#ifndef stack_h
#define stack_h 1

#include <mutex>
#include <optional>
#include <semaphore>
#include <stack>

using namespace std::chrono_literals;

class semaphore : public std::binary_semaphore
{
public:
    semaphore() : std::binary_semaphore(1) {}

    void lock()
    {
        auto delay = 50us;
        while (!try_acquire())
            std::this_thread::sleep_for(delay *= 2);
    }

    void unlock() { release(); }
};

template<class T> class stack
{
public:
    void push(T t)
    {
        std::scoped_lock lock(sem);
        container.push(t);
    }

    std::optional<T> pop()
    {
        std::scoped_lock lock(sem);
        if (!container.empty())
        {
            auto data = container.top();
            container.pop();
            return data;
        }
        else
        {
            return std::nullopt;
        }
    }

private:
    semaphore sem;
    std::stack<T> container;
};

#endif // stack_h