/**
 * Copyright (c) The openTCS Authors.
 *
 * This program is free software and subject to the MIT license. (For details,
 * see the licensing information (LICENSE.txt) you should have received with
 * this copy of the software.)
 */
package org.opentcs.kernel.extensions.rmi;

import java.rmi.NotBoundException;
import java.rmi.RemoteException;
import java.rmi.registry.Registry;
import java.rmi.server.UnicastRemoteObject;
import static java.util.Objects.requireNonNull;
import java.util.concurrent.ExecutionException;
import java.util.concurrent.ExecutorService;
import javax.inject.Inject;
import org.opentcs.access.rmi.ClientID;
import org.opentcs.access.rmi.factories.SocketFactoryProvider;
import org.opentcs.access.rmi.services.RegistrationName;
import org.opentcs.access.rmi.services.RemoteDispatcherService;
import org.opentcs.components.kernel.services.DispatcherService;
import org.opentcs.customizations.kernel.KernelExecutor;
import org.opentcs.data.TCSObjectReference;
import org.opentcs.data.model.Vehicle;
import org.opentcs.data.order.TransportOrder;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

/**
 * This class is the standard implementation of the {@link RemoteDispatcherService} interface.
 * <p>
 * Upon creation, an instance of this class registers itself with the RMI registry by the name
 * declared as {@link RemoteDispatcherService#getRegistrationName()}.
 * </p>
 *
 * @author Martin Grzenia (Fraunhofer IML)
 */
public class StandardRemoteDispatcherService
    extends KernelRemoteService
    implements RemoteDispatcherService {

  /**
   * This class's logger.
   */
  private static final Logger LOG = LoggerFactory.getLogger(StandardRemoteDispatcherService.class);
  /**
   * The dispatcher service to invoke methods on.
   */
  private final DispatcherService dispatcherService;
  /**
   * The user manager.
   */
  private final UserManager userManager;
  /**
   * Provides configuration data.
   */
  private final RmiKernelInterfaceConfiguration configuration;
  /**
   * Provides socket factories used for RMI.
   */
  private final SocketFactoryProvider socketFactoryProvider;
  /**
   * Provides the registry with which this remote service registers.
   */
  private final RegistryProvider registryProvider;
  /**
   * Executes tasks modifying kernel data.
   */
  private final ExecutorService kernelExecutor;
  /**
   * The registry with which this remote service registers.
   */
  private Registry rmiRegistry;
  /**
   * Whether this remote service is initialized or not.
   */
  private boolean initialized;

  /**
   * Creates a new instance.
   *
   * @param dispatcherService The dispatcher service.
   * @param userManager The user manager.
   * @param configuration This class' configuration.
   * @param socketFactoryProvider The socket factory provider used for RMI.
   * @param registryProvider The provider for the registry with which this remote service registers.
   * @param kernelExecutor Executes tasks modifying kernel data.
   */
  @Inject
  public StandardRemoteDispatcherService(DispatcherService dispatcherService,
                                         UserManager userManager,
                                         RmiKernelInterfaceConfiguration configuration,
                                         SocketFactoryProvider socketFactoryProvider,
                                         RegistryProvider registryProvider,
                                         @KernelExecutor ExecutorService kernelExecutor) {
    this.dispatcherService = requireNonNull(dispatcherService, "dispatcherService");
    this.userManager = requireNonNull(userManager, "userManager");
    this.configuration = requireNonNull(configuration, "configuration");
    this.socketFactoryProvider = requireNonNull(socketFactoryProvider, "socketFactoryProvider");
    this.registryProvider = requireNonNull(registryProvider, "registryProvider");
    this.kernelExecutor = requireNonNull(kernelExecutor, "kernelExecutor");
  }

  @Override
  public void initialize() {
    if (isInitialized()) {
      return;
    }

    rmiRegistry = registryProvider.get();

    // Export this instance via RMI.
    try {
      LOG.debug("Exporting proxy...");
      UnicastRemoteObject.exportObject(this,
                                       configuration.remoteDispatcherServicePort(),
                                       socketFactoryProvider.getClientSocketFactory(),
                                       socketFactoryProvider.getServerSocketFactory());
      LOG.debug("Binding instance with RMI registry...");
      rmiRegistry.rebind(RegistrationName.REMOTE_DISPATCHER_SERVICE, this);
    }
    catch (RemoteException exc) {
      LOG.error("Could not export or bind with RMI registry", exc);
      return;
    }

    initialized = true;
  }

  @Override
  public boolean isInitialized() {
    return initialized;
  }

  @Override
  public void terminate() {
    if (!isInitialized()) {
      return;
    }

    try {
      LOG.debug("Unbinding from RMI registry...");
      rmiRegistry.unbind(RegistrationName.REMOTE_DISPATCHER_SERVICE);
      LOG.debug("Unexporting RMI interface...");
      UnicastRemoteObject.unexportObject(this, true);
    }
    catch (RemoteException | NotBoundException exc) {
      LOG.warn("Exception shutting down RMI interface", exc);
    }

    initialized = false;
  }

  @Override
  public void dispatch(ClientID clientId) {
    userManager.verifyCredentials(clientId, UserPermission.MODIFY_ORDER);

    try {
      kernelExecutor.submit(() -> dispatcherService.dispatch()).get();
    }
    catch (InterruptedException | ExecutionException exc) {
      throw findSuitableExceptionFor(exc);
    }
  }

  @Override
  @Deprecated
  public void releaseVehicle(ClientID clientId, TCSObjectReference<Vehicle> ref) {
    userManager.verifyCredentials(clientId, UserPermission.MODIFY_VEHICLES);

    try {
      kernelExecutor.submit(() -> dispatcherService.releaseVehicle(ref)).get();
    }
    catch (InterruptedException | ExecutionException exc) {
      throw findSuitableExceptionFor(exc);
    }
  }

  @Override
  @Deprecated
  public void withdrawByVehicle(ClientID clientId,
                                TCSObjectReference<Vehicle> ref,
                                boolean immediateAbort,
                                boolean disableVehicle) {
    userManager.verifyCredentials(clientId, UserPermission.MODIFY_ORDER);

    try {
      kernelExecutor.submit(() -> dispatcherService.withdrawByVehicle(ref,
                                                                      immediateAbort,
                                                                      disableVehicle))
          .get();
    }
    catch (InterruptedException | ExecutionException exc) {
      throw findSuitableExceptionFor(exc);
    }
  }

  @Override
  @Deprecated
  public void withdrawByTransportOrder(ClientID clientId,
                                       TCSObjectReference<TransportOrder> ref,
                                       boolean immediateAbort,
                                       boolean disableVehicle) {
    userManager.verifyCredentials(clientId, UserPermission.MODIFY_ORDER);

    try {
      kernelExecutor.submit(() -> dispatcherService.withdrawByTransportOrder(ref,
                                                                             immediateAbort,
                                                                             disableVehicle))
          .get();
    }
    catch (InterruptedException | ExecutionException exc) {
      throw findSuitableExceptionFor(exc);
    }
  }

  @Override
  public void withdrawByVehicle(ClientID clientId,
                                TCSObjectReference<Vehicle> ref,
                                boolean immediateAbort) {
    userManager.verifyCredentials(clientId, UserPermission.MODIFY_ORDER);

    try {
      kernelExecutor.submit(() -> dispatcherService.withdrawByVehicle(ref, immediateAbort))
          .get();
    }
    catch (InterruptedException | ExecutionException exc) {
      throw findSuitableExceptionFor(exc);
    }
  }

  @Override
  public void withdrawByTransportOrder(ClientID clientId,
                                       TCSObjectReference<TransportOrder> ref,
                                       boolean immediateAbort) {
    userManager.verifyCredentials(clientId, UserPermission.MODIFY_ORDER);

    try {
      kernelExecutor.submit(() -> dispatcherService.withdrawByTransportOrder(ref, immediateAbort))
          .get();
    }
    catch (InterruptedException | ExecutionException exc) {
      throw findSuitableExceptionFor(exc);
    }
  }
}