/**
 ******************************************************************************
 *
 * @file       uavtalk.cpp
 * @author     The OpenPilot Team, http://www.openpilot.org Copyright (C) 2010.
 * @addtogroup GCSPlugins GCS Plugins
 * @{
 * @addtogroup UAVTalkPlugin UAVTalk Plugin
 * @{
 * @brief The UAVTalk protocol plugin
 *****************************************************************************/
/*
 * This program is free software; you can redistribute it and/or modify 
 * it under the terms of the GNU General Public License as published by 
 * the Free Software Foundation; either version 3 of the License, or 
 * (at your option) any later version.
 * 
 * This program 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 General Public License 
 * for more details.
 * 
 * You should have received a copy of the GNU General Public License along 
 * with this program; if not, write to the Free Software Foundation, Inc., 
 * 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
 */
#include "uavtalk.h"
#include <QtEndian>
#include <QDebug>

#define SYNC_VAL 0x3C

const quint8 UAVTalk::crc_table[256] = {
    0x00, 0x07, 0x0e, 0x09, 0x1c, 0x1b, 0x12, 0x15, 0x38, 0x3f, 0x36, 0x31, 0x24, 0x23, 0x2a, 0x2d,
    0x70, 0x77, 0x7e, 0x79, 0x6c, 0x6b, 0x62, 0x65, 0x48, 0x4f, 0x46, 0x41, 0x54, 0x53, 0x5a, 0x5d,
    0xe0, 0xe7, 0xee, 0xe9, 0xfc, 0xfb, 0xf2, 0xf5, 0xd8, 0xdf, 0xd6, 0xd1, 0xc4, 0xc3, 0xca, 0xcd,
    0x90, 0x97, 0x9e, 0x99, 0x8c, 0x8b, 0x82, 0x85, 0xa8, 0xaf, 0xa6, 0xa1, 0xb4, 0xb3, 0xba, 0xbd,
    0xc7, 0xc0, 0xc9, 0xce, 0xdb, 0xdc, 0xd5, 0xd2, 0xff, 0xf8, 0xf1, 0xf6, 0xe3, 0xe4, 0xed, 0xea,
    0xb7, 0xb0, 0xb9, 0xbe, 0xab, 0xac, 0xa5, 0xa2, 0x8f, 0x88, 0x81, 0x86, 0x93, 0x94, 0x9d, 0x9a,
    0x27, 0x20, 0x29, 0x2e, 0x3b, 0x3c, 0x35, 0x32, 0x1f, 0x18, 0x11, 0x16, 0x03, 0x04, 0x0d, 0x0a,
    0x57, 0x50, 0x59, 0x5e, 0x4b, 0x4c, 0x45, 0x42, 0x6f, 0x68, 0x61, 0x66, 0x73, 0x74, 0x7d, 0x7a,
    0x89, 0x8e, 0x87, 0x80, 0x95, 0x92, 0x9b, 0x9c, 0xb1, 0xb6, 0xbf, 0xb8, 0xad, 0xaa, 0xa3, 0xa4,
    0xf9, 0xfe, 0xf7, 0xf0, 0xe5, 0xe2, 0xeb, 0xec, 0xc1, 0xc6, 0xcf, 0xc8, 0xdd, 0xda, 0xd3, 0xd4,
    0x69, 0x6e, 0x67, 0x60, 0x75, 0x72, 0x7b, 0x7c, 0x51, 0x56, 0x5f, 0x58, 0x4d, 0x4a, 0x43, 0x44,
    0x19, 0x1e, 0x17, 0x10, 0x05, 0x02, 0x0b, 0x0c, 0x21, 0x26, 0x2f, 0x28, 0x3d, 0x3a, 0x33, 0x34,
    0x4e, 0x49, 0x40, 0x47, 0x52, 0x55, 0x5c, 0x5b, 0x76, 0x71, 0x78, 0x7f, 0x6a, 0x6d, 0x64, 0x63,
    0x3e, 0x39, 0x30, 0x37, 0x22, 0x25, 0x2c, 0x2b, 0x06, 0x01, 0x08, 0x0f, 0x1a, 0x1d, 0x14, 0x13,
    0xae, 0xa9, 0xa0, 0xa7, 0xb2, 0xb5, 0xbc, 0xbb, 0x96, 0x91, 0x98, 0x9f, 0x8a, 0x8d, 0x84, 0x83,
    0xde, 0xd9, 0xd0, 0xd7, 0xc2, 0xc5, 0xcc, 0xcb, 0xe6, 0xe1, 0xe8, 0xef, 0xfa, 0xfd, 0xf4, 0xf3
};


/**
 * Constructor
 */
UAVTalk::UAVTalk(QIODevice* iodev, UAVObjectManager* objMngr)
{
    io = iodev;

    this->objMngr = objMngr;

    rxState = STATE_SYNC;
    rxPacketLength = 0;

    mutex = new QMutex(QMutex::Recursive);

    respObj = NULL;

    memset(&stats, 0, sizeof(ComStats));

    connect(io, SIGNAL(readyRead()), this, SLOT(processInputStream()));
}

UAVTalk::~UAVTalk()
{
    // According to Qt, it is not necessary to disconnect upon
    // object deletion.
    //disconnect(io, SIGNAL(readyRead()), this, SLOT(processInputStream()));
}


/**
 * Reset the statistics counters
 */
void UAVTalk::resetStats()
{
    QMutexLocker locker(mutex);
    memset(&stats, 0, sizeof(ComStats));
}

/**
 * Get the statistics counters
 */
UAVTalk::ComStats UAVTalk::getStats()
{
    QMutexLocker locker(mutex);
    return stats;
}

/**
 * Called each time there are data in the input buffer
 */
void UAVTalk::processInputStream()
{
    quint8 tmp;

    while (io->bytesAvailable() > 0)
    {
        io->read((char*)&tmp, 1);
        processInputByte(tmp);
    }
}

/**
 * Request an update for the specified object, on success the object data would have been
 * updated by the GCS.
 * \param[in] obj Object to update
 * \param[in] allInstances If set true then all instances will be updated
 * \return Success (true), Failure (false)
 */
bool UAVTalk::sendObjectRequest(UAVObject* obj, bool allInstances)
{
    QMutexLocker locker(mutex);
    return objectTransaction(obj, TYPE_OBJ_REQ, allInstances);
}

/**
 * Send the specified object through the telemetry link.
 * \param[in] obj Object to send
 * \param[in] acked Selects if an ack is required
 * \param[in] allInstances If set true then all instances will be updated
 * \return Success (true), Failure (false)
 */
bool UAVTalk::sendObject(UAVObject* obj, bool acked, bool allInstances)
{
    QMutexLocker locker(mutex);
    if (acked)
    {
        return objectTransaction(obj, TYPE_OBJ_ACK, allInstances);
    }
    else
    {
        return objectTransaction(obj, TYPE_OBJ, allInstances);
    }
}

/**
 * Cancel a pending transaction
 */
void UAVTalk::cancelTransaction()
{
    QMutexLocker locker(mutex);
    respObj = NULL;
}

/**
 * Execute the requested transaction on an object.
 * \param[in] obj Object
 * \param[in] type Transaction type
 * 			  TYPE_OBJ: send object,
 * 			  TYPE_OBJ_REQ: request object update
 * 			  TYPE_OBJ_ACK: send object with an ack
 * \param[in] allInstances If set true then all instances will be updated
 * \return Success (true), Failure (false)
 */
bool UAVTalk::objectTransaction(UAVObject* obj, quint8 type, bool allInstances)
{
    // Send object depending on if a response is needed
    if (type == TYPE_OBJ_ACK || type == TYPE_OBJ_REQ)
    {
        if ( transmitObject(obj, type, allInstances) )
        {
            respObj = obj;
            respAllInstances = allInstances;    
            return true;
        }
        else
        {
            return false;
        }
    }
    else if (type == TYPE_OBJ)
    {
        return transmitObject(obj, TYPE_OBJ, allInstances);
    }
    else
    {
        return false;
    }
}

/**
 * Process an byte from the telemetry stream.
 * \param[in] rxbyte Received byte
 * \return Success (true), Failure (false)
 */
bool UAVTalk::processInputByte(quint8 rxbyte)
{
    // Update stats
    stats.rxBytes++;

    rxPacketLength++;   // update packet byte count

    // Receive state machine
    switch (rxState)
    {
        case STATE_SYNC:

            if (rxbyte != SYNC_VAL)
                break;

            // Initialize and update CRC
            rxCS = updateCRC(0, rxbyte);

            rxPacketLength = 1;

            rxState = STATE_TYPE;
            break;

        case STATE_TYPE:

            // Update CRC
            rxCS = updateCRC(rxCS, rxbyte);

            if ((rxbyte & TYPE_MASK) != TYPE_VER)
            {
                rxState = STATE_SYNC;
                break;
            }

            rxType = rxbyte;

            packetSize = 0;

            rxState = STATE_SIZE;
            rxCount = 0;
            break;

        case STATE_SIZE:

            // Update CRC
            rxCS = updateCRC(rxCS, rxbyte);

            if (rxCount == 0)
            {
                packetSize += rxbyte;
                rxCount++;
                break;
            }

            packetSize += (quint32)rxbyte << 8;

            if (packetSize < MIN_HEADER_LENGTH || packetSize > MAX_HEADER_LENGTH + MAX_PAYLOAD_LENGTH)
            {   // incorrect packet size
                rxState = STATE_SYNC;
                break;
            }

            rxCount = 0;
            rxState = STATE_OBJID;
            break;

        case STATE_OBJID:

            // Update CRC
            rxCS = updateCRC(rxCS, rxbyte);

            rxTmpBuffer[rxCount++] = rxbyte;
            if (rxCount < 4)
                break;

            // Search for object, if not found reset state machine
            rxObjId = (qint32)qFromLittleEndian<quint32>(rxTmpBuffer);
            {
                UAVObject *rxObj = objMngr->getObject(rxObjId);
                if (rxObj == NULL && rxType != TYPE_NACK)
                {
                    stats.rxErrors++;
                    rxState = STATE_SYNC;
                    break;
                }

                // Determine data length
                if (rxType == TYPE_OBJ_REQ || rxType == TYPE_ACK || rxType == TYPE_NACK)
                    rxLength = 0;
                else
                    rxLength = rxObj->getNumBytes();

                // Check length and determine next state
                if (rxLength >= MAX_PAYLOAD_LENGTH)
                {
                    stats.rxErrors++;
                    rxState = STATE_SYNC;
                    break;
                }

                // Check the lengths match
                if ((rxPacketLength + rxLength) != packetSize)
                {   // packet error - mismatched packet size
                    stats.rxErrors++;
                    rxState = STATE_SYNC;
                    break;
                }

                // Check if this is a single instance object (i.e. if the instance ID field is coming next)
                if (rxType == TYPE_NACK)
                {
                   // If this is a NACK, just skip to checksum
                   rxState   = STATE_CS;
                   rxInstId = 0;
                   rxCount = 0;
                }
                else if (rxObj->isSingleInstance())
                {
                    // If there is a payload get it, otherwise receive checksum
                    if (rxLength > 0)
                        rxState = STATE_DATA;
                    else
                        rxState = STATE_CS;
                    rxInstId = 0;
                    rxCount = 0;
                }
                else
                {
                    rxState = STATE_INSTID;
                    rxCount = 0;
                }
            }

            break;

        case STATE_INSTID:

            // Update CRC
            rxCS = updateCRC(rxCS, rxbyte);

            rxTmpBuffer[rxCount++] = rxbyte;
            if (rxCount < 2)
                break;

            rxInstId = (qint16)qFromLittleEndian<quint16>(rxTmpBuffer);

            rxCount = 0;

            // If there is a payload get it, otherwise receive checksum
            if (rxLength > 0)
                rxState = STATE_DATA;
            else
                rxState = STATE_CS;

            break;

        case STATE_DATA:

            // Update CRC
            rxCS = updateCRC(rxCS, rxbyte);

            rxBuffer[rxCount++] = rxbyte;
            if (rxCount < rxLength)
                break;

            rxState = STATE_CS;
            rxCount = 0;
            break;

        case STATE_CS:

            // The CRC byte
            rxCSPacket = rxbyte;

            if (rxCS != rxCSPacket)
            {   // packet error - faulty CRC
                stats.rxErrors++;
                rxState = STATE_SYNC;
                break;
            }

            if (rxPacketLength != packetSize + 1)
            {   // packet error - mismatched packet size
                stats.rxErrors++;
                rxState = STATE_SYNC;
                break;
            }

            mutex->lock();
                receiveObject(rxType, rxObjId, rxInstId, rxBuffer, rxLength);
                stats.rxObjectBytes += rxLength;
                stats.rxObjects++;
            mutex->unlock();

            rxState = STATE_SYNC;
            break;

        default:
            rxState = STATE_SYNC;
            stats.rxErrors++;
    }

    // Done
    return true;
}

/**
 * Receive an object. This function process objects received through the telemetry stream.
 * \param[in] type Type of received message (TYPE_OBJ, TYPE_OBJ_REQ, TYPE_OBJ_ACK, TYPE_ACK, TYPE_NACK)
 * \param[in] obj Handle of the received object
 * \param[in] instId The instance ID of UAVOBJ_ALL_INSTANCES for all instances.
 * \param[in] data Data buffer
 * \param[in] length Buffer length
 * \return Success (true), Failure (false)
 */
bool UAVTalk::receiveObject(quint8 type, quint32 objId, quint16 instId, quint8* data, qint32 length)
{
    Q_UNUSED(length);

    UAVObject* obj = NULL;
    bool error = false;
    bool allInstances =  (instId == ALL_INSTANCES);

    // Process message type
    switch (type) {
    case TYPE_OBJ:
        // All instances, not allowed for OBJ messages
        if (!allInstances)
        {
            // Get object and update its data
            obj = updateObject(objId, instId, data);
            // Check if an ack is pending
            if ( obj != NULL )
            {
                updateAck(obj);
            }
            else
            {
                error = true;
            }
        }
        else
        {
            error = true;
        }
        break;
    case TYPE_OBJ_ACK:
        // All instances, not allowed for OBJ_ACK messages
        if (!allInstances)
        {
            // Get object and update its data
            obj = updateObject(objId, instId, data);
            // Transmit ACK
            if ( obj != NULL )
            {
               transmitObject(obj, TYPE_ACK, false);
            }
            else
            {
                error = true;
            }
        }
        else
        {
            error = true;
        }
        break;
    case TYPE_OBJ_REQ:
        // Get object, if all instances are requested get instance 0 of the object
        if (allInstances)
        {
            obj = objMngr->getObject(objId);
        }
        else
        {
            obj = objMngr->getObject(objId, instId);
        }
        // If object was found transmit it
        if (obj != NULL)
        {
            transmitObject(obj, TYPE_OBJ, allInstances);
        }
        else
        {
            // Object was not found, transmit a NACK with the
            // objId which was not found.
            transmitNack(objId);
            error = true;
        }
        break;
    case TYPE_NACK:
        // All instances, not allowed for NACK messages
        if (!allInstances)
        {
            // Get object
            obj = objMngr->getObject(objId, instId);
            // Check if object exists:
            if (obj != NULL)
            {
                updateNack(obj);
            }
            else
            {
             error = true;
            }
        }
        break;
    case TYPE_ACK:
        // All instances, not allowed for ACK messages
        if (!allInstances)
        {
            // Get object
            obj = objMngr->getObject(objId, instId);
            // Check if an ack is pending
            if (obj != NULL)
            {
                updateAck(obj);
            }
            else
            {
                error = true;
            }
        }
        break;
    default:
        error = true;
    }
    // Done
    return !error;
}

/**
 * Update the data of an object from a byte array (unpack).
 * If the object instance could not be found in the list, then a
 * new one is created.
 */
UAVObject* UAVTalk::updateObject(quint32 objId, quint16 instId, quint8* data)
{
    // Get object
    UAVObject* obj = objMngr->getObject(objId, instId);
    // If the instance does not exist create it
    if (obj == NULL)
    {
        // Get the object type
        UAVObject* tobj = objMngr->getObject(objId);
        if (tobj == NULL)
        {
            return NULL;
        }
        // Make sure this is a data object
        UAVDataObject* dobj = dynamic_cast<UAVDataObject*>(tobj);
        if (dobj == NULL)
        {
            return NULL;
        }
        // Create a new instance, unpack and register
        UAVDataObject* instobj = dobj->clone(instId);
        if ( !objMngr->registerObject(instobj) )
        {
            return NULL;
        }
        instobj->unpack(data);
        return instobj;
    }
    else
    {
        // Unpack data into object instance
        obj->unpack(data);
        return obj;
    }
}

/**
 * Check if a transaction is pending and if yes complete it.
 */
void UAVTalk::updateNack(UAVObject* obj)
{
    if (respObj != NULL && respObj->getObjID() == obj->getObjID() && (respObj->getInstID() == obj->getInstID() || respAllInstances))
    {
        respObj = NULL;
        emit transactionCompleted(obj, false);
    }
}


/**
 * Check if a transaction is pending and if yes complete it.
 */
void UAVTalk::updateAck(UAVObject* obj)
{
    if (respObj != NULL && respObj->getObjID() == obj->getObjID() && (respObj->getInstID() == obj->getInstID() || respAllInstances))
    {
        respObj = NULL;
        emit transactionCompleted(obj, true);
    }
}


/**
 * Send an object through the telemetry link.
 * \param[in] obj Object to send
 * \param[in] type Transaction type
 * \param[in] allInstances True is all instances of the object are to be sent
 * \return Success (true), Failure (false)
 */
bool UAVTalk::transmitObject(UAVObject* obj, quint8 type, bool allInstances)
{   
    // If all instances are requested on a single instance object it is an error
    if (allInstances && obj->isSingleInstance())
    {
        allInstances = false;
    }

    // Process message type
    if ( type == TYPE_OBJ || type == TYPE_OBJ_ACK )
    {
        if (allInstances)
        {
            // Get number of instances
            quint32 numInst = objMngr->getNumInstances(obj->getObjID());
            // Send all instances
            for (quint32 instId = 0; instId < numInst; ++instId)
            {
                UAVObject* inst = objMngr->getObject(obj->getObjID(), instId);
                transmitSingleObject(inst, type, false);
            }
            return true;
        }
        else
        {
            return transmitSingleObject(obj, type, false);
        }
    }
    else if (type == TYPE_OBJ_REQ)
    {
        return transmitSingleObject(obj, TYPE_OBJ_REQ, allInstances);
    }
    else if (type == TYPE_ACK)
    {
        if (!allInstances)
        {
            return transmitSingleObject(obj, TYPE_ACK, false);
        }
        else
        {
            return false;
        }
    }
    else
    {
        return false;
    }
}

/**
 * Transmit a NACK through the telemetry link.
 * \param[in] objId the ObjectID we rejected
 */
bool UAVTalk::transmitNack(quint32 objId)
{
    txBuffer[0] = SYNC_VAL;
    txBuffer[1] = TYPE_NACK;
    qToLittleEndian<quint16>(0x0, &txBuffer[2]); // Length
    qToLittleEndian<quint32>(objId, &txBuffer[4]);

    // Calculate checksum
    txBuffer[8] = updateCRC(0, txBuffer, 8);

    // Send buffer, check that the transmit backlog does not grow above limit
    if ( io->bytesToWrite() < TX_BUFFER_SIZE )
    {
        io->write((const char*)txBuffer, 8+CHECKSUM_LENGTH);
    }
    else
    {
        ++stats.txErrors;
        return false;
    }

    // Update stats
    stats.txBytes += 8+CHECKSUM_LENGTH;

    // Done
    return true;

}


/**
 * Send an object through the telemetry link.
 * \param[in] obj Object handle to send
 * \param[in] type Transaction type
 * \return Success (true), Failure (false)
 */
bool UAVTalk::transmitSingleObject(UAVObject* obj, quint8 type, bool allInstances)
{
    qint32 length;
    qint32 dataOffset;
    quint32 objId;
    quint16 instId;
    quint16 allInstId = ALL_INSTANCES;

    // Setup type and object id fields
    objId = obj->getObjID();
    txBuffer[0] = SYNC_VAL;
    txBuffer[1] = type;
    qToLittleEndian<quint32>(objId, &txBuffer[4]);

    // Setup instance ID if one is required
    if ( obj->isSingleInstance() )
    {
        dataOffset = 8;
    }
    else
    {
        // Check if all instances are requested
        if (allInstances)
        {
            qToLittleEndian<quint16>(allInstId, &txBuffer[8]);
        }
        else
        {
            instId = obj->getInstID();
            qToLittleEndian<quint16>(instId, &txBuffer[8]);
        }
        dataOffset = 10;
    }

    // Determine data length
    if (type == TYPE_OBJ_REQ || type == TYPE_ACK)
    {
        length = 0;
    }
    else
    {
        length = obj->getNumBytes();
    }

    // Check length
    if (length >= MAX_PAYLOAD_LENGTH)
    {
        return false;
    }

    // Copy data (if any)
    if (length > 0)
    {
        if ( !obj->pack(&txBuffer[dataOffset]) )
        {
            return false;
        }
    }

    qToLittleEndian<quint16>(dataOffset + length, &txBuffer[2]);

    // Calculate checksum
    txBuffer[dataOffset+length] = updateCRC(0, txBuffer, dataOffset + length);

    // Send buffer, check that the transmit backlog does not grow above limit
    if ( io->bytesToWrite() < TX_BUFFER_SIZE )
    {
        io->write((const char*)txBuffer, dataOffset+length+CHECKSUM_LENGTH);
    }
    else
    {
        ++stats.txErrors;
        return false;
    }

    // Update stats
    ++stats.txObjects;
    stats.txBytes += dataOffset+length+CHECKSUM_LENGTH;
    stats.txObjectBytes += length;

    // Done
    return true;
}

/**
 * Update the crc value with new data.
 *
 * Generated by pycrc v0.7.5, http://www.tty1.net/pycrc/
 * using the configuration:
 *    Width        = 8
 *    Poly         = 0x07
 *    XorIn        = 0x00
 *    ReflectIn    = False
 *    XorOut       = 0x00
 *    ReflectOut   = False
 *    Algorithm    = table-driven
 *
 * \param crc      The current crc value.
 * \param data     Pointer to a buffer of \a data_len bytes.
 * \param length   Number of bytes in the \a data buffer.
 * \return         The updated crc value.
 */
quint8 UAVTalk::updateCRC(quint8 crc, const quint8 data)
{
    return crc_table[crc ^ data];
}
quint8 UAVTalk::updateCRC(quint8 crc, const quint8* data, qint32 length)
{
    while (length--)
        crc = crc_table[crc ^ *data++];
    return crc;
}