Group.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.aggregation;

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

import java.util.List;
import java.util.Optional;

@Data
public class Group implements Aggregation {
    public static final String NAME = "group";
    public static final String ALL = "*";

    @NonNull
    private final Optional<List<String>> of;
    @NonNull
    private final Optional<AggregationOrList> each;

    public static Aggregation of(
        final Optional<List<String>> of, final Optional<Aggregation> aggregation
    ) {
        return new Group(of, aggregation.map(AggregationOrList::fromAggregation));
    }

    @Override
    public GroupInstance apply(final AggregationContext context) {
        final AggregationInstance instance =
            each.flatMap(AggregationOrList::toAggregation).orElse(Empty.INSTANCE).apply(context);

        final Optional<List<String>> of = this.of.map(o -> {
            final ImmutableSet.Builder<String> b = ImmutableSet.builder();
            b.addAll(o).addAll(context.requiredTags());
            return ImmutableList.copyOf(b.build());
        });

        return new GroupInstance(of, instance);
    }
}