/*
 * This file is part of the Flowee project
 * Copyright (C) 2009-2010 Satoshi Nakamoto
 * Copyright (C) 2009-2015 The Bitcoin Core developers
 * Copyright (C) 2019 Tom Zander <tomz@freedommail.ch>
 *
 * 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 3 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 FLOWEE_UINT256_H
#define FLOWEE_UINT256_H

#include <crypto/common.h>
#include "Logger.h"

#include <cassert>
#include <cstring>
#include <stdexcept>
#include <cstdint>
#include <string>
#include <vector>

/** Template base class for fixed-sized opaque blobs. */
template<unsigned int BITS>
class base_blob
{
protected:
    enum { WIDTH=BITS/8 };
    uint8_t data[WIDTH];
public:
    base_blob()
    {
        memset(data, 0, sizeof(data));
    }

    explicit base_blob(const std::vector<unsigned char>& vch);
    explicit base_blob(const char *_data)
    {
        memcpy(data, _data, WIDTH);
    }

    bool IsNull() const
    {
        for (int i = 0; i < WIDTH; i++)
            if (data[i] != 0)
                return false;
        return true;
    }

    void SetNull()
    {
        memset(data, 0, sizeof(data));
    }

    inline int Compare(const base_blob &other) const {
        for (size_t i = sizeof(data); i > 0; --i) {
            const uint8_t a = data[i - 1];
            const uint8_t b = other.data[i - 1];
            if (a > b)
                return 1;
            if (a < b)
                return -1;
        }
        return 0;
    }

    friend inline bool operator==(const base_blob& a, const base_blob& b) { return memcmp(a.data, b.data, sizeof(a.data)) == 0; }
    friend inline bool operator!=(const base_blob& a, const base_blob& b) { return memcmp(a.data, b.data, sizeof(a.data)) != 0; }
    friend inline bool operator<(const base_blob& a, const base_blob& b) { return memcmp(a.data, b.data, sizeof(a.data)) < 0; }

    std::string GetHex() const;
    void SetHex(const char* psz);
    void SetHex(const std::string& str);
    std::string ToString() const;

    unsigned char* begin()
    {
        return &data[0];
    }

    unsigned char* end()
    {
        return &data[WIDTH];
    }

    const unsigned char* begin() const
    {
        return &data[0];
    }

    const unsigned char* end() const
    {
        return &data[WIDTH];
    }

    unsigned int size() const
    {
        return sizeof(data);
    }

    unsigned int GetSerializeSize(int nType, int nVersion) const
    {
        return sizeof(data);
    }

    template<typename Stream>
    void Serialize(Stream& s, int nType, int nVersion) const
    {
        s.write((char*)data, sizeof(data));
    }

    template<typename Stream>
    void Unserialize(Stream& s, int nType, int nVersion)
    {
        s.read((char*)data, sizeof(data));
    }
};

/** 160-bit opaque blob.
 * @note This type is called uint160 for historical reasons only. It is an opaque
 * blob of 160 bits and has no integer operations.
 */
class uint160 : public base_blob<160> {
public:
    uint160() {}
    uint160(const base_blob<160>& b) : base_blob<160>(b) {}
    explicit uint160(const char *d) : base_blob<160>(d) {}
    explicit uint160(const std::vector<unsigned char>& vch) : base_blob<160>(vch) {}
};

/** 256-bit opaque blob.
 * @note This type is called uint256 for historical reasons only. It is an
 * opaque blob of 256 bits and has no integer operations. Use arith_uint256 if
 * those are required.
 */
class uint256 : public base_blob<256> {
public:
    uint256() {}
    uint256(const char *data) : base_blob<256>(data) {}
    uint256(const base_blob<256>& b) : base_blob<256>(b) {}
    explicit uint256(const std::vector<unsigned char>& vch) : base_blob<256>(vch) {}

    /** A cheap hash function that just returns 64 bits from the result, it can be
     * used when the contents are considered uniformly random. It is not appropriate
     * when the value can easily be influenced from outside as e.g. a network adversary could
     * provide values to trigger worst-case behavior.
     */
    uint64_t GetCheapHash() const
    {
        return ReadLE64(data);
    }
};

/* uint256 from const char *.
 * This is a separate function because the constructor uint256(const char*) can result
 * in dangerously catching uint256(0).
 */
inline uint256 uint256S(const char *str)
{
    uint256 rv;
    rv.SetHex(str);
    return rv;
}
/* uint256 from std::string.
 * This is a separate function because the constructor uint256(const std::string &str) can result
 * in dangerously catching uint256(0) via std::string(const char*).
 */
inline uint256 uint256S(const std::string& str)
{
    uint256 rv;
    rv.SetHex(str);
    return rv;
}

/**
 * Useful structure to use for maps.
 * For instance:
 *
 *  typedef boost::unordered_map<uint256, int, HashShortener> MyMap;
 */
struct HashShortener {
    inline size_t operator()(const uint256& hash) const {
        return hash.GetCheapHash();
    }
};

template<unsigned int BITS>
inline Log::Item operator<<(Log::Item item, const base_blob<BITS> &data) {
    if (item.isEnabled())
        item << data.ToString().c_str();
    return item;
}
template<unsigned int BITS>
inline Log::SilentItem operator<<(Log::SilentItem item, const base_blob<BITS> &data) {
    return item;
}

#endif