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package org.glassfish.jersey.server.internal.routing;

import java.util.Collections;
import java.util.List;

import org.glassfish.hk2.api.Factory;

import com.google.common.base.Function;
import com.google.common.collect.Lists;

/**
 * Request routing information. Contains a {@link #routingPattern() routing pattern}
 * and a {@link #next() list of next-level stages} to be processed in case the
 * routing pattern successfully matches the un-matched right-hand part of the request.
 *
 * @param <T> routing pattern type.
 * @author Marek Potociar (marek.potociar at oracle.com)
 */
final class Route<T> {
    /**
     * Transformation function that converts router provider into router.
     */
    private static final Function<Factory<Router>, Router> PROVIDER_TO_ROUTER_TRANSFORMATION =
            new Function<Factory<Router>, Router>() {

                @Override
                public Router apply(Factory<Router> f) {
                    return f.provide();
                }
            };

    private final T routingPattern;
    private final List<Factory<Router>> routerProviders;

    /**
     * Create a new request route.
     *
     * @param <T>             routing pattern type.
     * @param routingPattern  request path routing pattern.
     * @param routerProviders next-level routers to be processed in case the routing
     *                        pattern matches the unmatched right-hand part of the request path.
     * @return new request route.
     */
    static <T> Route<T> of(T routingPattern, List<Factory<Router>> routerProviders) {
        return new Route<T>(routingPattern, routerProviders);
    }

    private Route(T routingPattern, List<Factory<Router>> routerProviders) {
        this.routingPattern = routingPattern;
        this.routerProviders = routerProviders;
    }

    /**
     * Get the request path routing pattern.
     *
     * @return request path routing pattern.
     */
    public T routingPattern() {
        return routingPattern;
    }

    /**
     * Get next-level routers to be processed in case the routing pattern matches
     * the unmatched right-hand part of the request path.
     *
     * @return routed next-level next.
     */
    public List<Router> next() {
        if (routerProviders.isEmpty()) {
            return Collections.emptyList();
        } else {
            return Lists.transform(routerProviders, Route.PROVIDER_TO_ROUTER_TRANSFORMATION);
        }
    }
}
