// Copyright (c) 2009-2010 Satoshi Nakamoto
// Copyright (c) 2011 The Bitcoin developers
// Distributed under the MIT/X11 software license, see the accompanying
// file license.txt or http://www.opensource.org/licenses/mit-license.php.

CBigNum::CBigNum()
{
	BN_init(this);
}

CBigNum::CBigNum(const CBigNum& b)
{
	BN_init(this);
	if (!BN_copy(this, &b))
	{
		BN_clear_free(this);
		throw bignum_error("CBigNum::CBigNum(const CBigNum&) : BN_copy failed");
	}
}

CBigNum& CBigNum::operator=(const CBigNum& b)
{
	if (!BN_copy(this, &b))
		throw bignum_error("CBigNum::operator= : BN_copy failed");
	return (*this);
}

CBigNum::~CBigNum()
{
	BN_clear_free(this);
}

CBigNum::CBigNum(char n)			{ BN_init(this); if (n >= 0) setulong(n); else setint64(n); }
CBigNum::CBigNum(short n)			{ BN_init(this); if (n >= 0) setulong(n); else setint64(n); }
CBigNum::CBigNum(int n)				{ BN_init(this); if (n >= 0) setulong(n); else setint64(n); }
CBigNum::CBigNum(long n)			{ BN_init(this); if (n >= 0) setulong(n); else setint64(n); }
CBigNum::CBigNum(int64 n)			{ BN_init(this); setint64(n); }
CBigNum::CBigNum(unsigned char n)	{ BN_init(this); setulong(n); }
CBigNum::CBigNum(unsigned short n)  { BN_init(this); setulong(n); }
CBigNum::CBigNum(unsigned int n)	{ BN_init(this); setulong(n); }
CBigNum::CBigNum(uint64 n)			{ BN_init(this); setuint64(n); }
CBigNum::CBigNum(uint256 n)			{ BN_init(this); setuint256(n); }

CBigNum::CBigNum(Blob const& vch)
{
	BN_init(this);
	setvch(vch);
}

void CBigNum::setuint(unsigned int n)
{
	setulong(static_cast<unsigned long>(n));
}

unsigned int CBigNum::getuint() const
{
	return BN_get_word(this);
}

int CBigNum::getint() const
{
	unsigned long n = BN_get_word(this);
	if (!BN_is_negative(this))
		return (n > INT_MAX ? INT_MAX : n);
	else
		return (n > INT_MAX ? INT_MIN : -(int)n);
}

void CBigNum::setint64(int64 n)
{
	unsigned char pch[sizeof(n) + 6];
	unsigned char* p = pch + 4;
	bool fNegative = false;
	if (n < (int64)0)
	{
		n = -n;
		fNegative = true;
	}
	bool fLeadingZeroes = true;
	for (int i = 0; i < 8; i++)
	{
		unsigned char c = (n >> 56) & 0xff;
		n <<= 8;
		if (fLeadingZeroes)
		{
			if (c == 0)
				continue;
			if (c & 0x80)
				*p++ = (fNegative ? 0x80 : 0);
			else if (fNegative)
				c |= 0x80;
			fLeadingZeroes = false;
		}
		*p++ = c;
	}
	unsigned int nSize = p - (pch + 4);
	pch[0] = (nSize >> 24) & 0xff;
	pch[1] = (nSize >> 16) & 0xff;
	pch[2] = (nSize >> 8) & 0xff;
	pch[3] = (nSize) & 0xff;
	BN_mpi2bn(pch, p - pch, this);
}

uint64 CBigNum::getuint64() const
{
#if (ULONG_MAX > UINT_MAX)
	return static_cast<uint64>(getulong());
#else
	int len = BN_num_bytes(this);
	if (len > 8)
		throw std::runtime_error("BN getuint64 overflow");

	unsigned char buf[8];
	memset(buf, 0, sizeof(buf));
	BN_bn2bin(this, buf + 8 - len);
	return
		static_cast<uint64>(buf[0]) << 56 | static_cast<uint64>(buf[1]) << 48 |
		static_cast<uint64>(buf[2]) << 40 | static_cast<uint64>(buf[3]) << 32 |
		static_cast<uint64>(buf[4]) << 24 | static_cast<uint64>(buf[5]) << 16 |
		static_cast<uint64>(buf[6]) << 8 | static_cast<uint64>(buf[7]);
#endif
}

void CBigNum::setuint64(uint64 n)
{
#if (ULONG_MAX > UINT_MAX)
	setulong(static_cast<unsigned long>(n));
#else
	unsigned char buf[8];
	buf[0] = static_cast<unsigned char>((n >> 56) & 0xff);
	buf[1] = static_cast<unsigned char>((n >> 48) & 0xff);
	buf[2] = static_cast<unsigned char>((n >> 40) & 0xff);
	buf[3] = static_cast<unsigned char>((n >> 32) & 0xff);
	buf[4] = static_cast<unsigned char>((n >> 24) & 0xff);
	buf[5] = static_cast<unsigned char>((n >> 16) & 0xff);
	buf[6] = static_cast<unsigned char>((n >> 8) & 0xff);
	buf[7] = static_cast<unsigned char>((n) & 0xff);
	BN_bin2bn(buf, 8, this);
#endif
}

void CBigNum::setuint256(const uint256& n)
{
	BN_bin2bn(n.begin(), n.size(), NULL);
}

uint256 CBigNum::getuint256()
{
	uint256 ret;
	unsigned int size = BN_num_bytes(this);
	if (size > ret.size())
		return ret;
	BN_bn2bin(this, ret.begin() + (ret.size() - BN_num_bytes(this)));
	return ret;
}

void CBigNum::setvch(Blob const& vch)
{
	Blob vch2(vch.size() + 4);
	unsigned int nSize = vch.size();
	// BIGNUM's byte stream format expects 4 bytes of
	// big endian size data info at the front
	vch2[0] = (nSize >> 24) & 0xff;
	vch2[1] = (nSize >> 16) & 0xff;
	vch2[2] = (nSize >> 8) & 0xff;
	vch2[3] = (nSize >> 0) & 0xff;
	// swap data to big endian
	std::reverse_copy(vch.begin(), vch.end(), vch2.begin() + 4);
	BN_mpi2bn(&vch2[0], vch2.size(), this);
}

Blob CBigNum::getvch() const
{
	unsigned int nSize = BN_bn2mpi(this, NULL);
	if (nSize < 4)
		return Blob ();
	Blob vch(nSize);
	BN_bn2mpi(this, &vch[0]);
	vch.erase(vch.begin(), vch.begin() + 4);
	reverse(vch.begin(), vch.end());
	return vch;
}

CBigNum& CBigNum::SetCompact(unsigned int nCompact)
{
	unsigned int nSize = nCompact >> 24;
	Blob vch(4 + nSize);
	vch[3] = nSize;
	if (nSize >= 1) vch[4] = (nCompact >> 16) & 0xff;
	if (nSize >= 2) vch[5] = (nCompact >> 8) & 0xff;
	if (nSize >= 3) vch[6] = (nCompact >> 0) & 0xff;
	BN_mpi2bn(&vch[0], vch.size(), this);
	return *this;
}

unsigned int CBigNum::GetCompact() const
{
	unsigned int nSize = BN_bn2mpi(this, NULL);
	Blob vch(nSize);
	nSize -= 4;
	BN_bn2mpi(this, &vch[0]);
	unsigned int nCompact = nSize << 24;
	if (nSize >= 1) nCompact |= (vch[4] << 16);
	if (nSize >= 2) nCompact |= (vch[5] << 8);
	if (nSize >= 3) nCompact |= (vch[6] << 0);
	return nCompact;
}

void CBigNum::SetHex(const std::string& str)
{
	// skip 0x
	const char* psz = str.c_str();
	while (isspace(*psz))
		psz++;
	bool fNegative = false;
	if (*psz == '-')
	{
		fNegative = true;
		psz++;
	}
	if (psz[0] == '0' && tolower(psz[1]) == 'x')
		psz += 2;
	while (isspace(*psz))
		psz++;

	// hex string to bignum
	static char phexdigit[256] = {
		0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,
		0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,
		0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,
		0,1,2,3,4,5,6,7,8,9,0,0,0,0,0,0,
		0,0xa,0xb,0xc,0xd,0xe,0xf,0,0,0,0,0,0,0,0,0,
		0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,
		0,0xa,0xb,0xc,0xd,0xe,0xf,0,0,0,0,0,0,0,0,0 };
	*this = 0;
	while (isxdigit(*psz))
	{
		*this <<= 4;
		int n = phexdigit[(int) *psz++];
		*this += n;
	}
	if (fNegative)
		*this = 0 - *this;
}

std::string CBigNum::ToString(int nBase) const
{
	CAutoBN_CTX pctx;
	CBigNum bnBase = nBase;
	CBigNum bn0 = 0;
	std::string str;
	CBigNum bn = *this;
	BN_set_negative(&bn, false);
	CBigNum dv;
	CBigNum rem;
	if (BN_cmp(&bn, &bn0) == 0)
		return "0";
	while (BN_cmp(&bn, &bn0) > 0)
	{
		if (!BN_div(&dv, &rem, &bn, &bnBase, pctx))
			throw bignum_error("CBigNum::ToString() : BN_div failed");
		bn = dv;
		unsigned int c = rem.getuint();
		str += "0123456789abcdef"[c];
	}
	if (BN_is_negative(this))
		str += "-";
	reverse(str.begin(), str.end());
	return str;
}

std::string CBigNum::GetHex() const
{
	return ToString(16);
}

bool CBigNum::operator!() const
{
	return BN_is_zero(this);
}

CBigNum& CBigNum::operator+=(const CBigNum& b)
{
	if (!BN_add(this, this, &b))
		throw bignum_error("CBigNum::operator+= : BN_add failed");
	return *this;
}

CBigNum& CBigNum::operator-=(const CBigNum& b)
{
	*this = *this - b;
	return *this;
}

CBigNum& CBigNum::operator*=(const CBigNum& b)
{
	CAutoBN_CTX pctx;
	if (!BN_mul(this, this, &b, pctx))
		throw bignum_error("CBigNum::operator*= : BN_mul failed");
	return *this;
}

CBigNum& CBigNum::operator/=(const CBigNum& b)
{
	*this = *this / b;
	return *this;
}

CBigNum& CBigNum::operator%=(const CBigNum& b)
{
	*this = *this % b;
	return *this;
}

CBigNum& CBigNum::operator<<=(unsigned int shift)
{
	if (!BN_lshift(this, this, shift))
		throw bignum_error("CBigNum:operator<<= : BN_lshift failed");
	return *this;
}

CBigNum& CBigNum::operator>>=(unsigned int shift)
{
	// Note: BN_rshift segfaults on 64-bit if 2^shift is greater than the number
	//   if built on ubuntu 9.04 or 9.10, probably depends on version of openssl
	CBigNum a = 1;
	a <<= shift;
	if (BN_cmp(&a, this) > 0)
	{
		*this = 0;
		return *this;
	}

	if (!BN_rshift(this, this, shift))
		throw bignum_error("CBigNum:operator>>= : BN_rshift failed");
	return *this;
}


CBigNum& CBigNum::operator++()
{
	// prefix operator
	if (!BN_add(this, this, BN_value_one()))
		throw bignum_error("CBigNum::operator++ : BN_add failed");
	return *this;
}

const CBigNum CBigNum::operator++(int)
{
	// postfix operator
	const CBigNum ret = *this;
	++(*this);
	return ret;
}

CBigNum& CBigNum::operator--()
{
	// prefix operator
	CBigNum r;
	if (!BN_sub(&r, this, BN_value_one()))
		throw bignum_error("CBigNum::operator-- : BN_sub failed");
	*this = r;
	return *this;
}

const CBigNum CBigNum::operator--(int)
{
	// postfix operator
	const CBigNum ret = *this;
	--(*this);
	return ret;
}

void CBigNum::setulong(unsigned long n)
{
	if (!BN_set_word(this, n))
		throw bignum_error("CBigNum conversion from unsigned long : BN_set_word failed");
}

unsigned long CBigNum::getulong() const
{
	return BN_get_word(this);
}

const CBigNum operator+(const CBigNum& a, const CBigNum& b)
{
	CBigNum r;
	if (!BN_add(&r, &a, &b))
		throw bignum_error("CBigNum::operator+ : BN_add failed");
	return r;
}

const CBigNum operator-(const CBigNum& a, const CBigNum& b)
{
	CBigNum r;
	if (!BN_sub(&r, &a, &b))
		throw bignum_error("CBigNum::operator- : BN_sub failed");
	return r;
}

const CBigNum operator-(const CBigNum& a)
{
	CBigNum r(a);
	BN_set_negative(&r, !BN_is_negative(&r));
	return r;
}

const CBigNum operator*(const CBigNum& a, const CBigNum& b)
{
	CAutoBN_CTX pctx;
	CBigNum r;
	if (!BN_mul(&r, &a, &b, pctx))
		throw bignum_error("CBigNum::operator* : BN_mul failed");
	return r;
}

const CBigNum operator/(const CBigNum& a, const CBigNum& b)
{
	CAutoBN_CTX pctx;
	CBigNum r;
	if (!BN_div(&r, NULL, &a, &b, pctx))
		throw bignum_error("CBigNum::operator/ : BN_div failed");
	return r;
}

const CBigNum operator%(const CBigNum& a, const CBigNum& b)
{
	CAutoBN_CTX pctx;
	CBigNum r;
	if (!BN_mod(&r, &a, &b, pctx))
		throw bignum_error("CBigNum::operator% : BN_div failed");
	return r;
}

const CBigNum operator<<(const CBigNum& a, unsigned int shift)
{
	CBigNum r;
	if (!BN_lshift(&r, &a, shift))
		throw bignum_error("CBigNum:operator<< : BN_lshift failed");
	return r;
}

const CBigNum operator>>(const CBigNum& a, unsigned int shift)
{
	CBigNum r = a;
	r >>= shift;
	return r;
}

bool operator== (const CBigNum& a, const CBigNum& b)
{
	return (BN_cmp(&a, &b) == 0);
}

bool operator!= (const CBigNum& a, const CBigNum& b)
{
	return (BN_cmp(&a, &b) != 0);
}

bool operator<= (const CBigNum& a, const CBigNum& b)
{
	return (BN_cmp(&a, &b) <= 0);
}

bool operator>= (const CBigNum& a, const CBigNum& b)
{
	return (BN_cmp(&a, &b) >= 0);
}

bool operator<  (const CBigNum& a, const CBigNum& b)
{
	return (BN_cmp(&a, &b) < 0);
}

bool operator>  (const CBigNum& a, const CBigNum& b)
{
	return (BN_cmp(&a, &b) > 0);
}

#if (ULONG_MAX > UINT_MAX)

int BN_add_word64 (BIGNUM* bn, uint64 word)
{
	return BN_add_word(bn, word);
}

int BN_sub_word64 (BIGNUM* bn, uint64 word)
{
	return BN_sub_word(bn, word);
}

int BN_mul_word64 (BIGNUM* bn, uint64 word)
{
	return BN_mul_word(bn, word);
}

uint64 BN_div_word64 (BIGNUM* bn, uint64 word)
{
	return BN_div_word(bn, word);
}

#else

int BN_add_word64 (BIGNUM *a, uint64 w)
{
	CBigNum bn(w);
	return BN_add(a, &bn, a);
}

int BN_sub_word64 (BIGNUM *a, uint64 w)
{
	CBigNum bn(w);
	return BN_sub(a, &bn, a);
}

int BN_mul_word64 (BIGNUM *a, uint64 w)
{
	CBigNum bn(w);
	CAutoBN_CTX ctx;
	return BN_mul(a, &bn, a, ctx);
}

uint64 BN_div_word64 (BIGNUM *a, uint64 w)
{
	CBigNum bn(w);
	CAutoBN_CTX ctx;
	return (BN_div(a, NULL, a, &bn, ctx) == 1) ? 0 : ((uint64)-1);
}

#endif