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RetrieveSubjectsStrategy.java
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RetrieveSubjectsStrategy.java
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/*
* Copyright (c) 2019 Contributors to the Eclipse Foundation
*
* See the NOTICE file(s) distributed with this work for additional
* information regarding copyright ownership.
*
* This program and the accompanying materials are made available under the
* terms of the Eclipse Public License 2.0 which is available at
* http://www.eclipse.org/legal/epl-2.0
*
* SPDX-License-Identifier: EPL-2.0
*/
package org.eclipse.ditto.services.policies.persistence.actors.strategies.commands;
import static org.eclipse.ditto.model.base.common.ConditionChecker.checkNotNull;
import java.util.Optional;
import javax.annotation.Nullable;
import org.eclipse.ditto.model.base.headers.WithDittoHeaders;
import org.eclipse.ditto.model.base.headers.entitytag.EntityTag;
import org.eclipse.ditto.model.policies.Policy;
import org.eclipse.ditto.model.policies.PolicyEntry;
import org.eclipse.ditto.model.policies.PolicyId;
import org.eclipse.ditto.services.utils.persistentactors.results.Result;
import org.eclipse.ditto.services.utils.persistentactors.results.ResultFactory;
import org.eclipse.ditto.signals.commands.policies.query.RetrieveSubjects;
import org.eclipse.ditto.signals.commands.policies.query.RetrieveSubjectsResponse;
import org.eclipse.ditto.signals.events.policies.PolicyEvent;
/**
* This strategy handles the {@link org.eclipse.ditto.signals.commands.policies.query.RetrieveSubjects} command.
*/
final class RetrieveSubjectsStrategy extends AbstractPolicyQueryCommandStrategy<RetrieveSubjects> {
RetrieveSubjectsStrategy() {
super(RetrieveSubjects.class);
}
@Override
protected Result<PolicyEvent> doApply(final Context<PolicyId> context, @Nullable final Policy policy,
final long nextRevision, final RetrieveSubjects command) {
final Policy nonNullPolicy = checkNotNull(policy, "policy");
final PolicyId policyId = context.getState();
final Optional<PolicyEntry> optionalEntry = nonNullPolicy.getEntryFor(command.getLabel());
if (optionalEntry.isPresent()) {
final WithDittoHeaders response = appendETagHeaderIfProvided(command,
RetrieveSubjectsResponse.of(policyId, command.getLabel(), optionalEntry.get().getSubjects(),
command.getDittoHeaders()),
nonNullPolicy);
return ResultFactory.newQueryResult(command, response);
} else {
return ResultFactory.newErrorResult(
policyEntryNotFound(policyId, command.getLabel(), command.getDittoHeaders()), command);
}
}
@Override
public Optional<EntityTag> nextEntityTag(final RetrieveSubjects command, @Nullable final Policy newEntity) {
return Optional.ofNullable(newEntity)
.flatMap(p -> p.getEntryFor(command.getLabel()))
.map(PolicyEntry::getSubjects)
.flatMap(EntityTag::fromEntity);
}
}