//------------------------------------------------------------------------------
/*
    Copyright (c) 2011-2013, OpenCoin, Inc.
*/
//==============================================================================

// 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 (uint256 const& 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
