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

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

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/**
 *
 * Copyright (C) 2010 Cloud Conscious, LLC. <info@cloudconscious.com>
 *
 * ====================================================================
 * 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.jclouds.location.suppliers;

import static com.google.common.base.Preconditions.checkNotNull;
import static com.google.common.collect.Iterables.getOnlyElement;

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.location.Region;

import com.google.common.base.Predicate;
import com.google.common.base.Supplier;
import com.google.common.collect.Iterables;
import com.google.inject.Injector;
import com.google.inject.Key;

/**
 * @author Adrian Cole
 */
@Singleton
public class OnlyLocationOrFirstZoneOrRegionMatchingRegionId implements Supplier<Location> {
    @Singleton
    public static final class IsRegionAndIdEqualsOrIsZoneParentIdEquals implements Predicate<Location> {

        private final String region;

        @Inject
        IsRegionAndIdEqualsOrIsZoneParentIdEquals(@Region String region) {
            this.region = checkNotNull(region, "region");
        }

        @Override
        public boolean apply(Location input) {
            switch (input.getScope()) {
            case ZONE:
                return input.getParent().getId().equals(region);
            case REGION:
                return input.getId().equals(region);
            default:
                return false;
            }
        }

        @Override
        public String toString() {
            return "isRegionAndIdEqualsOrIsZoneParentIdEquals(" + region + ")";
        }
    }

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

    @Inject
    OnlyLocationOrFirstZoneOrRegionMatchingRegionId(Injector injector,
            @Memoized Supplier<Set<? extends Location>> locationsSupplier) {
        this.injector = checkNotNull(injector, "injector");
        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());
        IsRegionAndIdEqualsOrIsZoneParentIdEquals matcher = null;
        try {
            String region = injector.getInstance(Key.get(String.class, Region.class));
            if (region == null)
                return Iterables.get(locationsSupplier.get(), 0);
            matcher = injector.getInstance(IsRegionAndIdEqualsOrIsZoneParentIdEquals.class);
            Location toReturn = Iterables.find(locations, matcher);
            return toReturn.getScope() == LocationScope.REGION ? toReturn : toReturn.getParent();
        } catch (NoSuchElementException e) {
            throw new IllegalStateException(String.format("region %s not found in %s", matcher, locations));
        }
    }
}