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Resolvers.java
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Resolvers.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.connectivity.service.messaging;
import java.util.Arrays;
import java.util.Collections;
import java.util.List;
import java.util.Map;
import java.util.Optional;
import javax.annotation.Nullable;
import org.eclipse.ditto.base.model.auth.AuthorizationContext;
import org.eclipse.ditto.base.model.entity.id.EntityId;
import org.eclipse.ditto.base.model.entity.id.WithEntityId;
import org.eclipse.ditto.base.model.headers.DittoHeaders;
import org.eclipse.ditto.base.model.signals.Signal;
import org.eclipse.ditto.connectivity.api.ExternalMessage;
import org.eclipse.ditto.connectivity.api.OutboundSignal;
import org.eclipse.ditto.connectivity.model.ConnectionId;
import org.eclipse.ditto.connectivity.service.placeholders.ConnectivityPlaceholders;
import org.eclipse.ditto.json.JsonFieldSelector;
import org.eclipse.ditto.json.JsonObject;
import org.eclipse.ditto.placeholders.ExpressionResolver;
import org.eclipse.ditto.placeholders.Placeholder;
import org.eclipse.ditto.placeholders.PlaceholderFactory;
import org.eclipse.ditto.placeholders.PlaceholderResolver;
import org.eclipse.ditto.protocol.Adaptable;
import org.eclipse.ditto.protocol.TopicPath;
import org.eclipse.ditto.protocol.adapter.DittoProtocolAdapter;
import org.eclipse.ditto.things.model.signals.events.ThingEventToThingConverter;
/**
* Creator of expression resolvers for incoming and outgoing messages.
*/
public final class Resolvers {
private Resolvers() {
throw new AssertionError();
}
private static final DittoProtocolAdapter PROTOCOL_ADAPTER = DittoProtocolAdapter.newInstance();
/**
* Placeholder resolver creators for incoming and outgoing messages.
*/
private static final List<ResolverCreator<?>> RESOLVER_CREATORS = Arrays.asList(
// For incoming messages, header mapping injects headers of external messages into Ditto headers.
ResolverCreator.of(PlaceholderFactory.newHeadersPlaceholder(), (h, s, t, a, c, e) -> h),
ResolverCreator.of(ConnectivityPlaceholders.newEntityPlaceholder(),
(h, s, t, a, c, e) -> WithEntityId.getEntityIdOfType(EntityId.class, s).orElse(null)),
ResolverCreator.of(ConnectivityPlaceholders.newThingPlaceholder(),
(h, s, t, a, c, e) -> WithEntityId.getEntityIdOfType(EntityId.class, s).orElse(null)),
ResolverCreator.of(ConnectivityPlaceholders.newThingJsonPlaceholder(),
(h, s, t, a, c, e) -> ThingEventToThingConverter
.mergeThingWithExtraFields(s,
JsonFieldSelector.newInstance(""),
Optional.ofNullable(e).orElse(JsonObject.empty())
)
.orElse(null)
),
ResolverCreator.of(ConnectivityPlaceholders.newFeaturePlaceholder(), (h, s, t, a, c, e) -> s),
ResolverCreator.of(ConnectivityPlaceholders.newTopicPathPlaceholder(), (h, s, t, a, c, e) -> t),
ResolverCreator.of(ConnectivityPlaceholders.newResourcePlaceholder(), (h, s, t, a, c, e) -> s),
ResolverCreator.of(ConnectivityPlaceholders.newTimePlaceholder(), (h, s, t, a, c, e) -> new Object()),
ResolverCreator.of(ConnectivityPlaceholders.newRequestPlaceholder(), (h, s, t, a, c, e) -> a),
ResolverCreator.of(ConnectivityPlaceholders.newConnectionIdPlaceholder(), (h, s, t, a, c, e) -> c)
);
private static final List<Placeholder<?>> PLACEHOLDERS = Collections.unmodifiableList(
RESOLVER_CREATORS.stream()
.map(ResolverCreator::getPlaceholder)
.toList()
);
/**
* @return Array of all placeholders for target address and source/target header mappings.
*/
@SuppressWarnings({"rawtypes", "java:S3740"})
public static Placeholder[] getPlaceholders() {
return PLACEHOLDERS.toArray(new Placeholder[0]);
}
/**
* Create an expression resolver for an outbound message.
*
* @param mappedOutboundSignal the mapped external message.
* @param sendingConnectionId the ID of the connection sending the message.
* @return the expression resolver.
*/
public static ExpressionResolver forOutbound(final OutboundSignal.Mapped mappedOutboundSignal,
final ConnectionId sendingConnectionId) {
final Signal<?> signal = mappedOutboundSignal.getSource();
final ExternalMessage externalMessage = mappedOutboundSignal.getExternalMessage();
final Adaptable adaptable = mappedOutboundSignal.getAdaptable();
return PlaceholderFactory.newExpressionResolver(
RESOLVER_CREATORS.stream()
.map(creator -> creator.create(adaptable.getDittoHeaders(),
signal,
externalMessage.getTopicPath().orElse(null),
signal.getDittoHeaders().getAuthorizationContext(),
sendingConnectionId,
mappedOutboundSignal.getExtra()
.or(() -> mappedOutboundSignal.getAdaptable().getPayload().getExtra())
.orElse(null)
))
.toArray(PlaceholderResolver[]::new)
);
}
/**
* Create an expression resolver for a signal.
*
* @param signal the signal.
* @param connectionId the ID of the connection that handles the signal
* @return the expression resolver.
* @since 1.3.0
*/
public static ExpressionResolver forSignal(final Signal<?> signal,
final ConnectionId connectionId) {
return PlaceholderFactory.newExpressionResolver(
RESOLVER_CREATORS.stream()
.map(creator -> creator.create(signal.getDittoHeaders(),
signal,
PROTOCOL_ADAPTER.toTopicPath(signal),
signal.getDittoHeaders().getAuthorizationContext(),
connectionId,
null
))
.toArray(PlaceholderResolver[]::new)
);
}
/**
* Create an expression resolver for an external Message.
*
* @param message the external message.
* @param receivingConnectionId the ID of the connection receiving the message.
* @return the expression resolver.
* @since 1.3.0
*/
public static ExpressionResolver forExternalMessage(final ExternalMessage message,
final ConnectionId receivingConnectionId) {
return PlaceholderFactory.newExpressionResolver(
RESOLVER_CREATORS.stream()
.map(creator -> creator.create(makeCaseInsensitive(message.getHeaders()),
null,
message.getTopicPath().orElse(null),
message.getAuthorizationContext().orElse(null),
receivingConnectionId,
null
))
.toArray(PlaceholderResolver[]::new)
);
}
/**
* Create an expression resolver for an mappable outbound signal.
*
* @param outboundSignal the outbound signal.
* @param sendingConnectionId the ID of the connection sending the message.
* @return the expression resolver.
* @since 1.2.0
*/
public static ExpressionResolver forOutboundSignal(final OutboundSignal.Mappable outboundSignal,
final ConnectionId sendingConnectionId) {
return PlaceholderFactory.newExpressionResolver(
RESOLVER_CREATORS.stream()
.map(creator -> creator.create(outboundSignal.getSource().getDittoHeaders(),
outboundSignal.getSource(),
PROTOCOL_ADAPTER.toTopicPath(outboundSignal.getSource()),
outboundSignal.getSource().getDittoHeaders().getAuthorizationContext(),
sendingConnectionId,
outboundSignal.getExtra().orElse(null)
))
.toArray(PlaceholderResolver[]::new)
);
}
/**
* Create an expression resolver for an inbound message.
*
* @param externalMessage the inbound external message.
* @param signal the mapped Ditto signal without internal headers.
* @param topicPath the topic path of the inbound message, or null if it cannot be determined.
* @param authorizationContext the authorization context of the inbound message, or null if it cannot be determined.
* @param connectionId The ID of the connection that received the inbound message.
* @return the expression resolver.
*/
public static ExpressionResolver forInbound(final ExternalMessage externalMessage, final Signal<?> signal,
@Nullable final TopicPath topicPath, @Nullable final AuthorizationContext authorizationContext,
@Nullable final ConnectionId connectionId) {
return PlaceholderFactory.newExpressionResolver(
RESOLVER_CREATORS.stream()
.map(creator -> creator.create(makeCaseInsensitive(externalMessage.getHeaders()),
signal,
topicPath,
authorizationContext,
connectionId,
null
))
.toArray(PlaceholderResolver[]::new)
);
}
private static DittoHeaders makeCaseInsensitive(final Map<String, String> externalHeaders) {
return DittoHeaders.of(externalHeaders);
}
/**
* Extract data for a placeholder.
*
* @param <T> the data required by the placeholder.
*/
@FunctionalInterface
private interface ResolverDataExtractor<T> {
@Nullable
T extract(Map<String, String> headers, @Nullable Signal<?> signal, @Nullable TopicPath topicPath,
@Nullable AuthorizationContext authorizationContext, @Nullable ConnectionId connectionId,
@Nullable JsonObject extraFields);
}
/**
* Creator of a placeholder resolver.
* Must be an inner class due to the lack of existential types in Java 8.
*
* @param <T> the data required by the placeholder.
*/
private static final class ResolverCreator<T> {
private final Placeholder<T> placeholder;
private final ResolverDataExtractor<T> dataExtractor;
private ResolverCreator(final Placeholder<T> placeholder, final ResolverDataExtractor<T> dataExtractor) {
this.placeholder = placeholder;
this.dataExtractor = dataExtractor;
}
private static <T> ResolverCreator<T> of(final Placeholder<T> placeholder,
final ResolverDataExtractor<T> dataExtractor) {
return new ResolverCreator<>(placeholder, dataExtractor);
}
private PlaceholderResolver<T> create(final Map<String, String> inputHeaders, @Nullable final Signal<?> signal,
@Nullable final TopicPath topicPath, @Nullable final AuthorizationContext authorizationContext,
@Nullable final ConnectionId connectionId, @Nullable final JsonObject extraFields) {
return PlaceholderFactory.newPlaceholderResolver(placeholder, dataExtractor.extract(
inputHeaders, signal, topicPath, authorizationContext, connectionId, extraFields
));
}
private Placeholder<T> getPlaceholder() {
return placeholder;
}
}
}