/*

 * Copyright 2013-2022 Step Function I/O, LLC

 *

 * Licensed to Green Energy Corp (www.greenenergycorp.com) and Step Function I/O

 * LLC (https://stepfunc.io) under one or more contributor license agreements.

 * See the NOTICE file distributed with this work for additional information

 * regarding copyright ownership. Green Energy Corp and Step Function I/O LLC license

 * this file to you under the Apache License, Version 2.0 (the "License"); you

 * may not use this file except in compliance with the License. You may obtain

 * a copy of the License at:

 *

 * http://www.apache.org/licenses/LICENSE-2.0

 *

 * Unless required by applicable law or agreed to in writing, software

 * distributed under the License is distributed on an "AS IS" BASIS,

 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.

 * See the License for the specific language governing permissions and

 * limitations under the License.

 */

#ifndef OPENDNP3_LAYERINTERFACES_H

#define OPENDNP3_LAYERINTERFACES_H

#include "app/Message.h"

#include <cassert>

namespace opendnp3

{

/**

 * Describes a layer that can be opened or closed in response to the

 * availability of the layer below it.

 */

class IUpDown

{

public:

    virtual ~IUpDown() {}

    // Called by a lower Layer when it is available to this layer

    // return false if the layer is already up

    virtual bool OnLowerLayerUp() = 0;

    // Called by a lower layer when it is no longer available to this layer

    // return false if the layer is already down

    virtual bool OnLowerLayerDown() = 0;

};

class IUpperLayer : public IUpDown

{

public:

    virtual ~IUpperLayer() {}

    // Called by the lower layer when data arrives

    // return false if the layer is down

    virtual bool OnReceive(const Message& message) = 0;

    // Called by the lower layer when it is ready to transmit more data

    virtual bool OnTxReady() = 0;

};

class ILowerLayer

{

public:

    virtual ~ILowerLayer() {}

    virtual bool BeginTransmit(const Message& message) = 0;

};

class HasLowerLayer

{

public:

    HasLowerLayer() : pLowerLayer(nullptr) {}

    // Called by the lower layer when data arrives

    void SetLowerLayer(ILowerLayer& lowerLayer)

    {

        assert(!pLowerLayer);

        pLowerLayer = &lowerLayer;

    }

protected:

    ILowerLayer* pLowerLayer;

};

class HasUpperLayer

{

public:

    HasUpperLayer() : pUpperLayer(nullptr) {}

    // Called by the lower layer when data arrives

    void SetUpperLayer(IUpperLayer& upperLayer)

    {

        assert(!pUpperLayer);

        pUpperLayer = &upperLayer;

    }

protected:

    IUpperLayer* pUpperLayer;

};

} // namespace opendnp3

#endif