/*
 * Copyright (C) 2020 BfaCore
 *
 * 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, see <http://www.gnu.org/licenses/>.
 */

#ifndef _AUTH_BIGNUMBER_H
#define _AUTH_BIGNUMBER_H

#include "Define.h"
#include <memory>
#include <string>
#include <vector>
#include "advstd.h" // data/size

struct bignum_st;

class TC_COMMON_API BigNumber
{
    public:
        BigNumber();
        BigNumber(BigNumber const& bn);
        BigNumber(uint32 v) : BigNumber() { SetDword(v); }
        BigNumber(int32 v) : BigNumber() { SetDword(v); }
        BigNumber(std::string const& v) : BigNumber() { SetHexStr(v); }
        template <size_t Size>
        BigNumber(std::array<uint8, Size> const& v, bool littleEndian = true) : BigNumber() { SetBinary(v.data(), Size, littleEndian); }

        ~BigNumber();

        void SetDword(int32);
        void SetDword(uint32);
        void SetQword(uint64);
        void SetBinary(uint8 const* bytes, int32 len, bool littleEndian = true);
        template <typename Container>
        auto SetBinary(Container const& c, bool littleEndian = true) -> std::enable_if_t<!advstd::is_pointer_v<std::decay_t<Container>>> { SetBinary(advstd::data(c), advstd::size(c), littleEndian); }
        bool SetHexStr(char const* str);
        bool SetHexStr(std::string const& str) { return SetHexStr(str.c_str()); }

        void SetRand(int32 numbits);

        BigNumber& operator=(BigNumber const& bn);

        BigNumber& operator+=(BigNumber const& bn);
        BigNumber operator+(BigNumber const& bn) const
        {
            BigNumber t(*this);
            return t += bn;
        }

        BigNumber& operator-=(BigNumber const& bn);
        BigNumber operator-(BigNumber const& bn) const
        {
            BigNumber t(*this);
            return t -= bn;
        }

        BigNumber& operator*=(BigNumber const& bn);
        BigNumber operator*(BigNumber const& bn) const
        {
            BigNumber t(*this);
            return t *= bn;
        }

        BigNumber& operator/=(BigNumber const& bn);
        BigNumber operator/(BigNumber const& bn) const
        {
            BigNumber t(*this);
            return t /= bn;
        }

        BigNumber& operator%=(BigNumber const& bn);
        BigNumber operator%(BigNumber const& bn) const
        {
            BigNumber t(*this);
            return t %= bn;
        }

        BigNumber& operator<<=(int n);
        BigNumber operator<<(int n) const
        {
            BigNumber t(*this);
            return t <<= n;
        }

        int CompareTo(BigNumber const& bn) const;
        bool operator<=(BigNumber const& bn) const { return (CompareTo(bn) <= 0); }
        bool operator==(BigNumber const& bn) const { return (CompareTo(bn) == 0); }
        bool operator>=(BigNumber const& bn) const { return (CompareTo(bn) >= 0); }
        bool operator<(BigNumber const& bn) const { return (CompareTo(bn) < 0); }
        bool operator>(BigNumber const& bn) const { return (CompareTo(bn) > 0); }

        bool IsZero() const;
        bool IsNegative() const;

        BigNumber ModExp(BigNumber const& bn1, BigNumber const& bn2) const;
        BigNumber Exp(BigNumber const&) const;

        int32 GetNumBytes() const;

        struct bignum_st* BN() { return _bn; }
        struct bignum_st const* BN() const { return _bn; }

        uint32 AsDword() const;

        void GetBytes(uint8* buf, size_t bufsize, bool littleEndian = true) const;
        std::vector<uint8> ToByteVector(int32 minSize = 0, bool littleEndian = true) const;

        template <std::size_t Size>
        std::array<uint8, Size> ToByteArray(bool littleEndian = true) const
        {
            std::array<uint8, Size> buf;
            GetBytes(buf.data(), Size, littleEndian);
            return buf;
        }

        std::string AsHexStr() const;
        std::string AsDecStr() const;

    private:
        struct bignum_st* _bn;

};
#endif
