#ifndef _c_fixed_q_h_
#define _c_fixed_q_h_

#include <deque>
#include <condition_variable>
#include <functional>

#define notify notify_one
// #define notify notify_all

constexpr int du = 6;

template <class T>
class fixed_q{
public:
    fixed_q(const size_t qsize, std::function<bool()> fn)
    :qsize(qsize),pred(move(fn)){}
    fixed_q(const fixed_q&)=delete;
    fixed_q& operator=(const fixed_q&)=delete;

    const size_t capacity()const{ return qsize; }
    const size_t size(){
        std::lock_guard<std::mutex> l{mtx_q};
        return q.size();
    }
    int push(const T& m){
        std::unique_lock<std::mutex> l{mtx_q};
        auto d = std::chrono::milliseconds{du};
        while(!cond_spare.wait_for(l, d, [this]{ return q.size() < qsize; })){
            if (pred()) return -1;
        }

        q.push_back(m);
        cond_node.notify();
        return q.size();
    }
    int emplace(T&& m){
        std::unique_lock<std::mutex> l{mtx_q};
        auto d = std::chrono::milliseconds{du};
        while(!cond_spare.wait_for(l, d, [this]{ return q.size() < qsize; })){
            if (pred()) {
                return -1;
            }
        }
        q.emplace_back(move(m));
        cond_node.notify();
        return q.size();
    }
    int pop(T& m){
        std::unique_lock<std::mutex> l{mtx_q};
        auto d = std::chrono::milliseconds{du};
        while(!cond_node.wait_for(l, d, [this]{ return !q.empty(); })){
            if (pred()) return -1;
        }
        m = q.front();
        q.pop_front();
        cond_spare.notify();
        return q.size();
    }
    T pop(){
        std::unique_lock<std::mutex> l{mtx_q};
        auto d = std::chrono::milliseconds{du};
        while(!cond_node.wait_for(l, d, [this]{ return !q.empty(); })){
            if (pred()) return T{};
        }
        auto m(move(q.front()));
        q.pop_front();
        cond_spare.notify();
        return m;
    }

    template<typename F> void clear(F&& f){
        std::lock_guard<std::mutex> l{mtx_q};
        while(!q.empty()){
            auto& msg = q.front();
            f(msg);
            q.pop_front();
        }
    }

private:
    const size_t qsize;
    std::function<bool()> pred;
    std::deque<T> q;
    std::mutex mtx_q;
    std::condition_variable cond_node;
    std::condition_variable cond_spare;
};

#endif