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

    File: auFNV1Utils.hpp
    Date: 2022-3-23
    File: fnv1.hpp
    Date: 2021-6-10
    Author: Reece
***/
#pragma once

#include "auTypeUtils.hpp"

// Note: we're too early for AuroraEnv.hpp w/ AuroraEnums
#if defined(AURORA_IS_32BIT)
    #define _AU_FNV1_32 1
#else
    #define _AU_FNV1_32 0
#endif

constexpr AuUInt64 kFnv1MagicVal64   = 0xcbf29ce484222325;
constexpr AuUInt64 kFnv1MagicPrime64 = 0x100000001b3;
constexpr AuUInt32 kFnv1MagicVal32   = 0x811c9dc5;
constexpr AuUInt32 kFnv1MagicPrime32 = 0x01000193;

constexpr auto     kFnv1MagicValPlatform   = _AU_FNV1_32 ? kFnv1MagicVal32   : kFnv1MagicVal64;
constexpr auto     kFnv1MagicPrimePlatform = _AU_FNV1_32 ? kFnv1MagicPrime32 : kFnv1MagicPrime64;

inline constexpr AuUInt64 AuFnv1a64(const char *const str, const AuUInt64 value = kFnv1MagicVal64) noexcept
{
    return (str[0] == '\0') ? value : AuFnv1a64(&str[1], (value ^ AuUInt64(str[0])) * kFnv1MagicPrime64);
}

inline constexpr AuUInt32 AuFnv1aTrunc(const char *const str) noexcept
{
    return static_cast<AuUInt32>(AuFnv1a64(str));
}

inline constexpr AuUInt32 AuFnv1a32(const char *const str, const AuUInt32 value = kFnv1MagicVal32) noexcept
{
    return (str[0] == '\0') ? value : AuFnv1a32(&str[1], (value ^ AuUInt32(str[0])) * kFnv1MagicPrime32);
}

inline constexpr AuUInt AuFnv1aType(const char *type, AuUInt size, AuUInt index, const AuUInt value) noexcept
{
    return (index == size) ? value : AuFnv1aType(type + 1, size, index + 1, (value ^ AuUInt(*type) * kFnv1MagicPrimePlatform));
}

template <class T>
inline constexpr AuUInt AuFnv1aType(const T &type, const AuUInt value = kFnv1MagicValPlatform) noexcept
{
    return AuFnv1aType(((const char *)&type) + 1, sizeof(T), 1, (value ^ AuUInt(*(const char *)&type) * kFnv1MagicPrimePlatform));
}

inline constexpr auto AuFnv1a(const char *const str) noexcept
{
    return _AU_FNV1_32 ? AuFnv1a32(str) : AuFnv1a64(str);
}

inline AuUInt32 AuFnv1a32Runtime(const void *base, AuUInt length) noexcept
{
    AuUInt32 result {kFnv1MagicVal32};

    AuUInt i {};
    for (; i < length; i++)
    {
        result ^= AuUInt(AuReadU8(base, i)) * kFnv1MagicPrime32;
    }

    return result;
}

inline AuUInt64 AuFnv1a64Runtime(const void *base, AuUInt length) noexcept
{
    AuUInt64 result {kFnv1MagicVal64};

    AuUInt i {};
    for (; i < length; i++)
    {
        result ^= AuUInt64(AuReadU8(base, i)) * kFnv1MagicPrime64;
    }

    return result;
}

#undef _AU_FNV1_32