org.jclouds.location.suppliers.OnlyLocationOrFirstRegionOptionallyMatchingRegionId.java Source code

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Here is the source code for org.jclouds.location.suppliers.OnlyLocationOrFirstRegionOptionallyMatchingRegionId.java

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/**
 * 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;

import static com.google.common.base.Preconditions.checkNotNull;
import static com.google.common.collect.Iterables.getOnlyElement;
import static com.google.common.collect.Iterables.transform;
import static org.jclouds.location.predicates.LocationPredicates.isRegion;
import static org.jclouds.location.predicates.LocationPredicates.isZone;
import static org.jclouds.location.predicates.LocationPredicates.isZoneOrRegionWhereRegionIdEquals;

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.domain.LocationScope;
import org.jclouds.javax.annotation.Nullable;
import org.jclouds.location.Region;
import org.jclouds.location.functions.ToIdAndScope;

import com.google.common.base.Predicate;
import com.google.common.base.Predicates;
import com.google.common.base.Supplier;
import com.google.common.collect.Iterables;

/**
 * @author Adrian Cole
 */
@Singleton
public class OnlyLocationOrFirstRegionOptionallyMatchingRegionId implements Supplier<Location> {

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

    @Inject
    OnlyLocationOrFirstRegionOptionallyMatchingRegionId(@Nullable @Region String region,
            @Memoized Supplier<Set<? extends Location>> locationsSupplier) {
        this.locationPredicate = region == null ? Predicates.<Location>or(isZone(), isRegion())
                : isZoneOrRegionWhereRegionIdEquals(region);
        this.locationsSupplier = checkNotNull(locationsSupplier, "locationsSupplier");
    }

    @Override
    @Singleton
    public Location get() {
        Set<? extends Location> locations = locationsSupplier.get();
        if (locationsSupplier.get().size() == 1)
            return getOnlyElement(locationsSupplier.get());
        try {
            Location toReturn = Iterables.find(locations, locationPredicate);
            return toReturn.getScope() == LocationScope.REGION ? toReturn : toReturn.getParent();
        } catch (NoSuchElementException e) {
            throw new NoSuchElementException(String.format("couldn't find region matching %s in %s",
                    locationPredicate, transform(locations, ToIdAndScope.INSTANCE)));
        }
    }
}