/*
 * Copyright (C) 2015 by Multi-Tech Systems
 *
 * This file is part of libmts.
 *
 * libmts is free software: you can redistribute it and/or modify
 * it under the terms of the GNU Lesser General Public License as published by
 * the Free Software Foundation, either version 2 of the License, or
 * (at your option) any later version.
 *
 * libmts is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU Lesser General Public License for more details.
 *
 * You should have received a copy of the GNU Lesser General Public License
 * along with libmts.  If not, see <http://www.gnu.org/licenses/>.
 *
 */

/*! \file   MTS_Queue.h
 \brief  A queue
 \date   15JUN11
 \author Sean Godinez

 A thread-safe queue with condition signaling
 */
#ifndef _MTS_QUEUE_H_
#define _MTS_QUEUE_H_

#include <mts/MTS_NonCopyable.h>
#include <mts/MTS_AutoPtr.h>
#include <mts/MTS_Lock.h>
#include <mts/MTS_Logger.h>
#include <mts/MTS_Stdint.h>
#include <queue>
#include <cassert>

namespace MTS {

    //! A queue
    /*!
     A thread-safe, blocking, template queue that signals when it is not empty, and when it is not full.

     \sa AutoPtr, Lock
     */
    template<class T> class Queue : public NonCopyable {

        public:
            explicit Queue(uint32_t capacity = UINT32_MAX); //!< Constructs the queue
            ~Queue();                                       //!< Destructs the queue

            bool empty() const;                             //!< Returns true if queue is empty
            bool full() const;                              //!< Returns true if queue is full
            uint32_t size() const;                          //!< Returns the number of elements in the queue
            uint32_t capacity() const;                      //!< Returns the maximum capacity of the queue

            void push(const T& object);                     //!< Pushes an object on the queue (BLOCKS IF FULL)
            void pop(T& object);                            //!< Pops an object off the queue (BLOCKS IF EMPTY)

            bool offer(const T& object, uint32_t waitMillis);
            bool poll(T& object, uint32_t waitMillis);
            bool peek(T& object, uint32_t waitMillis);

        private:
            const uint32_t m_iMaxSize;
            std::queue<T> m_qContainer;
            AutoPtr<Lock> m_apLock;
            AutoPtr<Condition> m_apNotEmpty;
            AutoPtr<Condition> m_apNotFull;
    };

    template<class T> Queue<T>::Queue(uint32_t capacity)
    : m_iMaxSize(capacity) {
        m_apLock.reset(new Lock());
        m_apNotEmpty.reset(m_apLock->createCondition());
        m_apNotFull.reset(m_apLock->createCondition());
    }

    template<class T> Queue<T>::~Queue() {
        m_apNotFull.reset();
        m_apNotEmpty.reset();
        m_apLock.reset();
    }

    template<class T> bool Queue<T>::empty() const {
        bool result = false;
        m_apLock->lock();
        result = m_qContainer.empty();
        m_apLock->unlock();
        return result;
    }

    template<class T> bool Queue<T>::full() const {
        bool result = false;
        m_apLock->lock();
        result = (m_qContainer.size() >= m_iMaxSize);
        m_apLock->unlock();
        return result;
    }

    template<class T> uint32_t Queue<T>::size() const {
        uint32_t result = 0;
        m_apLock->lock();
        result = static_cast<uint32_t>(m_qContainer.size());
        m_apLock->unlock();
        return result;
    }

    template<class T> uint32_t Queue<T>::capacity() const {
        return m_iMaxSize;
    }

    template<class T> void Queue<T>::push(const T& object) {
        // Block forever until there is room on the queue
        m_apLock->lock();
        try {
            while (m_qContainer.size() >= m_iMaxSize) {
                m_apNotFull->wait();
            }
            m_qContainer.push(object);
            m_apNotEmpty->signal();
        } catch (...) {
            printWarning("Queue| failed to push object");
            assert(false);
        }
        m_apLock->unlock();
    }

    template<class T> void Queue<T>::pop(T& object) {
        //Block on not-empty condition if empty
        m_apLock->lock();
        while (m_qContainer.empty()) {
            m_apNotEmpty->wait();
        }
        object = m_qContainer.front();
        m_qContainer.pop();
        m_apNotFull->signal();
        m_apLock->unlock();
    }

    //! Attempts to push an object onto the queue within the given milliseconds
    /*!
     \param object an object to push onto the queue
     \param waitMillis the amount of milliseonds to wait if the queue is full
     \return Returns true if the object was pushed onto the queue, false otherwise
     \sa push()
     */
    template<class T> bool Queue<T>::offer(const T& object,
    uint32_t waitMillis) {
        bool result = false;
        m_apLock->lock();
        try {
            if (waitMillis > 0 && m_qContainer.size() >= m_iMaxSize) {
                m_apNotFull->wait(waitMillis);
            }
            if (m_qContainer.size() < m_iMaxSize) {
                m_qContainer.push(object);
                m_apNotEmpty->signal();
                result = true;
            }
        } catch (...) {
            printWarning("Queue| failed to offer object");
            assert(false);
        }
        m_apLock->unlock();
        return result;
    }

    //! Attempts to pop an object from the queue within the given milliseconds
    /*!
     \param object if successful, a reference to the object that was popped
     \param waitMillis the amount of milliseonds to wait if the queue is empty
     \return Returns true if an object was popped from the queue, false otherwise
     \sa pop(), peek()
     */
    template<class T> bool Queue<T>::poll(T& object, uint32_t waitMillis) {
        bool result = false;
        m_apLock->lock();
        if (waitMillis > 0 && m_qContainer.empty()) {
            m_apNotEmpty->wait(waitMillis);
        }
        if (!m_qContainer.empty()) {
            object = m_qContainer.front();
            m_qContainer.pop();
            m_apNotFull->signal();
            result = true;
        }
        m_apLock->unlock();
        return result;
    }

    //! Attempts to view the top of the queue within the given milliseconds
    /*!
     \param object if successful, a reference to the object that is at the head of the queue
     \param waitMillis the amount of milliseonds to wait if the queue is empty
     \return Returns true if there is an object in the queue, false otherwise
     \sa pop(), poll()
     */
    template<class T> bool Queue<T>::peek(T& object, uint32_t waitMillis) {
        bool result = false;
        m_apLock->lock();
        if (waitMillis > 0 && m_qContainer.empty()) {
            m_apNotEmpty->wait(waitMillis);
        }
        if (!m_qContainer.empty()) {
            object = m_qContainer.front();
            result = true;
        }
        m_apLock->unlock();
        return result;
    }
}

#endif