// 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.flows.host;

import static google.registry.dns.DnsUtils.requestHostDnsRefresh;
import static google.registry.flows.FlowUtils.validateRegistrarIsLoggedIn;
import static google.registry.flows.ResourceFlowUtils.verifyResourceDoesNotExist;
import static google.registry.flows.host.HostFlowUtils.lookupSuperordinateDomain;
import static google.registry.flows.host.HostFlowUtils.validateHostName;
import static google.registry.flows.host.HostFlowUtils.verifySuperordinateDomainNotInPendingDelete;
import static google.registry.flows.host.HostFlowUtils.verifySuperordinateDomainNotServerUpdateProhibited;
import static google.registry.flows.host.HostFlowUtils.verifySuperordinateDomainOwnership;
import static google.registry.model.EppResourceUtils.createRepoId;
import static google.registry.model.reporting.HistoryEntry.Type.HOST_CREATE;
import static google.registry.persistence.transaction.TransactionManagerFactory.tm;
import static google.registry.util.CollectionUtils.isNullOrEmpty;

import com.google.common.collect.ImmutableSet;
import google.registry.config.RegistryConfig.Config;
import google.registry.flows.EppException;
import google.registry.flows.EppException.ParameterValueRangeErrorException;
import google.registry.flows.EppException.RequiredParameterMissingException;
import google.registry.flows.ExtensionManager;
import google.registry.flows.FlowModule.RegistrarId;
import google.registry.flows.FlowModule.TargetId;
import google.registry.flows.MutatingFlow;
import google.registry.flows.annotations.ReportingSpec;
import google.registry.flows.exceptions.ResourceAlreadyExistsForThisClientException;
import google.registry.flows.exceptions.ResourceCreateContentionException;
import google.registry.model.ImmutableObject;
import google.registry.model.domain.Domain;
import google.registry.model.domain.metadata.MetadataExtension;
import google.registry.model.eppinput.ResourceCommand;
import google.registry.model.eppoutput.CreateData.HostCreateData;
import google.registry.model.eppoutput.EppResponse;
import google.registry.model.host.Host;
import google.registry.model.host.HostCommand.Create;
import google.registry.model.host.HostHistory;
import google.registry.model.reporting.IcannReportingTypes.ActivityReportField;
import jakarta.inject.Inject;
import java.time.Instant;
import java.util.Optional;

/**
 * An EPP flow that creates a new host.
 *
 * <p>Hosts can be "external", or "internal" (also known as "in bailiwick"). Internal hosts are
 * those that are under a top level domain within this registry, and external hosts are all other
 * hosts. Internal hosts must have at least one ip address associated with them, whereas external
 * hosts cannot have any. This flow allows creating a host name, and if necessary enqueues tasks to
 * update DNS.
 *
 * @error {@link google.registry.flows.FlowUtils.IpAddressVersionMismatchException}
 * @error {@link google.registry.flows.FlowUtils.NotLoggedInException}
 * @error {@link ResourceAlreadyExistsForThisClientException}
 * @error {@link ResourceCreateContentionException}
 * @error {@link HostFlowUtils.HostNameTooLongException}
 * @error {@link HostFlowUtils.HostNameTooShallowException}
 * @error {@link HostFlowUtils.InvalidHostNameException}
 * @error {@link HostFlowUtils.HostNameNotLowerCaseException}
 * @error {@link HostFlowUtils.HostNameNotNormalizedException}
 * @error {@link HostFlowUtils.HostNameNotPunyCodedException}
 * @error {@link HostFlowUtils.SuperordinateDomainDoesNotExistException}
 * @error {@link HostFlowUtils.SuperordinateDomainInPendingDeleteException}
 * @error {@link HostFlowUtils.SuperordinateDomainServerUpdateProhibitedException}
 * @error {@link SubordinateHostMustHaveIpException}
 * @error {@link UnexpectedExternalHostIpException}
 */
@ReportingSpec(ActivityReportField.HOST_CREATE)
public final class HostCreateFlow implements MutatingFlow {

  @Inject ResourceCommand resourceCommand;
  @Inject ExtensionManager extensionManager;
  @Inject @RegistrarId String registrarId;
  @Inject @TargetId String targetId;
  @Inject HostHistory.Builder historyBuilder;
  @Inject EppResponse.Builder responseBuilder;

  @Inject
  @Config("hostRoidSuffix")
  String roidSuffix;

  @Inject
  HostCreateFlow() {}

  @Override
  public EppResponse run() throws EppException {
    extensionManager.register(MetadataExtension.class);
    validateRegistrarIsLoggedIn(registrarId);
    extensionManager.validate();
    Create command = (Create) resourceCommand;
    Instant now = tm().getTxTime();
    verifyResourceDoesNotExist(Host.class, targetId, now, registrarId);
    // The superordinate domain of the host object if creating an in-bailiwick host, or null if
    // creating an external host. This is looked up before we actually create the Host object, so
    // we can detect error conditions earlier.
    Optional<Domain> superordinateDomain =
        lookupSuperordinateDomain(validateHostName(targetId), now);
    verifySuperordinateDomainNotInPendingDelete(superordinateDomain.orElse(null));
    verifySuperordinateDomainNotServerUpdateProhibited(superordinateDomain.orElse(null));
    verifySuperordinateDomainOwnership(registrarId, superordinateDomain.orElse(null));
    boolean willBeSubordinate = superordinateDomain.isPresent();
    boolean hasIpAddresses = !isNullOrEmpty(command.getInetAddresses());
    if (willBeSubordinate != hasIpAddresses) {
      // Subordinate hosts must have ip addresses and external hosts must not have them.
      throw willBeSubordinate
          ? new SubordinateHostMustHaveIpException()
          : new UnexpectedExternalHostIpException();
    }
    HostFlowUtils.validateInetAddresses(command.getInetAddresses());
    Host newHost =
        new Host.Builder()
            .setCreationRegistrarId(registrarId)
            .setPersistedCurrentSponsorRegistrarId(registrarId)
            .setHostName(targetId)
            .setInetAddresses(command.getInetAddresses())
            .setRepoId(createRepoId(tm().allocateId(), roidSuffix))
            .setSuperordinateDomain(superordinateDomain.map(Domain::createVKey).orElse(null))
            .build();
    historyBuilder.setType(HOST_CREATE).setHost(newHost);
    ImmutableSet<ImmutableObject> entitiesToInsert =
        ImmutableSet.of(newHost, historyBuilder.build());
    if (superordinateDomain.isPresent()) {
      tm().update(
              superordinateDomain
                  .get()
                  .asBuilder()
                  .addSubordinateHost(command.getHostName())
                  .build());
      // Only update DNS if this is a subordinate host. External hosts have no glue to write, so
      // they are only written as NS records from the referencing domain.
      requestHostDnsRefresh(targetId);
    }
    tm().insertAll(entitiesToInsert);
    return responseBuilder.setResData(HostCreateData.create(targetId, now)).build();
  }

  /** Subordinate hosts must have an ip address. */
  static class SubordinateHostMustHaveIpException extends RequiredParameterMissingException {
    SubordinateHostMustHaveIpException() {
      super("Subordinate hosts must have an ip address");
    }
  }

  /** External hosts must not have ip addresses. */
  static class UnexpectedExternalHostIpException extends ParameterValueRangeErrorException {
    UnexpectedExternalHostIpException() {
      super("External hosts must not have ip addresses");
    }
  }
}
