DefaultRouter.java

/***
 * Copyright (c) 2009 Caelum - www.caelum.com.br/opensource
 * All rights reserved.
 *
 * 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 br.com.caelum.vraptor.http.route;

import static com.google.common.base.Preconditions.checkState;

import java.lang.reflect.Method;
import java.util.ArrayList;
import java.util.Collection;
import java.util.Collections;
import java.util.EnumSet;
import java.util.Iterator;
import java.util.List;

import javax.enterprise.context.ApplicationScoped;
import javax.inject.Inject;

import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

import br.com.caelum.vraptor.cache.CacheStore;
import br.com.caelum.vraptor.controller.ControllerMethod;
import br.com.caelum.vraptor.controller.HttpMethod;
import br.com.caelum.vraptor.core.Converters;
import br.com.caelum.vraptor.http.EncodingHandler;
import br.com.caelum.vraptor.http.MutableRequest;
import br.com.caelum.vraptor.http.ParameterNameProvider;
import br.com.caelum.vraptor.proxy.Proxifier;

import com.google.common.base.Predicate;
import com.google.common.base.Supplier;
import com.google.common.collect.FluentIterable;

/**
 * The default implementation of controller localization rules. It also uses a Path annotation to discover
 * path->method mappings using the supplied ControllerLookupInterceptor.
 * 
 * @author Guilherme Silveira
 */
@ApplicationScoped
public class DefaultRouter implements Router {
	
	private static final Logger logger = LoggerFactory.getLogger(DefaultRouter.class);

	private final Collection<Route> routes = new PriorityRoutesList();
	private final Proxifier proxifier;
	private final TypeFinder finder;
	private final Converters converters;
	private final ParameterNameProvider nameProvider;
	private final Evaluator evaluator;
	private final CacheStore<Invocation, Route> cache;
	private final EncodingHandler encodingHandler;

	private static final Route NULL = new NoStrategy() {
		@Override
		public String urlFor(Class<?> type, Method m, Object... params) {
			throw new RouteNotFoundException("The selected route is invalid for redirection: " + type + "." + m.getName());
		}
	};

	/**
	 * @deprecated CDI eyes only
	 */
	protected DefaultRouter() {
		this(null, null, null, null, null, null, null);
	}

	@Inject
	public DefaultRouter(Proxifier proxifier, TypeFinder finder, Converters converters,
			ParameterNameProvider nameProvider, Evaluator evaluator, EncodingHandler encodingHandler,
			CacheStore<Invocation, Route> cache) {
		this.proxifier = proxifier;
		this.finder = finder;
		this.converters = converters;
		this.nameProvider = nameProvider;
		this.evaluator = evaluator;
		this.encodingHandler = encodingHandler;
		this.cache = cache;
	}

	@Override
	public RouteBuilder builderFor(String uri) {
		return new DefaultRouteBuilder(proxifier, finder, converters, nameProvider, evaluator, uri, encodingHandler);
	}

	/**
	 * You can override this method to get notified by all added routes.
	 */
	@Override
	public void add(Route r) {
		routes.add(r);
	}

	@Override
	public ControllerMethod parse(String uri, HttpMethod method, MutableRequest request) throws MethodNotAllowedException {
		Collection<Route> routesMatchingUriAndMethod = routesMatchingUriAndMethod(uri, method);

		Iterator<Route> iterator = routesMatchingUriAndMethod.iterator();

		Route route = iterator.next();
		checkIfThereIsAnotherRoute(uri, method, iterator, route);

		return route.controllerMethod(request, uri);
	}

	private void checkIfThereIsAnotherRoute(String uri, HttpMethod method, Iterator<Route> iterator, Route route) {
		if (iterator.hasNext()) {
			Route otherRoute = iterator.next();
			checkState(route.getPriority() != otherRoute.getPriority(),
					"There are two rules that matches the uri '%s' with method %s: %s, %s with same priority."
						+ " Consider using @Path priority attribute.", uri, method, route, otherRoute);
		}
	}

	private Collection<Route> routesMatchingUriAndMethod(String uri, HttpMethod method) {
		Collection<Route> routesMatchingMethod = FluentIterable.from(routesMatchingUri(uri))
				.filter(allow(method)).toSet();

		if (routesMatchingMethod.isEmpty()) {
			EnumSet<HttpMethod> allowed = allowedMethodsFor(uri);
			throw new MethodNotAllowedException(allowed, method.toString());
		}
		return routesMatchingMethod;
	}

	@Override
	public EnumSet<HttpMethod> allowedMethodsFor(String uri) {
		EnumSet<HttpMethod> allowed = EnumSet.noneOf(HttpMethod.class);
		for (Route route : routesMatchingUri(uri)) {
			allowed.addAll(route.allowedMethods());
		}
		return allowed;
	}

	private Collection<Route> routesMatchingUri(String uri) {
		Collection<Route> routesMatchingURI = FluentIterable.from(routes)
				.filter(canHandle(uri)).toSet();

		if (routesMatchingURI.isEmpty()) {
			throw new ControllerNotFoundException();
		}
		return routesMatchingURI;
	}

	@Override
	public <T> String urlFor(final Class<T> type, final Method method, Object... params) {
		final Class<?> rawtype = proxifier.isProxyType(type) ? type.getSuperclass() : type;
		final Invocation invocation = new Invocation(rawtype, method);

		Route route = cache.fetch(invocation, new Supplier<Route>() {
			@Override
			public Route get() {
				return FluentIterable.from(routes).filter(canHandle(rawtype, method))
					.first().or(NULL);
			}
		});

		logger.debug("Selected route for {} is {}", method, route);
		String url = route.urlFor(type, method, params);
		logger.debug("Returning URL {} for {}", url, route);

		return url;
	}

	@Override
	public List<Route> allRoutes() {
		return Collections.unmodifiableList(new ArrayList<>(routes));
	}

	private Predicate<Route> canHandle(final Class<?> type, final Method method) {
		return new Predicate<Route>() {
			@Override
			public boolean apply(Route route) {
				return route.canHandle(type, method);
			}
		};
	}

	private Predicate<Route> canHandle(final String uri) {
		return new Predicate<Route>() {
			@Override
			public boolean apply(Route route) {
				return route.canHandle(uri);
			}
		};
	}

	private Predicate<Route> allow(final HttpMethod method) {
		return new Predicate<Route>() {
			@Override
			public boolean apply(Route route) {
				return route.allowedMethods().contains(method);
			}
		};
	}
}