/*
 * Author: Sven Gothel <sgothel@jausoft.com>
 * Copyright (c) 2020 Gothel Software e.K.
 * Copyright (c) 2020 ZAFENA AB
 *
 * Permission is hereby granted, free of charge, to any person obtaining
 * a copy of this software and associated documentation files (the
 * "Software"), to deal in the Software without restriction, including
 * without limitation the rights to use, copy, modify, merge, publish,
 * distribute, sublicense, and/or sell copies of the Software, and to
 * permit persons to whom the Software is furnished to do so, subject to
 * the following conditions:
 *
 * The above copyright notice and this permission notice shall be
 * included in all copies or substantial portions of the Software.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
 * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
 * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
 * NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE
 * LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
 * OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
 * WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
 */

#include <cstring>
#include <string>
#include <memory>
#include <cstdint>
#include <vector>
#include <cstdio>

#include  <algorithm>

extern "C" {
    #include <unistd.h>
    #include <sys/socket.h>
    #include <poll.h>
    #include <signal.h>
}

// #define PERF_PRINT_ON 1
// PERF2_PRINT_ON for read/write single values
// #define PERF2_PRINT_ON 1
// PERF3_PRINT_ON for disconnect
// #define PERF3_PRINT_ON 1
#include <jau/debug.hpp>

#include <jau/basic_algos.hpp>

#include "L2CAPIoctl.hpp"
#include "GATTNumbers.hpp"

#include "GATTHandler.hpp"

#include "HCIComm.hpp"
#include "DBTTypes.hpp"
#include "DBTDevice.hpp"

using namespace direct_bt;
using namespace jau;

GATTEnv::GATTEnv() noexcept
: exploding( environment::getExplodingProperties("direct_bt.gatt") ),
  GATT_READ_COMMAND_REPLY_TIMEOUT( environment::getInt32Property("direct_bt.gatt.cmd.read.timeout", 500, 250 /* min */, INT32_MAX /* max */) ),
  GATT_WRITE_COMMAND_REPLY_TIMEOUT(  environment::getInt32Property("direct_bt.gatt.cmd.write.timeout", 500, 250 /* min */, INT32_MAX /* max */) ),
  GATT_INITIAL_COMMAND_REPLY_TIMEOUT( environment::getInt32Property("direct_bt.gatt.cmd.init.timeout", 2500, 2000 /* min */, INT32_MAX /* max */) ),
  ATTPDU_RING_CAPACITY( environment::getInt32Property("direct_bt.gatt.ringsize", 128, 64 /* min */, 1024 /* max */) ),
  DEBUG_DATA( environment::getBooleanProperty("direct_bt.debug.gatt.data", false) )
{
}

#define CASE_TO_STRING(V) case V: return #V;

std::shared_ptr<DBTDevice> GATTHandler::getDeviceChecked() const {
    std::shared_ptr<DBTDevice> ref = wbr_device.lock();
    if( nullptr == ref ) {
        throw IllegalStateException("GATTHandler's device already destructed: "+deviceString, E_FILE_LINE);
    }
    return ref;
}

bool GATTHandler::validateConnected() noexcept {
    bool l2capIsConnected = l2cap.isConnected();
    bool l2capHasIOError = l2cap.hasIOError();

    if( has_ioerror || l2capHasIOError ) {
        has_ioerror = true; // propagate l2capHasIOError -> has_ioerror
        ERR_PRINT("IOError state: GattHandler %s, l2cap %s: %s",
                getStateString().c_str(), l2cap.getStateString().c_str(), deviceString.c_str());
        return false;
    }

    if( !is_connected || !l2capIsConnected ) {
        ERR_PRINT("Disconnected state: GattHandler %s, l2cap %s: %s",
                getStateString().c_str(), l2cap.getStateString().c_str(), deviceString.c_str());
        return false;
    }
    return true;
}

static jau::cow_vector<std::shared_ptr<GATTCharacteristicListener>>::equal_comparator _characteristicListenerRefEqComparator =
        [](const std::shared_ptr<GATTCharacteristicListener> &a, const std::shared_ptr<GATTCharacteristicListener> &b) -> bool { return *a == *b; };

bool GATTHandler::addCharacteristicListener(std::shared_ptr<GATTCharacteristicListener> l) {
    if( nullptr == l ) {
        throw IllegalArgumentException("GATTEventListener ref is null", E_FILE_LINE);
    }
    return characteristicListenerList.push_back_unique(l, _characteristicListenerRefEqComparator);
}

bool GATTHandler::removeCharacteristicListener(std::shared_ptr<GATTCharacteristicListener> l) noexcept {
    if( nullptr == l ) {
        ERR_PRINT("Given GATTCharacteristicListener ref is null");
        return false;
    }
    const int count = characteristicListenerList.erase_matching(l, false /* all_matching */, _characteristicListenerRefEqComparator);
    return count > 0;
}

bool GATTHandler::removeCharacteristicListener(const GATTCharacteristicListener * l) noexcept {
    if( nullptr == l ) {
        ERR_PRINT("Given GATTCharacteristicListener ref is null");
        return false;
    }
    const std::lock_guard<std::recursive_mutex> lock(characteristicListenerList.get_write_mutex());
    std::shared_ptr<std::vector<std::shared_ptr<GATTCharacteristicListener>>> snapshot = characteristicListenerList.copy_store();
    int count = 0;
    for(auto it = snapshot->begin(); it != snapshot->end(); ) {
        if ( **it == *l ) {
            it = snapshot->erase(it);
            count++;
            break;
        } else {
            ++it;
        }
    }
    if( 0 < count ) {
        characteristicListenerList.set_store(std::move(snapshot));
        return true;
    }
    return false;
}

int GATTHandler::removeAllAssociatedCharacteristicListener(std::shared_ptr<GATTCharacteristic> associatedCharacteristic) noexcept {
    if( nullptr == associatedCharacteristic ) {
        ERR_PRINT("Given GATTCharacteristic ref is null");
        return false;
    }
    return removeAllAssociatedCharacteristicListener( associatedCharacteristic.get() );
}

int GATTHandler::removeAllAssociatedCharacteristicListener(const GATTCharacteristic * associatedCharacteristic) noexcept {
    if( nullptr == associatedCharacteristic ) {
        ERR_PRINT("Given GATTCharacteristic ref is null");
        return false;
    }
    const std::lock_guard<std::recursive_mutex> lock(characteristicListenerList.get_write_mutex());
    std::shared_ptr<std::vector<std::shared_ptr<GATTCharacteristicListener>>> snapshot = characteristicListenerList.copy_store();
    int count = 0;
    for(auto it = snapshot->begin(); it != snapshot->end(); ) {
        if ( (*it)->match(*associatedCharacteristic) ) {
            it = snapshot->erase(it);
            count++;
            break;
        } else {
            ++it;
        }
    }
    if( 0 < count ) {
        characteristicListenerList.set_store(std::move(snapshot));
        return true;
    }
    return false;
}

int GATTHandler::removeAllCharacteristicListener() noexcept {
    int count = characteristicListenerList.size();
    characteristicListenerList.clear();
    return count;
}

void GATTHandler::setSendIndicationConfirmation(const bool v) {
    sendIndicationConfirmation = v;
}

bool GATTHandler::getSendIndicationConfirmation() noexcept {
    return sendIndicationConfirmation;
}

void GATTHandler::l2capReaderThreadImpl() {
    {
        const std::lock_guard<std::mutex> lock(mtx_l2capReaderLifecycle); // RAII-style acquire and relinquish via destructor
        l2capReaderShallStop = false;
        l2capReaderRunning = true;
        DBG_PRINT("GATTHandler::reader Started");
        cv_l2capReaderInit.notify_all();
    }

    while( !l2capReaderShallStop ) {
        int len;
        if( !validateConnected() ) {
            ERR_PRINT("GATTHandler::reader: Invalid IO state -> Stop");
            l2capReaderShallStop = true;
            break;
        }

        len = l2cap.read(rbuffer.get_wptr(), rbuffer.getSize());
        if( 0 < len ) {
            std::shared_ptr<const AttPDUMsg> attPDU = AttPDUMsg::getSpecialized(rbuffer.get_ptr(), len);
            const AttPDUMsg::Opcode opc = attPDU->getOpcode();

            if( AttPDUMsg::Opcode::ATT_HANDLE_VALUE_NTF == opc ) {
                const AttHandleValueRcv * a = static_cast<const AttHandleValueRcv*>(attPDU.get());
                COND_PRINT(env.DEBUG_DATA, "GATTHandler::reader: NTF: %s, listener %zd", a->toString().c_str(), characteristicListenerList.size());
                GATTCharacteristicRef decl = findCharacterisicsByValueHandle(a->getHandle());
                const std::shared_ptr<TROOctets> data(new POctets(a->getValue()));
                const uint64_t timestamp = a->ts_creation;
                int i=0;
                jau::for_each_cow(characteristicListenerList, [&](std::shared_ptr<GATTCharacteristicListener> &l) {
                    try {
                        if( l->match(*decl) ) {
                            l->notificationReceived(decl, data, timestamp);
                        }
                    } catch (std::exception &e) {
                        ERR_PRINT("GATTHandler::notificationReceived-CBs %d/%zd: GATTCharacteristicListener %s: Caught exception %s",
                                i+1, characteristicListenerList.size(),
                                aptrHexString((void*)l.get()).c_str(), e.what());
                    }
                    i++;
                });
            } else if( AttPDUMsg::Opcode::ATT_HANDLE_VALUE_IND == opc ) {
                const AttHandleValueRcv * a = static_cast<const AttHandleValueRcv*>(attPDU.get());
                COND_PRINT(env.DEBUG_DATA, "GATTHandler::reader: IND: %s, sendIndicationConfirmation %d, listener %zd",
                        a->toString().c_str(), sendIndicationConfirmation.load(), characteristicListenerList.size());
                bool cfmSent = false;
                if( sendIndicationConfirmation ) {
                    AttHandleValueCfm cfm;
                    send(cfm);
                    cfmSent = true;
                }
                GATTCharacteristicRef decl = findCharacterisicsByValueHandle(a->getHandle());
                const std::shared_ptr<TROOctets> data(new POctets(a->getValue()));
                const uint64_t timestamp = a->ts_creation;
                int i=0;
                jau::for_each_cow(characteristicListenerList, [&](std::shared_ptr<GATTCharacteristicListener> &l) {
                    try {
                        if( l->match(*decl) ) {
                            l->indicationReceived(decl, data, timestamp, cfmSent);
                        }
                    } catch (std::exception &e) {
                        ERR_PRINT("GATTHandler::indicationReceived-CBs %d/%zd: GATTCharacteristicListener %s, cfmSent %d: Caught exception %s",
                                i+1, characteristicListenerList.size(),
                                aptrHexString((void*)l.get()).c_str(), cfmSent, e.what());
                    }
                    i++;
                });
            } else if( AttPDUMsg::Opcode::ATT_MULTIPLE_HANDLE_VALUE_NTF == opc ) {
                // FIXME TODO ..
                ERR_PRINT("GATTHandler::reader: MULTI-NTF not implemented: %s", attPDU->toString().c_str());
            } else {
                attPDURing.putBlocking( attPDU );
            }
        } else if( ETIMEDOUT != errno && !l2capReaderShallStop ) { // expected exits
            IRQ_PRINT("GATTHandler::reader: l2cap read error -> Stop; l2cap.read %d", len);
            l2capReaderShallStop = true;
            has_ioerror = true;
        }
    }
    {
        const std::lock_guard<std::mutex> lock(mtx_l2capReaderLifecycle); // RAII-style acquire and relinquish via destructor
        WORDY_PRINT("GATTHandler::reader: Ended. Ring has %zu entries flushed", attPDURing.getSize());
        attPDURing.clear();
        l2capReaderRunning = false;
        cv_l2capReaderInit.notify_all();
    }
    disconnect(true /* disconnectDevice */, has_ioerror);
}

GATTHandler::GATTHandler(const std::shared_ptr<DBTDevice> &device) noexcept
: env(GATTEnv::get()),
  wbr_device(device), deviceString(device->getAddressString()), rbuffer(number(Defaults::MAX_ATT_MTU)),
  l2cap(device, L2CAP_PSM_UNDEF, L2CAP_CID_ATT),
  is_connected(true), has_ioerror(false),
  attPDURing(env.ATTPDU_RING_CAPACITY), l2capReaderShallStop(false),
  l2capReaderThreadId(0), l2capReaderRunning(false),
  serverMTU(number(Defaults::MIN_ATT_MTU)), usedMTU(number(Defaults::MIN_ATT_MTU))
{
    if( !validateConnected() ) {
        ERR_PRINT("GATTHandler.ctor: L2CAP could not connect");
        is_connected = false;
        return;
    }
    DBG_PRINT("GATTHandler::ctor: Start Connect: GattHandler[%s], l2cap[%s]: %s",
                getStateString().c_str(), l2cap.getStateString().c_str(), deviceString.c_str());

    /**
     * We utilize DBTManager's mgmthandler_sigaction SIGALRM handler,
     * as we only can install one handler.
     */
    {
        std::unique_lock<std::mutex> lock(mtx_l2capReaderLifecycle); // RAII-style acquire and relinquish via destructor

        std::thread l2capReaderThread(&GATTHandler::l2capReaderThreadImpl, this); // @suppress("Invalid arguments")
        l2capReaderThreadId = l2capReaderThread.native_handle();
        // Avoid 'terminate called without an active exception'
        // as l2capReaderThread may end due to I/O errors.
        l2capReaderThread.detach();

        while( false == l2capReaderRunning ) {
            cv_l2capReaderInit.wait(lock);
        }
    }

    // First point of failure if device exposes no GATT functionality. Allow a longer timeout!
    uint16_t mtu = 0;
    try {
        mtu = exchangeMTUImpl(number(Defaults::MAX_ATT_MTU), env.GATT_INITIAL_COMMAND_REPLY_TIMEOUT);
    } catch (std::exception &e) {
        ERR_PRINT("GattHandler.ctor: exchangeMTU failed: %s", e.what());
    } catch (std::string &msg) {
        ERR_PRINT("GattHandler.ctor: exchangeMTU failed: %s", msg.c_str());
    } catch (const char *msg) {
        ERR_PRINT("GattHandler.ctor: exchangeMTU failed: %s", msg);
    }
    if( 0 == mtu ) {
        ERR_PRINT("GATTHandler::ctor: Zero serverMTU -> disconnect: %s", deviceString.c_str());
        disconnect(true /* disconnectDevice */, false /* ioErrorCause */);
    } else {
        serverMTU = mtu;
        usedMTU = std::min(number(Defaults::MAX_ATT_MTU), (int)serverMTU);
    }
}

GATTHandler::~GATTHandler() noexcept {
    disconnect(false /* disconnectDevice */, false /* ioErrorCause */);
    characteristicListenerList.clear();
    services.clear();
    genericAccess = nullptr;
}

bool GATTHandler::disconnect(const bool disconnectDevice, const bool ioErrorCause) noexcept {
    PERF3_TS_T0();
    // Interrupt GATT's L2CAP::connect(..) and L2CAP::read(..), avoiding prolonged hang
    // and pull all underlying l2cap read operations!
    l2cap.disconnect();

    // Avoid disconnect re-entry -> potential deadlock
    bool expConn = true; // C++11, exp as value since C++20
    if( !is_connected.compare_exchange_strong(expConn, false) ) {
        // not connected
        DBG_PRINT("GATTHandler::disconnect: Not connected: disconnectDevice %d, ioErrorCause %d: GattHandler[%s], l2cap[%s]: %s",
                  disconnectDevice, ioErrorCause, getStateString().c_str(), l2cap.getStateString().c_str(), deviceString.c_str());
        characteristicListenerList.clear();
        return false;
    }
    // Lock to avoid other threads using instance while disconnecting
    const std::lock_guard<std::recursive_mutex> lock(mtx_command); // RAII-style acquire and relinquish via destructor
    DBG_PRINT("GATTHandler::disconnect: Start: disconnectDevice %d, ioErrorCause %d: GattHandler[%s], l2cap[%s]: %s",
              disconnectDevice, ioErrorCause, getStateString().c_str(), l2cap.getStateString().c_str(), deviceString.c_str());
    characteristicListenerList.clear();

    PERF3_TS_TD("GATTHandler::disconnect.1");
    {
        std::unique_lock<std::mutex> lockReader(mtx_l2capReaderLifecycle); // RAII-style acquire and relinquish via destructor
        has_ioerror = false;

        const pthread_t tid_self = pthread_self();
        const pthread_t tid_l2capReader = l2capReaderThreadId;
        l2capReaderThreadId = 0;
        const bool is_l2capReader = tid_l2capReader == tid_self;
        DBG_PRINT("GATTHandler.disconnect: l2capReader[running %d, shallStop %d, isReader %d, tid %p)",
                  l2capReaderRunning, l2capReaderShallStop.load(), is_l2capReader, (void*)tid_l2capReader);
        if( l2capReaderRunning ) {
            l2capReaderShallStop = true;
            if( !is_l2capReader && 0 != tid_l2capReader ) {
                int kerr;
                if( 0 != ( kerr = pthread_kill(tid_l2capReader, SIGALRM) ) ) {
                    ERR_PRINT("GATTHandler::disconnect: pthread_kill %p FAILED: %d", (void*)tid_l2capReader, kerr);
                }
            }
            // Ensure the reader thread has ended, no runaway-thread using *this instance after destruction
            while( true == l2capReaderRunning ) {
                cv_l2capReaderInit.wait(lockReader);
            }
        }
    }
    PERF3_TS_TD("GATTHandler::disconnect.2");

    if( disconnectDevice ) {
        std::shared_ptr<DBTDevice> device = getDeviceUnchecked();
        if( nullptr != device ) {
            // Cleanup device resources, proper connection state
            // Intentionally giving the POWER_OFF reason for the device in case of ioErrorCause!
            const HCIStatusCode reason = ioErrorCause ?
                                   HCIStatusCode::REMOTE_DEVICE_TERMINATED_CONNECTION_POWER_OFF :
                                   HCIStatusCode::REMOTE_USER_TERMINATED_CONNECTION;
            device->disconnect(reason);
        }
    }

    PERF3_TS_TD("GATTHandler::disconnect.X");
    DBG_PRINT("GATTHandler::disconnect: End: %s", deviceString.c_str());
    return true;
}

void GATTHandler::send(const AttPDUMsg & msg) {
    if( !validateConnected() ) {
        throw IllegalStateException("GATTHandler::send: Invalid IO State: req "+msg.toString()+" to "+deviceString, E_FILE_LINE);
    }
    if( msg.pdu.getSize() > usedMTU ) {
        throw IllegalArgumentException("clientMaxMTU "+std::to_string(msg.pdu.getSize())+" > usedMTU "+std::to_string(usedMTU)+
                                       " to "+deviceString, E_FILE_LINE);
    }

    // Thread safe l2cap.write(..) operation..
    const int res = l2cap.write(msg.pdu.get_ptr(), msg.pdu.getSize());
    if( 0 > res ) {
        IRQ_PRINT("GATTHandler::send: l2cap write error -> disconnect: %s to %s", msg.toString().c_str(), deviceString.c_str());
        has_ioerror = true;
        disconnect(true /* disconnectDevice */, true /* ioErrorCause */); // state -> Disconnected
        throw BluetoothException("GATTHandler::send: l2cap write error: req "+msg.toString()+" to "+deviceString, E_FILE_LINE);
    }
    if( res != msg.pdu.getSize() ) {
        ERR_PRINT("GATTHandler::send: l2cap write count error, %d != %d: %s -> disconnect: %s",
                res, msg.pdu.getSize(), msg.toString().c_str(), deviceString.c_str());
        has_ioerror = true;
        disconnect(true /* disconnectDevice */, true /* ioErrorCause */); // state -> Disconnected
        throw BluetoothException("GATTHandler::send: l2cap write count error, "+std::to_string(res)+" != "+std::to_string(res)
                                 +": "+msg.toString()+" -> disconnect: "+deviceString, E_FILE_LINE);
    }
}

std::shared_ptr<const AttPDUMsg> GATTHandler::sendWithReply(const AttPDUMsg & msg, const int timeout) {
    send( msg );

    // Ringbuffer read is thread safe
    std::shared_ptr<const AttPDUMsg> res = attPDURing.getBlocking(timeout);
    if( nullptr == res ) {
        errno = ETIMEDOUT;
        IRQ_PRINT("GATTHandler::sendWithReply: nullptr result (timeout %d): req %s to %s", timeout, msg.toString().c_str(), deviceString.c_str());
        has_ioerror = true;
        disconnect(true /* disconnectDevice */, true /* ioErrorCause */);
        throw BluetoothException("GATTHandler::sendWithReply: nullptr result (timeout "+std::to_string(timeout)+"): req "+msg.toString()+" to "+deviceString, E_FILE_LINE);
    }
    return res;
}

uint16_t GATTHandler::exchangeMTUImpl(const uint16_t clientMaxMTU, const int32_t timeout) {
    /***
     * BT Core Spec v5.2: Vol 3, Part G GATT: 4.3.1 Exchange MTU (Server configuration)
     */
    if( clientMaxMTU > number(Defaults::MAX_ATT_MTU) ) {
        throw IllegalArgumentException("clientMaxMTU "+std::to_string(clientMaxMTU)+" > ClientMaxMTU "+std::to_string(number(Defaults::MAX_ATT_MTU)), E_FILE_LINE);
    }
    const AttExchangeMTU req(clientMaxMTU);
    // called by ctor only, no locking: const std::lock_guard<std::recursive_mutex> lock(mtx_command);
    PERF_TS_T0();

    uint16_t mtu = 0;
    DBG_PRINT("GATT send: %s", req.toString().c_str());

    std::shared_ptr<const AttPDUMsg> pdu = sendWithReply(req, timeout); // valid reply or exception

    if( pdu->getOpcode() == AttPDUMsg::ATT_EXCHANGE_MTU_RSP ) {
        const AttExchangeMTU * p = static_cast<const AttExchangeMTU*>(pdu.get());
        mtu = p->getMTUSize();
    }
    PERF_TS_TD("GATT exchangeMTU");

    return mtu;
}

GATTCharacteristicRef GATTHandler::findCharacterisicsByValueHandle(const uint16_t charValueHandle) noexcept {
    return findCharacterisicsByValueHandle(charValueHandle, services);
}

GATTCharacteristicRef GATTHandler::findCharacterisicsByValueHandle(const uint16_t charValueHandle, std::vector<GATTServiceRef> &services) noexcept {
    for(auto it = services.begin(); it != services.end(); it++) {
        GATTCharacteristicRef decl = findCharacterisicsByValueHandle(charValueHandle, *it);
        if( nullptr != decl ) {
            return decl;
        }
    }
    return nullptr;
}

GATTCharacteristicRef GATTHandler::findCharacterisicsByValueHandle(const uint16_t charValueHandle, GATTServiceRef service) noexcept {
    for(auto it = service->characteristicList.begin(); it != service->characteristicList.end(); it++) {
        GATTCharacteristicRef decl = *it;
        if( charValueHandle == decl->value_handle ) {
            return decl;
        }
    }
    return nullptr;
}

std::vector<GATTServiceRef> & GATTHandler::discoverCompletePrimaryServices(std::shared_ptr<GATTHandler> shared_this) {
    const std::lock_guard<std::recursive_mutex> lock(mtx_command); // RAII-style acquire and relinquish via destructor
    if( !discoverPrimaryServices(shared_this, services) ) {
        return services;
    }
    for(auto it = services.begin(); it != services.end(); it++) {
        GATTServiceRef primSrv = *it;
        if( discoverCharacteristics(primSrv) ) {
            discoverDescriptors(primSrv);
        }
    }
    genericAccess = getGenericAccess(services);
    return services;
}

bool GATTHandler::discoverPrimaryServices(std::shared_ptr<GATTHandler> shared_this, std::vector<GATTServiceRef> & result) {
    {
        // validate shared_this first!
        GATTHandler *given_this = shared_this.get();
        if( given_this != this ) {
            throw IllegalArgumentException("Given shared GATTHandler reference "+aptrHexString(given_this)+" not matching this "+aptrHexString(this), E_FILE_LINE);
        }
    }
    /***
     * BT Core Spec v5.2: Vol 3, Part G GATT: 4.4.1 Discover All Primary Services
     *
     * This sub-procedure is complete when the ATT_ERROR_RSP PDU is received
     * and the error code is set to Attribute Not Found or when the End Group Handle
     * in the Read by Type Group Response is 0xFFFF.
     */
    const uuid16_t groupType = uuid16_t(GattAttributeType::PRIMARY_SERVICE);
    const std::lock_guard<std::recursive_mutex> lock(mtx_command); // RAII-style acquire and relinquish via destructor
    PERF_TS_T0();

    bool done=false;
    uint16_t startHandle=0x0001;
    result.clear();
    while(!done) {
        const AttReadByNTypeReq req(true /* group */, startHandle, 0xffff, groupType);
        COND_PRINT(env.DEBUG_DATA, "GATT PRIM SRV discover send: %s to %s", req.toString().c_str(), deviceString.c_str());

        std::shared_ptr<const AttPDUMsg> pdu = sendWithReply(req, env.GATT_READ_COMMAND_REPLY_TIMEOUT); // valid reply or exception
        COND_PRINT(env.DEBUG_DATA, "GATT PRIM SRV discover recv: %s on %s", pdu->toString().c_str(), deviceString.c_str());

        if( pdu->getOpcode() == AttPDUMsg::ATT_READ_BY_GROUP_TYPE_RSP ) {
            const AttReadByGroupTypeRsp * p = static_cast<const AttReadByGroupTypeRsp*>(pdu.get());
            const int count = p->getElementCount();

            for(int i=0; i<count; i++) {
                const int ePDUOffset = p->getElementPDUOffset(i);
                const int esz = p->getElementTotalSize();
                result.push_back( GATTServiceRef( new GATTService( shared_this, true,
                        p->pdu.get_uint16(ePDUOffset), // start-handle
                        p->pdu.get_uint16(ePDUOffset + 2), // end-handle
                        p->pdu.get_uuid( ePDUOffset + 2 + 2, uuid_t::toTypeSize(esz-2-2) ) // uuid
                    ) ) );
                COND_PRINT(env.DEBUG_DATA, "GATT PRIM SRV discovered[%d/%d]: %s on %s", i,
                        count, result.at(result.size()-1)->toString().c_str(), deviceString.c_str());
            }
            startHandle = p->getElementEndHandle(count-1);
            if( startHandle < 0xffff ) {
                startHandle++;
            } else {
                done = true; // OK by spec: End of communication
            }
        } else if( pdu->getOpcode() == AttPDUMsg::ATT_ERROR_RSP ) {
            done = true; // OK by spec: End of communication
        } else {
            ERR_PRINT("GATT discoverPrimary unexpected reply %s, req %s from %s",
                    pdu->toString().c_str(), req.toString().c_str(), deviceString.c_str());
            done = true;
        }
    }
    PERF_TS_TD("GATT discoverPrimaryServices");

    return result.size() > 0;
}

bool GATTHandler::discoverCharacteristics(GATTServiceRef & service) {
    /***
     * BT Core Spec v5.2: Vol 3, Part G GATT: 4.6.1 Discover All Characteristics of a Service
     * <p>
     * BT Core Spec v5.2: Vol 3, Part G GATT: 3.3.1 Characteristic Declaration Attribute Value
     * </p>
     * <p>
     * BT Core Spec v5.2: Vol 3, Part G GATT: 3.3.3.3 Client Characteristic Configuration
     * </p>
     */
    const uuid16_t characteristicTypeReq = uuid16_t(GattAttributeType::CHARACTERISTIC);
    const std::lock_guard<std::recursive_mutex> lock(mtx_command); // RAII-style acquire and relinquish via destructor
    COND_PRINT(env.DEBUG_DATA, "GATT discoverCharacteristics Service: %s on %s", service->toString().c_str(), deviceString.c_str());

    PERF_TS_T0();

    bool done=false;
    uint16_t handle=service->startHandle;
    service->characteristicList.clear();
    while(!done) {
        const AttReadByNTypeReq req(false /* group */, handle, service->endHandle, characteristicTypeReq);
        COND_PRINT(env.DEBUG_DATA, "GATT C discover send: %s to %s", req.toString().c_str(), deviceString.c_str());

        std::shared_ptr<const AttPDUMsg> pdu = sendWithReply(req, env.GATT_READ_COMMAND_REPLY_TIMEOUT); // valid reply or exception
        COND_PRINT(env.DEBUG_DATA, "GATT C discover recv: %s from %s", pdu->toString().c_str(), deviceString.c_str());

        if( pdu->getOpcode() == AttPDUMsg::ATT_READ_BY_TYPE_RSP ) {
            const AttReadByTypeRsp * p = static_cast<const AttReadByTypeRsp*>(pdu.get());
            const int e_count = p->getElementCount();

            for(int e_iter=0; e_iter<e_count; e_iter++) {
                // handle: handle for the Characteristics declaration
                // value: Characteristics Property, Characteristics Value Handle _and_ Characteristics UUID
                const int ePDUOffset = p->getElementPDUOffset(e_iter);
                const int esz = p->getElementTotalSize();
                service->characteristicList.push_back( GATTCharacteristicRef( new GATTCharacteristic(
                    service,
                    p->pdu.get_uint16(ePDUOffset), // Characteristics's Service Handle
                    p->getElementHandle(e_iter), // Characteristic Handle
                    static_cast<GATTCharacteristic::PropertyBitVal>(p->pdu.get_uint8(ePDUOffset  + 2)), // Characteristics Property
                    p->pdu.get_uint16(ePDUOffset + 2 + 1), // Characteristics Value Handle
                    p->pdu.get_uuid(ePDUOffset   + 2 + 1 + 2, uuid_t::toTypeSize(esz-2-1-2) ) ) ) ); // Characteristics Value Type UUID
                COND_PRINT(env.DEBUG_DATA, "GATT C discovered[%d/%d]: char%s on %s", e_iter, e_count,
                        service->characteristicList.at(service->characteristicList.size()-1)->toString().c_str(), deviceString.c_str());
            }
            handle = p->getElementHandle(e_count-1); // Last Characteristic Handle
            if( handle < service->endHandle ) {
                handle++;
            } else {
                done = true; // OK by spec: End of communication
            }
        } else if( pdu->getOpcode() == AttPDUMsg::ATT_ERROR_RSP ) {
            done = true; // OK by spec: End of communication
        } else {
            ERR_PRINT("GATT discoverCharacteristics unexpected reply %s, req %s within service%s from %s",
                    pdu->toString().c_str(), req.toString().c_str(), service->toString().c_str(), deviceString.c_str());
            done = true;
        }
    }

    PERF_TS_TD("GATT discoverCharacteristics");

    return service->characteristicList.size() > 0;
}

bool GATTHandler::discoverDescriptors(GATTServiceRef & service) {
    /***
     * BT Core Spec v5.2: Vol 3, Part G GATT: 4.7.1 Discover All Characteristic Descriptors
     * <p>
     * BT Core Spec v5.2: Vol 3, Part G GATT: 3.3.1 Characteristic Declaration Attribute Value
     * </p>
     */
    COND_PRINT(env.DEBUG_DATA, "GATT discoverDescriptors Service: %s on %s", service->toString().c_str(), deviceString.c_str());
    const std::lock_guard<std::recursive_mutex> lock(mtx_command); // RAII-style acquire and relinquish via destructor
    PERF_TS_T0();

    bool done=false;
    const int charCount = service->characteristicList.size();
    for(int charIter=0; !done && charIter < charCount; charIter++ ) {
        GATTCharacteristicRef charDecl = service->characteristicList[charIter];
        charDecl->clearDescriptors();
        COND_PRINT(env.DEBUG_DATA, "GATT discoverDescriptors Characteristic[%d/%d]: %s on %s", charIter, charCount, charDecl->toString().c_str(), deviceString.c_str());

        uint16_t cd_handle_iter = charDecl->value_handle + 1; // Start @ Characteristic Value Handle + 1
        uint16_t cd_handle_end;
        if( charIter+1 < charCount ) {
            cd_handle_end = service->characteristicList.at(charIter+1)->value_handle;
        } else {
            cd_handle_end = service->endHandle;
        }

        while( !done && cd_handle_iter <= cd_handle_end ) {
            const AttFindInfoReq req(cd_handle_iter, cd_handle_end);
            COND_PRINT(env.DEBUG_DATA, "GATT CD discover send: %s", req.toString().c_str());

            std::shared_ptr<const AttPDUMsg> pdu = sendWithReply(req, env.GATT_READ_COMMAND_REPLY_TIMEOUT); // valid reply or exception
            COND_PRINT(env.DEBUG_DATA, "GATT CD discover recv: %s from ", pdu->toString().c_str(), deviceString.c_str());

            if( pdu->getOpcode() == AttPDUMsg::ATT_FIND_INFORMATION_RSP ) {
                const AttFindInfoRsp * p = static_cast<const AttFindInfoRsp*>(pdu.get());
                const int e_count = p->getElementCount();

                for(int e_iter=0; e_iter<e_count; e_iter++) {
                    // handle: handle of Characteristic Descriptor.
                    // value: Characteristic Descriptor UUID.
                    const uint16_t cd_handle = p->getElementHandle(e_iter);
                    const std::shared_ptr<const uuid_t> cd_uuid = p->getElementValue(e_iter);

                    std::shared_ptr<GATTDescriptor> cd( new GATTDescriptor(charDecl, cd_uuid, cd_handle) );
                    if( cd_handle <= charDecl->value_handle || cd_handle > cd_handle_end ) { // should never happen!
                        ERR_PRINT("GATT discoverDescriptors CD handle %s not in range ]%s..%s]: descr%s within char%s on %s",
                                uint16HexString(cd_handle).c_str(),
                                uint16HexString(charDecl->value_handle).c_str(), uint16HexString(cd_handle_end).c_str(),
                                cd->toString().c_str(), charDecl->toString().c_str(), deviceString.c_str());
                        done = true;
                        break;

                    }
                    if( !readDescriptorValue(*cd, 0) ) {
                        ERR_PRINT("GATT discoverDescriptors readDescriptorValue failed: req %s, descr%s within char%s on %s",
                                req.toString().c_str(), cd->toString().c_str(), charDecl->toString().c_str(), deviceString.c_str());
                        done = true;
                        break;
                    }
                    if( cd->isClientCharacteristicConfiguration() ) {
                        charDecl->clientCharacteristicsConfigIndex = charDecl->descriptorList.size();
                    }
                    charDecl->descriptorList.push_back(cd);
                    COND_PRINT(env.DEBUG_DATA, "GATT CD discovered[%d/%d]: %s", e_iter, e_count, cd->toString().c_str());
                }
                cd_handle_iter = p->getElementHandle(e_count-1); // Last Descriptor Handle
                if( cd_handle_iter < cd_handle_end ) {
                    cd_handle_iter++;
                } else {
                    done = true; // OK by spec: End of communication
                }
            } else if( pdu->getOpcode() == AttPDUMsg::ATT_ERROR_RSP ) {
                done = true; // OK by spec: End of communication
            } else {
                ERR_PRINT("GATT discoverDescriptors unexpected reply %s; req %s within char%s from %s",
                        pdu->toString().c_str(), req.toString().c_str(), charDecl->toString().c_str(), deviceString.c_str());
                done = true;
            }
        }
    }
    PERF_TS_TD("GATT discoverDescriptors");

    return service->characteristicList.size() > 0;
}

bool GATTHandler::readDescriptorValue(GATTDescriptor & desc, int expectedLength) {
    COND_PRINT(env.DEBUG_DATA, "GATTHandler::readDescriptorValue expLen %d, desc %s", expectedLength, desc.toString().c_str());
    const bool res = readValue(desc.handle, desc.value, expectedLength);
    if( !res ) {
        ERR_PRINT("GATT readDescriptorValue error on desc%s within char%s from %s",
                desc.toString().c_str(), desc.getCharacteristicChecked()->toString().c_str(), deviceString.c_str());
    }
    return res;
}

bool GATTHandler::readCharacteristicValue(const GATTCharacteristic & decl, POctets & resValue, int expectedLength) {
    COND_PRINT(env.DEBUG_DATA, "GATTHandler::readCharacteristicValue expLen %d, decl %s", expectedLength, decl.toString().c_str());
    const bool res = readValue(decl.value_handle, resValue, expectedLength);
    if( !res ) {
        ERR_PRINT("GATT readCharacteristicValue error on char%s from %s", decl.toString().c_str(), deviceString.c_str());
    }
    return res;
}

bool GATTHandler::readValue(const uint16_t handle, POctets & res, int expectedLength) {
    /* BT Core Spec v5.2: Vol 3, Part G GATT: 4.8.1 Read Characteristic Value */
    /* BT Core Spec v5.2: Vol 3, Part G GATT: 4.8.3 Read Long Characteristic Value */
    const std::lock_guard<std::recursive_mutex> lock(mtx_command); // RAII-style acquire and relinquish via destructor
    PERF2_TS_T0();

    bool done=false;
    int offset=0;

    COND_PRINT(env.DEBUG_DATA, "GATTHandler::readValue expLen %d, handle %s from %s", expectedLength, uint16HexString(handle).c_str(), deviceString.c_str());

    while(!done) {
        if( 0 < expectedLength && expectedLength <= offset ) {
            break; // done
        } else if( 0 == expectedLength && 0 < offset ) {
            break; // done w/ only one request
        } // else 0 > expectedLength: implicit

        std::shared_ptr<const AttPDUMsg> pdu = nullptr;

        const AttReadReq req0(handle);
        const AttReadBlobReq req1(handle, offset);
        const AttPDUMsg & req = ( 0 == offset ) ? static_cast<const AttPDUMsg &>(req0) : static_cast<const AttPDUMsg &>(req1);
        COND_PRINT(env.DEBUG_DATA, "GATT RV send: %s", req.toString().c_str());
        pdu = sendWithReply(req, env.GATT_READ_COMMAND_REPLY_TIMEOUT); // valid reply or exception

        COND_PRINT(env.DEBUG_DATA, "GATT RV recv: %s from %s", pdu->toString().c_str(), deviceString.c_str());
        if( pdu->getOpcode() == AttPDUMsg::ATT_READ_RSP ) {
            const AttReadRsp * p = static_cast<const AttReadRsp*>(pdu.get());
            const TOctetSlice & v = p->getValue();
            res += v;
            offset += v.getSize();
            if( p->getPDUValueSize() < p->getMaxPDUValueSize(usedMTU) ) {
                done = true; // No full ATT_MTU PDU used - end of communication
            }
        } else if( pdu->getOpcode() == AttPDUMsg::ATT_READ_BLOB_RSP ) {
            const AttReadBlobRsp * p = static_cast<const AttReadBlobRsp*>(pdu.get());
            const TOctetSlice & v = p->getValue();
            if( 0 == v.getSize() ) {
                done = true; // OK by spec: No more data - end of communication
            } else {
                res += v;
                offset += v.getSize();
                if( p->getPDUValueSize() < p->getMaxPDUValueSize(usedMTU) ) {
                    done = true; // No full ATT_MTU PDU used - end of communication
                }
            }
        } else if( pdu->getOpcode() == AttPDUMsg::ATT_ERROR_RSP ) {
            /**
             * BT Core Spec v5.2: Vol 3, Part G GATT: 4.8.3 Read Long Characteristic Value
             *
             * If the Characteristic Value is not longer than (ATT_MTU – 1)
             * an ATT_ERROR_RSP PDU with the error
             * code set to Attribute Not Long shall be received on the first
             * ATT_READ_BLOB_REQ PDU.
             */
            const AttErrorRsp * p = static_cast<const AttErrorRsp *>(pdu.get());
            if( AttErrorRsp::ATTRIBUTE_NOT_LONG == p->getErrorCode() ) {
                done = true; // OK by spec: No more data - end of communication
            } else {
                ERR_PRINT("GATT readValue unexpected error %s; req %s from %s", pdu->toString().c_str(), req.toString().c_str(), deviceString.c_str());
                done = true;
            }
        } else {
            ERR_PRINT("GATT readValue unexpected reply %s; req %s from %s", pdu->toString().c_str(), req.toString().c_str(), deviceString.c_str());
            done = true;
        }
    }
    PERF2_TS_TD("GATT readValue");

    return offset > 0;
}

bool GATTHandler::writeDescriptorValue(const GATTDescriptor & cd) {
    /* BT Core Spec v5.2: Vol 3, Part G GATT: 3.3.3.3 Client Characteristic Configuration */
    /* BT Core Spec v5.2: Vol 3, Part G GATT: 4.9.3 Write Characteristic Value */
    /* BT Core Spec v5.2: Vol 3, Part G GATT: 4.11 Characteristic Value Indication */
    /* BT Core Spec v5.2: Vol 3, Part G GATT: 4.12.3 Write Characteristic Descriptor */
    COND_PRINT(env.DEBUG_DATA, "GATTHandler::writeDesccriptorValue desc %s", cd.toString().c_str());
    const bool res = writeValue(cd.handle, cd.value, true);
    if( !res ) {
        ERR_PRINT("GATT writeDescriptorValue error on desc%s within char%s from %s",
                cd.toString().c_str(), cd.getCharacteristicChecked()->toString().c_str(), deviceString.c_str());
    }
    return res;
}

bool GATTHandler::writeCharacteristicValue(const GATTCharacteristic & c, const TROOctets & value) {
    /* BT Core Spec v5.2: Vol 3, Part G GATT: 4.9.3 Write Characteristic Value */
    COND_PRINT(env.DEBUG_DATA, "GATTHandler::writeCharacteristicValue desc %s, value %s", c.toString().c_str(), value.toString().c_str());
    const bool res = writeValue(c.value_handle, value, true);
    if( !res ) {
        ERR_PRINT("GATT writeCharacteristicValue error on char%s from %s", c.toString().c_str(), deviceString.c_str());
    }
    return res;
}

bool GATTHandler::writeCharacteristicValueNoResp(const GATTCharacteristic & c, const TROOctets & value) {
    /* BT Core Spec v5.2: Vol 3, Part G GATT: 4.9.1 Write Characteristic Value Without Response */
    COND_PRINT(env.DEBUG_DATA, "GATT writeCharacteristicValueNoResp decl %s, value %s", c.toString().c_str(), value.toString().c_str());
    return writeValue(c.value_handle, value, false); // complete or exception
}

bool GATTHandler::writeValue(const uint16_t handle, const TROOctets & value, const bool withResponse) {
    /* BT Core Spec v5.2: Vol 3, Part G GATT: 3.3.3.3 Client Characteristic Configuration */
    /* BT Core Spec v5.2: Vol 3, Part G GATT: 4.9.3 Write Characteristic Value */
    /* BT Core Spec v5.2: Vol 3, Part G GATT: 4.11 Characteristic Value Indication */
    /* BT Core Spec v5.2: Vol 3, Part G GATT: 4.12.3 Write Characteristic Descriptor */

    if( value.getSize() <= 0 ) {
        WARN_PRINT("GATT writeValue size <= 0, no-op: %s", value.toString().c_str());
        return false;
    }
    const std::lock_guard<std::recursive_mutex> lock(mtx_command); // RAII-style acquire and relinquish via destructor

    // FIXME TODO: Long Value if value.getSize() > ( ATT_MTU - 3 )
    PERF2_TS_T0();

    if( !withResponse ) {
        AttWriteCmd req(handle, value);
        COND_PRINT(env.DEBUG_DATA, "GATT WV send(resp %d): %s to %s", withResponse, req.toString().c_str(), deviceString.c_str());

        send( req ); // complete or exception
        PERF2_TS_TD("GATT writeValue (no-resp)");
        return true;
    }

    AttWriteReq req(handle, value);
    COND_PRINT(env.DEBUG_DATA, "GATT WV send(resp %d): %s to %s", withResponse, req.toString().c_str(), deviceString.c_str());

    bool res = false;
    std::shared_ptr<const AttPDUMsg> pdu = sendWithReply(req, env.GATT_WRITE_COMMAND_REPLY_TIMEOUT); // valid reply or exception
    COND_PRINT(env.DEBUG_DATA, "GATT WV recv: %s from %s", pdu->toString().c_str(), deviceString.c_str());

    if( pdu->getOpcode() == AttPDUMsg::ATT_WRITE_RSP ) {
        // OK
        res = true;
    } else if( pdu->getOpcode() == AttPDUMsg::ATT_ERROR_RSP ) {
        ERR_PRINT("GATT writeValue unexpected error %s; req %s from %s", pdu->toString().c_str(), req.toString().c_str(), deviceString.c_str());
    } else {
        ERR_PRINT("GATT writeValue unexpected reply %s; req %s from %s", pdu->toString().c_str(), req.toString().c_str(), deviceString.c_str());
    }
    PERF2_TS_TD("GATT writeValue (with-resp)");
    return res;
}

bool GATTHandler::configNotificationIndication(GATTDescriptor & cccd, const bool enableNotification, const bool enableIndication) {
    if( !cccd.isClientCharacteristicConfiguration() ) {
        throw IllegalArgumentException("Not a ClientCharacteristicConfiguration: "+cccd.toString(), E_FILE_LINE);
    }
    /* BT Core Spec v5.2: Vol 3, Part G GATT: 3.3.3.3 Client Characteristic Configuration */
    const uint16_t ccc_value = enableNotification | ( enableIndication << 1 );
    COND_PRINT(env.DEBUG_DATA, "GATTHandler::configNotificationIndication decl %s, enableNotification %d, enableIndication %d",
            cccd.toString().c_str(), enableNotification, enableIndication);
    cccd.value.resize(2, 2);
    cccd.value.put_uint16_nc(0, ccc_value);
    try {
        return writeDescriptorValue(cccd);
    } catch (BluetoothException & bte) {
        if( !enableNotification && !enableIndication ) {
            // OK to have lost connection @ disable
            WORDY_PRINT("GATTHandler::configNotificationIndication(disable) on %s caught exception: %s", deviceString.c_str(), bte.what());
            return false;
        } else {
            throw; // re-throw current exception
        }
    }
}

/*********************************************************************************************************************/
/*********************************************************************************************************************/
/*********************************************************************************************************************/

static const uuid16_t _GENERIC_ACCESS(GattServiceType::GENERIC_ACCESS);
static const uuid16_t _DEVICE_NAME(GattCharacteristicType::DEVICE_NAME);
static const uuid16_t _APPEARANCE(GattCharacteristicType::APPEARANCE);
static const uuid16_t _PERIPHERAL_PREFERRED_CONNECTION_PARAMETERS(GattCharacteristicType::PERIPHERAL_PREFERRED_CONNECTION_PARAMETERS);

static const uuid16_t _DEVICE_INFORMATION(GattServiceType::DEVICE_INFORMATION);
static const uuid16_t _SYSTEM_ID(GattCharacteristicType::SYSTEM_ID);
static const uuid16_t _MODEL_NUMBER_STRING(GattCharacteristicType::MODEL_NUMBER_STRING);
static const uuid16_t _SERIAL_NUMBER_STRING(GattCharacteristicType::SERIAL_NUMBER_STRING);
static const uuid16_t _FIRMWARE_REVISION_STRING(GattCharacteristicType::FIRMWARE_REVISION_STRING);
static const uuid16_t _HARDWARE_REVISION_STRING(GattCharacteristicType::HARDWARE_REVISION_STRING);
static const uuid16_t _SOFTWARE_REVISION_STRING(GattCharacteristicType::SOFTWARE_REVISION_STRING);
static const uuid16_t _MANUFACTURER_NAME_STRING(GattCharacteristicType::MANUFACTURER_NAME_STRING);
static const uuid16_t _REGULATORY_CERT_DATA_LIST(GattCharacteristicType::REGULATORY_CERT_DATA_LIST);
static const uuid16_t _PNP_ID(GattCharacteristicType::PNP_ID);

std::shared_ptr<GattGenericAccessSvc> GATTHandler::getGenericAccess(std::vector<GATTCharacteristicRef> & genericAccessCharDeclList) {
    std::shared_ptr<GattGenericAccessSvc> res = nullptr;
    POctets value(number(Defaults::MAX_ATT_MTU), 0);
    std::string deviceName = "";
    AppearanceCat appearance = AppearanceCat::UNKNOWN;
    std::shared_ptr<GattPeriphalPreferredConnectionParameters> prefConnParam = nullptr;

    const std::lock_guard<std::recursive_mutex> lock(mtx_command); // RAII-style acquire and relinquish via destructor

    for(size_t i=0; i<genericAccessCharDeclList.size(); i++) {
        const GATTCharacteristic & charDecl = *genericAccessCharDeclList.at(i);
        std::shared_ptr<GATTService> service = charDecl.getServiceUnchecked();
        if( nullptr == service || _GENERIC_ACCESS != *(service->type) ) {
        	continue;
        }
        if( _DEVICE_NAME == *charDecl.value_type ) {
            if( readCharacteristicValue(charDecl, value.resize(0)) ) {
            	deviceName = GattNameToString(value); // mandatory
            }
        } else if( _APPEARANCE == *charDecl.value_type ) {
            if( readCharacteristicValue(charDecl, value.resize(0)) && value.getSize() >= 2 ) {
            	appearance = static_cast<AppearanceCat>(value.get_uint16(0)); // manatory
            }
        } else if( _PERIPHERAL_PREFERRED_CONNECTION_PARAMETERS == *charDecl.value_type ) {
            if( readCharacteristicValue(charDecl, value.resize(0)) ) {
            	prefConnParam = GattPeriphalPreferredConnectionParameters::get(value); // optional
            }
        }
    }
    if( deviceName.size() > 0 ) {
    	res = std::shared_ptr<GattGenericAccessSvc>(new GattGenericAccessSvc(deviceName, appearance, prefConnParam));
    }
    return res;
}

std::shared_ptr<GattGenericAccessSvc> GATTHandler::getGenericAccess(std::vector<GATTServiceRef> & primServices) {
	std::shared_ptr<GattGenericAccessSvc> res = nullptr;
	for(size_t i=0; i<primServices.size() && nullptr == res; i++) {
		res = getGenericAccess(primServices.at(i)->characteristicList);
	}
	return res;
}

bool GATTHandler::ping() {
    const std::lock_guard<std::recursive_mutex> lock(mtx_command); // RAII-style acquire and relinquish via destructor
    bool isOK = true;

    for(size_t i=0; isOK && i<services.size(); i++) {
        std::vector<GATTCharacteristicRef> & genericAccessCharDeclList = services.at(i)->characteristicList;
        POctets value(32, 0);

        for(size_t i=0; isOK && i<genericAccessCharDeclList.size(); i++) {
            const GATTCharacteristic & charDecl = *genericAccessCharDeclList.at(i);
            std::shared_ptr<GATTService> service = charDecl.getServiceUnchecked();
            if( nullptr == service || _GENERIC_ACCESS != *(service->type) ) {
                continue;
            }
            if( _APPEARANCE == *charDecl.value_type ) {
                if( readCharacteristicValue(charDecl, value.resize(0)) ) {
                    return true; // unique success case
                }
                // read failure, but not disconnected as no exception thrown from sendWithReply
                isOK = false;
            }
        }
    }
    if( isOK ) {
        INFO_PRINT("GATTHandler::pingGATT: No GENERIC_ACCESS Service with APPEARANCE Characteristic available -> disconnect");
    } else {
        INFO_PRINT("GATTHandler::pingGATT: Read error -> disconnect");
    }
    disconnect(true /* disconnectDevice */, true /* ioErrorCause */); // state -> Disconnected
    return false;
}

std::shared_ptr<GattDeviceInformationSvc> GATTHandler::getDeviceInformation(std::vector<GATTCharacteristicRef> & characteristicDeclList) {
    std::shared_ptr<GattDeviceInformationSvc> res = nullptr;
    POctets value(number(Defaults::MAX_ATT_MTU), 0);

    POctets systemID(8, 0);
    std::string modelNumber;
    std::string serialNumber;
    std::string firmwareRevision;
    std::string hardwareRevision;
    std::string softwareRevision;
    std::string manufacturer;
    POctets regulatoryCertDataList(128, 0);
    std::shared_ptr<GattPnP_ID> pnpID = nullptr;
    bool found = false;

    const std::lock_guard<std::recursive_mutex> lock(mtx_command); // RAII-style acquire and relinquish via destructor

    for(size_t i=0; i<characteristicDeclList.size(); i++) {
        const GATTCharacteristic & charDecl = *characteristicDeclList.at(i);
        std::shared_ptr<GATTService> service = charDecl.getServiceUnchecked();
        if( nullptr == service || _DEVICE_INFORMATION != *(service->type) ) {
            continue;
        }
        found = true;
        if( _SYSTEM_ID == *charDecl.value_type ) {
            if( readCharacteristicValue(charDecl, systemID.resize(0)) ) {
                // nop
            }
        } else if( _REGULATORY_CERT_DATA_LIST == *charDecl.value_type ) {
            if( readCharacteristicValue(charDecl, regulatoryCertDataList.resize(0)) ) {
                // nop
            }
        } else if( _PNP_ID == *charDecl.value_type ) {
            if( readCharacteristicValue(charDecl, value.resize(0)) ) {
                pnpID = GattPnP_ID::get(value);
            }
        } else if( _MODEL_NUMBER_STRING == *charDecl.value_type ) {
            if( readCharacteristicValue(charDecl, value.resize(0)) ) {
                modelNumber = GattNameToString(value);
            }
        } else if( _SERIAL_NUMBER_STRING == *charDecl.value_type ) {
            if( readCharacteristicValue(charDecl, value.resize(0)) ) {
                serialNumber = GattNameToString(value);
            }
        } else if( _FIRMWARE_REVISION_STRING == *charDecl.value_type ) {
            if( readCharacteristicValue(charDecl, value.resize(0)) ) {
                firmwareRevision = GattNameToString(value);
            }
        } else if( _HARDWARE_REVISION_STRING == *charDecl.value_type ) {
            if( readCharacteristicValue(charDecl, value.resize(0)) ) {
                hardwareRevision = GattNameToString(value);
            }
        } else if( _SOFTWARE_REVISION_STRING == *charDecl.value_type ) {
            if( readCharacteristicValue(charDecl, value.resize(0)) ) {
                softwareRevision = GattNameToString(value);
            }
        } else if( _MANUFACTURER_NAME_STRING == *charDecl.value_type ) {
            if( readCharacteristicValue(charDecl, value.resize(0)) ) {
                manufacturer = GattNameToString(value);
            }
        }
    }
    if( found ) {
        res = std::shared_ptr<GattDeviceInformationSvc>(new GattDeviceInformationSvc(systemID, modelNumber, serialNumber,
                                                      firmwareRevision, hardwareRevision, softwareRevision,
                                                      manufacturer, regulatoryCertDataList, pnpID) );
    }
    return res;
}

std::shared_ptr<GattDeviceInformationSvc> GATTHandler::getDeviceInformation(std::vector<GATTServiceRef> & primServices) {
    std::shared_ptr<GattDeviceInformationSvc> res = nullptr;
    for(size_t i=0; i<primServices.size() && nullptr == res; i++) {
        res = getDeviceInformation(primServices.at(i)->characteristicList);
    }
    return res;
}