/**
* JBoss, Home of Professional Open Source
* Copyright Red Hat, Inc., and individual contributors
* by the @authors tag. See the copyright.txt in the distribution for a
* full listing of individual contributors.
*
* 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 org.jboss.aerogear.controller.router.rest.pagination;
import static org.jboss.aerogear.controller.util.ParameterExtractor.extractArguments;
import java.util.Collection;
import java.util.HashMap;
import java.util.Map;
import java.util.Map.Entry;
import javax.decorator.Decorator;
import javax.decorator.Delegate;
import javax.enterprise.inject.Instance;
import javax.inject.Inject;
import javax.servlet.http.HttpServletResponse;
import org.jboss.aerogear.controller.router.Consumer;
import org.jboss.aerogear.controller.router.EndpointInvoker;
import org.jboss.aerogear.controller.router.InvocationResult;
import org.jboss.aerogear.controller.router.Route;
import org.jboss.aerogear.controller.router.RouteContext;
import org.jboss.aerogear.controller.router.RouteProcessor;
/**
* PaginationHandler is a CDI Decorator that decorates a {@link RouteProcessor} and is responsible for handling
* paginated invocations on endpoints that support it.
*/
@Decorator
public class PaginationHandler implements RouteProcessor {
private final RouteProcessor delegate;
private final PaginationStrategy pagingStrategy;
private final Map<String, Consumer> consumers = new HashMap<String, Consumer>();
private final EndpointInvoker endpointInvoker;
/**
* Sole contructor which will have its parameters injected by CDI.
*
* @param delegate the {@link RouteProcessor} that this class decorates.
* @param pagingStrategies a CDI {@link Instance} of {@link PaginationStrategy}s enabling the strategy to be configured.
* @param consumers CDI {@link Instance} of {@link Consumer} that are used for unmarshalling a HTTP request body into
* a Java Object representation.
* @param endpointInvoker {@link EndpointInvoker} which is responsible for invoking endpoints.
*/
@Inject
public PaginationHandler(final @Delegate RouteProcessor delegate, final Instance<PaginationStrategy> pagingStrategies,
final Instance<Consumer> consumers, final EndpointInvoker endpointInvoker) {
this.delegate = delegate;
this.pagingStrategy = pagingStrategies.isUnsatisfied() ? defaultPagingStrategy() : pagingStrategies.get();
this.endpointInvoker = endpointInvoker;
for (Consumer consumer : consumers) {
this.consumers.put(consumer.mediaType(), consumer);
}
}
@Override
public InvocationResult process(final RouteContext routeContext) throws Exception {
if (hasPaginatedAnnotation(routeContext.getRoute())) {
final Map<String, Object> requestArgs = extractArguments(routeContext, consumers);
final PaginationInfo paginationInfo = pagingStrategy.createPaginationInfo(routeContext, requestArgs);
final Object[] args = pagingStrategy.preInvocation(paginationInfo, requestArgs);
final Collection<?> results = (Collection<?>) endpointInvoker.invoke(routeContext, args);
return new InvocationResult(pagingStrategy.postInvocation(results, routeContext, paginationInfo), routeContext);
} else {
return delegate.process(routeContext);
}
}
private boolean hasPaginatedAnnotation(final Route route) {
return route.getTargetMethod().getAnnotation(Paginated.class) != null;
}
public static PaginationStrategy defaultPagingStrategy() {
return new AbstractPaginationStrategy() {
@Override
public void setResponseHeaders(final PaginationMetadata metadata, final HttpServletResponse response,
final int resultSize) {
for (Entry<String, String> entry : metadata.getHeaders(resultSize).entrySet()) {
response.setHeader(entry.getKey(), entry.getValue());
}
}
};
}
}