/*
 * Copyright (c) 2012-2017 Red Hat, Inc.
 * All rights reserved. This program and the accompanying materials
 * are made available under the terms of the Eclipse Public License v1.0
 * which accompanies this distribution, and is available at
 * http://www.eclipse.org/legal/epl-v10.html
 *
 * Contributors:
 *   Red Hat, Inc. - initial API and implementation
 */
package org.eclipse.che.multiuser.organization.api.resource;

import static java.util.Collections.emptyList;
import static java.util.Objects.requireNonNull;
import static java.util.stream.Collectors.toList;

import com.google.common.annotations.VisibleForTesting;
import java.util.List;
import java.util.Map;
import java.util.function.Function;
import java.util.stream.Collectors;
import javax.inject.Inject;
import javax.inject.Singleton;
import org.eclipse.che.api.core.ConflictException;
import org.eclipse.che.api.core.NotFoundException;
import org.eclipse.che.api.core.Page;
import org.eclipse.che.api.core.ServerException;
import org.eclipse.che.api.core.notification.EventService;
import org.eclipse.che.commons.lang.concurrent.Unlocker;
import org.eclipse.che.core.db.cascade.CascadeEventSubscriber;
import org.eclipse.che.multiuser.organization.api.OrganizationManager;
import org.eclipse.che.multiuser.organization.api.event.BeforeOrganizationRemovedEvent;
import org.eclipse.che.multiuser.organization.shared.model.OrganizationDistributedResources;
import org.eclipse.che.multiuser.organization.spi.OrganizationDistributedResourcesDao;
import org.eclipse.che.multiuser.organization.spi.impl.OrganizationDistributedResourcesImpl;
import org.eclipse.che.multiuser.resource.api.ResourceAggregator;
import org.eclipse.che.multiuser.resource.api.exception.NoEnoughResourcesException;
import org.eclipse.che.multiuser.resource.api.type.RamResourceType;
import org.eclipse.che.multiuser.resource.api.type.RuntimeResourceType;
import org.eclipse.che.multiuser.resource.api.type.WorkspaceResourceType;
import org.eclipse.che.multiuser.resource.api.usage.ResourceUsageManager;
import org.eclipse.che.multiuser.resource.api.usage.ResourcesLocks;
import org.eclipse.che.multiuser.resource.model.Resource;

/**
 * Facade for organization resources operations.
 *
 * @author Sergii Leschenko
 */
@Singleton
public class OrganizationResourcesDistributor {
  private final OrganizationDistributedResourcesDao organizationDistributedResourcesDao;
  private final OrganizationManager organizationManager;
  private final ResourcesLocks resourcesLocks;
  private final ResourceUsageManager usageManager;
  private final ResourceAggregator resourceAggregator;

  @Inject
  public OrganizationResourcesDistributor(
      OrganizationDistributedResourcesDao organizationDistributedResourcesDao,
      OrganizationManager organizationManager,
      ResourcesLocks resourcesLocks,
      ResourceUsageManager usageManager,
      ResourceAggregator resourceAggregator) {
    this.organizationDistributedResourcesDao = organizationDistributedResourcesDao;
    this.organizationManager = organizationManager;
    this.resourcesLocks = resourcesLocks;
    this.usageManager = usageManager;
    this.resourceAggregator = resourceAggregator;
  }

  @Inject
  public void subscribe(EventService eventService) {
    eventService.subscribe(
        new RemoveOrganizationDistributedResourcesSubscriber(),
        BeforeOrganizationRemovedEvent.class);
  }

  /**
   * Cap usage of shared resources.
   *
   * <p>By default suborganization is able to use all parent organization resources Cap allow to
   * limit usage of shared resources by suborganization.
   *
   * @param suborganizationId suborganization id
   * @param resourcesCaps resources to capped
   * @throws NotFoundException when specified suborganization was not found
   * @throws ConflictException when organization with specified id is root organization
   * @throws ConflictException when suborganization is currently using more shared resources than
   *     should be capped
   * @throws ServerException when any other error occurs
   */
  public void capResources(String suborganizationId, List<? extends Resource> resourcesCaps)
      throws NotFoundException, ConflictException, ServerException {
    requireNonNull(suborganizationId, "Required non-null suborganization id");
    requireNonNull(resourcesCaps, "Required non-null resources to capResources");
    checkIsSuborganization(suborganizationId);

    // remove caps with amount -1
    resourcesCaps = resourcesCaps.stream().filter(res -> res.getAmount() != -1).collect(toList());

    // locking resources by suborganization should lock resources whole organization tree
    // so we can check resource availability for suborganization organization
    try (@SuppressWarnings("unused")
        Unlocker u = resourcesLocks.lock(suborganizationId)) {
      if (resourcesCaps.isEmpty()) {
        organizationDistributedResourcesDao.remove(suborganizationId);
      } else {
        checkResourcesAvailability(suborganizationId, resourcesCaps);

        organizationDistributedResourcesDao.store(
            new OrganizationDistributedResourcesImpl(suborganizationId, resourcesCaps));
      }
    }
  }

  /**
   * Returns resources cap or empty list.
   *
   * @param suborganizationId suborganization id to fetch resources cap
   * @return resources cap or empty list
   * @throws NotFoundException when specified suborganization was not found
   * @throws ConflictException when organization with specified id is root organization
   * @throws ServerException when any other error occurs
   */
  public List<? extends Resource> getResourcesCaps(String suborganizationId)
      throws NotFoundException, ConflictException, ServerException {
    requireNonNull(suborganizationId, "Required non-null suborganization id");
    checkIsSuborganization(suborganizationId);
    try {
      return organizationDistributedResourcesDao.get(suborganizationId).getResourcesCap();
    } catch (NotFoundException e) {
      return emptyList();
    }
  }

  /**
   * Returns distributed resources for specified suborganization.
   *
   * @param suborganizationId organization id
   * @return distributed resources for suborganization with specified id
   * @throws NullPointerException when either {@code suborganizationId} is null
   * @throws NotFoundException when there is not distributed resources for specified suborganization
   * @throws ServerException when any other error occurs
   */
  public OrganizationDistributedResources get(String suborganizationId)
      throws NotFoundException, ServerException {
    requireNonNull(suborganizationId, "Required non-null organization id");

    return organizationDistributedResourcesDao.get(suborganizationId);
  }

  /**
   * Returns distributed resources for suborganizations by specified parent organization.
   *
   * @param organizationId organization id
   * @return distributed resources for suborganizations by specified parent organization
   * @throws NullPointerException when either {@code organizationId} is null
   * @throws ServerException when any other error occurs
   */
  public Page<? extends OrganizationDistributedResources> getByParent(
      String organizationId, int maxItems, long skipCount) throws ServerException {
    requireNonNull(organizationId, "Required non-null organization id");

    return organizationDistributedResourcesDao.getByParent(organizationId, maxItems, skipCount);
  }

  /**
   * Checks that suborganization is using less resources that new resources cap defines.
   *
   * @param suborganizationId identifier of suborganization
   * @param newResourcesCap resources to capResources
   * @throws ConflictException when parent organization doesn't have enough resources to increase
   *     distributed resource amount
   * @throws ConflictException when resources can't be distributed because suborganization is using
   *     existing resources or when they are distributed to next organizations level
   * @throws ServerException when any other error occurs
   */
  @VisibleForTesting
  void checkResourcesAvailability(
      String suborganizationId, List<? extends Resource> newResourcesCap)
      throws NotFoundException, ConflictException, ServerException {
    Map<String, Resource> usedResources =
        usageManager
            .getUsedResources(suborganizationId)
            .stream()
            .collect(Collectors.toMap(Resource::getType, Function.identity()));
    for (Resource resourceToCheck : newResourcesCap) {
      Resource usedResource = usedResources.get(resourceToCheck.getType());
      if (usedResource != null) {
        try {
          resourceAggregator.deduct(resourceToCheck, usedResource);
        } catch (NoEnoughResourcesException e) {
          throw new ConflictException(
              "Resources are currently in use. "
                  + getMessage(e.getMissingResources().get(0).getType()));
        }
      }
    }
  }

  @VisibleForTesting
  String getMessage(String requiredResourceType) {
    switch (requiredResourceType) {
      case RamResourceType.ID:
        return "You can't decrease RAM CAP, while the resources are in use. "
            + "Free resources, by stopping workspaces, before changing the RAM CAP.";
      case WorkspaceResourceType.ID:
        return "You can't reduce the workspaces CAP to a value lower than the number of workspaces currently created. "
            + "Free resources, by removing workspaces, before changing the workspaces CAP.";
      case RuntimeResourceType.ID:
        return "You can't reduce the running workspaces CAP to a value lower than the number of workspaces currently running. "
            + "Free resources, by stopping workspaces, before changing the running workspaces CAP.";
      default:
        return "You can't reduce them while they are used. "
            + "Free resources before changing the resources CAP.";
    }
  }

  private String checkIsSuborganization(String organizationId)
      throws NotFoundException, ConflictException, ServerException {
    String parentOrganization = organizationManager.getById(organizationId).getParent();
    if (parentOrganization == null) {
      throw new ConflictException("It is not allowed to cap resources for root organization.");
    }
    return parentOrganization;
  }

  class RemoveOrganizationDistributedResourcesSubscriber
      extends CascadeEventSubscriber<BeforeOrganizationRemovedEvent> {
    @Override
    public void onCascadeEvent(BeforeOrganizationRemovedEvent event) throws ServerException {
      if (event.getOrganization().getParent() != null) {
        organizationDistributedResourcesDao.remove(event.getOrganization().getId());
      }
    }
  }
}
