// Copyright 2017 The Nomulus Authors. All Rights Reserved.
//
// 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 google.registry.tools.server;

import static com.google.common.base.Preconditions.checkArgument;
import static com.google.common.collect.ImmutableList.toImmutableList;
import static google.registry.model.ofy.ObjectifyService.ofy;
import static google.registry.model.registry.Registries.assertTldsExist;
import static google.registry.request.Action.Method.GET;
import static google.registry.request.Action.Method.POST;
import static google.registry.request.RequestParameters.PARAM_TLDS;
import static java.util.Comparator.comparing;

import com.google.common.annotations.VisibleForTesting;
import com.google.common.collect.ImmutableList;
import com.google.common.collect.ImmutableSet;
import com.google.common.collect.Lists;
import google.registry.model.EppResource;
import google.registry.model.EppResourceUtils;
import google.registry.model.domain.DomainBase;
import google.registry.request.Action;
import google.registry.request.Parameter;
import google.registry.request.auth.Auth;
import google.registry.util.Clock;
import google.registry.util.NonFinalForTesting;
import java.util.List;
import javax.inject.Inject;
import org.joda.time.DateTime;

/** An action that lists domains, for use by the {@code nomulus list_domains} command. */
@Action(
    service = Action.Service.TOOLS,
    path = ListDomainsAction.PATH,
    method = {GET, POST},
    auth = Auth.AUTH_INTERNAL_OR_ADMIN)
public final class ListDomainsAction extends ListObjectsAction<DomainBase> {

  /** An App Engine limitation on how many subqueries can be used in a single query. */
  @VisibleForTesting @NonFinalForTesting static int maxNumSubqueries = 30;

  public static final String PATH = "/_dr/admin/list/domains";

  @Inject
  @Parameter(PARAM_TLDS)
  ImmutableSet<String> tlds;

  @Inject
  @Parameter("limit")
  int limit;

  @Inject Clock clock;

  @Inject
  ListDomainsAction() {}

  @Override
  public ImmutableSet<String> getPrimaryKeyFields() {
    return ImmutableSet.of("fullyQualifiedDomainName");
  }

  @Override
  public ImmutableSet<DomainBase> loadObjects() {
    checkArgument(!tlds.isEmpty(), "Must specify TLDs to query");
    assertTldsExist(tlds);
    DateTime now = clock.nowUtc();
    ImmutableList.Builder<DomainBase> domainsBuilder = new ImmutableList.Builder<>();
    for (List<String> tldsBatch : Lists.partition(tlds.asList(), maxNumSubqueries)) {
      domainsBuilder.addAll(
          ofy()
              .load()
              .type(DomainBase.class)
              .filter("tld in", tldsBatch)
              // Get the N most recently created domains (requires ordering in descending order).
              .order("-creationTime")
              .limit(limit)
              .list()
              .stream()
              .map(EppResourceUtils.transformAtTime(now))
              // Deleted entities must be filtered out post-query because queries don't allow
              // ordering with two filters.
              .filter(d -> d.getDeletionTime().isAfter(now))
              .collect(toImmutableList()));
    }
    // Combine the batches together by sorting all domains together with newest first, applying the
    // limit, and then reversing for display order.
    return ImmutableSet.copyOf(
        domainsBuilder
            .build()
            .stream()
            .sorted(comparing(EppResource::getCreationTime).reversed())
            .limit(limit)
            .collect(toImmutableList())
            .reverse());
  }
}