/***************************************************************************
 *   Copyright (C) 2005 by Joris Guisson                                   *
 *   joris.guisson@gmail.com                                               *
 *                                                                         *
 *   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 2 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, write to the                         *
 *   Free Software Foundation, Inc.,                                       *
 *   51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.             *
 ***************************************************************************/
#ifndef MSEBIGINT_H
#define MSEBIGINT_H

#include <qstring.h>
#include <util/constants.h>
#include <cstdio>
#include <gmp.h>

using bt::Uint8;
using bt::Uint16;
using bt::Uint32;
using bt::Uint64;

namespace mse
{

/**
 * @author Joris Guisson <joris.guisson@gmail.com>
 *
 * Class which can hold an arbitrary large integer. This will be a very important part of our
 * MSE implementation.
*/
class BigInt
{
public:
    /**
     * Create a big integer, with num_bits bits.
     * All bits will be set to 0.
     * @param num_bits The number of bits
     */
    BigInt(Uint32 num_bits = 0);

    /**
     * Create a big integer of a string. The string must be
     * a hexadecimal representation of an integer. For example :
     * 12AFFE123488BBBE123
     *
     * Letters can be upper or lower case. Invalid chars will create an invalid number.
     * @param value The hexadecimal representation of the number
     */
    BigInt(const QString & value);

    /**
     * Copy constructor.
     * @param bi BigInt to copy
     */
    BigInt(const BigInt & bi);
    ~BigInt();

    /**
     * Assignment operator.
     * @param bi The BigInt to copy
     * @return *this
     */
    BigInt & operator = (const BigInt & bi);

    /**
     * Calculates
     * (x ^ e) mod d
     * ^ is power
     */
    static BigInt powerMod(const BigInt & x, const BigInt & e, const BigInt & d);

    /// Make a random BigInt
    static BigInt random();

    /// Export the bigint ot a buffer
    Uint32 toBuffer(Uint8* buf, Uint32 max_size) const;

    /// Make a BigInt out of a buffer
    static BigInt fromBuffer(const Uint8* buf, Uint32 size);

private:
    mpz_t val;
};

}

#endif
