// Copyright (c) 2012-2017, The CryptoNote developers, The Bytecoin developers
// Copyright (c) 2018-2019, The TurtleCoin Developers
//
// Please see the included LICENSE file for more information.

#pragma once

#include <limits>
#include <sstream>
#include <string>
#include <type_traits>
#include <utility>

namespace Tools
{
    template<typename OutputIt, typename T>
    typename std::enable_if<std::is_integral<T>::value && std::is_unsigned<T>::value, void>::type
        write_varint(OutputIt &&dest, T i)
    {
        while (i >= 0x80)
        {
            *dest++ = (static_cast<char>(i) & 0x7f) | 0x80;
            i >>= 7;
        }
        *dest++ = static_cast<char>(i);
    }

    template<typename t_type> std::string get_varint_data(const t_type &v)
    {
        std::stringstream ss;
        write_varint(std::ostreambuf_iterator<char>(ss), v);

        return ss.str();
    }

    template<int bits, typename InputIt, typename T>
    typename std::enable_if<
        std::is_integral<T>::value && std::is_unsigned<T>::value && 0 <= bits && bits <= std::numeric_limits<T>::digits,
        int>::type
        read_varint(InputIt &&first, InputIt &&last, T &i)
    {
        int read = 0;

        i = 0;
        for (int shift = 0;; shift += 7)
        {
            if (first == last)
            {
                return read; // End of input.
            }
            unsigned char byte = *first++;

            ++read;
            if (shift + 7 >= bits && byte >= 1 << (bits - shift))
            {
                return -1; // Overflow.
            }
            if (byte == 0 && shift != 0)
            {
                return -2; // Non-canonical representation.
            }
            i |= static_cast<T>(byte & 0x7f) << shift;
            if ((byte & 0x80) == 0)
            {
                break;
            }
        }
        return read;
    }

    template<typename InputIt, typename T> int read_varint(InputIt &&first, InputIt &&last, T &i)
    {
        return read_varint<std::numeric_limits<T>::digits, InputIt, T>(std::move(first), std::move(last), i);
    }
} // namespace Tools