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RootRouteHeadersStepBuilder.java
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RootRouteHeadersStepBuilder.java
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/*
* Copyright (c) 2020 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.gateway.service.endpoints.routes;
import static org.eclipse.ditto.base.model.common.ConditionChecker.checkNotNull;
import java.text.MessageFormat;
import java.util.Map;
import java.util.concurrent.CompletionStage;
import java.util.stream.Collectors;
import java.util.stream.StreamSupport;
import javax.annotation.Nullable;
import javax.annotation.concurrent.NotThreadSafe;
import org.eclipse.ditto.base.model.headers.DittoHeaders;
import org.eclipse.ditto.base.model.headers.DittoHeadersBuilder;
import org.eclipse.ditto.base.model.headers.translator.HeaderTranslator;
import org.eclipse.ditto.edge.service.headers.DittoHeadersValidator;
import org.eclipse.ditto.gateway.api.GatewayDuplicateHeaderException;
import org.apache.pekko.http.javadsl.model.HttpHeader;
import org.apache.pekko.http.javadsl.model.HttpMessage;
import org.apache.pekko.http.javadsl.server.RequestContext;
/**
* This class provides a fluent API for building a CompletionStage that eventually supplies the {@link DittoHeaders} for
* usage within the RootRoute.
* Building the CompletionStage is designed to take place stepwise to guarantee that all required information is
* provided in correct order.
*
* @since 1.1.0
*/
@NotThreadSafe
final class RootRouteHeadersStepBuilder {
private final HeaderTranslator headerTranslator;
private final QueryParametersToHeadersMap queryParamsToHeaders;
private final CustomHeadersHandler customHeadersHandler;
private final DittoHeadersValidator dittoHeadersValidator;
private RootRouteHeadersStepBuilder(final HeaderTranslator headerTranslator,
final QueryParametersToHeadersMap queryParamsToHeaders,
final CustomHeadersHandler customHeadersHandler,
final DittoHeadersValidator dittoHeadersValidator) {
this.headerTranslator = checkNotNull(headerTranslator, "headerTranslator");
this.queryParamsToHeaders = checkNotNull(queryParamsToHeaders, "queryParamsToHeaders");
this.customHeadersHandler = checkNotNull(customHeadersHandler, "customHeadersHandler");
this.dittoHeadersValidator = checkNotNull(dittoHeadersValidator, "dittoHeadersValidator");
}
/**
* Returns an instance of {@code RootRouteHeadersStepBuilder}.
* The returned instance can be re-used for building a CompletionStage of DittoHeaders from scratch.
*
* @param headerTranslator translates request headers into valid DittoHeaders.
* @param queryParamsToHeaders converts query parameters into a Map of header key-values pairs.
* @param customHeadersHandler adds custom headers.
* @param dittoHeadersValidator ensures that Ditto headers are small enough to be sent around the cluster.
* @return the instance.
* @throws NullPointerException if any argument is {@code null}.
*/
static RootRouteHeadersStepBuilder getInstance(final HeaderTranslator headerTranslator,
final QueryParametersToHeadersMap queryParamsToHeaders,
final CustomHeadersHandler customHeadersHandler,
final DittoHeadersValidator dittoHeadersValidator) {
return new RootRouteHeadersStepBuilder(headerTranslator, queryParamsToHeaders, customHeadersHandler,
dittoHeadersValidator);
}
/**
* Sets the initial DittoHeaders builder.
*
* @param initialDittoHeadersBuilder initial DittoHeaders builder which might be pre-initialized with some header
* values.
* @return the next builder step.
* @throws NullPointerException if {@code initialDittoHeadersBuilder} is {@code null}.
*/
RequestContextStep withInitialDittoHeadersBuilder(final DittoHeadersBuilder<?, ?> initialDittoHeadersBuilder) {
return new RequestContextStep(checkNotNull(initialDittoHeadersBuilder, "initialDittoHeadersBuilder"));
}
/**
* Builder step for setting the RequestContext that provides the original request headers.
*/
@NotThreadSafe
final class RequestContextStep {
private final DittoHeadersBuilder<?, ?> dittoHeadersBuilder;
private RequestContextStep(final DittoHeadersBuilder<?, ?> dittoHeadersBuilder) {
this.dittoHeadersBuilder = dittoHeadersBuilder;
}
/**
* Sets the RequestContext that provides the original request headers which will be put to the eventual
* DittoHeaders.
*
* @param requestContext the request context containing request headers to be set after header keys are
* converted to lower-case.
* @return the next builder step.
* @throws NullPointerException if {@code requestContext} is {@code null}.
* @throws GatewayDuplicateHeaderException if a collision of header keys occurred.
*/
QueryParametersStep withRequestContext(final RequestContext requestContext) {
checkNotNull(requestContext, "requestContext");
final Map<String, String> filteredExternalHeaders = getFilteredExternalHeaders(requestContext.getRequest());
return new QueryParametersStep(dittoHeadersBuilder, requestContext, filteredExternalHeaders);
}
private Map<String, String> getFilteredExternalHeaders(final HttpMessage httpRequest) {
final Iterable<HttpHeader> headers = httpRequest.getHeaders();
final Map<String, String> externalHeaders = StreamSupport.stream(headers.spliterator(), false)
.collect(Collectors.toMap(HttpHeader::lowercaseName, HttpHeader::value, (dv1, dv2) -> {
throw GatewayDuplicateHeaderException.newBuilder()
.dittoHeaders(dittoHeadersBuilder.build())
.build();
}));
return headerTranslator.fromExternalHeaders(externalHeaders);
}
}
/**
* Builder step for setting the query parameters of the original request as part of the eventual DittoHeaders.
*/
@NotThreadSafe
final class QueryParametersStep {
private final DittoHeadersBuilder<?, ?> dittoHeadersBuilder;
private final RequestContext requestContext;
private final Map<String, String> filteredExternalHeaders;
private QueryParametersStep(final DittoHeadersBuilder<?, ?> dittoHeadersBuilder,
final RequestContext requestContext,
final Map<String, String> filteredExternalHeaders) {
this.dittoHeadersBuilder = dittoHeadersBuilder;
this.requestContext = requestContext;
this.filteredExternalHeaders = filteredExternalHeaders;
}
/**
* Sets the query parameters of the original request.
* These parameters will be converted into headers and put to the eventual DittoHeaders.
*
* @param queryParameters the query parameters to be set.
* @return the final builder step.
* @throws NullPointerException if {@code queryParameters} is {@code null}.
* @throws GatewayDuplicateHeaderException if the query parameters contain a key which is also contained in the
* original request headers but which is associated with a divergent value.
*/
BuildStep withQueryParameters(final Map<String, String> queryParameters) {
checkNotNull(queryParameters, "queryParameters");
final Map<String, String> externalQueryParams = headerTranslator.fromExternalHeaders(queryParameters);
final Map<String, String> headersFromQueryParameters = queryParamsToHeaders.apply(externalQueryParams);
avoidConflictingHeaders(headersFromQueryParameters);
dittoHeadersBuilder.putHeaders(filteredExternalHeaders);
dittoHeadersBuilder.putHeaders(headersFromQueryParameters);
return new BuildStep(dittoHeadersBuilder, requestContext);
}
private void avoidConflictingHeaders(final Map<String, String> headersFromQueryParameters) {
headersFromQueryParameters.forEach((key, value) -> {
@Nullable final String externalHeaderValue = filteredExternalHeaders.get(key);
if (null != externalHeaderValue && !value.equals(externalHeaderValue)) {
throw getDuplicateHeaderException(key);
}
});
}
private GatewayDuplicateHeaderException getDuplicateHeaderException(final String headerKey) {
final String msgPattern = "<{0}> was provided as header as well as query parameter with divergent values!";
return GatewayDuplicateHeaderException.newBuilder()
.message(MessageFormat.format(msgPattern, headerKey))
.dittoHeaders(dittoHeadersBuilder.build())
.build();
}
}
/**
* Final builder step which provides a CompletionStage of the eventual DittoHeaders.
*/
@NotThreadSafe
final class BuildStep {
private final DittoHeadersBuilder<?, ?> dittoHeadersBuilder;
private final RequestContext requestContext;
private BuildStep(final DittoHeadersBuilder<?, ?> dittoHeadersBuilder, final RequestContext requestContext) {
this.dittoHeadersBuilder = dittoHeadersBuilder;
this.requestContext = requestContext;
}
/**
* Builds a CompletionStage providing the eventual DittoHeaders.
* The eventual DittoHeaders are guaranteed to fit within the size limits of cluster messages.
*
* @param requestType the request type which is required for adding custom headers.
* @return a CompletionStage providing the eventual DittoHeaders.
* @throws NullPointerException if {@code requestType} is {@code null}.
*/
CompletionStage<DittoHeaders> build(final CustomHeadersHandler.RequestType requestType) {
checkNotNull(requestType, "requestType");
final DittoHeaders dittoDefaultHeaders = dittoHeadersBuilder.build();
// At this point it is ensured that a correlation ID was set
final String correlationId = dittoDefaultHeaders.getCorrelationId().orElseThrow();
CompletionStage<DittoHeaders> result = customHeadersHandler.handleCustomHeaders(correlationId,
requestContext,
requestType,
dittoDefaultHeaders);
return result.thenCompose(dittoHeadersValidator::validate);
}
}
}