Session.java

package eu.chargetime.ocpp;

/*
ChargeTime.eu - Java-OCA-OCPP
Copyright (C) 2015-2016 Thomas Volden <tv@chargetime.eu>

MIT License

Copyright (C) 2016-2018 Thomas Volden

Permission is hereby granted, free of charge, to any person obtaining a copy
of this software and associated documentation files (the "Software"), to deal
in the Software without restriction, including without limitation the rights
to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
copies of the Software, and to permit persons to whom the Software is
furnished to do so, subject to the following conditions:

The above copyright notice and this permission notice shall be included in all
copies or substantial portions of the Software.

THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
SOFTWARE.
*/

import static eu.chargetime.ocpp.ProtocolVersion.OCPP1_6;
import static eu.chargetime.ocpp.ProtocolVersion.OCPP2_0_1;

import eu.chargetime.ocpp.feature.Feature;
import eu.chargetime.ocpp.model.Confirmation;
import eu.chargetime.ocpp.model.Request;
import eu.chargetime.ocpp.utilities.MoreObjects;
import java.util.AbstractMap.SimpleImmutableEntry;
import java.util.Map;
import java.util.Optional;
import java.util.UUID;
import java.util.concurrent.CompletableFuture;
import java.util.concurrent.ConcurrentHashMap;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

/**
 * Unites outgoing {@link Request} with incoming {@link Confirmation}s or errors. Catches errors and
 * responds with error messages.
 */
public class Session implements ISession {

  private static final Logger logger = LoggerFactory.getLogger(Session.class);

  private final UUID sessionId = UUID.randomUUID();
  private final Communicator communicator;
  private final Queue queue;
  private final RequestDispatcher dispatcher;
  private final IFeatureRepository featureRepository;
  private final Map<String, SimpleImmutableEntry<String, CompletableFuture<Confirmation>>>
      pendingPromises = new ConcurrentHashMap<>();
  private SessionEvents events;

  /**
   * Handles required injections.
   *
   * @param communicator send and receive messages.
   * @param queue store and restore requests based on unique ids.
   * @param fulfiller the {@link PromiseFulfiller} to use
   * @param featureRepository the {@link IFeatureRepository} to use
   */
  public Session(
      Communicator communicator,
      Queue queue,
      PromiseFulfiller fulfiller,
      IFeatureRepository featureRepository) {
    this.communicator = communicator;
    this.queue = queue;
    this.dispatcher = new RequestDispatcher(fulfiller);
    this.featureRepository = featureRepository;
  }

  /**
   * Get the {@link FeatureRepository} used in this session
   *
   * @return the {@link FeatureRepository} used in this session
   */
  @Override
  public IFeatureRepository getFeatureRepository() {
    return featureRepository;
  }

  /**
   * Get a unique session {@link UUID} identifier.
   *
   * @return the unique session {@link UUID} identifier
   */
  public UUID getSessionId() {
    return sessionId;
  }

  /**
   * Send a {@link Request}.
   *
   * @param action action name to identify the feature.
   * @param payload the {@link Request} payload to send
   * @param uuid unique identification to identify the request
   */
  public void sendRequest(String action, Request payload, String uuid) {
    communicator.sendCall(uuid, action, payload);
  }

  /**
   * Send a {@link Request} which has no confirmation.
   *
   * @param action action name to identify the feature.
   * @param payload the {@link Request} payload to send
   * @param uuid unique identification to identify the request
   */
  public void sendMessage(String action, Request payload, String uuid) {
    if (isSendCapableRPC()) {
      communicator.send(uuid, action, payload);
      events.handleConfirmation(uuid, null);
    } else {
      events.handleError(
          uuid,
          "MessageTypeNotSupported",
          "SEND message type is not supported in " + featureRepository.getProtocolVersion(),
          payload);
    }
  }

  /**
   * Store a {@link Request} and get the unique id.
   *
   * @param payload the {@link Request} payload to send
   * @return unique identification to identify the request.
   */
  public String storeRequest(Request payload) {
    return queue.store(payload);
  }

  /**
   * Remove a stored {@link Request} using a unique identifier. If no request is found for the
   * identifier this method has no effect.
   *
   * @param ticket unique identifier returned when {@link Request} was initially stored.
   */
  public void removeRequest(String ticket) {
    queue.removeRequest(ticket);
  }

  /**
   * Send a {@link Confirmation} to a {@link Request}
   *
   * @param uniqueId the unique identification the receiver expects.
   * @param action action name to identify the feature.
   * @param confirmation the {@link Confirmation} payload to send.
   */
  public void sendConfirmation(String uniqueId, String action, Confirmation confirmation) {
    communicator.sendCallResult(uniqueId, action, confirmation);
  }

  private Optional<Class<? extends Confirmation>> getConfirmationType(String uniqueId)
      throws UnsupportedFeatureException {
    Optional<Request> requestOptional = queue.restoreRequest(uniqueId);

    if (requestOptional.isPresent()) {
      Optional<Feature> featureOptional = featureRepository.findFeature(requestOptional.get());
      if (featureOptional.isPresent()) {
        return Optional.ofNullable(featureOptional.get().getConfirmationType());
      } else {
        logger.debug("Feature for request with id: {} not found in session: {}", uniqueId, this);
        throw new UnsupportedFeatureException(
            "Error with getting confirmation type by request id = " + uniqueId);
      }
    } else {
      logger.debug("Request with id: {} not found in session: {}", uniqueId, this);
    }

    return Optional.empty();
  }

  /**
   * Connect to a specific uri, provided a call back handler for connection related events.
   *
   * @param uri url and port of the remote system.
   * @param eventHandler call back handler for connection related events.
   */
  public void open(String uri, SessionEvents eventHandler) {
    this.events = eventHandler;
    dispatcher.setEventHandler(eventHandler);
    communicator.connect(uri, new CommunicatorEventHandler());
  }

  /** Close down the connection. */
  public void close() {
    communicator.disconnect();
  }

  public void accept(SessionEvents eventHandler) {
    this.events = eventHandler;
    dispatcher.setEventHandler(eventHandler);
    communicator.accept(new CommunicatorEventHandler());
  }

  private class CommunicatorEventHandler implements CommunicatorEvents {
    private static final String OCCURRENCE_CONSTRAINT_VIOLATION =
        "Payload for Action is syntactically correct but at least one of the fields violates"
            + " occurrence constraints";
    private static final String PROPERTY_CONSTRAINT_VIOLATION =
        "Payload is syntactically correct but at least one field contains an invalid value";
    private static final String INTERNAL_ERROR =
        "An internal error occurred and the receiver was not able to process the requested Action"
            + " successfully";
    private static final String UNABLE_TO_PROCESS = "Unable to process action";

    @Override
    public void onCallResult(String id, String action, Object payload) {
      try {
        Optional<Class<? extends Confirmation>> confirmationTypeOptional = getConfirmationType(id);

        if (confirmationTypeOptional.isPresent()) {
          Confirmation confirmation =
              communicator.unpackPayload(payload, confirmationTypeOptional.get());
          if (confirmation.validate()) {
            events.handleConfirmation(id, confirmation);
          } else {
            logger.warn(PROPERTY_CONSTRAINT_VIOLATION);
            if (isCallResultErrorCapableRPC()) {
              communicator.sendCallResultError(
                  id, action, "PropertyConstraintViolation", PROPERTY_CONSTRAINT_VIOLATION);
            }
          }
        } else {
          logger.warn(INTERNAL_ERROR);
          if (isCallResultErrorCapableRPC()) {
            communicator.sendCallResultError(id, action, "InternalError", INTERNAL_ERROR);
          }
        }
      } catch (OccurenceConstraintException ex) {
        logger.warn(ex.getMessage(), ex);
        if (isCallResultErrorCapableRPC()) {
          communicator.sendCallResultError(
              id, action, "OccurrenceConstraintViolation", ex.getMessage());
        }
      } catch (PropertyConstraintException ex) {
        logger.warn(ex.getMessage(), ex);
        if (isCallResultErrorCapableRPC()) {
          communicator.sendCallResultError(
              id, action, "PropertyConstraintViolation", ex.getMessage());
        }
      } catch (SecurityErrorException ex) {
        logger.warn(ex.getMessage(), ex);
        if (isCallResultErrorCapableRPC()) {
          communicator.sendCallResultError(id, action, "SecurityError", ex.getMessage());
        }
      } catch (UnsupportedFeatureException ex) {
        logger.warn(ex.getMessage(), ex);
        if (isCallResultErrorCapableRPC()) {
          communicator.sendCallResultError(id, action, "NotSupported", ex.getMessage());
        }
      } catch (Exception ex) {
        logger.warn(ex.getMessage(), ex);
        if (isCallResultErrorCapableRPC()) {
          communicator.sendCallResultError(
              id, action, "InternalError", ex.getClass().getSimpleName() + ": " + ex.getMessage());
        }
      }
    }

    @Override
    public void onCall(String id, String action, Object payload) {
      Optional<Feature> featureOptional = featureRepository.findFeature(action);
      if (!featureOptional.isPresent() || featureOptional.get().getConfirmationType() == null) {
        communicator.sendCallError(
            id, action, "NotImplemented", "Requested Action is not known by receiver");
      } else {
        try {
          Request request =
              communicator.unpackPayload(payload, featureOptional.get().getRequestType());
          request.setOcppMessageId(id);
          if (request.validate()) {
            CompletableFuture<Confirmation> promise = new CompletableFuture<>();
            promise.whenComplete(new ConfirmationHandler(id, action, communicator));
            promise.whenComplete((result, error) -> pendingPromises.remove(id));
            addPendingPromise(id, action, promise);
            dispatcher.handleRequest(promise, request);
          } else {
            communicator.sendCallError(
                id,
                action,
                isLegacyRPC() ? "OccurenceConstraintViolation" : "OccurrenceConstraintViolation",
                OCCURRENCE_CONSTRAINT_VIOLATION);
          }
        } catch (PropertyConstraintException ex) {
          logger.warn(ex.getMessage(), ex);
          communicator.sendCallError(id, action, "TypeConstraintViolation", ex.getMessage());
        } catch (SecurityErrorException ex) {
          logger.warn(ex.getMessage(), ex);
          communicator.sendCallError(id, action, "SecurityError", ex.getMessage());
        } catch (Exception ex) {
          logger.warn(UNABLE_TO_PROCESS, ex);
          communicator.sendCallError(
              id,
              action,
              isLegacyRPC() ? "FormationViolation" : "FormatViolation",
              UNABLE_TO_PROCESS);
        }
      }
    }

    @Override
    public void onError(String id, String errorCode, String errorDescription, Object payload) {
      events.handleError(id, errorCode, errorDescription, payload);
    }

    @Override
    public void onCallResultError(
        String id, String errorCode, String errorDescription, Object payload) {
      if (!isCallResultErrorCapableRPC()) {
        logger.warn(
            "Received CALLRESULTERROR message type is not supported in {}",
            featureRepository.getProtocolVersion());
        return;
      }
      events.handleConfirmationError(id, errorCode, errorDescription, payload);
    }

    @Override
    public void onSend(String id, String action, Object payload) {
      if (!isSendCapableRPC()) {
        logger.warn(
            "Received SEND message type is not supported in {}",
            featureRepository.getProtocolVersion());
        return;
      }
      Optional<Feature> featureOptional = featureRepository.findFeature(action);
      if (!featureOptional.isPresent() || featureOptional.get().getConfirmationType() != null) {
        logger.warn("Requested Action {} is not known by receiver", action);
      } else {
        try {
          Request request =
              communicator.unpackPayload(payload, featureOptional.get().getRequestType());
          request.setOcppMessageId(id);
          if (request.validate()) {
            dispatcher.handleRequest(null, request);
          } else {
            logger.warn("Received SEND message with id {} is invalid: {}", id, request);
          }
        } catch (PropertyConstraintException | SecurityErrorException ex) {
          logger.warn(ex.getMessage(), ex);
        } catch (Exception ex) {
          logger.warn(UNABLE_TO_PROCESS, ex);
        }
      }
    }

    @Override
    public void onDisconnected() {
      events.handleConnectionClosed();
    }

    @Override
    public void onConnected() {
      events.handleConnectionOpened();
    }

    private boolean isLegacyRPC() {
      ProtocolVersion protocolVersion = featureRepository.getProtocolVersion();
      return protocolVersion == null || protocolVersion.equals(OCPP1_6);
    }
  }

  private boolean isCallResultErrorCapableRPC() {
    ProtocolVersion protocolVersion = featureRepository.getProtocolVersion();
    return protocolVersion != null
        && !protocolVersion.equals(OCPP1_6)
        && !protocolVersion.equals(OCPP2_0_1);
  }

  private boolean isSendCapableRPC() {
    ProtocolVersion protocolVersion = featureRepository.getProtocolVersion();
    return protocolVersion != null
        && !protocolVersion.equals(OCPP1_6)
        && !protocolVersion.equals(OCPP2_0_1);
  }

  private void addPendingPromise(
      String id, String action, CompletableFuture<Confirmation> promise) {
    pendingPromises.put(id, new SimpleImmutableEntry<>(action, promise));
  }

  @Override
  public boolean completePendingPromise(String id, Confirmation confirmation)
      throws UnsupportedFeatureException, OccurenceConstraintException {
    SimpleImmutableEntry<String, CompletableFuture<Confirmation>> promiseAction =
        pendingPromises.remove(id);
    if (promiseAction == null) {
      return false;
    }
    // check confirmation type, it has to correspond to original request type
    Optional<Feature> featureOptional = featureRepository.findFeature(promiseAction.getKey());
    if (featureOptional.isPresent() && featureOptional.get().getConfirmationType() != null) {
      if (!featureOptional.get().getConfirmationType().isInstance(confirmation)) {
        throw new OccurenceConstraintException();
      }
    } else {
      logger.debug("Feature for confirmation with id: {} not found in session: {}", id, this);
      throw new UnsupportedFeatureException(
          "Error with getting confirmation type by request id = " + id);
    }
    promiseAction.getValue().complete(confirmation);
    return true;
  }

  @Override
  public boolean equals(Object o) {
    if (this == o) return true;
    if (o == null || getClass() != o.getClass()) return false;
    Session session = (Session) o;
    return MoreObjects.equals(sessionId, session.sessionId);
  }

  @Override
  public int hashCode() {
    return MoreObjects.hash(sessionId);
  }

  @Override
  public String toString() {
    return MoreObjects.toStringHelper(this)
        .add("sessionId", sessionId)
        .add("communicator", communicator)
        .add("queue", queue)
        .add("dispatcher", dispatcher)
        .add("featureRepository", featureRepository)
        .add("events", events)
        .toString();
  }
}