byte - 'A' + 10;
            }
            else if (byte >= 'a' && byte <= 'f')
            {
                byte = byte - 'a' + 10;
            }
            else
            {
                return false;
            }

            val = (val << 4) | (byte & 0xF);
        }

        return true;
    }
    
    AUKN_SYM bool HexToByte(const char (hex)[2], AuUInt8 &val)
    {
        return HexToOctet(hex, val);
    }

    static inline char NibbleToChar(AuUInt8 nib)
    {
        if (nib < 10)
            return '0' + nib;
        else
            return 'A' + (nib - 10);
    }
    
    AUKN_SYM void ByteToHex(AuUInt8 val, char (& hex)[2])
    {
        AuUInt8 lowNibble = val & 0xF;
        AuUInt8 hiNibble  = (val >> 4) & 0xF;
        
        hex[0] = NibbleToChar(hiNibble);
        hex[1] = NibbleToChar(lowNibble);
    }

    AUKN_SYM bool DecodeHex(const AuROString &in, AuByteBuffer &out)
    {
    #define HEX_GRAMMAR_CONSUME_ALL(x) \
        for (; i < in.size(); i++)     \
        {                              \
            if (in[i] != x)            \
            {                          \
                break;                 \
            }                          \
        }
        
    #define HEX_GRAMMAR_CONSUME_ONE(x) \
        if (i < in.size())             \
        {                              \
            if (in[i] == x)            \
            {                          \
                i ++;                  \
            }                          \
        }

    #define HEX_GRAMMAR_CONSUME_EITHER(a, b) \
        if (i < in.size())                   \
        {                                    \
            if ((in[i] == a) ||              \
                (in[i] == b))                \
            {                                \
                i++;                         \
            }                                \
        }

    #define HEX_GRAMMAR_CONSUME_SPACE    \
        HEX_GRAMMAR_CONSUME_ALL(' ')

    #define HEX_GRAMMAR_CONSUME_NEW_LINE \
        HEX_GRAMMAR_CONSUME_ONE('\r')    \
        HEX_GRAMMAR_CONSUME_ALL('\n')

    #define HEX_GRAMMAR_CONSUME_END_OF_LINE \
        HEX_GRAMMAR_CONSUME_SPACE           \
        HEX_GRAMMAR_CONSUME_NEW_LINE        \
        HEX_GRAMMAR_CONSUME_SPACE

        AuUInt i = 0u;

        auto writeView = out.GetOrAllocateLinearWriteable(in.size() / 2);
        if (!writeView)
        {
            SysPushErrorMem();
            return false;
        }

        // Consume whitespace and/or literal start
        {
            HEX_GRAMMAR_CONSUME_SPACE;
            HEX_GRAMMAR_CONSUME_EITHER('{', '[');
            HEX_GRAMMAR_CONSUME_END_OF_LINE;
        }

        // Consume array
        for (; i < in.size(); )
        {
            // Consume 0x prefix
            if ((i + 1) < in.size())
            {
                if ((in[i] == '0') && 
                    (in[i + 1] == 'x'))
                {
                    i += 2;
                }
            }
            
            // Consume octal
            if ((i + 1) < in.size())
            {
                AuUInt8 byte;

                if (!HexToOctet(&in[i], byte))
                {
                    out.clear();
                    return false;
                }

                *(out.writePtr++) = byte;
                i += 2;
            }

            HEX_GRAMMAR_CONSUME_ONE('h'); // some hex dump code and people prefer FFh over 0xFF

            HEX_GRAMMAR_CONSUME_EITHER(':' /*wireshark and other networking tools*/, ',' /*latin array splitter*/);
            HEX_GRAMMAR_CONSUME_END_OF_LINE; // all whitespace [+newline[+all whitespace]]
            
            // Consume end literal hint
            if (i < in.size())
            {
                if ((in[i] == '}' /*c-like*/) ||
                    (in[i] == ']' /*more latin array tag*/))
                {
                    break;
                }
            }
        }

        return true;
    }

    AUKN_SYM bool EncodeHex(Memory::MemoryViewRead view, EHexDump formatting, AuString &in)
    {
        auto pBuf    = view.ptr;
        auto uLength = view.length;

        bool hexedit = formatting == EHexDump::eHexEditor;
        
        bool squareBracket = formatting == EHexDump::eJSLiteral;
        bool curlyBracket = formatting == EHexDump::eCLiteral;

        bool zeroX = formatting == EHexDump::eCLiteral || 
                     formatting == EHexDump::eJSLiteral ||
                     formatting == EHexDump::eZeroXSpace;
        
        bool space = formatting != EHexDump::eString;

        if (!pBuf && uLength)
        {
            SysPushErrorArg();
            return false;
        }

        try
        {
            AuTryReserve(in, uLength * 4);

            auto &newLine = AuLocale::NewLine();

            if (hexedit)
            {
                in.insert(in.size(), "00 01 02 03 04 05 06 07 08 09 10 11 12 13 14 15");
                in.insert(in.size(), newLine);
                in.insert(in.size(), "00 01 02 03 04 05 06 07 08 09 0A 0B 0C 0D 0E 0F");
                in.insert(in.size(), newLine);
                in.insert(in.size(), "                                               ");
                in.insert(in.size(), newLine);
            }
            else if (squareBracket)
            {
                in.insert(in.end(), '[');
                in.insert(in.size(), newLine);
            }
            else if (curlyBracket)
            {
                in.insert(in.end(), '{');
                in.insert(in.size(), newLine);
            }

            for (auto i = 0u; i < uLength; )
            {
                AuUInt32 x, rowMax;

                if (i != 0)
                {
                    if (hexedit || squareBracket || curlyBracket)
                    {
                        in.insert(in.size(), newLine);
                    }
                }

                if (squareBracket || curlyBracket)
                {
                    in.insert(in.size(), "    ");
                }

                rowMax = AuMin(AuUInt32(i + 16), AuUInt32(uLength));

                for (x = i;
                     x < rowMax;
                     x++)
                {
                    if (space)
                    {
                        if (x != i)
                        {
                            in.insert(in.end(), ' ');
                        }
                    }

                    if (zeroX)
                    {
                        in.insert(in.size(), "0x");
                    }

                    {
                        char hex[2];
                        ByteToHex(reinterpret_cast<const AuUInt8 *>(pBuf)[x], hex);
                        in.insert(in.size(), hex, 2);
                    }

                    if (x != (uLength - 1))
                    {
                        if (squareBracket || curlyBracket)
                        {
                            in.insert(in.end(), ',');
                        }
                    }
                }

                i = x;

                if (hexedit)
                {
                    // TODO: print space + i * 16 padded + space hex(i * 16 padded)
                }
            }

            if (squareBracket)
            {
                in.insert(in.size(), newLine);
                in.insert(in.end(), ']');
            }
            else if (curlyBracket)
            {
                in.insert(in.size(), newLine);
                in.insert(in.end(), '}');
            }

            in.shrink_to_fit();
        }
        catch (...)
        {
            SysPushErrorCatch("EncodeHex failed");
            in.clear();
            return false;
        }

        return true;
    }
}