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

    File: Encoding.cpp
    Date: 2021-8-19
    Author: Reece
***/
#include <Source/RuntimeInternal.hpp>
#include "../Locale.hpp"
#include "Encoding.hpp"

namespace Aurora::Locale::Encoding
{
    AUKN_SYM BOM DecodeBOM(const Memory::MemoryViewRead & binary)
    {
    #define ADD_PATTERN(str, code) {str, {ECodePage::code, AuArraySize(str) - 1}}
        AuList<std::tuple<const char *, BOM>> bows = 
        {
            ADD_PATTERN("\xFF\xFE\x00\x00", eUTF32),
            ADD_PATTERN("\x00\x00\xFE\xFF", eUTF32BE),
            ADD_PATTERN("\x84\x31\x95\x33", e18030),
            ADD_PATTERN("\xDD\x73\x66\x73", eUnsupported), // UTF-EBCDIC
            ADD_PATTERN("\xEF\xBB\xBF", eUTF8), 
            ADD_PATTERN("\xF7\x64\x4C", eUnsupported),  // UTF-1
            ADD_PATTERN("\xFB\xEE\x28", eUTF7),  // UTF-7
            ADD_PATTERN("\x2B\x2F\x76", eUnsupported),  // BOCU-1
            ADD_PATTERN("\x0E\xFE\xFF", eUnsupported),  // SCSU
            ADD_PATTERN("\xFF\xFE", eUTF16),  // UTF-16
            ADD_PATTERN("\xFE\xFF", eUTF16BE)   // UTF-16
        };
    #undef ADD_PATTERN

        for (const auto &[string, bom] : bows)
        {
            if (binary.length < bom.length) continue;
            if (std::memcmp(binary.ptr, string, bom.length) != 0) continue;
            
            return bom;
        }

        return {};
    }
    
    // OLD SHIT API

    AUKN_SYM AuStreamReadWrittenPair_t EncodeUTF8(const Memory::MemoryViewRead &utf8, const Memory::MemoryViewWrite & binary, ECodePage page)
    {
        TextStreamEncoder re(page);
        return re.DecodeUTF8(utf8.ptr, utf8.length, binary.ptr, binary.length);
    }

    AUKN_SYM AuStreamReadWrittenPair_t DecodeUTF8(const Memory::MemoryViewRead &binary, const Memory::MemoryViewWrite & utf8, ECodePage page)
    {
        TextStreamProcessor re(page);
        return re.EncodeUTF8(binary.ptr, binary.length, utf8.ptr, utf8.length);
    }

    AUKN_SYM AuStreamReadWrittenPair_t DecodeUTF8(const Memory::MemoryViewRead &binary, AuString &out, ECodePage page)
    {
        auto aaa = DecodeUTF8(binary, {}, page);
        out.resize(aaa.second);
        auto ret = DecodeUTF8(binary, Memory::MemoryViewWrite(out.data(), out.size()), page);
        out.resize(ret.second);
        return ret;
    }
        
    AuStreamReadWrittenPair_t DecodeUTF8(void *binary, AuUInt32 binaryLength, AuString &out, ECodePage page)
    {
        auto aaa = DecodeUTF8(Memory::MemoryViewRead(binary, binaryLength), {}, page);
        out.resize(aaa.second);
        auto ret = DecodeUTF8(Memory::MemoryViewRead(binary, binaryLength), Memory::MemoryViewWrite(out.data(), out.size()), page);
        out.resize(ret.second);
        return ret;
    }


    // NEW API

    /// Supporting full 6 byte UTF-8, copies or returns the available streams from @param utf8 to @param utf32

    AUKN_SYM AuStreamReadWrittenPair_t ReadUTF8IntoUTF32ByteString(const Memory::MemoryViewRead &utf8, const Memory::MemoryViewWrite &utf32)
    {
        const char *begin = utf8.Begin<const char>();
        const char *end = utf8.End<const char>();
        AuUInt32 *begin2 = utf32.Begin<AuUInt32>();
        AuUInt32 *end2 = utf32.End<AuUInt32>();
        UTF32::ReadUtf8ByteString(begin2, end2, begin, end);
        return AuStreamReadWrittenPair_t {begin - utf8.Begin<const char>(), (begin2 - utf32.Begin<AuUInt32>()) * sizeof(AuUInt32)};
    }

    
    /// Supporting full 6 byte UTF-8, copies or returns the available streams from @param utf32 to @param utf8
    AUKN_SYM AuStreamReadWrittenPair_t ReadUTF32IntoUTF8ByteString(const Memory::MemoryViewRead &utf32, const Memory::MemoryViewWrite &utf8)
    {
        const AuUInt32 *begin = utf32.Begin<const AuUInt32>();
        const AuUInt32 *end = utf32.End<const AuUInt32>();
        char *dest = utf8.Begin<char>();
        char *destEnd = utf8.End<char>();

        AuUInt32 counter {};
        const AuUInt32 *cur = begin;
        for (; cur < end; cur++)
        {
            UTF32::WriteCp(*cur, dest, counter, destEnd - dest);
        }

        return AuStreamReadWrittenPair_t {(cur - begin) * sizeof(AuUInt32), dest - utf8.Begin<char>()};
    }
    
    AUKN_SYM void SwapUTF32(const Memory::MemoryViewWrite &utf32)
    {
        UTF32::SwapU32(utf32.Begin<AuUInt32>(), utf32.ToCount<AuUInt32>());
    }
    
    AUKN_SYM void SwapUTF16(const Memory::MemoryViewWrite &utf32)
    {
        UTF16::SwapU16(utf32.Begin<AuUInt32>(), utf32.ToCount<AuUInt32>());
    }
    
    AUKN_SYM AuUInt32 CountUTF32Length(const Memory::MemoryViewRead &utf32, bool bytes)
    {
        return UTF32::Count32(utf32.ptr, utf32.length, bytes);
    }
    
    AUKN_SYM AuUInt32 CountUTF16Length(const Memory::MemoryViewRead &utf16, bool bytes)
    {
        return UTF16::Count16(utf16.ptr, utf16.length, bytes);
    }
    
    AUKN_SYM AuUInt32 CountUTF8Length(const Memory::MemoryViewRead &utf8, bool bytes)
    {
        auto pair = ReadUTF8IntoUTF32ByteString(utf8, {});
        return bytes ? pair.first : pair.second / sizeof(AuUInt32);
    }

    AUKN_SYM AuUInt32 CountSJISLength(const Memory::MemoryViewRead &sjis, bool bytes)
    {
        return SJIS::CountSJIS(sjis.ptr, sjis.length, bytes);
    }
    
    AUKN_SYM AuUInt32 CountGBK16Length(const Memory::MemoryViewRead &gbk, bool bytes)
    {
        return GBK::CountGbk(gbk.ptr, gbk.length, bytes);
    }
}