// SPDX-FileCopyrightText: Deutsches Elektronen-Synchrotron DESY, MSK, ChimeraTK Project <chimeratk-support@desy.de>
// SPDX-License-Identifier: LGPL-3.0-or-later
#pragma once

#include "Application.h"
#include "FanOut.h"
#include "InternalModule.h"

#include <ChimeraTK/NDRegisterAccessor.h>
#include <ChimeraTK/ReadAnyGroup.h>

namespace ChimeraTK {

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

  /** FanOut implementation with an internal thread which waits for new data which
   * is read from the given feeding implementation and distributed to any number
   * of slaves. */
  template<typename UserType>
  class ThreadedFanOut : public FanOut<UserType>, public InternalModule {
   public:
    ThreadedFanOut(boost::shared_ptr<ChimeraTK::NDRegisterAccessor<UserType>> feedingImpl, VariableNetwork& network,
        ConsumerImplementationPairs<UserType> const& consumerImplementationPairs);

    ~ThreadedFanOut();

    void activate() override;

    void deactivate() override;

    /** Synchronise feeder and the consumers. This function is executed in the
     * separate thread. */
    virtual void run();

    VersionNumber readInitialValues();

   protected:
    /** Thread handling the synchronisation, if needed */
    boost::thread _thread;

    /** Reference to VariableNetwork which is being realised by this FanOut. **/
    VariableNetwork& _network;
  };

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

  /** Same as ThreadedFanOut but with return channel */
  template<typename UserType>
  class ThreadedFanOutWithReturn : public ThreadedFanOut<UserType> {
   public:
    ThreadedFanOutWithReturn(boost::shared_ptr<ChimeraTK::NDRegisterAccessor<UserType>> feedingImpl,
        VariableNetwork& network, ConsumerImplementationPairs<UserType> const& consumerImplementationPairs);

    void setReturnChannelSlave(boost::shared_ptr<ChimeraTK::NDRegisterAccessor<UserType>> returnChannelSlave);

    void addSlave(
        boost::shared_ptr<ChimeraTK::NDRegisterAccessor<UserType>> slave, VariableNetworkNode& consumer) override;

    void run() override;

   protected:
    /** Thread handling the synchronisation, if needed */
    boost::thread _thread;

    boost::shared_ptr<ChimeraTK::NDRegisterAccessor<UserType>> _returnChannelSlave;

    using ThreadedFanOut<UserType>::_network;
    using ThreadedFanOut<UserType>::readInitialValues;
    using EntityOwner::testableModeReached;
  };

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

  template<typename UserType>
  ThreadedFanOut<UserType>::ThreadedFanOut(boost::shared_ptr<ChimeraTK::NDRegisterAccessor<UserType>> feedingImpl,
      VariableNetwork& network, ConsumerImplementationPairs<UserType> const& consumerImplementationPairs)
  : FanOut<UserType>(feedingImpl), _network(network) {
    assert(feedingImpl->getAccessModeFlags().has(AccessMode::wait_for_new_data));
    for(auto el : consumerImplementationPairs) {
      FanOut<UserType>::addSlave(el.first, el.second);
    }
  }

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

  template<typename UserType>
  ThreadedFanOut<UserType>::~ThreadedFanOut() {
    deactivate();
  }

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

  template<typename UserType>
  void ThreadedFanOut<UserType>::activate() {
    if(this->_disabled) return;
    assert(!_thread.joinable());
    _thread = boost::thread([this] { this->run(); });
  }

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

  template<typename UserType>
  void ThreadedFanOut<UserType>::deactivate() {
    if(_thread.joinable()) {
      _thread.interrupt();
      FanOut<UserType>::interrupt();
      _thread.join();
    }
    assert(!_thread.joinable());
  }

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

  template<typename UserType>
  void ThreadedFanOut<UserType>::run() {
    Application::registerThread("ThFO" + FanOut<UserType>::impl->getName());
    Application::getInstance().getTestableMode().lock("start");
    testableModeReached = true;

    ChimeraTK::VersionNumber version{nullptr};
    version = readInitialValues();
    while(true) {
      // send out copies to slaves
      boost::this_thread::interruption_point();
      auto validity = FanOut<UserType>::impl->dataValidity();
      for(auto& slave : FanOut<UserType>::slaves) {
        // do not send copy if no data is expected (e.g. trigger)
        if(slave->getNumberOfSamples() != 0) {
          slave->accessChannel(0) = FanOut<UserType>::impl->accessChannel(0);
        }
        slave->setDataValidity(validity);
        bool dataLoss = slave->writeDestructively(version);
        if(dataLoss) Application::incrementDataLossCounter(slave->getName());
      }
      // receive data
      boost::this_thread::interruption_point();
      FanOut<UserType>::impl->read();
      version = FanOut<UserType>::impl->getVersionNumber();
    }
  }

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

  template<typename UserType>
  VersionNumber ThreadedFanOut<UserType>::readInitialValues() {
    Application::getInstance().getTestableMode().unlock("readInitialValues");
    FanOut<UserType>::impl->read();
    if(!Application::getInstance().getTestableMode().testLock()) {
      Application::getInstance().getTestableMode().lock("readInitialValues");
    }
    return FanOut<UserType>::impl->getVersionNumber();
  }

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

  template<typename UserType>
  ThreadedFanOutWithReturn<UserType>::ThreadedFanOutWithReturn(
      boost::shared_ptr<ChimeraTK::NDRegisterAccessor<UserType>> feedingImpl, VariableNetwork& network,
      ConsumerImplementationPairs<UserType> const& consumerImplementationPairs)
  : ThreadedFanOut<UserType>(feedingImpl, network, consumerImplementationPairs) {
    for(auto el : consumerImplementationPairs) {
      // TODO Calling a virtual in the constructor seems odd,
      //      but works because we want this version's implementation
      addSlave(el.first, el.second);
    }
  }

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

  template<typename UserType>
  void ThreadedFanOutWithReturn<UserType>::setReturnChannelSlave(
      boost::shared_ptr<ChimeraTK::NDRegisterAccessor<UserType>> returnChannelSlave) {
    _returnChannelSlave = returnChannelSlave;
  }

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

  template<typename UserType>
  void ThreadedFanOutWithReturn<UserType>::addSlave(
      boost::shared_ptr<ChimeraTK::NDRegisterAccessor<UserType>> slave, VariableNetworkNode& consumer) {
    // TODO Adding slaves is currently by done by the ThreadedFanOut base class.
    //      Refactor constructors and addSlaves for all FanOuts?
    // FanOut<UserType>::addSlave(slave, consumer);
    if(consumer.getDirection().withReturn) {
      assert(_returnChannelSlave == nullptr);
      _returnChannelSlave = slave;
    }
  }

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

  template<typename UserType>
  void ThreadedFanOutWithReturn<UserType>::run() {
    Application::registerThread("ThFO" + FanOut<UserType>::impl->getName());
    Application::getInstance().getTestableMode().lock("start");
    testableModeReached = true;

    TransferElementID var;
    ChimeraTK::VersionNumber version{nullptr};

    version = readInitialValues();

    ReadAnyGroup group({FanOut<UserType>::impl, _returnChannelSlave});
    while(true) {
      // send out copies to slaves
      for(auto& slave : FanOut<UserType>::slaves) {
        // do not feed back value returnChannelSlave if it was received from it
        if(slave->getId() == var) continue;
        // do not send copy if no data is expected (e.g. trigger)
        if(slave->getNumberOfSamples() != 0) {
          slave->accessChannel(0) = FanOut<UserType>::impl->accessChannel(0);
        }
        bool dataLoss = slave->writeDestructively(version);
        if(dataLoss) Application::incrementDataLossCounter(slave->getName());
      }
      // receive data
      boost::this_thread::interruption_point();
      var = group.readAny();
      boost::this_thread::interruption_point();
      // if the update came through the return channel, return it to the feeder
      if(var == _returnChannelSlave->getId()) {
        FanOut<UserType>::impl->accessChannel(0).swap(_returnChannelSlave->accessChannel(0));
        if(version < _returnChannelSlave->getVersionNumber()) {
          version = _returnChannelSlave->getVersionNumber();
        }
        FanOut<UserType>::impl->write(version);
      }
      else {
        version = FanOut<UserType>::impl->getVersionNumber();
      }
    }
  }

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

} /* namespace ChimeraTK */