/***
    Copyright (C) 2022 J Reece Wilson (a/k/a "Reece"). All rights reserved.

    File: BOM.cpp
    Date: 2022-2-14
    Author: Reece
***/
#include <Source/RuntimeInternal.hpp>
#include "Encoding.hpp"
#include "BOM.hpp"

namespace Aurora::Locale::Encoding
{
#define ADD_PATTERN(str, code) {str, {ECodePage::code, AuArraySize(str) - 1}}
    static const AuList<AuTuple<const char *, BOM>> gKnownBoms =
    {
        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", eEnumInvalid), // UTF-EBCDIC
        ADD_PATTERN("\xEF\xBB\xBF", eUTF8),
        ADD_PATTERN("\xF7\x64\x4C", eEnumInvalid),     // UTF-1
        ADD_PATTERN("\xFB\xEE\x28", eUTF7),            // UTF-7
        ADD_PATTERN("\x2B\x2F\x76", eEnumInvalid),     // BOCU-1
        ADD_PATTERN("\x0E\xFE\xFF", eEnumInvalid),     // SCSU
        ADD_PATTERN("\xFF\xFE", eUTF16),               // UTF-16
        ADD_PATTERN("\xFE\xFF", eUTF16BE)              // UTF-16
    };
#undef ADD_PATTERN

    AUKN_SYM BOM DecodeBOM(const AuMemoryViewRead &binary)
    {
        for (const auto &[string, bom] : gKnownBoms)
        {
            if (binary.length < bom.length)
            {
                continue;
            }

            if (AuMemcmp(binary.ptr, string, bom.length) != 0)
            {
                continue;
            }

            return bom;
        }

        return {};
    }
}