//
// libtgvoip is free and unencumbered public domain software.
// For more information, see http://unlicense.org or the UNLICENSE file
// you should have received with this source code distribution.
//

#pragma once
#include <algorithm>
#include <assert.h>
#include <numeric>

#define TGVOIP_DISALLOW_COPY_AND_ASSIGN(TypeName) \
    TypeName(const TypeName &) = delete;          \
    void operator=(TypeName &) = delete

#define TGVOIP_MOVE_ONLY(TypeName)             \
    TGVOIP_DISALLOW_COPY_AND_ASSIGN(TypeName); \
    TypeName(TypeName &&) = default;           \
    TypeName &operator=(TypeName &&) = default

template <typename T, size_t size, typename AVG_T = T>
class HistoricBuffer
{
public:
    HistoricBuffer()
    {
    }

    AVG_T Average() const
    {
        return std::accumulate(data.begin(), data.end(), static_cast<AVG_T>(0)) / static_cast<AVG_T>(size);
    }

    AVG_T Average(size_t firstN) const
    {
        AVG_T avg = static_cast<AVG_T>(0);
        for (size_t i = 0; i < firstN; i++) // Manual iteration required to wrap around array with specific offset
        {
            avg += (*this)[i];
        }
        return avg / static_cast<AVG_T>(firstN);
    }

    AVG_T NonZeroAverage() const
    {
        AVG_T avg = static_cast<AVG_T>(0);
        int nonZeroCount = 0;
        for (const T &i : data)
        {
            if (i)
            {
                nonZeroCount++;
                avg += i;
            }
        }
        if (nonZeroCount == 0)
            return static_cast<AVG_T>(0);
        return avg / static_cast<AVG_T>(nonZeroCount);
    }

    void Add(T el)
    {
        data[offset] = el;
        offset = (offset + 1) % size;
    }

    T Min() const
    {
        return *std::min_element(data.begin(), data.end());
    }

    T Max() const
    {
        return *std::max_element(data.begin(), data.end());
    }

    void Reset()
    {
        std::fill(data.begin(), data.end(), static_cast<T>(0));
        offset = 0;
    }

    T operator[](size_t i) const
    {
        assert(i < size);
        // [0] should return the most recent entry, [1] the one before it, and so on
        ptrdiff_t _i = offset - i - 1;
        if (_i < 0) // Wrap around offset a-la posmod
            _i = size + _i;
        return data[_i];
    }

    T &operator[](size_t i)
    {
        assert(i < size);
        // [0] should return the most recent entry, [1] the one before it, and so on
        ptrdiff_t _i = offset - i - 1;
        if (_i < 0) // Wrap around offset a-la posmod
            _i = size + _i;
        return data[_i];
    }

    constexpr size_t Size() const
    {
        return size;
    }

    // Non-wrapping iterators
    auto begin() noexcept
    {
        return data.begin();
    }
    auto end() noexcept
    {
        return data.end();
    }

    // Non-wrapping iterators
    const auto begin() const noexcept
    {
        return data.begin();
    }
    const auto end() const noexcept
    {
        return data.end();
    }

private:
    std::array<T, size> data{};
    ptrdiff_t offset = 0;
};