Groups.java

/*
 * Copyright (c) 2015 Spotify AB.
 *
 * Licensed to the Apache Software Foundation (ASF) under one
 * or more contributor license agreements.  See the NOTICE file
 * distributed with this work for additional information
 * regarding copyright ownership.  The ASF 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 com.spotify.heroic.common;

import com.google.common.collect.ImmutableSet;
import lombok.Data;

import java.util.Arrays;
import java.util.Iterator;
import java.util.Set;

@Data
public final class Groups implements Iterable<String> {
    public static final Groups EMPTY = new Groups(ImmutableSet.of());

    private final Set<String> groups;

    public Groups or(String... defaultGroups) {
        if (defaultGroups.length == 0) {
            throw new IllegalArgumentException("Set of default groups must not be empty");
        }

        if (!groups.isEmpty()) {
            return this;
        }

        return new Groups(ImmutableSet.copyOf(defaultGroups));
    }

    public static Groups empty() {
        return EMPTY;
    }

    @Override
    public Iterator<String> iterator() {
        return groups.iterator();
    }

    public boolean isEmpty() {
        return groups.isEmpty();
    }

    public static Groups combine(final Groups first, final Groups... other) {
        final ImmutableSet.Builder<String> all =
            ImmutableSet.<String>builder().addAll(first.groups);
        Arrays.stream(other).forEach(all::addAll);
        return new Groups(all.build());
    }

    public static Groups of(final String group) {
        return new Groups(ImmutableSet.of(group));
    }
}