/*
 * SPDX-License-Identifier: Apache-2.0
 *
 * The OpenSearch Contributors require contributions made to
 * this file be licensed under the Apache-2.0 license or a
 * compatible open source license.
 */

/*
 * Licensed to Elasticsearch under one or more contributor
 * license agreements. See the NOTICE file distributed with
 * this work for additional information regarding copyright
 * ownership. Elasticsearch 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.
 */

/*
 * Modifications Copyright OpenSearch Contributors. See
 * GitHub history for details.
 */

package org.opensearch.search.aggregations.bucket.range;

import org.apache.lucene.util.InPlaceMergeSorter;
import org.opensearch.core.common.io.stream.StreamInput;
import org.opensearch.core.common.io.stream.StreamOutput;
import org.opensearch.core.common.io.stream.Writeable;
import org.opensearch.core.xcontent.XContentBuilder;
import org.opensearch.search.aggregations.AggregatorFactories;
import org.opensearch.search.aggregations.bucket.range.RangeAggregator.Range;
import org.opensearch.search.aggregations.support.ValuesSourceAggregationBuilder;
import org.opensearch.search.aggregations.support.ValuesSourceType;

import java.io.IOException;
import java.util.ArrayList;
import java.util.List;
import java.util.Map;
import java.util.Objects;
import java.util.function.Function;

/**
 * Base Aggregation Builder for range aggs
 *
 * @opensearch.internal
 */
public abstract class AbstractRangeBuilder<AB extends AbstractRangeBuilder<AB, R>, R extends Range> extends ValuesSourceAggregationBuilder<
    AB> {

    protected final InternalRange.Factory<?, ?> rangeFactory;
    protected List<R> ranges = new ArrayList<>();
    protected boolean keyed = false;

    protected AbstractRangeBuilder(String name, InternalRange.Factory<?, ?> rangeFactory) {
        super(name);
        this.rangeFactory = rangeFactory;
    }

    protected AbstractRangeBuilder(
        AbstractRangeBuilder<AB, R> clone,
        AggregatorFactories.Builder factoriesBuilder,
        Map<String, Object> metadata
    ) {
        super(clone, factoriesBuilder, metadata);
        this.rangeFactory = clone.rangeFactory;
        this.ranges = new ArrayList<>(clone.ranges);
        this.keyed = clone.keyed;
    }

    /**
     * Read from a stream.
     */
    protected AbstractRangeBuilder(StreamInput in, InternalRange.Factory<?, ?> rangeFactory, Writeable.Reader<R> rangeReader)
        throws IOException {
        super(in);
        this.rangeFactory = rangeFactory;
        ranges = in.readList(rangeReader);
        keyed = in.readBoolean();
    }

    @Override
    protected ValuesSourceType defaultValueSourceType() {
        // Copied over from the old targetValueType setting. Not sure what cases this is still relevant for. --Tozzi 2020-01-13
        return rangeFactory.getValueSourceType();
    }

    /**
     * Resolve any strings in the ranges so we have a number value for the from
     * and to of each range. The ranges are also sorted before being returned.
     */
    protected Range[] processRanges(Function<Range, Range> rangeProcessor) {
        Range[] ranges = new Range[this.ranges.size()];
        for (int i = 0; i < ranges.length; i++) {
            ranges[i] = rangeProcessor.apply(this.ranges.get(i));
        }
        sortRanges(ranges);
        return ranges;
    }

    private static void sortRanges(final Range[] ranges) {
        new InPlaceMergeSorter() {

            @Override
            protected void swap(int i, int j) {
                final Range tmp = ranges[i];
                ranges[i] = ranges[j];
                ranges[j] = tmp;
            }

            @Override
            protected int compare(int i, int j) {
                int cmp = Double.compare(ranges[i].from, ranges[j].from);
                if (cmp == 0) {
                    cmp = Double.compare(ranges[i].to, ranges[j].to);
                }
                return cmp;
            }
        }.sort(0, ranges.length);
    }

    @Override
    protected void innerWriteTo(StreamOutput out) throws IOException {
        out.writeVInt(ranges.size());
        for (Range range : ranges) {
            range.writeTo(out);
        }
        out.writeBoolean(keyed);
    }

    public AB addRange(R range) {
        if (range == null) {
            throw new IllegalArgumentException("[range] must not be null: [" + name + "]");
        }
        ranges.add(range);
        return (AB) this;
    }

    public List<R> ranges() {
        return ranges;
    }

    public AB keyed(boolean keyed) {
        this.keyed = keyed;
        return (AB) this;
    }

    public boolean keyed() {
        return keyed;
    }

    @Override
    public BucketCardinality bucketCardinality() {
        return BucketCardinality.MANY;
    }

    @Override
    protected XContentBuilder doXContentBody(XContentBuilder builder, Params params) throws IOException {
        builder.field(RangeAggregator.RANGES_FIELD.getPreferredName(), ranges);
        builder.field(RangeAggregator.KEYED_FIELD.getPreferredName(), keyed);
        return builder;
    }

    @Override
    public int hashCode() {
        return Objects.hash(super.hashCode(), ranges, keyed);
    }

    @Override
    public boolean equals(Object obj) {
        if (this == obj) return true;
        if (obj == null || getClass() != obj.getClass()) return false;
        if (super.equals(obj) == false) return false;
        AbstractRangeBuilder<AB, R> other = (AbstractRangeBuilder<AB, R>) obj;
        return Objects.equals(ranges, other.ranges) && Objects.equals(keyed, other.keyed);
    }
}
