core/src/main/java/org/jclouds/location/suppliers/implicit/FirstNetwork.java

/**
 * Licensed to jclouds, Inc. (jclouds) under one or more
 * contributor license agreements.  See the NOTICE file
 * distributed with this work for additional information
 * regarding copyright ownership.  jclouds licenses this file
 * to you 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.jclouds.location.suppliers.implicit;

import static com.google.common.base.Preconditions.checkNotNull;
import static com.google.common.collect.Iterables.find;
import static com.google.common.collect.Iterables.transform;
import static org.jclouds.location.predicates.LocationPredicates.isNetwork;

import java.util.NoSuchElementException;
import java.util.Set;

import javax.inject.Inject;
import javax.inject.Singleton;

import org.jclouds.collect.Memoized;
import org.jclouds.domain.Location;
import org.jclouds.location.functions.ToIdAndScope;
import org.jclouds.location.suppliers.ImplicitLocationSupplier;

import com.google.common.base.Supplier;

/**
 * 
 * @author Dies Koper
 * 
 */
@Singleton
public class FirstNetwork implements ImplicitLocationSupplier {

    private final Supplier<Set<? extends Location>> locationsSupplier;

    @Inject
    FirstNetwork(@Memoized Supplier<Set<? extends Location>> locationsSupplier) {
        this.locationsSupplier = checkNotNull(locationsSupplier,
                "locationsSupplierSupplier");
    }

    @Override
    public Location get() {
        Set<? extends Location> locations = locationsSupplier.get();
        try {
            return find(locations, isNetwork());
        } catch (NoSuchElementException e) {
            throw new NoSuchElementException(
                    "none of the locations are scope NETWORK: "
                            + transform(locations, ToIdAndScope.INSTANCE));
        }
    }

}