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

    File: HashCash.cpp
    Date: 2022-9-18
    Author: Reece
***/
#include <Source/RuntimeInternal.hpp>
#include "HashCash.hpp"

namespace Aurora::Crypto::HashCash
{
    AUKN_SYM bool CheckSalt(AuUInt64 token, AuUInt8 power, const HashCashAnswer &answer)
    {
        AuUInt8 count {};
        AuArray<AuUInt8, 16> hashBuffer;

        struct Hash
        {
            AuUInt64 token;
            AuUInt64 y;
        } hash;
        static_assert(sizeof(Hash) == 16);

        hash.token = token;
        hash.y = answer.y;

        AuHashing::RMD128(AuMemoryViewRead(&hash, 16), hashBuffer);
        
        AuBitScanForward(count, AuReadU64LE(hashBuffer.data(), 0));
        
        return count == power;
    }

    AUKN_SYM HashCashAnswer FindAnswer(AuUInt64 token, AuUInt8 power)
    {
        HashCashAnswer answer;
        AuArray<AuUInt8, 16> hashBuffer;

        struct Hash
        {
            AuUInt64 token;
            AuUInt64 y;
        } hash;
        static_assert(sizeof(Hash) == 16);

        hash.token = token;
        hash.y = AuRng::RngU64();

        AuUInt8 count {};
        do
        {
            hash.y++;
            AuHashing::RMD128(AuMemoryViewRead(&hash, 16), hashBuffer);
        }
        while (AuBitScanForward(count, AuReadU64LE(hashBuffer.data(), 0)), count != power);

        answer.y = hash.y;
        return answer;
    }
}