/**
 * Copyright 2017, Digi International Inc.
 *
 * This Source Code Form is subject to the terms of the Mozilla Public
 * License, v. 2.0. If a copy of the MPL was not distributed with this
 * file, you can obtain one at http://mozilla.org/MPL/2.0/.
 *
 * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES 
 * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF 
 * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR 
 * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES 
 * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN 
 * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF 
 * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
 */
package com.digi.xbee.api.models;

import java.net.Inet4Address;
import java.net.Inet6Address;
import java.util.LinkedList;

import com.digi.xbee.api.RemoteXBeeDevice;
import com.digi.xbee.api.packet.APIFrameType;
import com.digi.xbee.api.packet.XBeeAPIPacket;
import com.digi.xbee.api.packet.XBeePacket;
import com.digi.xbee.api.packet.common.ExplicitRxIndicatorPacket;
import com.digi.xbee.api.packet.common.ReceivePacket;
import com.digi.xbee.api.packet.common.RemoteATCommandResponsePacket;
import com.digi.xbee.api.packet.ip.RXIPv4Packet;
import com.digi.xbee.api.packet.raw.RX16IOPacket;
import com.digi.xbee.api.packet.raw.RX16Packet;
import com.digi.xbee.api.packet.raw.RX64IOPacket;
import com.digi.xbee.api.packet.raw.RX64Packet;
import com.digi.xbee.api.packet.thread.RXIPv6Packet;

/**
 * This class represents a queue of XBee packets used for sequential packets 
 * reading within the XBee Java API. 
 * 
 * <p>The class provides some methods to get specific packet types from 
 * different source nodes.</p>
 * 
 * @see com.digi.xbee.api.packet.XBeePacket
 */
public class XBeePacketsQueue {

        // Constants.
        /**
         * Default maximum number of packets to store in the queue 
         * (value: {@value}).
         */
        public static final int DEFAULT_MAX_LENGTH = 50;
        
        // Variables.
        private int maxLength = DEFAULT_MAX_LENGTH;
        
        private LinkedList<XBeePacket> packetsList;
        
        private Object lock = new Object();
        
        /**
         * Class constructor. Instantiates a new object of type 
         * {@code XBeePacketsQueue}.
         */
        public XBeePacketsQueue() {
                this(DEFAULT_MAX_LENGTH);
        }
        
        /**
         * Class constructor. Instantiates a new object of type 
         * {@code XBeePacketsQueue} with the given maximum length.
         * 
         * @param maxLength Maximum length of the queue.
         * 
         * @throws IllegalArgumentException if {@code maxLength < 1}.
         */
        public XBeePacketsQueue(int maxLength) {
                if (maxLength < 1)
                        throw new IllegalArgumentException("Queue length must be greater than 0.");
                
                this.maxLength = maxLength;
                packetsList = new LinkedList<XBeePacket>();
        }
        
        /**
         * Adds the provided packet to the list of packets. If the queue is full 
         * the first packet will be discarded to add the given one.
         * 
         * @param xbeePacket The XBee packet to be added to the list.
         * 
         * @see com.digi.xbee.api.packet.XBeePacket
         */
        public void addPacket(XBeePacket xbeePacket) {
                synchronized (lock) {
                        if (packetsList.size() == maxLength)
                                packetsList.removeFirst();
                        packetsList.add(xbeePacket);
                }
        }
        
        /**
         * Clears the list of packets.
         */
        public void clearQueue() {
                synchronized (lock) {
                        packetsList.clear();
                }
        }
        
        /**
         * Returns the first packet from the queue waiting up to the specified 
         * timeout if  necessary for an XBee packet to become available. 
         * {@code null }if the queue is empty.
         * 
         * @param timeout The time in milliseconds to wait for an XBee packet to 
         *                become available. 0 to return immediately.
         * @return The first packet from the queue, {@code null} if it is empty.
         * 
         * @see com.digi.xbee.api.packet.XBeePacket
         */
        public XBeePacket getFirstPacket(int timeout) {
                if (timeout > 0) {
                        XBeePacket xbeePacket = getFirstPacket(0);
                        // Wait for a timeout or until an XBee packet is read.
                        Long deadLine = System.currentTimeMillis() + timeout;
                        while (xbeePacket == null && deadLine > System.currentTimeMillis()) {
                                sleep(100);
                                xbeePacket = getFirstPacket(0);
                        }
                        return xbeePacket;
                } 
                synchronized (lock) {
                        if (!packetsList.isEmpty())
                                return packetsList.pop();
                }
                return null;
        }
        
        /**
         * Returns the first packet from the queue whose 64-bit source address 
         * matches the address of the provided remote XBee device.
         * 
         * <p>The methods waits up to the specified timeout if necessary for an 
         * XBee packet to become available. Null if the queue is empty or there is 
         * not any XBee packet sent by the provided remote XBee device.</p>
         * 
         * @param remoteXBeeDevice The remote XBee device containing the 64-bit 
         *                         address to look for in the list of packets.
         * @param timeout The time in milliseconds to wait for an XBee packet from 
         *                the specified remote XBee device to become available. 
         *                0 to return immediately.
         * 
         * @return The first XBee packet whose 64-bit address matches the address 
         *         of the provided remote XBee device. {@code null} if no packets 
         *         from the specified XBee device are found in the queue.
         * 
         * @see com.digi.xbee.api.RemoteXBeeDevice
         * @see com.digi.xbee.api.packet.XBeePacket
         */
        public XBeePacket getFirstPacketFrom(RemoteXBeeDevice remoteXBeeDevice, int timeout) {
                if (timeout > 0) {
                        XBeePacket xbeePacket = getFirstPacketFrom(remoteXBeeDevice, 0);
                        // Wait for a timeout or until an XBee packet from remoteXBeeDevice is read.
                        Long deadLine = System.currentTimeMillis() + timeout;
                        while (xbeePacket == null && deadLine > System.currentTimeMillis()) {
                                sleep(100);
                                xbeePacket = getFirstPacketFrom(remoteXBeeDevice, 0);
                        }
                        return xbeePacket;
                } else {
                        synchronized (lock) {
                                for (int i = 0; i < packetsList.size(); i++) {
                                        XBeePacket xbeePacket = packetsList.get(i);
                                        if (addressesMatch(xbeePacket, remoteXBeeDevice))
                                                return packetsList.remove(i);
                                }
                        }
                }
                return null;
        }
        
        /**
         * Returns the first data packet from the queue waiting up to the 
         * specified timeout if necessary for an XBee data packet to become 
         * available. {@code null} if the queue is empty or there is not any data 
         * packet inside.
         * 
         * @param timeout The time in milliseconds to wait for an XBee data packet 
         *                to become available. 0 to return immediately.
         * 
         * @return The first data packet from the queue, {@code null} if it is 
         *         empty or no data packets are contained in the queue.
         * 
         * @see com.digi.xbee.api.packet.XBeePacket
         */
        public XBeePacket getFirstDataPacket(int timeout) {
                if (timeout > 0) {
                        XBeePacket xbeePacket = getFirstDataPacket(0);
                        // Wait for a timeout or until a data XBee packet is read.
                        Long deadLine = System.currentTimeMillis() + timeout;
                        while (xbeePacket == null && deadLine > System.currentTimeMillis()) {
                                sleep(100);
                                xbeePacket = getFirstDataPacket(0);
                        }
                        return xbeePacket;
                } else {
                        synchronized (lock) {
                                for (int i = 0; i < packetsList.size(); i++) {
                                        XBeePacket xbeePacket = packetsList.get(i);
                                        if (isDataPacket(xbeePacket))
                                                return packetsList.remove(i);
                                }
                        }
                }
                return null;
        }
        
        /**
         * Returns the first data packet from the queue whose 64-bit source 
         * address matches the address of the provided remote XBee device.
         * 
         * <p>The methods waits up to the specified timeout if necessary for an 
         * XBee data packet to become available. {@code null} if the queue is 
         * empty or there is not any XBee data packet sent by the provided remote 
         * XBee device.</p>
         * 
         * @param remoteXBeeDevice The XBee device containing the 64-bit address 
         *                         to look for in the list of packets.
         * @param timeout The time in milliseconds to wait for an XBee data packet 
         *                from the specified remote XBee device to become 
         *                available. 0 to return immediately.
         * 
         * @return The first XBee data packet whose its 64-bit address matches the 
         *         address of the provided remote XBee device. {@code null} if no 
         *         data packets from the specified XBee device are found in the 
         *         queue.
         * 
         * @see com.digi.xbee.api.RemoteXBeeDevice
         * @see com.digi.xbee.api.packet.XBeePacket
         */
        public XBeePacket getFirstDataPacketFrom(RemoteXBeeDevice remoteXBeeDevice, int timeout) {
                if (timeout > 0) {
                        XBeePacket xbeePacket = getFirstDataPacketFrom(remoteXBeeDevice, 0);
                        // Wait for a timeout or until an XBee packet from remoteXBeeDevice is read.
                        Long deadLine = System.currentTimeMillis() + timeout;
                        while (xbeePacket == null && deadLine > System.currentTimeMillis()) {
                                sleep(100);
                                xbeePacket = getFirstDataPacketFrom(remoteXBeeDevice, 0);
                        }
                        return xbeePacket;
                } else {
                        synchronized (lock) {
                                for (int i = 0; i < packetsList.size(); i++) {
                                        XBeePacket xbeePacket = packetsList.get(i);
                                        if (isDataPacket(xbeePacket) && addressesMatch(xbeePacket, remoteXBeeDevice))
                                                return packetsList.remove(i);
                                }
                        }
                }
                return null;
        }
        
        /**
         * Returns the first explicit data packet from the queue waiting up to the 
         * specified timeout if necessary for an XBee explicit data packet to 
         * become available. {@code null} if the queue is empty or there is not 
         * any explicit data packet inside.
         * 
         * @param timeout The time in milliseconds to wait for an XBee explicit 
         *                data packet to become available. 0 to return immediately.
         * 
         * @return The first explicit data packet from the queue, {@code null} if 
         *         it is empty or no data packets are contained in the queue.
         * 
         * @see com.digi.xbee.api.packet.XBeePacket
         * @see com.digi.xbee.api.packet.common.ExplicitRxIndicatorPacket
         */
        public XBeePacket getFirstExplicitDataPacket(int timeout) {
                if (timeout > 0) {
                        XBeePacket xbeePacket = getFirstExplicitDataPacket(0);
                        // Wait for a timeout or until an explicit data XBee packet is read.
                        Long deadLine = System.currentTimeMillis() + timeout;
                        while (xbeePacket == null && deadLine > System.currentTimeMillis()) {
                                sleep(100);
                                xbeePacket = getFirstExplicitDataPacket(0);
                        }
                        return xbeePacket;
                } else {
                        synchronized (lock) {
                                for (int i = 0; i < packetsList.size(); i++) {
                                        XBeePacket xbeePacket = packetsList.get(i);
                                        if (isExplicitDataPacket(xbeePacket))
                                                return packetsList.remove(i);
                                }
                        }
                }
                return null;
        }
        
        /**
         * Returns the first explicit data packet from the queue whose 64-bit 
         * source address matches the address of the provided remote XBee device.
         * 
         * <p>The methods waits up to the specified timeout if necessary for an 
         * XBee explicit data packet to become available. {@code null} if the 
         * queue is empty or there is not any XBee explicit data packet sent by 
         * the provided remote XBee device.</p>
         * 
         * @param remoteXBeeDevice The XBee device containing the 64-bit address 
         *                         to look for in the list of packets.
         * @param timeout The time in milliseconds to wait for an XBee explicit 
         *                data packet from the specified remote XBee device to 
         *                become available. 0 to return immediately.
         * 
         * @return The first XBee explicit data packet whose its 64-bit address 
         *         matches the address of the provided remote XBee device. 
         *         {@code null} if no explicit data packets from the specified 
         *         XBee device are found in the queue.
         * 
         * @see com.digi.xbee.api.RemoteXBeeDevice
         * @see com.digi.xbee.api.packet.XBeePacket
         * @see com.digi.xbee.api.packet.common.ExplicitRxIndicatorPacket
         */
        public XBeePacket getFirstExplicitDataPacketFrom(RemoteXBeeDevice remoteXBeeDevice, int timeout) {
                if (timeout > 0) {
                        XBeePacket xbeePacket = getFirstExplicitDataPacketFrom(remoteXBeeDevice, 0);
                        // Wait for a timeout or until an XBee explicit data packet from remoteXBeeDevice is read.
                        Long deadLine = System.currentTimeMillis() + timeout;
                        while (xbeePacket == null && deadLine > System.currentTimeMillis()) {
                                sleep(100);
                                xbeePacket = getFirstExplicitDataPacketFrom(remoteXBeeDevice, 0);
                        }
                        return xbeePacket;
                } else {
                        synchronized (lock) {
                                for (int i = 0; i < packetsList.size(); i++) {
                                        XBeePacket xbeePacket = packetsList.get(i);
                                        if (isExplicitDataPacket(xbeePacket) && addressesMatch(xbeePacket, remoteXBeeDevice))
                                                return packetsList.remove(i);
                                }
                        }
                }
                return null;
        }
        
        /**
         * Returns the first IP data packet from the queue waiting up to the 
         * specified timeout if necessary for a IP data packet to 
         * become available. {@code null} if the queue is empty or there is not 
         * any IP data packet inside.
         * 
         * @param timeout The time in milliseconds to wait for a IP data 
         *                packet to become available. 0 to return immediately.
         * 
         * @return The first IP data packet from the queue, {@code null} if 
         *         it is empty or no IP packets are contained in the queue.
         * 
         * @see com.digi.xbee.api.packet.XBeePacket
         * @see com.digi.xbee.api.packet.ip.RXIPv4Packet
         * 
         * @since 1.2.0
         */
        public XBeePacket getFirstIPDataPacket(int timeout) {
                if (timeout > 0) {
                        XBeePacket xbeePacket = getFirstIPDataPacket(0);
                        // Wait for a timeout or until a IP data packet is read.
                        Long deadLine = System.currentTimeMillis() + timeout;
                        while (xbeePacket == null && deadLine > System.currentTimeMillis()) {
                                sleep(100);
                                xbeePacket = getFirstIPDataPacket(0);
                        }
                        return xbeePacket;
                } else {
                        synchronized (lock) {
                                for (int i = 0; i < packetsList.size(); i++) {
                                        XBeePacket xbeePacket = packetsList.get(i);
                                        if (isIPDataPacket(xbeePacket))
                                                return packetsList.remove(i);
                                }
                        }
                }
                return null;
        }
        
        /**
         * Returns the first IPv6 data packet from the queue waiting up to the 
         * specified timeout if necessary for a IPv6 data packet to 
         * become available. {@code null} if the queue is empty or there is not 
         * any IPv6 data packet inside.
         * 
         * @param timeout The time in milliseconds to wait for a IPv6 data 
         *                packet to become available. 0 to return immediately.
         * 
         * @return The first IPv6 data packet from the queue, {@code null} if 
         *         it is empty or no IPv6 packets are contained in the queue.
         * 
         * @see com.digi.xbee.api.packet.XBeePacket
         * @see com.digi.xbee.api.packet.thread.RXIPv6Packet
         * 
         * @since 1.2.1
         */
        public XBeePacket getFirstIPv6DataPacket(int timeout) {
                if (timeout > 0) {
                        XBeePacket xbeePacket = getFirstIPv6DataPacket(0);
                        // Wait for a timeout or until a IPv6 data packet is read.
                        Long deadLine = System.currentTimeMillis() + timeout;
                        while (xbeePacket == null && deadLine > System.currentTimeMillis()) {
                                sleep(100);
                                xbeePacket = getFirstIPv6DataPacket(0);
                        }
                        return xbeePacket;
                } else {
                        synchronized (lock) {
                                for (int i = 0; i < packetsList.size(); i++) {
                                        XBeePacket xbeePacket = packetsList.get(i);
                                        if (isIPv6DataPacket(xbeePacket))
                                                return packetsList.remove(i);
                                }
                        }
                }
                return null;
        }
        
        /**
         * Returns the first IP data packet from the queue whose IP address 
         * matches the provided address.
         * 
         * <p>The methods waits up to the specified timeout if necessary for a 
         * IP data packet to become available. {@code null} if the 
         * queue is empty or there is not any IP data packet sent by 
         * the provided IP address.</p>
         * 
         * @param ipAddress The IP address to look for in the list of packets.
         * @param timeout The time in milliseconds to wait for a IP data 
         *                packet from the specified IP address to become available.
         *                0 to return immediately.
         * 
         * @return The first IP packet whose IP address matches the provided 
         *         IP address. {@code null} if no IP data packets from the 
         *         specified IP address are found in the queue.
         * 
         * @see com.digi.xbee.api.packet.XBeePacket
         * @see com.digi.xbee.api.packet.ip.RXIPv4Packet
         * @see java.net.Inet4Address
         * 
         * @since 1.2.0
         */
        public XBeePacket getFirstIPDataPacketFrom(Inet4Address ipAddress, int timeout) {
                if (timeout > 0) {
                        XBeePacket xbeePacket = getFirstIPDataPacketFrom(ipAddress, 0);
                        // Wait for a timeout or until a IP data packet with the provided IP address is read.
                        Long deadLine = System.currentTimeMillis() + timeout;
                        while (xbeePacket == null && deadLine > System.currentTimeMillis()) {
                                sleep(100);
                                xbeePacket = getFirstIPDataPacketFrom(ipAddress, 0);
                        }
                        return xbeePacket;
                } else {
                        synchronized (lock) {
                                for (int i = 0; i < packetsList.size(); i++) {
                                        XBeePacket xbeePacket = packetsList.get(i);
                                        if (isIPDataPacket(xbeePacket) && ipAddressesMatch(xbeePacket, ipAddress))
                                                return packetsList.remove(i);
                                }
                        }
                }
                return null;
        }
        
        /**
         * Returns the first IPv6 data packet from the queue whose IPv6 address 
         * matches the provided address.
         * 
         * <p>The methods waits up to the specified timeout if necessary for a 
         * IPv6 data packet to become available. {@code null} if the 
         * queue is empty or there is not any IPv6 data packet sent by 
         * the provided IPv6 address.</p>
         * 
         * @param ipv6Address The IPv6 address to look for in the list of packets.
         * @param timeout The time in milliseconds to wait for a IPv6 data 
         *                packet from the specified IPv6 address to become available.
         *                0 to return immediately.
         * 
         * @return The first IPv6 packet whose IPv6 address matches the provided 
         *         IPv6 address. {@code null} if no IPv6 data packets from the 
         *         specified IPv6 address are found in the queue.
         * 
         * @see com.digi.xbee.api.packet.XBeePacket
         * @see com.digi.xbee.api.packet.thread.RXIPv6Packet
         * @see java.net.Inet6Address
         * 
         * @since 1.2.1
         */
        public XBeePacket getFirstIPv6DataPacketFrom(Inet6Address ipv6Address, int timeout) {
                if (timeout > 0) {
                        XBeePacket xbeePacket = getFirstIPv6DataPacketFrom(ipv6Address, 0);
                        // Wait for a timeout or until a IPv6 data packet with the provided IPv6 address is read.
                        Long deadLine = System.currentTimeMillis() + timeout;
                        while (xbeePacket == null && deadLine > System.currentTimeMillis()) {
                                sleep(100);
                                xbeePacket = getFirstIPv6DataPacketFrom(ipv6Address, 0);
                        }
                        return xbeePacket;
                } else {
                        synchronized (lock) {
                                for (int i = 0; i < packetsList.size(); i++) {
                                        XBeePacket xbeePacket = packetsList.get(i);
                                        if (isIPv6DataPacket(xbeePacket) && ipv6AddressesMatch(xbeePacket, ipv6Address))
                                                return packetsList.remove(i);
                                }
                        }
                }
                return null;
        }
        
        /**
         * Returns whether or not the source address of the provided XBee packet 
         * matches the address of the given remote XBee device.
         * 
         * @param xbeePacket The XBee packet to compare its address with the 
         *                   remote XBee device.
         * @param remoteXBeeDevice The remote XBee device to compare its address 
         *                         with the XBee packet.
         * 
         * @return {@code true} if the source address of the provided packet (if 
         *         it has) matches the address of the remote XBee device.
         * 
         * @see com.digi.xbee.api.RemoteXBeeDevice
         * @see com.digi.xbee.api.packet.XBeePacket
         */
        private boolean addressesMatch(XBeePacket xbeePacket, RemoteXBeeDevice remoteXBeeDevice) {
                if (!(xbeePacket instanceof XBeeAPIPacket))
                        return false;
                APIFrameType packetType = ((XBeeAPIPacket)xbeePacket).getFrameType();
                switch (packetType) {
                case RECEIVE_PACKET:
                        if (remoteXBeeDevice.get64BitAddress() != null && ((ReceivePacket)xbeePacket).get64bitSourceAddress().equals(remoteXBeeDevice.get64BitAddress()))
                                return true;
                        if (remoteXBeeDevice.get16BitAddress() != null && ((ReceivePacket)xbeePacket).get16bitSourceAddress().equals(remoteXBeeDevice.get16BitAddress()))
                                return true;
                        break;
                case REMOTE_AT_COMMAND_RESPONSE:
                        if (remoteXBeeDevice.get64BitAddress() != null && ((RemoteATCommandResponsePacket)xbeePacket).get64bitSourceAddress().equals(remoteXBeeDevice.get64BitAddress()))
                                return true;
                        if (remoteXBeeDevice.get16BitAddress() != null && ((RemoteATCommandResponsePacket)xbeePacket).get16bitSourceAddress().equals(remoteXBeeDevice.get16BitAddress()))
                                return true;
                        break;
                case RX_16:
                        if (((RX16Packet)xbeePacket).get16bitSourceAddress().equals(remoteXBeeDevice.get16BitAddress()))
                                return true;
                        break;
                case RX_64:
                        if (((RX64Packet)xbeePacket).get64bitSourceAddress().equals(remoteXBeeDevice.get64BitAddress()))
                                return true;
                        break;
                case RX_IO_16:
                        if (((RX16IOPacket)xbeePacket).get16bitSourceAddress().equals(remoteXBeeDevice.get16BitAddress()))
                                return true;
                        break;
                case RX_IO_64:
                        if (((RX64IOPacket)xbeePacket).get64bitSourceAddress().equals(remoteXBeeDevice.get64BitAddress()))
                                return true;
                        break;
                case EXPLICIT_RX_INDICATOR:
                        if (((ExplicitRxIndicatorPacket)xbeePacket).get64BitSourceAddress().equals(remoteXBeeDevice.get64BitAddress()))
                                return true;
                        break;
                default:
                        return false;
                }
                return false;
        }
        
        /**
         * Returns whether or not the IP address of the XBee packet matches the 
         * provided one. 
         * 
         * @param xbeePacket The XBee packet to compare its IP address with the 
         *                   provided one.
         * @param ipAddress The IP address to be compared with the XBee packet's one.
         * 
         * @return {@code true} if the IP address of the XBee packet (if it has) 
         *         matches the provided one. {@code false} otherwise.
         * 
         * @see com.digi.xbee.api.packet.XBeePacket
         * @see java.net.Inet4Address
         * 
         * @since 1.2.0
         */
        private boolean ipAddressesMatch(XBeePacket xbeePacket, Inet4Address ipAddress) {
                if (xbeePacket == null || ipAddress == null 
                                || !(xbeePacket instanceof XBeeAPIPacket))
                        return false;
                APIFrameType packetType = ((XBeeAPIPacket)xbeePacket).getFrameType();
                switch (packetType) {
                case RX_IPV4:
                        if (((RXIPv4Packet)xbeePacket).getSourceAddress().equals(ipAddress))
                                return true;
                        break;
                default:
                        return false;
                }
                return false;
        }
        
        /**
         * Returns whether the IPv6 address of the XBee packet matches the 
         * provided one or not. 
         * 
         * @param xbeePacket The XBee packet to compare its IPv6 address with the 
         *                   provided one.
         * @param ipv6Address The IPv6 address to be compared with the XBee 
         *                    packet's one.
         * 
         * @return {@code true} if the Iv6P address of the XBee packet (if it has) 
         *         matches the provided one. {@code false} otherwise.
         * 
         * @see com.digi.xbee.api.packet.XBeePacket
         * @see java.net.Inet6Address
         * 
         * @since 1.2.1
         */
        private boolean ipv6AddressesMatch(XBeePacket xbeePacket, Inet6Address ipv6Address) {
                if (xbeePacket == null || ipv6Address == null 
                                || !(xbeePacket instanceof XBeeAPIPacket))
                        return false;
                APIFrameType packetType = ((XBeeAPIPacket)xbeePacket).getFrameType();
                switch (packetType) {
                case RX_IPV6:
                        if (((RXIPv6Packet)xbeePacket).getSourceAddress().equals(ipv6Address))
                                return true;
                        break;
                default:
                        return false;
                }
                return false;
        }
        
        /**
         * Returns whether or not the given XBee packet is a data packet.
         * 
         * @param xbeePacket The XBee packet to check if is data packet.
         * 
         * @return {@code true} if the XBee packet is a data packet, {@code false} 
         *         otherwise.
         * 
         * @see com.digi.xbee.api.packet.XBeePacket
         */
        private boolean isDataPacket(XBeePacket xbeePacket) {
                if (!(xbeePacket instanceof XBeeAPIPacket))
                        return false;
                APIFrameType packetType = ((XBeeAPIPacket)xbeePacket).getFrameType();
                switch (packetType) {
                        case RECEIVE_PACKET:
                        case RX_16:
                        case RX_64:
                                return true;
                        default:
                                return false;
                }
        }
        
        /**
         * Returns whether or not the given XBee packet is an explicit data packet.
         * 
         * @param xbeePacket The XBee packet to check if is an explicit data packet.
         * 
         * @return {@code true} if the XBee packet is an explicit data packet, 
         *         {@code false} otherwise.
         * 
         * @see com.digi.xbee.api.packet.XBeePacket
         * @see com.digi.xbee.api.packet.common.ExplicitRxIndicatorPacket
         */
        private boolean isExplicitDataPacket(XBeePacket xbeePacket) {
                if (!(xbeePacket instanceof XBeeAPIPacket))
                        return false;
                APIFrameType packetType = ((XBeeAPIPacket)xbeePacket).getFrameType();
                return packetType == APIFrameType.EXPLICIT_RX_INDICATOR;
        }
        
        /**
         * Returns whether or not the given XBee packet is a IP data packet.
         * 
         * @param xbeePacket The XBee packet to check if is a IP data packet.
         * 
         * @return {@code true} if the XBee packet is a IP data packet, 
         *         {@code false} otherwise.
         * 
         * @see com.digi.xbee.api.packet.XBeePacket
         * @see com.digi.xbee.api.packet.ip.RXIPv4Packet
         * 
         * @since 1.2.0
         */
        private boolean isIPDataPacket(XBeePacket xbeePacket) {
                if (!(xbeePacket instanceof XBeeAPIPacket))
                        return false;
                APIFrameType packetType = ((XBeeAPIPacket)xbeePacket).getFrameType();
                return packetType == APIFrameType.RX_IPV4;
        }
        
        /**
         * Returns whether the given XBee packet is an IPv6 data packet or not.
         * 
         * @param xbeePacket The XBee packet to check if is an IPv6 data packet.
         * 
         * @return {@code true} if the XBee packet is an IPv6 data packet, 
         *         {@code false} otherwise.
         * 
         * @see com.digi.xbee.api.packet.XBeePacket
         * @see com.digi.xbee.api.packet.thread.RXIPv6Packet
         * 
         * @since 1.2.1
         */
        private boolean isIPv6DataPacket(XBeePacket xbeePacket) {
                if (!(xbeePacket instanceof XBeeAPIPacket))
                        return false;
                APIFrameType packetType = ((XBeeAPIPacket)xbeePacket).getFrameType();
                return packetType == APIFrameType.RX_IPV6;
        }
        
        /**
         * Sleeps the thread for the given number of milliseconds.
         * 
         * @param milliseconds The number of milliseconds that the thread should 
         *        be sleeping.
         */
        private void sleep(int milliseconds) {
                try {
                        Thread.sleep(milliseconds);
                } catch (InterruptedException e) { }
        }
        
        /**
         * Returns the maximum size of the XBee packets queue.
         * 
         * @return The maximum size of the XBee packets queue.
         */
        public int getMaxSize() {
                return maxLength;
        }
        
        /**
         * Returns the current size of the XBee packets queue.
         * 
         * @return The current size of the XBee packets queue.
         */
        public int getCurrentSize() {
                synchronized (lock) {
                        return packetsList.size();
                }
        }
}