// Copyright (C) 2017 The Qt Company Ltd.
// SPDX-License-Identifier: LicenseRef-Qt-Commercial OR LGPL-3.0-only OR GPL-2.0-only OR GPL-3.0-only

#include "qcanbusdevice.h"
#include "qcanbusdevice_p.h"
#include "qcanbusdeviceinfo_p.h"

#include "qcanbusframe.h"

#include <QtCore/qdebug.h>
#include <QtCore/qdatastream.h>
#include <QtCore/qeventloop.h>
#include <QtCore/qloggingcategory.h>
#include <QtCore/qscopedvaluerollback.h>
#include <QtCore/qtimer.h>

QT_BEGIN_NAMESPACE

Q_LOGGING_CATEGORY(QT_CANBUS, "qt.canbus")

/*!
    \class QCanBusDevice
    \inmodule QtSerialBus
    \since 5.8

    \brief The QCanBusDevice class is the interface class for CAN bus.

    QCanBusDevice communicates with a CAN plugin providing users with a convenient API.
    The CAN plugin must be specified during the object creation.
*/

/*!
    \enum QCanBusDevice::CanBusError
    This enum describes all the possible error conditions.

    \value NoError              No errors have occurred.
    \value ReadError            An error occurred during a read operation.
    \value WriteError           An error occurred during a write operation.
    \value ConnectionError      An error occurred when attempting to open the plugin.
    \value ConfigurationError   An error occurred when attempting to set a configuration
                                parameter.
    \value UnknownError         An unknown error occurred.
    \value OperationError       An operation was attempted while the device was in
                                a state that did not permit it. This enum was introduced
                                in Qt 5.14.
    \value TimeoutError         An timeout occurred while waiting for frames written or
                                received. This enum was introduced in Qt 5.14.
*/

/*!
    \enum QCanBusDevice::CanBusDeviceState
    This enum describes all possible device states.

    \value UnconnectedState The device is disconnected.
    \value ConnectingState  The device is being connected.
    \value ConnectedState   The device is connected to the CAN bus.
    \value ClosingState     The device is being closed.
*/

/*!
    \enum QCanBusDevice::ConfigurationKey
    This enum describes the possible configuration options for
    the CAN bus connection.

    \value RawFilterKey     This configuration determines the type of CAN bus frames
                            that the current device accepts. The expected value
                            is \c QList<QCanBusDevice::Filter>. Passing an empty list clears
                            all previously set filters including default filters. For more details
                            see \l QCanBusDevice::Filter.
    \value ErrorFilterKey   This key defines the type of error that should be
                            forwarded via the current connection. The associated
                            value should be of type \l QCanBusFrame::FrameErrors.
    \value LoopbackKey      This key defines whether the CAN bus device should operate in loopback
                            mode. Loopback means, whenever a CAN frame is transmitted on the CAN
                            bus, a local echo of this frame is sent to all applications connected to
                            this CAN device. The expected value for this key is \c bool.
    \value ReceiveOwnKey    This key defines whether this CAN device receives its own send frames.
                            This can be used to check if the transmission was successful.
                            The expected value for this key is \c bool.
    \value BitRateKey       This key defines the CAN bitrate in bits per second. With CAN FD,
                            the payload can be transmitted at a higher data bitrate,
                            if \l QCanBusFrame::hasBitrateSwitch() is set. In this case,
                            \c QCanBusDevice::BitRateKey is only used for the CAN ID arbitration
                            phase. See also \c QCanBusDevice::DataBitRateKey
    \value CanFdKey         This key defines whether sending and receiving of CAN FD frames
                            should be enabled. The expected value for this key is \c bool.
    \value DataBitRateKey   This key defines the CAN FD payload bitrate in bits per second.
                            CAN FD allows to transmit the payload of frames with
                            \l QCanBusFrame::hasBitrateSwitch() flag at a higher data bitrate,
                            after the arbitration phase at the nominal bitrate is finished.
                            This enum value was introduced in Qt 5.9.
                            See also \c QCanBusDevice::BitRateKey
    \value ProtocolKey      This key allows to specify another protocol. For now, this
                            parameter can only be set and used in the SocketCAN plugin.
                            This enum value was introduced in Qt 5.14.
    \value UserKey          This key defines the range where custom keys start. Its most
                            common purpose is to permit platform-specific configuration
                            options.

    \sa configurationParameter()
*/

/*!
    \class QCanBusDevice::Filter
    \inmodule QtSerialBus
    \since 5.8

    \brief The QCanBusDevice::Filter struct defines a filter for CAN bus frames.

    A list of QCanBusDevice::Filter instances is passed to
    \l QCanBusDevice::setConfigurationParameter() to enable filtering. If a received CAN frame
    matches at least one of the filters in the list, the QCanBusDevice will accept it.

    The example below demonstrates how to use the struct:

    \snippet snippetmain.cpp Filter Examples
*/

/*!
    \fn bool QCanBusDevice::Filter::operator==(const QCanBusDevice::Filter &a, const QCanBusDevice::Filter &b)

    Returns \c true, if the filter \a a is equal to the filter \a b,
    otherwise returns \c false.
*/

/*!
    \fn bool QCanBusDevice::Filter::operator!=(const QCanBusDevice::Filter &a, const QCanBusDevice::Filter &b)

    Returns \c true, if the filter \a a is not equal to the filter \a b,
    otherwise returns \c false.
*/

/*!
    \enum QCanBusDevice::Filter::FormatFilter
    This enum describes the format pattern, which is used to filter incoming
    CAN bus frames.

    \value MatchBaseFormat              The CAN bus frame must use the base frame format
                                        (11 bit identifier).
    \value MatchExtendedFormat          The CAN bus frame must use the extended frame format
                                        (29 bit identifier).
    \value MatchBaseAndExtendedFormat   The CAN bus frame can have a base or an extended
                                        frame format.
*/

/*!
    \variable QCanBusDevice::Filter::frameId

    \brief The frame id used to filter the incoming frames.

    The frameId is used in conjunction with \a frameIdMask.
    The matching is successful if the following evaluates to \c true:

    \code
        (receivedFrameId & frameIdMask) == (frameId & frameIdMask)
    \endcode

    By default this field is set to \c 0x0.

    \sa frameIdMask
*/

/*!
    \variable QCanBusDevice::Filter::frameIdMask

    \brief The bit mask that is applied to the frame id of the filter and the received frame.

    The two frame ids are matching if the following evaluates to \c true:

    \code
        (receivedFrameId & frameIdMask) == (frameId & frameIdMask)
    \endcode

    By default this field is set to \c 0x0.

    \sa frameId
*/

/*!
    \variable QCanBusDevice::Filter::type

    \brief The type of the frame to be filtered.

    Any CAN bus frame type can be matched by setting this variable
    to \l QCanBusFrame::InvalidFrame. The filter object is invalid if
    type is equal to \l QCanBusFrame::UnknownFrame.

    By default this field is set to \l QCanBusFrame::InvalidFrame.

    \sa QCanBusFrame::FrameType
*/

/*!
    \variable QCanBusDevice::Filter::format

    \brief The frame format of the matching CAN bus frame.

    By default this field is set to \l QCanBusDevice::Filter::MatchBaseAndExtendedFormat.
*/

/*!
    \fn void QCanBusDevice::errorOccurred(CanBusError)

    This signal is emitted when an error occurs.
*/

/*!
    Constructs a serial bus device with the specified \a parent.
*/
QCanBusDevice::QCanBusDevice(QObject *parent) :
    QObject(*new QCanBusDevicePrivate, parent)
{
}


/*!
    Sets the human readable description of the last device error to
    \a errorText. \a errorId categorizes the type of error.

    CAN bus implementations must use this function to update the device's
    error state.

    \sa error(), errorOccurred(), clearError()
*/
void QCanBusDevice::setError(const QString &errorText, CanBusError errorId)
{
    Q_D(QCanBusDevice);

    d->errorText = errorText;
    d->lastError = errorId;

    emit errorOccurred(errorId);
}

/*!
    \since 5.14
    Clears the error id and the human readable description of the last
    device error.

    CAN bus implementations must use this function to update the device's
    error state.

    \sa error(), errorOccurred(), setError()
*/
void QCanBusDevice::clearError()
{
    Q_D(QCanBusDevice);

    d->errorText.clear();
    d->lastError = NoError;
}

/*!
    Appends \a newFrames to the internal list of frames which can be
    accessed using \l readFrame() and emits the \l framesReceived()
    signal.

    Subclasses must call this function when they receive frames.

*/
void QCanBusDevice::enqueueReceivedFrames(const QList<QCanBusFrame> &newFrames)
{
    Q_D(QCanBusDevice);

    if (Q_UNLIKELY(newFrames.isEmpty()))
        return;

    d->incomingFramesGuard.lock();
    d->incomingFrames.append(newFrames);
    d->incomingFramesGuard.unlock();
    emit framesReceived();
}

/*!
    Appends \a newFrame to the internal list of outgoing frames which
    can be accessed by \l writeFrame().

    Subclasses must call this function when they write a new frame.
*/
void QCanBusDevice::enqueueOutgoingFrame(const QCanBusFrame &newFrame)
{
    Q_D(QCanBusDevice);

    d->outgoingFrames.append(newFrame);
}

/*!
    Returns the next \l QCanBusFrame from the internal list of outgoing frames;
    otherwise returns an invalid QCanBusFrame. The returned frame is removed
    from the internal list.
*/
QCanBusFrame QCanBusDevice::dequeueOutgoingFrame()
{
    Q_D(QCanBusDevice);

    if (Q_UNLIKELY(d->outgoingFrames.isEmpty()))
        return QCanBusFrame(QCanBusFrame::InvalidFrame);
    return d->outgoingFrames.takeFirst();
}

/*!
    Returns \c true if the internal list of outgoing frames is not
    empty; otherwise returns \c false.
*/
bool QCanBusDevice::hasOutgoingFrames() const
{
    Q_D(const QCanBusDevice);

    return !d->outgoingFrames.isEmpty();
}

/*!
    Sets the configuration parameter \a key for the CAN bus connection
    to \a value. The potential keys are represented by \l ConfigurationKey.

    A parameter can be unset by setting an invalid \l QVariant.
    Unsetting a parameter implies that the configuration is reset to
    its default setting.

    \note In most cases, configuration changes only take effect
    after a reconnect.

    \sa configurationParameter()
*/
void QCanBusDevice::setConfigurationParameter(ConfigurationKey key, const QVariant &value)
{
    Q_D(QCanBusDevice);

    for (int i = 0; i < d->configOptions.size(); i++) {
        if (d->configOptions.at(i).first == key) {
            if (value.isValid()) {
                ConfigEntry &entry = d->configOptions[i];
                entry.second = value;
            } else {
                d->configOptions.remove(i);
            }
            return;
        }
    }

    if (!value.isValid())
        return;

    ConfigEntry newEntry(key, value);
    d->configOptions.append(newEntry);
}

/*!
    Returns the current value assigned to the \l ConfigurationKey \a key; otherwise
    an invalid \l QVariant.

    \sa setConfigurationParameter(), configurationKeys()
*/
QVariant QCanBusDevice::configurationParameter(ConfigurationKey key) const
{
    Q_D(const QCanBusDevice);

    for (const ConfigEntry &e : d->configOptions) {
        if (e.first == key)
            return e.second;
    }

    return QVariant();
}

/*!
    Returns the list of keys used by the CAN bus connection.

    The meaning of the keys is equivalent to \l ConfigurationKey.
    If a key is not explicitly mentioned, the platform's
    default setting for the relevant key is used.
*/
QList<QCanBusDevice::ConfigurationKey> QCanBusDevice::configurationKeys() const
{
    Q_D(const QCanBusDevice);

    QList<ConfigurationKey> result;
    for (const ConfigEntry &e : d->configOptions)
        result.append(e.first);

    return result;
}

/*!
    Returns the last error that has occurred. The error value is always set to last error that
    occurred and it is never reset.

    \sa errorString()
*/
QCanBusDevice::CanBusError QCanBusDevice::error() const
{
    return d_func()->lastError;
}

/*!
    Returns a human-readable description of the last device error that occurred.

    \sa error()
*/
QString QCanBusDevice::errorString() const
{
    Q_D(const QCanBusDevice);

    if (d->lastError == QCanBusDevice::NoError)
        return QString();

    return d->errorText;
}

/*!
    Returns the number of available frames. If no frames are available,
    this function returns 0.

    \sa clear(), readFrame(), readAllFrames()
*/
qint64 QCanBusDevice::framesAvailable() const
{
    Q_D(const QCanBusDevice);

    QMutexLocker locker(&d->incomingFramesGuard);
    return d->incomingFrames.size();
}

/*!
    For buffered devices, this function returns the number of frames waiting to be written.
    For unbuffered devices, this function always returns zero.

    \note There may be additional buffering in the CAN driver and CAN hardware layer.
    Therefore, if this function returns zero, that does not mean all CAN frames are
    already written to the CAN bus.

    \sa clear(), writeFrame()
*/
qint64 QCanBusDevice::framesToWrite() const
{
    return d_func()->outgoingFrames.size();
}

/*!
    \since 5.14

    Performs a CAN controller reset to release the CAN controller from
    bus off state, if possible.

    \note CAN controller resets disturb the running communication and
    may take up to one second to complete. Only call this function to
    recover from bus errors.

    \note This function may not be implemented in all CAN plugins.
    Please refer to the plugins help pages for more information.

    \sa busStatus()
*/
void QCanBusDevice::resetController()
{
    const char error[] = QT_TRANSLATE_NOOP("QCanBusDevice",
            "This CAN bus plugin does not support hardware controller reset.");
    qCWarning(QT_CANBUS, error);
    setError(tr(error), QCanBusDevice::CanBusError::ConfigurationError);
}

/*!
    \since 5.14

    Return true, if the CAN plugin supports requesting the CAN bus status.

    \sa busStatus()
 */
bool QCanBusDevice::hasBusStatus() const
{
    return false;
}

/*!
    \since 5.14
    \enum QCanBusDevice::CanBusStatus

    This enum describes possible CAN bus status values.

    \value Unknown  The CAN bus status is unknown
                    (e.g. not supported by the CAN plugin).
    \value Good     The CAN controller is fully operational
    \value Warning  The CAN controller is in warning status
    \value Error    The CAN controller is in error status
                    (no longer sending CAN frames)
    \value BusOff   The CAN controller is in bus off status
                    (disconnected from the CAN bus)
*/

/*!
    \since 5.14

    Returns the current CAN bus status. If the status cannot be requested,
    QCanBusDevice::UnknownStatus is returned.

    \note This function may not be implemented in all CAN plugins.
    Please refer to the plugins help pages for more information.
    The function hasBusStatus() can be used at runtime to check if
    the used CAN plugin has support for requesting the CAN bus status.

    \sa hasBusStatus(), resetController()
*/
QCanBusDevice::CanBusStatus QCanBusDevice::busStatus()
{
    return QCanBusDevice::CanBusStatus::Unknown;
}

/*!
    \since 5.12
    \enum QCanBusDevice::Direction

    This enum describes possible data transmission directions.

    \value Input            Input direction.
    \value Output           Output direction.
    \value AllDirections    Both directions, input and output.
*/

/*!
    \since 5.12
    Clears the devices input or output buffers, depending on \a direction.

    This function only operates on QCanBusDevice buffers. Frames that are
    already written to the CAN driver or CAN hardware layer, or that are
    not yet read from these layers, are not cleared by this function.

    \note Clearing the output buffers is only possible for buffered devices.

    \sa framesAvailable(), readFrame(), framesToWrite(), writeFrame(),
*/
void QCanBusDevice::clear(QCanBusDevice::Directions direction)
{
    Q_D(QCanBusDevice);

    if (Q_UNLIKELY(d->state != ConnectedState)) {
        const QString error = tr("Cannot clear buffers as device is not connected.");
        qCWarning(QT_CANBUS, "%ls", qUtf16Printable(error));
        setError(error, CanBusError::OperationError);
        return;
    }

    clearError();

    if (direction & Direction::Input) {
        QMutexLocker locker(&d->incomingFramesGuard);
        d->incomingFrames.clear();
    }

    if (direction & Direction::Output)
        d->outgoingFrames.clear();
}

/*!
    For buffered devices, this function waits until all buffered frames
    have been written to the device and the \l framesWritten() signal has been emitted,
    or until \a msecs milliseconds have passed. If \a msecs is -1,
    this function will not time out. For unbuffered devices, it returns immediately with \c false
    as \l writeFrame() does not require a write buffer.

    Returns \c true if the \l framesWritten() signal is emitted;
    otherwise returns \c false (i.e. if the operation timed out, or if an error occurred).

    \note This function will start a local event loop. This may lead to scenarios whereby
    other application slots may be called while the execution of this function scope is blocking.
    To avoid problems, the signals for this class should not be connected to slots.
    Similarly this function must never be called in response to the \l framesWritten()
    or \l errorOccurred() signals.

    \sa waitForFramesReceived()
 */
bool QCanBusDevice::waitForFramesWritten(int msecs)
{
    // do not enter this function recursively
    if (Q_UNLIKELY(d_func()->waitForWrittenEntered)) {
        qCWarning(QT_CANBUS, "QCanBusDevice::waitForFramesWritten() must not be called "
                             "recursively. Check that no slot containing waitForFramesWritten() "
                             "is called in response to framesWritten(qint64) or "
                             "errorOccurred(CanBusError) signals.");
        setError(tr("QCanBusDevice::waitForFramesWritten() must not be called recursively."),
                 CanBusError::OperationError);
        return false;
    }

    if (Q_UNLIKELY(d_func()->state != ConnectedState)) {
        const QString error = tr("Cannot wait for frames written as device is not connected.");
        qCWarning(QT_CANBUS, "%ls", qUtf16Printable(error));
        setError(error, CanBusError::OperationError);
        return false;
    }

    if (!framesToWrite())
        return false; // nothing pending, nothing to wait upon

    QScopedValueRollback<bool> guard(d_func()->waitForWrittenEntered);
    d_func()->waitForWrittenEntered = true;

    enum { Written = 0, Error, Timeout };
    QEventLoop loop;
    connect(this, &QCanBusDevice::framesWritten, &loop, [&]() { loop.exit(Written); });
    connect(this, &QCanBusDevice::errorOccurred, &loop, [&]() { loop.exit(Error); });
    if (msecs >= 0)
        QTimer::singleShot(msecs, &loop, [&]() { loop.exit(Timeout); });

    int result = Written;
    while (framesToWrite() > 0) {
        // wait till all written or time out
        result = loop.exec(QEventLoop::ExcludeUserInputEvents);
        if (Q_UNLIKELY(result == Timeout)) {
            const QString error = tr("Timeout (%1 ms) during wait for frames written.").arg(msecs);
            setError(error, CanBusError::TimeoutError);
            qCWarning(QT_CANBUS, "%ls", qUtf16Printable(error));
        }

        if (result > Written)
            return false;
    }

    clearError();
    return true;
}

/*!
    Blocks until new frames are available for reading and the \l framesReceived()
    signal has been emitted, or until \a msecs milliseconds have passed. If
    \a msecs is \c -1, this function will not time out.

    Returns \c true if new frames are available for reading and the \l framesReceived()
    signal is emitted; otherwise returns \c false (if the operation timed out
    or if an error occurred).

    \note This function will start a local event loop. This may lead to scenarios whereby
    other application slots may be called while the execution of this function scope is blocking.
    To avoid problems, the signals for this class should not be connected to slots.
    Similarly this function must never be called in response to the \l framesReceived()
    or \l errorOccurred() signals.

    \sa waitForFramesWritten()
 */
bool QCanBusDevice::waitForFramesReceived(int msecs)
{
    // do not enter this function recursively
    if (Q_UNLIKELY(d_func()->waitForReceivedEntered)) {
        qCWarning(QT_CANBUS, "QCanBusDevice::waitForFramesReceived() must not be called "
                             "recursively. Check that no slot containing waitForFramesReceived() "
                             "is called in response to framesReceived() or "
                             "errorOccurred(CanBusError) signals.");
        setError(tr("QCanBusDevice::waitForFramesReceived() must not be called recursively."),
                 CanBusError::OperationError);
        return false;
    }

    if (Q_UNLIKELY(d_func()->state != ConnectedState)) {
        const QString error = tr("Cannot wait for frames received as device is not connected.");
        qCWarning(QT_CANBUS, "%ls", qUtf16Printable(error));
        setError(error, CanBusError::OperationError);
        return false;
    }

    QScopedValueRollback<bool> guard(d_func()->waitForReceivedEntered);
    d_func()->waitForReceivedEntered = true;

    enum { Received = 0, Error, Timeout };
    QEventLoop loop;
    connect(this, &QCanBusDevice::framesReceived, &loop, [&]() { loop.exit(Received); });
    connect(this, &QCanBusDevice::errorOccurred, &loop, [&]() { loop.exit(Error); });
    if (msecs >= 0)
        QTimer::singleShot(msecs, &loop, [&]() { loop.exit(Timeout); });

    int result = loop.exec(QEventLoop::ExcludeUserInputEvents);

    if (Q_UNLIKELY(result == Timeout)) {
        const QString error = tr("Timeout (%1 ms) during wait for frames received.").arg(msecs);
        setError(error, CanBusError::TimeoutError);
        qCWarning(QT_CANBUS, "%ls", qUtf16Printable(error));
    }

    if (result == Received)
        clearError();
    return result == Received;
}

/*!
    \fn bool QCanBusDevice::open()

    This function is called by connectDevice(). Subclasses must provide
    an implementation which returns \c true if the CAN bus connection
    could be established; otherwise \c false. The QCanBusDevice implementation
    ensures upon entry of this function that the device's \l state() is set
    to \l QCanBusDevice::ConnectingState already.

    The implementation must ensure that upon success the instance's \l state()
    is set to \l QCanBusDevice::ConnectedState; otherwise
    \l QCanBusDevice::UnconnectedState. \l setState() must be used to set the new
    device state.

    The custom implementation is responsible for opening the socket, instanciation
    of a potentially required \l QSocketNotifier and the application of custom and default
    \l QCanBusDevice::configurationParameter().

    \sa connectDevice()
*/

/*!
    \fn void QCanBusDevice::close()

    This function is responsible for closing the CAN bus connection.
    The implementation must ensure that the instance's
    \l state() is set to \l QCanBusDevice::UnconnectedState.

    This function's most important task is to close the socket to the CAN device
    and to call \l QCanBusDevice::setState().

    \sa disconnectDevice()
*/

/*!
    \fn void QCanBusDevice::framesReceived()

    This signal is emitted when one or more frames have been received.
    The frames should be read using \l readFrame() and \l framesAvailable().
*/

/*!
    Returns the next \l QCanBusFrame from the queue; otherwise returns
    an empty QCanBusFrame. The returned frame is removed from the queue.

    The queue operates according to the FIFO principle.

    \sa clear(), framesAvailable(), readAllFrames()
*/
QCanBusFrame QCanBusDevice::readFrame()
{
    Q_D(QCanBusDevice);

    if (Q_UNLIKELY(d->state != ConnectedState)) {
        const QString error = tr("Cannot read frame as device is not connected.");
        qCWarning(QT_CANBUS, "%ls", qUtf16Printable(error));
        setError(error, CanBusError::OperationError);
        return QCanBusFrame(QCanBusFrame::InvalidFrame);
    }

    clearError();

    QMutexLocker locker(&d->incomingFramesGuard);

    if (Q_UNLIKELY(d->incomingFrames.isEmpty()))
        return QCanBusFrame(QCanBusFrame::InvalidFrame);

    return d->incomingFrames.takeFirst();
}

/*!
    \since 5.12
    Returns all \l{QCanBusFrame}s from the queue; otherwise returns
    an empty QList. The returned frames are removed from the queue.

    The queue operates according to the FIFO principle.

    \sa clear(), framesAvailable(), readFrame()
*/
QList<QCanBusFrame> QCanBusDevice::readAllFrames()
{
    Q_D(QCanBusDevice);

    if (Q_UNLIKELY(d->state != ConnectedState)) {
        const QString error = tr("Cannot read frame as device is not connected.");
        qCWarning(QT_CANBUS, "%ls", qUtf16Printable(error));
        setError(error, CanBusError::OperationError);
        return QList<QCanBusFrame>();
    }

    clearError();

    QMutexLocker locker(&d->incomingFramesGuard);

    QList<QCanBusFrame> result;
    result.swap(d->incomingFrames);
    return result;
}

/*!
    \fn void QCanBusDevice::framesWritten(qint64 framesCount)

    This signal is emitted every time a payload of frames has been
    written to the CAN bus. The \a framesCount argument is set to
    the number of frames that were written in this payload.
*/

/*!
    \fn bool QCanBusDevice::writeFrame(const QCanBusFrame &frame)

    Writes \a frame to the CAN bus and returns \c true on success;
    otherwise \c false.

    On some platforms, the frame may be put into a queue and the return
    value may only indicate a successful insertion into the queue.
    The actual frame will be send later on. Therefore the \l framesWritten()
    signal is the final confirmation that the frame has been handed off to
    the transport layer. If an error occurs the \l errorOccurred() is emitted.

    As per CAN bus specification, frames of type
    \l {QCanBusFrame::RemoteRequestFrame} {remote transfer request (RTR)}
    do not have a payload, but a length from 0 to 8 (including). This length
    indicates the expected response payload length from the remote party.
    Therefore when sending a RTR frame using this function it may still
    be required to set an arbitrary payload on \a frame. The length of
    the arbitrary payload is what is set as size expectation for the RTR frame.

    \sa QCanBusFrame::setPayload()
*/

/*!
    \fn QString QCanBusDevice::interpretErrorFrame(const QCanBusFrame &frame)

    Interprets \a frame as error frame and returns a human readable
    description of the error.

    If \a frame is not an error frame, the returned string is empty.
*/

/*!
    Connects the device to the CAN bus. Returns \c true on success;
    otherwise \c false.

    This function calls \l open() as part of its implementation.

    \sa disconnectDevice()
*/
bool QCanBusDevice::connectDevice()
{
    Q_D(QCanBusDevice);

    if (Q_UNLIKELY(d->state != QCanBusDevice::UnconnectedState)) {
        const char error[] = QT_TRANSLATE_NOOP("QCanBusDevice",
                                "Can not connect an already connected device.");
        qCWarning(QT_CANBUS, error);
        setError(tr(error), QCanBusDevice::ConnectionError);
        return false;
    }

    setState(ConnectingState);

    if (!open()) {
        setState(UnconnectedState);
        return false;
    }

    clearError();

    //Connected is set by backend -> might be delayed by event loop
    return true;
}


/*!
    Disconnects the device from the CAN bus.

    This function calls \l close() as part of its implementation.

    \note This function should only be called, if connectDevice()
    returned \c true.

    \sa connectDevice()
*/
void QCanBusDevice::disconnectDevice()
{
    Q_D(QCanBusDevice);

    if (Q_UNLIKELY(d->state == QCanBusDevice::UnconnectedState
            || d->state == QCanBusDevice::ClosingState)) {
        qCWarning(QT_CANBUS, "Can not disconnect an unconnected device.");
        return;
    }

    setState(QCanBusDevice::ClosingState);

    //Unconnected is set by backend -> might be delayed by event loop
    close();
}

/*!
    \fn void QCanBusDevice::stateChanged(QCanBusDevice::CanBusDeviceState state)

    This signal is emitted every time the state of the device changes.
    The new state is represented by \a state.

    \sa setState(), state()
*/

/*!
    Returns the current state of the device.

    \sa setState(), stateChanged()
*/
QCanBusDevice::CanBusDeviceState QCanBusDevice::state() const
{
    return d_func()->state;
}

/*!
    Sets the state of the device to \a newState. CAN bus implementations
    must use this function to update the device state.
*/
void QCanBusDevice::setState(QCanBusDevice::CanBusDeviceState newState)
{
    Q_D(QCanBusDevice);

    if (newState == d->state)
        return;

    d->state = newState;
    emit stateChanged(newState);
}

/*!
 * \since 6.2
 * Returns a QCanBusDeviceInfo created from the given parameters \a plugin,
 * \a name, \a isVirtual, and \a isFlexibleDataRateCapable.
 * \internal
 */
QCanBusDeviceInfo QCanBusDevice::createDeviceInfo(const QString &plugin, const QString &name,
                                                  bool isVirtual,
                                                  bool isFlexibleDataRateCapable)
{
    return createDeviceInfo(plugin, name, QString(), QString(), QString(),
                            0, isVirtual, isFlexibleDataRateCapable);
}

/*!
    \since 6.2
    Returns a QCanBusDeviceInfo created from the given parameters \a plugin,
    \a name, \a serialNumber, \a description, \a alias, \a channel, \a isVirtual,
    and \a isFlexibleDataRateCapable.
    \internal
 */
QCanBusDeviceInfo QCanBusDevice::createDeviceInfo(const QString &plugin,
                                                  const QString &name,
                                                  const QString &serialNumber,
                                                  const QString &description,
                                                  const QString &alias,
                                                  int channel,
                                                  bool isVirtual,
                                                  bool isFlexibleDataRateCapable)
{
    std::unique_ptr<QCanBusDeviceInfoPrivate> info(new QCanBusDeviceInfoPrivate);
    info->plugin = plugin;
    info->name = name;
    info->serialNumber = serialNumber;
    info->description = description;
    info->alias = alias;
    info->channel = channel;
    info->hasFlexibleDataRate = isFlexibleDataRateCapable;
    info->isVirtual = isVirtual;
    return QCanBusDeviceInfo(*info.release());
}

/*!
    \since 6.2

    Returns a QCanBusDeviceInfo for the current QCanBusDevice. If the function
    is not implemented by a sub-class of QCanBusDevice, a default constructed
    object is returned.
 */
QCanBusDeviceInfo QCanBusDevice::deviceInfo() const
{
    return QCanBusDeviceInfo(*(new QCanBusDeviceInfoPrivate));
}

QT_END_NAMESPACE
