#ifndef QUEUE2STACK_H
#define QUEUE2STACK_H

#include "LinkedQueue.h"
#include "Stack.h"
#include <initializer_list>

namespace Kylin {
template <typename T>
class QueueToStack : public Stack<T> {
public:
    QueueToStack(std::initializer_list<T> init) {
        for (auto &value : init) push(value);
    }
    void push(const T &value) final {
        makeOutQueueEmpty();
        m_inQueue.enqueue(value);
    }

    T pop() final {
        if (size() <= 0)
            THROW_EXCEPTION(InvalidOperationException, "There is no element in QueueToStack ...");
        if (m_outQueue.size() > 0) return m_outQueue.dequeue();
        moveAnElementToEmptyOutQueue();
        return m_outQueue.dequeue();
    }

    virtual T &top() {
        if (size() <= 0) THROW_EXCEPTION(InvalidOperationException, "There is no element in stack...");
        if (m_outQueue.size() > 0) return m_outQueue.head();
        moveAnElementToEmptyOutQueue();
        return m_outQueue.head();
    }

    virtual void clear() {
        m_inQueue.clear();
        m_outQueue.clear();
    }

    virtual size_t size() const { return m_inQueue.size() + m_outQueue.size(); }

protected:
    void moveAnElementToEmptyOutQueue() {
        while (m_inQueue.size() > 1) m_outQueue.enqueue(m_inQueue.dequeue());
        m_inQueue.swap(m_outQueue);
    }

    void makeOutQueueEmpty() {
        while (!m_outQueue.empty()) {
            m_inQueue.enqueue(m_outQueue.dequeue());
        }
    }

private:
    LinkedQueue<T> m_inQueue;
    LinkedQueue<T> m_outQueue;
};
} // namespace Kylin

#endif // QUEUE2STACK_H