/*==LICENSE==*

CyanWorlds.com Engine - MMOG client, server and tools
Copyright (C) 2011  Cyan Worlds, Inc.

This program is free software: you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation, either version 3 of the License, or
(at your option) any later version.

This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
GNU General Public License for more details.

You should have received a copy of the GNU General Public License
along with this program.  If not, see <http://www.gnu.org/licenses/>.

Additional permissions under GNU GPL version 3 section 7

If you modify this Program, or any covered work, by linking or
combining it with any of RAD Game Tools Bink SDK, Autodesk 3ds Max SDK,
NVIDIA PhysX SDK, Microsoft DirectX SDK, OpenSSL library, Independent
JPEG Group JPEG library, Microsoft Windows Media SDK, or Apple QuickTime SDK
(or a modified version of those libraries),
containing parts covered by the terms of the Bink SDK EULA, 3ds Max EULA,
PhysX SDK EULA, DirectX SDK EULA, OpenSSL and SSLeay licenses, IJG
JPEG Library README, Windows Media SDK EULA, or QuickTime SDK EULA, the
licensors of this Program grant you additional
permission to convey the resulting work. Corresponding Source for a
non-source form of such a combination shall include the source code for
the parts of OpenSSL and IJG JPEG Library used as well as that of the covered
work.

You can contact Cyan Worlds, Inc. by email legal@cyan.com
 or by snail mail at:
      Cyan Worlds, Inc.
      14617 N Newport Hwy
      Mead, WA   99021

*==LICENSE==*/
/*****************************************************************************
*
*   $/Plasma20/Sources/Plasma/NucleusLib/pnUtils/Private/pnUtBigNum.h
*   
***/

#ifdef PLASMA20_SOURCES_PLASMA_NUCLEUSLIB_PNUTILS_PRIVATE_PNUTBIGNUM_H
#error "Header $/Plasma20/Sources/Plasma/NucleusLib/pnUtils/Private/pnUtBigNum.h included more than once"
#endif
#define PLASMA20_SOURCES_PLASMA_NUCLEUSLIB_PNUTILS_PRIVATE_PNUTBIGNUM_H


/*****************************************************************************
*
*   BigNum class
*
***/

#include <openssl/bn.h>

class BigNum {
private:
    BIGNUM m_number;
    mutable BN_CTX * m_context;

    BN_CTX * GetContext () const
    {
        if (!m_context)
            m_context = BN_CTX_new();
        return m_context;
    }

public:
    BigNum ();
    BigNum (const BigNum & a);
    BigNum (unsigned a);
    BigNum (unsigned bytess, const void * data, bool le=false);
    ~BigNum ();

    BigNum & operator= (const BigNum & a)
    {
        BN_copy(&m_number, &a.m_number);
        return *this;
    }

    // Constant parameters need not be distinct from the destination or from
    // each other

    void Add (const BigNum & a, uint32_t b)
    {
        // this = a + b
        BN_copy(&m_number, &a.m_number);
        BN_add_word(&m_number, b);
    }

    void Add (const BigNum & a, const BigNum & b)
    {
        // this = a + b
        BN_add(&m_number, &a.m_number, &b.m_number);
    }

    int  Compare (uint32_t a) const;
    int  Compare (const BigNum & a) const
    {
        return BN_cmp(&m_number, &a.m_number);
    }
    bool isZero() const
    {
        return BN_is_zero(&m_number);
    }

    void Div (const BigNum & a, uint32_t b, uint32_t * remainder)
    {
        // this = a / b, remainder = a % b
        BN_copy(&m_number, &a.m_number);
        *remainder = (uint32_t)BN_div_word(&m_number, b);
    }

    void Div (const BigNum & a, const BigNum & b, BigNum * remainder)
    {
        // this = a / b, remainder = a % b
        // either this or remainder may be nil
        BN_div(this ? &m_number : nil, remainder ? &remainder->m_number : nil,
               &a.m_number, &b.m_number, GetContext());
    }

    void FromData_BE (unsigned bytess, const void * data)
    {
        BN_bin2bn((const unsigned char *)data, bytess, &m_number);
    }

    void FromData_LE (unsigned bytess, const void * data);

    unsigned char * GetData_BE (unsigned * bytess) const;
    unsigned char * GetData_LE (unsigned * bytess) const;

    bool IsPrime () const
    {
        // Cyan's code uses 3 checks, so we'll follow suit.
        // This provides an accurate answer to p < 0.015625
        return BN_is_prime_fasttest(&m_number, 3, nil, GetContext(), nil, 1) > 0;
    }

    void Mod (const BigNum & a, const BigNum & b)
    {
        // this = a % b
        BN_div(nil, &m_number, &a.m_number, &b.m_number, GetContext());
    }

    void Mul (const BigNum & a, uint32_t b)
    {
        // this = a * b
        BN_copy(&m_number, &a.m_number);
        BN_mul_word(&m_number, b);
    }

    void Mul (const BigNum & a, const BigNum & b)
    {
        // this = a * b
        BN_mul(&m_number, &a.m_number, &b.m_number, GetContext());
    }

    void PowMod (uint32_t a, const BigNum & b, const BigNum & c)
    {
        // this = a ^ b % c
        PowMod(BigNum(a), b, c);
    }

    void PowMod (const BigNum & a, const BigNum & b, const BigNum & c)
    {
        // this = a ^ b % c
        BN_mod_exp(&m_number, &a.m_number, &b.m_number, &c.m_number, GetContext());
    }

    void Rand (const BigNum & a, BigNum * seed)
    {
        // this = random number less than a
        int bits = BN_num_bits(&a.m_number);
        do
            Rand(bits, seed);
        while (Compare(a) >= 0);
    }

    void Rand (unsigned bits, BigNum * seed);

    void RandPrime (unsigned bits, BigNum * seed)
    {
        BN_generate_prime(&m_number, bits, 1, nil, nil, nil, nil);
    }

    void Set (const BigNum & a)
    {
        BN_copy(&m_number, &a.m_number);
    }

    void Set (unsigned a)
    {
        BN_set_word(&m_number, a);
    }

    void SetOne () { Set(1); }
    void SetZero () { Set(0); }

    void Shl (const BigNum & a, unsigned b)
    {
        // this = a << b
        BN_lshift(&m_number, &a.m_number, b);
    }

    void Shr (const BigNum & a, unsigned b)
    {
        // this = a >> b
        BN_rshift(&m_number, &a.m_number, b);
    }

    void Sub (const BigNum & a, uint32_t b)
    {
        // this = a - b
        BN_copy(&m_number, &a.m_number);
        BN_sub_word(&m_number, b);
    }

    void Sub (const BigNum & a, const BigNum & b)
    {
        // this = a - b
        BN_sub(&m_number, &a.m_number, &b.m_number);
    }
};