/*
 * Copyright (C) 2005-2012 MaNGOS <http://getmangos.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., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
 */

#include "Auth/BigNumber.h"
#include <openssl/bn.h>
#include <algorithm>

BigNumber::BigNumber()
{
 _bn = BN_new();
}

BigNumber::BigNumber(const BigNumber &bn)
{
 _bn = BN_dup(bn._bn);
}

BigNumber::BigNumber(uint32 val)
{
 _bn = BN_new();
 BN_set_word(_bn, val);
}

BigNumber::~BigNumber()
{
 BN_free(_bn);
}

void BigNumber::SetDword(uint32 val)
{
 BN_set_word(_bn, val);
}

void BigNumber::SetQword(uint64 val)
{
 BN_add_word(_bn, (uint32)(val >> 32));
 BN_lshift(_bn, _bn, 32);
 BN_add_word(_bn, (uint32)(val & 0xFFFFFFFF));
}

void BigNumber::SetBinary(const uint8 *bytes, int len)
{
 uint8 t[1000];
 for (int i = 0; i < len; i++)
 t[i] = bytes[len - 1 - i];
 BN_bin2bn(t, len, _bn);
}

void BigNumber::SetHexStr(const char *str)
{
 BN_hex2bn(&_bn, str);
}

void BigNumber::SetRand(int numbits)
{
 BN_rand(_bn, numbits, 0, 1);
}

BigNumber BigNumber::operator=(const BigNumber &bn)
{
 BN_copy(_bn, bn._bn);
 return *this;
}

BigNumber BigNumber::operator+=(const BigNumber &bn)
{
 BN_add(_bn, _bn, bn._bn);
 return *this;
}

BigNumber BigNumber::operator-=(const BigNumber &bn)
{
 BN_sub(_bn, _bn, bn._bn);
 return *this;
}

BigNumber BigNumber::operator*=(const BigNumber &bn)
{
 BN_CTX *bnctx;

 bnctx = BN_CTX_new();
 BN_mul(_bn, _bn, bn._bn, bnctx);
 BN_CTX_free(bnctx);

 return *this;
}

BigNumber BigNumber::operator/=(const BigNumber &bn)
{
 BN_CTX *bnctx;

 bnctx = BN_CTX_new();
 BN_div(_bn, NULL, _bn, bn._bn, bnctx);
 BN_CTX_free(bnctx);

 return *this;
}

BigNumber BigNumber::operator%=(const BigNumber &bn)
{
 BN_CTX *bnctx;

 bnctx = BN_CTX_new();
 BN_mod(_bn, _bn, bn._bn, bnctx);
 BN_CTX_free(bnctx);

 return *this;
}

BigNumber BigNumber::Exp(const BigNumber &bn)
{
 BigNumber ret;
 BN_CTX *bnctx;

 bnctx = BN_CTX_new();
 BN_exp(ret._bn, _bn, bn._bn, bnctx);
 BN_CTX_free(bnctx);

 return ret;
}

BigNumber BigNumber::ModExp(const BigNumber &bn1, const BigNumber &bn2)
{
 BigNumber ret;
 BN_CTX *bnctx;

 bnctx = BN_CTX_new();
 BN_mod_exp(ret._bn, _bn, bn1._bn, bn2._bn, bnctx);
 BN_CTX_free(bnctx);

 return ret;
}

int BigNumber::GetNumBytes(void)
{
 return BN_num_bytes(_bn);
}

uint32 BigNumber::AsDword()
{
 return (uint32)BN_get_word(_bn);
}

bool BigNumber::isZero() const
{
 return BN_is_zero(_bn)!=0;
}

std::vector<uint8> BigNumber::AsByteArray(int minSize, bool reverse)
{
 int length = (minSize >= GetNumBytes()) ? minSize : GetNumBytes();

 std::vector<uint8> byteArray(length);
 
 // If we need more bytes than length of BigNumber set the rest to 0
 if (length > GetNumBytes())
 memset((void*)byteArray.data(), 0, length);

 // Padding should add leading zeroes, not trailing
 int paddingOffset = length - GetNumBytes();

 BN_bn2bin(_bn, (unsigned char *)byteArray.data() + paddingOffset);

 if (reverse)
 std::reverse(byteArray.begin(), byteArray.end());


 return byteArray;
}

const char *BigNumber::AsHexStr()
{
 return BN_bn2hex(_bn);
}

const char *BigNumber::AsDecStr()
{
 return BN_bn2dec(_bn);
}