/**
 * Copyright (c) 2014 Digi International Inc.,
 * All rights not expressly granted are reserved.
 *
 * 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/.
 *
 * Digi International Inc. 11001 Bren Road East, Minnetonka, MN 55343
 * =======================================================================
 */
package com.digi.xbee.api.models;

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.ReceivePacket;
import com.digi.xbee.api.packet.common.RemoteATCommandResponsePacket;
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;

/**
 * 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;
        
        /**
         * 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) {
                if (packetsList.size() == maxLength)
                        packetsList.removeFirst();
                packetsList.add(xbeePacket);
        }
        
        /**
         * Clears the list of packets.
         */
        public void clearQueue() {
                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;
                } else 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 {
                        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 {
                        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 {
                        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 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;
                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;
                }
        }
        
        /**
         * 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() {
                return packetsList.size();
        }
}