#pragma once

#include <QMutexLocker>
#include <QWaitCondition>
#include <queue>

using namespace std;

const int BUFFSIZE = 100;

template<typename T>
class Monitor {
private:
    QMutex l;
    QWaitCondition full, empty;
    // full: Condition variable for queue itemQ.
    // empty: Condition variable for queue emptySpotsQ.

    queue<T *> emptySpotsQ;         // Queue of free item buffer places for items to be produced
    queue<T *> itemQ;               // Queue of item buffer places with items to be consumed
    T *buffer;                      // Item buffer
public:
    T *canPut() {
        QMutexLocker ml(&l);            // Lock entry controlling mutex l
        while (emptySpotsQ.size() == 0)    // If no free place in emptySpots queue:
            full.wait(&l);                // Block until condition variable full is given free by mutex l
        T *aux = emptySpotsQ.front();    // Get place in emptySpotsQ
        emptySpotsQ.pop();                // ?? Free one place in emptySpotsQ ?? (documentation of class queue currently not available)
        return aux;                        // Return pointer to place in emptySpotsQ for item to be produced

    };

    T *canGet() {
        QMutexLocker ml(&l);        // Lock entry controlling mutex l
        while (itemQ.size() == 0)    // If no item in itemQ:
            empty.wait(&l);            // Block until condition variable empty is given free by mutex l
        T *temp = itemQ.front();    // Get item out of itemQ
        itemQ.pop();                // ?? Free one place in itemQ ?? (documentation of class queue currently not available)
        return temp;                // Return pointer to item in itemQ, which will be consumed

    };

    void donePutting(T *x) {
        QMutexLocker ml(&l);    // Lock entry controlling mutex l
        itemQ.push(x);            // Push place with produced item into itemQ
        empty.wakeOne();        // Notify one consumer thread waiting for condition variable empty

    };

    void doneGetting(T *x) {
        QMutexLocker ml(&l);    // Lock entry controlling mutex l
        emptySpotsQ.push(
                x);    // Give free the buffer place which had hold the consumed item by pushing in into emptySpotsQ
        full.wakeOne();            // Notify one producer thread waiting for condition variable empty

    };

    Monitor(int n = BUFFSIZE) {
        buffer = new T[n];
        for (int i = 0; i < n; i++)
            emptySpotsQ.push(&buffer[i]);
    };

    ~Monitor() {
        delete[]buffer;
    };
};