// 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.domain;

import static com.google.common.collect.Iterables.getOnlyElement;
import static google.registry.flows.FlowUtils.validateClientIsLoggedIn;
import static google.registry.flows.ResourceFlowUtils.loadAndVerifyExistence;
import static google.registry.flows.ResourceFlowUtils.verifyHasPendingTransfer;
import static google.registry.flows.ResourceFlowUtils.verifyOptionalAuthInfo;
import static google.registry.flows.ResourceFlowUtils.verifyResourceOwnership;
import static google.registry.flows.domain.DomainFlowUtils.checkAllowedAccessToTld;
import static google.registry.flows.domain.DomainFlowUtils.createCancelingRecords;
import static google.registry.flows.domain.DomainFlowUtils.updateAutorenewRecurrenceEndTime;
import static google.registry.flows.domain.DomainTransferUtils.createGainingTransferPollMessage;
import static google.registry.flows.domain.DomainTransferUtils.createTransferResponse;
import static google.registry.model.ResourceTransferUtils.approvePendingTransfer;
import static google.registry.model.domain.DomainBase.extendRegistrationWithCap;
import static google.registry.model.ofy.ObjectifyService.ofy;
import static google.registry.model.reporting.DomainTransactionRecord.TransactionReportField.TRANSFER_SUCCESSFUL;
import static google.registry.model.transaction.TransactionManagerFactory.tm;
import static google.registry.pricing.PricingEngineProxy.getDomainRenewCost;
import static google.registry.util.CollectionUtils.union;
import static google.registry.util.DateTimeUtils.END_OF_TIME;

import com.google.common.collect.ImmutableSet;
import com.googlecode.objectify.Key;
import google.registry.flows.EppException;
import google.registry.flows.ExtensionManager;
import google.registry.flows.FlowModule.ClientId;
import google.registry.flows.FlowModule.Superuser;
import google.registry.flows.FlowModule.TargetId;
import google.registry.flows.TransactionalFlow;
import google.registry.flows.annotations.ReportingSpec;
import google.registry.model.ImmutableObject;
import google.registry.model.billing.BillingEvent;
import google.registry.model.billing.BillingEvent.Flag;
import google.registry.model.billing.BillingEvent.Reason;
import google.registry.model.domain.DomainBase;
import google.registry.model.domain.GracePeriod;
import google.registry.model.domain.metadata.MetadataExtension;
import google.registry.model.domain.rgp.GracePeriodStatus;
import google.registry.model.eppcommon.AuthInfo;
import google.registry.model.eppoutput.EppResponse;
import google.registry.model.poll.PollMessage;
import google.registry.model.registry.Registry;
import google.registry.model.reporting.DomainTransactionRecord;
import google.registry.model.reporting.HistoryEntry;
import google.registry.model.reporting.IcannReportingTypes.ActivityReportField;
import google.registry.model.transfer.TransferData;
import google.registry.model.transfer.TransferStatus;
import java.util.Optional;
import javax.inject.Inject;
import org.joda.time.DateTime;

/**
 * An EPP flow that approves a pending transfer on a domain.
 *
 * <p>The "gaining" registrar requests a transfer from the "losing" (aka current) registrar. The
 * losing registrar has a "transfer" time period to respond (by default five days) after which the
 * transfer is automatically approved. Within that window, this flow allows the losing client to
 * explicitly approve the transfer request, which then becomes effective immediately.
 *
 * <p>When the transfer was requested, poll messages and billing events were saved to Datastore with
 * timestamps such that they only would become active when the transfer period passed. In this flow,
 * those speculative objects are deleted and replaced with new ones with the correct approval time.
 *
 * @error {@link google.registry.flows.ResourceFlowUtils.BadAuthInfoForResourceException}
 * @error {@link google.registry.flows.ResourceFlowUtils.ResourceDoesNotExistException}
 * @error {@link google.registry.flows.ResourceFlowUtils.ResourceNotOwnedException}
 * @error {@link google.registry.flows.exceptions.NotPendingTransferException}
 * @error {@link DomainFlowUtils.NotAuthorizedForTldException}
 */
@ReportingSpec(ActivityReportField.DOMAIN_TRANSFER_APPROVE)
public final class DomainTransferApproveFlow implements TransactionalFlow {

  @Inject ExtensionManager extensionManager;
  @Inject Optional<AuthInfo> authInfo;
  @Inject @ClientId String clientId;
  @Inject @TargetId String targetId;
  @Inject @Superuser boolean isSuperuser;
  @Inject HistoryEntry.Builder historyBuilder;
  @Inject EppResponse.Builder responseBuilder;
  @Inject DomainTransferApproveFlow() {}

  /**
   * <p>The logic in this flow, which handles client approvals, very closely parallels the logic in
   * {@link DomainBase#cloneProjectedAtTime} which handles implicit server approvals.
   */
  @Override
  public final EppResponse run() throws EppException {
    extensionManager.register(MetadataExtension.class);
    extensionManager.validate();
    validateClientIsLoggedIn(clientId);
    DateTime now = tm().getTransactionTime();
    DomainBase existingDomain = loadAndVerifyExistence(DomainBase.class, targetId, now);
    verifyOptionalAuthInfo(authInfo, existingDomain);
    verifyHasPendingTransfer(existingDomain);
    verifyResourceOwnership(clientId, existingDomain);
    String tld = existingDomain.getTld();
    if (!isSuperuser) {
      checkAllowedAccessToTld(clientId, tld);
    }
    TransferData transferData = existingDomain.getTransferData();
    String gainingClientId = transferData.getGainingClientId();
    Registry registry = Registry.get(existingDomain.getTld());
    HistoryEntry historyEntry = buildHistoryEntry(existingDomain, registry, now, gainingClientId);
    // Create a transfer billing event for 1 year, unless the superuser extension was used to set
    // the transfer period to zero. There is not a transfer cost if the transfer period is zero.
    Optional<BillingEvent.OneTime> billingEvent =
        (transferData.getTransferPeriod().getValue() == 0)
            ? Optional.empty()
            : Optional.of(
                new BillingEvent.OneTime.Builder()
                    .setReason(Reason.TRANSFER)
                    .setTargetId(targetId)
                    .setClientId(gainingClientId)
                    .setPeriodYears(1)
                    .setCost(getDomainRenewCost(targetId, transferData.getTransferRequestTime(), 1))
                    .setEventTime(now)
                    .setBillingTime(now.plus(Registry.get(tld).getTransferGracePeriodLength()))
                    .setParent(historyEntry)
                    .build());
    // If we are within an autorenew grace period, cancel the autorenew billing event and don't
    // increase the registration time, since the transfer subsumes the autorenew's extra year.
    GracePeriod autorenewGrace =
        getOnlyElement(existingDomain.getGracePeriodsOfType(GracePeriodStatus.AUTO_RENEW), null);
    int extraYears = transferData.getTransferPeriod().getValue();
    if (autorenewGrace != null) {
      extraYears = 0;
      // During a normal transfer, if the domain is in the auto-renew grace period, the auto-renew
      // billing event is cancelled and the gaining registrar is charged for the one year renewal.
      // But, if the superuser extension is used to request a transfer without an additional year
      // then the gaining registrar is not charged for the one year renewal and the losing registrar
      // still needs to be charged for the auto-renew.
      if (billingEvent.isPresent()) {
        ofy().save().entity(
            BillingEvent.Cancellation.forGracePeriod(autorenewGrace, historyEntry, targetId));
      }
    }
    // Close the old autorenew event and poll message at the transfer time (aka now). This may end
    // up deleting the poll message.
    updateAutorenewRecurrenceEndTime(existingDomain, now);
    DateTime newExpirationTime = extendRegistrationWithCap(
        now, existingDomain.getRegistrationExpirationTime(), extraYears);
    // Create a new autorenew event starting at the expiration time.
    BillingEvent.Recurring autorenewEvent = new BillingEvent.Recurring.Builder()
        .setReason(Reason.RENEW)
        .setFlags(ImmutableSet.of(Flag.AUTO_RENEW))
        .setTargetId(targetId)
        .setClientId(gainingClientId)
        .setEventTime(newExpirationTime)
        .setRecurrenceEndTime(END_OF_TIME)
        .setParent(historyEntry)
        .build();
    // Create a new autorenew poll message.
    PollMessage.Autorenew gainingClientAutorenewPollMessage = new PollMessage.Autorenew.Builder()
        .setTargetId(targetId)
        .setClientId(gainingClientId)
        .setEventTime(newExpirationTime)
        .setAutorenewEndTime(END_OF_TIME)
        .setMsg("Domain was auto-renewed.")
        .setParent(historyEntry)
        .build();
    // Construct the post-transfer domain.
    DomainBase partiallyApprovedDomain =
        approvePendingTransfer(existingDomain, TransferStatus.CLIENT_APPROVED, now);
    DomainBase newDomain =
        partiallyApprovedDomain
            .asBuilder()
            // Update the transferredRegistrationExpirationTime here since approvePendingTransfer()
            // doesn't know what to set it to and leaves it null.
            .setTransferData(
                partiallyApprovedDomain
                    .getTransferData()
                    .asBuilder()
                    .setTransferredRegistrationExpirationTime(newExpirationTime)
                    .build())
            .setRegistrationExpirationTime(newExpirationTime)
            .setAutorenewBillingEvent(Key.create(autorenewEvent))
            .setAutorenewPollMessage(Key.create(gainingClientAutorenewPollMessage))
            // Remove all the old grace periods and add a new one for the transfer.
            .setGracePeriods(
                billingEvent.isPresent()
                    ? ImmutableSet.of(
                        GracePeriod.forBillingEvent(GracePeriodStatus.TRANSFER, billingEvent.get()))
                    : ImmutableSet.of())
            .setLastEppUpdateTime(now)
            .setLastEppUpdateClientId(clientId)
            .build();
    // Create a poll message for the gaining client.
    PollMessage gainingClientPollMessage = createGainingTransferPollMessage(
        targetId,
        newDomain.getTransferData(),
        newExpirationTime,
        historyEntry);
    ImmutableSet.Builder<ImmutableObject> entitiesToSave = new ImmutableSet.Builder<>();
    entitiesToSave.add(
        newDomain,
        historyEntry,
        autorenewEvent,
        gainingClientPollMessage,
        gainingClientAutorenewPollMessage);
    billingEvent.ifPresent(entitiesToSave::add);
    ofy().save().entities(entitiesToSave.build());
    // Delete the billing event and poll messages that were written in case the transfer would have
    // been implicitly server approved.
    ofy().delete().keys(existingDomain.getTransferData().getServerApproveEntities());
    return responseBuilder
        .setResData(createTransferResponse(
            targetId, newDomain.getTransferData(), newDomain.getRegistrationExpirationTime()))
        .build();
  }

  private HistoryEntry buildHistoryEntry(
      DomainBase existingDomain, Registry registry, DateTime now, String gainingClientId) {
    ImmutableSet<DomainTransactionRecord> cancelingRecords =
        createCancelingRecords(
            existingDomain,
            now,
            registry.getAutomaticTransferLength().plus(registry.getTransferGracePeriodLength()),
            ImmutableSet.of(TRANSFER_SUCCESSFUL));
    return historyBuilder
        .setType(HistoryEntry.Type.DOMAIN_TRANSFER_APPROVE)
        .setModificationTime(now)
        .setOtherClientId(gainingClientId)
        .setParent(Key.create(existingDomain))
        .setDomainTransactionRecords(
            union(
                cancelingRecords,
                DomainTransactionRecord.create(
                        existingDomain.getTld(),
                        now.plus(registry.getTransferGracePeriodLength()),
                        TRANSFER_SUCCESSFUL,
                        1)))
        .build();
  }
}
