/*
Copyright (c) 2013, 2014 Paolo Patierno

All rights reserved. This program and the accompanying materials
are made available under the terms of the Eclipse Public License v1.0
and Eclipse Distribution License v1.0 which accompany this distribution. 

The Eclipse Public License is available at 
   http://www.eclipse.org/legal/epl-v10.html
and the Eclipse Distribution License is available at 
   http://www.eclipse.org/org/documents/edl-v10.php.

Contributors:
   Paolo Patierno - initial API and implementation and/or initial documentation
*/

using System;
// if NOT .Net Micro Framework
#if (!MF_FRAMEWORK_VERSION_V4_2 && !MF_FRAMEWORK_VERSION_V4_3)
using System.Collections.Generic;
#endif
using System.Collections;
using System.Text;
using uPLibrary.Networking.M2Mqtt.Exceptions;

namespace uPLibrary.Networking.M2Mqtt.Messages
{
    /// <summary>
    /// Class for UNSUBSCRIBE message from client to broker
    /// </summary>
    public class MqttMsgUnsubscribe : MqttMsgBase
    {
        #region Properties...

        /// <summary>
        /// List of topics to unsubscribe
        /// </summary>
        public string[] Topics
        {
            get { return this.topics; }
            set { this.topics = value; }
        }

        #endregion

        // topics to unsubscribe
        string[] topics;
        
        /// <summary>
        /// Constructor
        /// </summary>
        public MqttMsgUnsubscribe()
        {
            this.type = MQTT_MSG_UNSUBSCRIBE_TYPE;
        }
        
        /// <summary>
        /// Constructor
        /// </summary>
        /// <param name="topics">List of topics to unsubscribe</param>
        public MqttMsgUnsubscribe(string[] topics)
        {
            this.type = MQTT_MSG_UNSUBSCRIBE_TYPE;

            this.topics = topics;

            // UNSUBSCRIBE message uses QoS Level 1 (not "officially" in 3.1.1)
            this.qosLevel = QOS_LEVEL_AT_LEAST_ONCE;
        }

        /// <summary>
        /// Parse bytes for a UNSUBSCRIBE message
        /// </summary>
        /// <param name="fixedHeaderFirstByte">First fixed header byte</param>
        /// <param name="protocolVersion">Protocol Version</param>
        /// <param name="channel">Channel connected to the broker</param>
        /// <returns>UNSUBSCRIBE message instance</returns>
        public static MqttMsgUnsubscribe Parse(byte fixedHeaderFirstByte, byte protocolVersion, IMqttNetworkChannel channel)
        {
            byte[] buffer;
            int index = 0;
            byte[] topicUtf8;
            int topicUtf8Length;
            MqttMsgUnsubscribe msg = new MqttMsgUnsubscribe();

            if (protocolVersion == MqttMsgConnect.PROTOCOL_VERSION_V3_1_1)
            {
                // [v3.1.1] check flag bits
                if ((fixedHeaderFirstByte & MSG_FLAG_BITS_MASK) != MQTT_MSG_UNSUBSCRIBE_FLAG_BITS)
                    throw new MqttClientException(MqttClientErrorCode.InvalidFlagBits);
            }

            // get remaining length and allocate buffer
            int remainingLength = MqttMsgBase.decodeRemainingLength(channel);
            buffer = new byte[remainingLength];

            // read bytes from socket...
            int received = channel.Receive(buffer);

            if (protocolVersion == MqttMsgConnect.PROTOCOL_VERSION_V3_1)
            {
                // only 3.1.0

                // read QoS level from fixed header
                msg.qosLevel = (byte)((fixedHeaderFirstByte & QOS_LEVEL_MASK) >> QOS_LEVEL_OFFSET);
                // read DUP flag from fixed header
                msg.dupFlag = (((fixedHeaderFirstByte & DUP_FLAG_MASK) >> DUP_FLAG_OFFSET) == 0x01);
                // retain flag not used
                msg.retain = false;
            }

            // message id
            msg.messageId = (ushort)((buffer[index++] << 8) & 0xFF00);
            msg.messageId |= (buffer[index++]);

            // payload contains topics
            // NOTE : before, I don't know how many topics will be in the payload (so use List)

// if .Net Micro Framework
#if (MF_FRAMEWORK_VERSION_V4_2 || MF_FRAMEWORK_VERSION_V4_3)
            IList tmpTopics = new ArrayList();
// else other frameworks (.Net, .Net Compact, Mono, Windows Phone) 
#else
            IList<String> tmpTopics = new List<String>();
#endif
            do
            {
                // topic name
                topicUtf8Length = ((buffer[index++] << 8) & 0xFF00);
                topicUtf8Length |= buffer[index++];
                topicUtf8 = new byte[topicUtf8Length];
                Array.Copy(buffer, index, topicUtf8, 0, topicUtf8Length);
                index += topicUtf8Length;
                tmpTopics.Add(new String(Encoding.UTF8.GetChars(topicUtf8)));
            } while (index < remainingLength);

            // copy from list to array
            msg.topics = new string[tmpTopics.Count];
            for (int i = 0; i < tmpTopics.Count; i++)
            {
                msg.topics[i] = (string)tmpTopics[i];
            }

            return msg;
        }

        public override byte[] GetBytes(byte protocolVersion)
        {
            int fixedHeaderSize = 0;
            int varHeaderSize = 0;
            int payloadSize = 0;
            int remainingLength = 0;
            byte[] buffer;
            int index = 0;

            // topics list empty
            if ((this.topics == null) || (this.topics.Length == 0))
                throw new MqttClientException(MqttClientErrorCode.TopicsEmpty);

            // message identifier
            varHeaderSize += MESSAGE_ID_SIZE;

            int topicIdx = 0;
            byte[][] topicsUtf8 = new byte[this.topics.Length][];

            for (topicIdx = 0; topicIdx < this.topics.Length; topicIdx++)
            {
                // check topic length
                if ((this.topics[topicIdx].Length < MIN_TOPIC_LENGTH) || (this.topics[topicIdx].Length > MAX_TOPIC_LENGTH))
                    throw new MqttClientException(MqttClientErrorCode.TopicLength);

                topicsUtf8[topicIdx] = Encoding.UTF8.GetBytes(this.topics[topicIdx]);
                payloadSize += 2; // topic size (MSB, LSB)
                payloadSize += topicsUtf8[topicIdx].Length;
            }

            remainingLength += (varHeaderSize + payloadSize);

            // first byte of fixed header
            fixedHeaderSize = 1;

            int temp = remainingLength;
            // increase fixed header size based on remaining length
            // (each remaining length byte can encode until 128)
            do
            {
                fixedHeaderSize++;
                temp = temp / 128;
            } while (temp > 0);

            // allocate buffer for message
            buffer = new byte[fixedHeaderSize + varHeaderSize + payloadSize];

            // first fixed header byte
            if (protocolVersion == MqttMsgConnect.PROTOCOL_VERSION_V3_1_1)
                buffer[index++] = (MQTT_MSG_UNSUBSCRIBE_TYPE << MSG_TYPE_OFFSET) | MQTT_MSG_UNSUBSCRIBE_FLAG_BITS; // [v.3.1.1]
            else
            {
                buffer[index] = (byte)((MQTT_MSG_UNSUBSCRIBE_TYPE << MSG_TYPE_OFFSET) |
                                   (this.qosLevel << QOS_LEVEL_OFFSET));
                buffer[index] |= this.dupFlag ? (byte)(1 << DUP_FLAG_OFFSET) : (byte)0x00;
                index++;
            }
            
            // encode remaining length
            index = this.encodeRemainingLength(remainingLength, buffer, index);

            // check message identifier assigned
            if (this.messageId == 0)
                throw new MqttClientException(MqttClientErrorCode.WrongMessageId);
            buffer[index++] = (byte)((messageId >> 8) & 0x00FF); // MSB
            buffer[index++] = (byte)(messageId & 0x00FF); // LSB 

            topicIdx = 0;
            for (topicIdx = 0; topicIdx < this.topics.Length; topicIdx++)
            {
                // topic name
                buffer[index++] = (byte)((topicsUtf8[topicIdx].Length >> 8) & 0x00FF); // MSB
                buffer[index++] = (byte)(topicsUtf8[topicIdx].Length & 0x00FF); // LSB
                Array.Copy(topicsUtf8[topicIdx], 0, buffer, index, topicsUtf8[topicIdx].Length);
                index += topicsUtf8[topicIdx].Length;
            }
            
            return buffer;
        }

        public override string ToString()
        {
#if TRACE
            return this.GetTraceString(
                "UNSUBSCRIBE",
                new object[] { "messageId", "topics" },
                new object[] { this.messageId, this.topics });
#else
            return base.ToString();
#endif
        }
    }
}