com.smoketurner.notification.application.riak.NotificationListResolver Maven / Gradle / Ivy

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/**
 * Copyright 2015 Smoke Turner, LLC.
 *
 * Licensed 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.
 */
package com.smoketurner.notification.application.riak;

import java.util.Collection;
import java.util.Iterator;
import java.util.List;
import java.util.Set;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import com.basho.riak.client.api.cap.ConflictResolver;
import com.basho.riak.client.api.cap.UnresolvedConflictException;
import com.google.common.base.Predicate;
import com.google.common.collect.ImmutableList;
import com.google.common.collect.Iterables;
import com.smoketurner.notification.api.Notification;

public class NotificationListResolver implements ConflictResolver {

  private static final Logger LOGGER = LoggerFactory.getLogger(NotificationListResolver.class);

  @Override
  public NotificationListObject resolve(final List siblings)
      throws UnresolvedConflictException {
    LOGGER.debug("Found {} siblings", siblings.size());
    if (siblings.size() > 1) {
      final Iterator iterator = siblings.iterator();
      final NotificationListObject resolved = new NotificationListObject(iterator.next());

      final Set deletedIds = resolved.getDeletedIds();

      // add all notifications
      while (iterator.hasNext()) {
        final NotificationListObject sibling = iterator.next();
        resolved.addNotifications(sibling.getNotifications());
        deletedIds.addAll(sibling.getDeletedIds());
      }

      // remove deleted notifications
      if (!deletedIds.isEmpty()) {
        LOGGER.debug("IDs to delete: {}", deletedIds);
        resolved.setNotifications(removeNotifications(resolved.getNotifications(), deletedIds));
        resolved.clearDeletedIds();
      }

      return resolved;
    } else if (siblings.size() == 1) {

      final NotificationListObject resolved = siblings.iterator().next();

      // remove deleted notifications
      if (!resolved.getDeletedIds().isEmpty()) {
        LOGGER.debug("IDs to delete: {}", resolved.getDeletedIds());
        resolved.setNotifications(removeNotifications(resolved.getNotifications(),
            resolved.getDeletedIds()));
        resolved.clearDeletedIds();
      }

      return resolved;
    } else {
      return null;
    }
  }

  /**
   * Remove the given notification IDs from the list of notifications. We have to copy the iterable
   * into a list to avoid modifying the original reference within the {@link NotificationListObject}
   * .
   * 
   * @param notifications Notifications to delete from
   * @param ids Notification IDs to delete
   * @return list of notifications with deleted notifications removed
   */
  public static List removeNotifications(final Iterable notifications,
      final Collection ids) {

    return ImmutableList.copyOf(Iterables.filter(notifications, new Predicate() {
      @Override
      public boolean apply(final Notification notification) {
        if (!notification.getId().isPresent()) {
          return false;
        }
        if (ids.contains(notification.getId().get())) {
          return false;
        }
        return true;
      }
    }));
  }
}