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

    File: ECCX25519Private.cpp
    Date: 2022-2-15
    Author: Reece
***/
#include <Source/RuntimeInternal.hpp>
#include "ECC.hpp"
#include "ECCX25519Private.hpp"
#include "ECCX25519Public.hpp"

namespace Aurora::Crypto::ECC
{
    PrivateCurve25519Impl::PrivateCurve25519Impl(bool isX25519, curve25519_key &&key) : bIsX25519_(isX25519), key_(key)
    {

    }

    PrivateCurve25519Impl::~PrivateCurve25519Impl()
    {

    }

    bool     PrivateCurve25519Impl::Sign(const Memory::MemoryViewRead &plainText,
                                         AuHashing::EHashType method,
                                         Memory::ByteBuffer &out)
    {
        const int salt = 0;

        if (this->bIsX25519_)
        {
            return false;
        }

        if (!plainText.HasMemory())
        {
            SysPushErrorParam();
            return {};
        }
        
        int hash = ::Crypto::HashMethodToId(method);
        if (hash == 0xFF)
        {
            SysPushErrorCrypt("invalid hash {}", AuUInt(method));
            return false;
        }
        
        AuByteBuffer hashVec;
        if (!AuTryResize(hashVec, 128))
        {
            SysPushErrorMem();
            return false;
        }
        
        unsigned long hashSize = 1024;
        auto iRet = ::hash_memory(hash,
                                 reinterpret_cast<const unsigned char *>(plainText.ptr), plainText.length,
                                 reinterpret_cast<unsigned char *>(hashVec.data()), &hashSize);
        if (iRet != CRYPT_OK)
        {
            SysPushErrorCrypt("{}", iRet);
            return false;
        }

        return Sign(hashVec, out);
    }

    bool     PrivateCurve25519Impl::Sign(const Memory::MemoryViewRead &hash,
                                         Memory::ByteBuffer &out)
    {
        if (this->bIsX25519_)
        {
            return false;
        }

        if (!hash.HasMemory())
        {
            SysPushErrorParam();
            return {};
        }

        if (!out.GetOrAllocateLinearWriteable(1024))
        {
            SysPushErrorMem();
            return {};
        }

        unsigned long len = 1024;
        
        auto iRet = ::ed25519_sign(AuReinterpretCast<const unsigned char *>(hash.ptr),
                                   hash.length,
                                   out.writePtr, &len,
                                   &this->key_);
        if (iRet != CRYPT_OK)
        {
            SysPushErrorCrypt("{}", iRet);
            return false;
        }

        out.writePtr += len;

        return true;
    }

    bool     PrivateCurve25519Impl::ECDH(const AuSPtr<IECCPublic> &partnerPublic,
                                         Memory::ByteBuffer &sharedKey)
    {
        if (!this->bIsX25519_)
        {
            return false;
        }

        auto writeView = sharedKey.GetOrAllocateLinearWriteable(128);
        if (!writeView)
        {
            SysPushErrorMem();
            return {};
        }

        if (partnerPublic->GetType() != this->GetType())
        {
            SysPushErrorCrypto("Can not EDCH with incompatible pairs curve (noting ed25519 requires translation to x25519)");
            return false;
        }

        unsigned long actualSize = 128;
        auto iRet = ::x25519_shared_secret(&this->key_,
                                           &(AuReinterpretCast<PublicCurve25519Impl>(partnerPublic)->GetKey()),
                                           sharedKey.writePtr,
                                           &actualSize);
        if (iRet != CRYPT_OK)
        {
            SysPushErrorCrypt("{}", iRet);
            return false;
        }

        sharedKey.writePtr += actualSize;
        return true;
    }

    bool     PrivateCurve25519Impl::AsPublicECC(Memory::ByteBuffer &out)
    {
        auto writeView = out.GetOrAllocateLinearWriteable(4096);
        if (!writeView)
        {
            SysPushErrorMem();
            return {};
        }

        unsigned long actualSize;
        int ret;

        actualSize = 4096;

        if (this->bIsX25519_)
        {
            ret = x25519_export(out.writePtr, &actualSize, PK_PUBLIC | PK_STD, &this->key_);
        }
        else
        {
            ret = ed25519_export(out.writePtr, &actualSize, PK_PUBLIC | PK_STD, &this->key_);
        }

        if (ret != CRYPT_OK)
        {
            SysPushErrorCrypt("{}", ret);
            return false;
        }

        out.writePtr += actualSize;

        return true;
    }

    bool     PrivateCurve25519Impl::AsPrivateECC(Memory::ByteBuffer &out)
    {
        auto writeView = out.GetOrAllocateLinearWriteable(4096);
        if (!writeView)
        {
            SysPushErrorMem();
            return {};
        }

        unsigned long actualSize;
        int ret;

        actualSize = 4096;

        if (this->bIsX25519_)
        {
            ret = x25519_export(out.writePtr, &actualSize, PK_PRIVATE | PK_STD, &this->key_);
        }
        else
        {
            ret = ed25519_export(out.writePtr, &actualSize, PK_PRIVATE | PK_STD, &this->key_);
        }

        if (ret != CRYPT_OK)
        {
            SysPushErrorCrypt("{}", ret);
            return false;
        }

        out.writePtr += actualSize;

        return true;
    }

    EECCCurve PrivateCurve25519Impl::GetType()
    {
        return this->bIsX25519_ ? EECCCurve::eCurveX25519 : EECCCurve::eCurveEd25519;
    }
}