// 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/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.
*/

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, QGrpcOperation::if_proto_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.

    The error can be retrieved using \l deserializationError.

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

    \sa read, deserializationError, deserializationErrorString
*/

/*!
    \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, and the error can be retrieved with \l
    deserializationError.

    \sa read, deserializationError, deserializationErrorString
*/
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();
    return ser && ser->deserialize(message, d->data);
}

/*!
    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") });
    }
}

/*!
   \since 6.8

   Returns the last deserialization error.

   \sa QAbstractProtobufSerializer::deserializationError
*/
QAbstractProtobufSerializer::DeserializationError QGrpcOperation::deserializationError() const
{
    Q_D(const QGrpcOperation);
    const auto ser = d->operationContext->serializer();
    if (!ser)
        return QAbstractProtobufSerializer::NoDeserializerError;
    return ser->deserializationError();
}

/*!
   \since 6.8

   Returns the last deserialization error string.

   \sa QAbstractProtobufSerializer::deserializationErrorString
*/
QString QGrpcOperation::deserializationErrorString() const
{
    Q_D(const QGrpcOperation);
    const auto ser = d->operationContext->serializer();
    if (!ser)
        return QStringLiteral("serializer not available");
    return ser->deserializationErrorString();
}

/*!
    Getter of the metadata received from the channel. For the HTTP2 channels it
    usually contains the HTTP headers received from the server.
*/
const QGrpcMetadata &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
    Returns a pointer to the assigned channel-side QGrpcOperationContext.
*/
QGrpcOperationContext *QGrpcOperation::operationContext() const noexcept
{
    Q_D(const QGrpcOperation);
    return d->operationContext.get();
}

QT_END_NAMESPACE

#include "moc_qgrpcoperation.cpp"