// Copyright (C) 2022 The Qt Company Ltd.
// Copyright (C) 2019 Alexey Edelev <semlanik@gmail.com>
// SPDX-License-Identifier: LicenseRef-Qt-Commercial OR GPL-3.0-only

#include <QtGrpc/private/qtgrpcglobal_p.h>
#include <QtGrpc/qgrpcoperation.h>
#include <QtGrpc/qgrpcoperationcontext.h>

#include <QtCore/private/qobject_p.h>
#include <QtCore/qatomic.h>
#include <QtCore/qbytearray.h>
#include <QtCore/qeventloop.h>
#include <QtCore/qpointer.h>

QT_BEGIN_NAMESPACE

using namespace Qt::StringLiterals;

/*!
    \class QGrpcOperation
    \inmodule QtGrpc
    \brief The QGrpcOperation class implements common logic to
           handle the gRPC communication from the client side.
*/

/*!
    \fn void QGrpcOperation::finished(const QGrpcStatus &status)

    This signal indicates the end of communication for this call.

    If this signal is emitted the respective operation when it's finished with
    the respective \a status.

    \note This signal is emitted only once, and in most cases, you will want to
    disconnect right after receiving it to avoid issues, such as lambda
    captures not being destroyed after receiving the signal. An easy way to
    achieve this is by using the Qt::SingleShotConnection \l {Qt::}
    {ConnectionType}.
*/

class QGrpcOperationPrivate : public QObjectPrivate
{
    Q_DECLARE_PUBLIC(QGrpcOperation)
public:
    explicit QGrpcOperationPrivate(std::shared_ptr<QGrpcOperationContext> &&operationContext_)
        : operationContext(operationContext_)
    {
    }

    QByteArray data;
    std::shared_ptr<QGrpcOperationContext> operationContext;
    QAtomicInteger<bool> isFinished{ false };
};

QGrpcOperation::QGrpcOperation(std::shared_ptr<QGrpcOperationContext> operationContext,
                               QObject *parent)
    : QObject(*new QGrpcOperationPrivate(std::move(operationContext)), parent)
{
    Q_D(QGrpcOperation);
    [[maybe_unused]] bool valid = QObject::connect(d->operationContext.get(),
                                                   &QGrpcOperationContext::messageReceived, this,
                                                   [this](const QByteArray &data) {
                                                       Q_D(QGrpcOperation);
                                                       d->data = data;
                                                   });
    Q_ASSERT_X(valid, "QGrpcOperation::QGrpcOperation",
               "Unable to make connection to the 'messageReceived' signal");

    valid = QObject::connect(d->operationContext.get(), &QGrpcOperationContext::finished, this,
                             [this](const QGrpcStatus &status) {
                                 if (!isFinished()) {
                                     Q_D(QGrpcOperation);
                                     d->isFinished.storeRelaxed(true);
                                     emit this->finished(status);
                                 }
                             });
    Q_ASSERT_X(valid, "QGrpcOperation::QGrpcOperation",
               "Unable to make connection to the 'finished' signal");
}

QGrpcOperation::~QGrpcOperation() = default;

/*!
    \fn template <typename T, QtProtobuf::if_protobuf_message<T> = true> std::optional<T> QGrpcOperation::read() const

    Reads a message from a raw byte array stored within this QGrpcOperation
    instance.

    Returns an optional deserialized message. On failure, \c {std::nullopt} is
    returned.

    \note This function only participates in overload resolution if \c T is a
    subclass of QProtobufMessage.

    \sa read
*/

/*!
    \since 6.8
    Reads a message from a raw byte array which is stored within this
    QGrpcOperation instance.

    The function writes the deserialized value to the \a message pointer.

    If the deserialization is successful, this function returns \c true.
    Otherwise, it returns \c false.

    \sa read
*/
bool QGrpcOperation::read(QProtobufMessage *message) const
{
    Q_ASSERT_X(message != nullptr, "QGrpcOperation::read",
               "Can't read to nullptr QProtobufMessage");
    Q_D(const QGrpcOperation);
    const auto ser = d->operationContext->serializer();
    Q_ASSERT_X(ser, "QGrpcOperation", "The serializer is null");
    if (!ser->deserialize(message, d->data)) {
        qGrpcWarning() << "Unable to deserialize message("<< ser->lastError() <<"): "
                       << ser->lastErrorString();
        return false;
    }
    return true;
}

/*!
    T.B.A
*/
void QGrpcOperation::cancel()
{
    if (!isFinished()) {
        Q_D(QGrpcOperation);
        d->isFinished.storeRelaxed(true);
        emit d->operationContext->cancelRequested();
        Q_EMIT finished(QGrpcStatus{ QtGrpc::StatusCode::Cancelled,
                                     tr("Operation is cancelled by client") });
    }
}

/*!
    Getter of the metadata received from the channel. For the HTTP2 channels it
    usually contains the HTTP headers received from the server.
*/
const QHash<QByteArray, QByteArray> &QGrpcOperation::metadata() const & noexcept
{
    Q_D(const QGrpcOperation);
    return d->operationContext->serverMetadata();
}

/*!
    Getter of the method that this operation was initialized with.
*/
QLatin1StringView QGrpcOperation::method() const noexcept
{
    Q_D(const QGrpcOperation);
    return d->operationContext->method();
}

/*!
    Returns true when QGrpcOperation finished its workflow,
    meaning it was finished, canceled, or error occurred, otherwise returns false.
*/
bool QGrpcOperation::isFinished() const noexcept
{
    Q_D(const QGrpcOperation);
    return d->isFinished.loadRelaxed();
}

/*!
    \internal
    \fn const QGrpcOperationContext &QGrpcOperation::context() const &
    \fn QGrpcOperationContext &QGrpcOperation::context() &

    Returns a reference to the internal operation context.
*/
const QGrpcOperationContext &QGrpcOperation::context() const & noexcept
{
    Q_D(const QGrpcOperation);
    return *d->operationContext;
}

bool QGrpcOperation::event(QEvent *event)
{
    return QObject::event(event);
}

QT_END_NAMESPACE

#include "moc_qgrpcoperation.cpp"