/
PlaceholderSubstitution.java
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/
PlaceholderSubstitution.java
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/*
* Copyright (c) 2017 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.concierge.enforcement.placeholders;
import static java.util.Objects.requireNonNull;
import java.util.Collections;
import java.util.LinkedHashMap;
import java.util.Map;
import java.util.Optional;
import java.util.concurrent.CompletableFuture;
import java.util.concurrent.CompletionStage;
import java.util.function.Function;
import javax.annotation.concurrent.Immutable;
import org.eclipse.ditto.model.base.headers.DittoHeaders;
import org.eclipse.ditto.model.base.headers.WithDittoHeaders;
import org.eclipse.ditto.services.concierge.enforcement.placeholders.strategies.SubstitutionStrategy;
import org.eclipse.ditto.services.concierge.enforcement.placeholders.strategies.SubstitutionStrategyRegistry;
/**
* A function which applies substitution of placeholders on a command (subtype of {@link WithDittoHeaders}) based on
* its {@link DittoHeaders}.
*/
@Immutable
public final class PlaceholderSubstitution implements Function<WithDittoHeaders, CompletionStage<WithDittoHeaders>> {
private final HeaderBasedPlaceholderSubstitutionAlgorithm substitutionAlgorithm;
private final SubstitutionStrategyRegistry substitutionStrategyRegistry;
private PlaceholderSubstitution(final HeaderBasedPlaceholderSubstitutionAlgorithm substitutionAlgorithm,
final SubstitutionStrategyRegistry substitutionStrategyRegistry) {
this.substitutionAlgorithm = substitutionAlgorithm;
this.substitutionStrategyRegistry = substitutionStrategyRegistry;
}
/**
* Creates a new instance with default replacement definitions.
*
* @return the created instance.
* @see #newExtendedInstance(Map)
*/
public static PlaceholderSubstitution newInstance() {
final Map<String, Function<DittoHeaders, String>> defaultReplacementDefinitions =
createDefaultReplacementDefinitions();
return createInstance(defaultReplacementDefinitions);
}
/**
* Creates a new instance with default replacement definitions, extended with
* {@code additionalReplacementDefinitions}.
*
* @param additionalReplacementDefinitions the additional replacement definitions.
* @return the created instance.
* @see #newInstance()
*/
public static PlaceholderSubstitution newExtendedInstance(
final Map<String, Function<DittoHeaders, String>> additionalReplacementDefinitions) {
requireNonNull(additionalReplacementDefinitions);
final Map<String, Function<DittoHeaders, String>> defaultReplacementDefinitions =
createDefaultReplacementDefinitions();
final Map<String, Function<DittoHeaders, String>> allReplacementDefinitions =
new LinkedHashMap<>();
allReplacementDefinitions.putAll(defaultReplacementDefinitions);
allReplacementDefinitions.putAll(additionalReplacementDefinitions);
return createInstance(allReplacementDefinitions);
}
@Override
public CompletionStage<WithDittoHeaders> apply(final WithDittoHeaders withDittoHeaders) {
requireNonNull(withDittoHeaders);
final Optional<SubstitutionStrategy> firstMatchingStrategyOpt =
substitutionStrategyRegistry.getMatchingStrategy(withDittoHeaders);
if (firstMatchingStrategyOpt.isPresent()) {
final SubstitutionStrategy firstMatchingStrategy = firstMatchingStrategyOpt.get();
return CompletableFuture.supplyAsync(() -> {
@SuppressWarnings("unchecked")
final WithDittoHeaders maybeSubstituted =
firstMatchingStrategy.apply(withDittoHeaders, substitutionAlgorithm);
return maybeSubstituted;
});
} else {
return CompletableFuture.completedFuture(withDittoHeaders);
}
}
private static Map<String, Function<DittoHeaders, String>> createDefaultReplacementDefinitions() {
final Map<String, Function<DittoHeaders, String>> defaultReplacementDefinitions = new LinkedHashMap<>();
defaultReplacementDefinitions.put(SubjectIdReplacementDefinition.REPLACER_NAME, SubjectIdReplacementDefinition.getInstance());
defaultReplacementDefinitions.put(SubjectIdReplacementDefinition.LEGACY_REPLACER_NAME,
SubjectIdReplacementDefinition.getInstance());
return Collections.unmodifiableMap(defaultReplacementDefinitions);
}
private static PlaceholderSubstitution createInstance(
final Map<String, Function<DittoHeaders, String>> replacementDefinitions) {
final HeaderBasedPlaceholderSubstitutionAlgorithm algorithm =
HeaderBasedPlaceholderSubstitutionAlgorithm.newInstance(replacementDefinitions);
final SubstitutionStrategyRegistry substitutionStrategyRegistry =
SubstitutionStrategyRegistry.newInstance();
return new PlaceholderSubstitution(algorithm, substitutionStrategyRegistry);
}
}