#ifndef HELPERS_H_
#define HELPERS_H_

#include <deque>
#include <iterator>

using std::deque;

template <typename T> 
int sign(const T& value) {
    return value < 0 ? -1 : (value > 0 ? 1 : 0);
}

template <typename T, class iter>
T ema(iter begin, iter end)
{
    const std::size_t N = std::distance(begin, end);
    const T a = T(1) - T(2) / T(N + 1);
    T b = T(1);

    T nominator = 0, denominator = 0;
    for(iter it = begin; it < end; it++) {
        nominator   += *it * b;
        denominator += b;

        b *= a;
    }

    return nominator / denominator;
}

template <typename T>
class buffer : public deque<T> 
{
    using deque<T>::deque;
    std::size_t limit;

    public:
        buffer(std::size_t limit) : limit(limit), deque<T>(limit) {};
        buffer(std::size_t limit, const T& value) : limit(limit), deque<T>(limit, value) {};

        void add(const T& value)
        {
            if (this->size() >= limit) {
                this->pop_back();
            }

            push_front(value);
        }
};

#endif