/*
 * 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.
 */

package org.elasticsearch.search.aggregations.bucket.histogram;

import org.elasticsearch.common.ParseField;
import org.elasticsearch.common.io.stream.StreamInput;
import org.elasticsearch.common.io.stream.StreamOutput;
import org.elasticsearch.common.io.stream.Writeable;
import org.elasticsearch.common.rounding.DateTimeUnit;
import org.elasticsearch.common.rounding.Rounding;
import org.elasticsearch.common.settings.Settings;
import org.elasticsearch.common.xcontent.ObjectParser;
import org.elasticsearch.common.xcontent.XContentBuilder;
import org.elasticsearch.common.xcontent.XContentParser;
import org.elasticsearch.search.aggregations.AggregationBuilder;
import org.elasticsearch.search.aggregations.AggregatorFactories.Builder;
import org.elasticsearch.search.aggregations.AggregatorFactory;
import org.elasticsearch.search.aggregations.MultiBucketConsumerService;
import org.elasticsearch.search.aggregations.support.ValueType;
import org.elasticsearch.search.aggregations.support.ValuesSource;
import org.elasticsearch.search.aggregations.support.ValuesSource.Numeric;
import org.elasticsearch.search.aggregations.support.ValuesSourceAggregationBuilder;
import org.elasticsearch.search.aggregations.support.ValuesSourceAggregatorFactory;
import org.elasticsearch.search.aggregations.support.ValuesSourceConfig;
import org.elasticsearch.search.aggregations.support.ValuesSourceParserHelper;
import org.elasticsearch.search.aggregations.support.ValuesSourceType;
import org.elasticsearch.search.internal.SearchContext;

import java.io.IOException;
import java.util.Arrays;
import java.util.Map;
import java.util.Objects;

public class AutoDateHistogramAggregationBuilder
        extends ValuesSourceAggregationBuilder<ValuesSource.Numeric, AutoDateHistogramAggregationBuilder> {

    public static final String NAME = "auto_date_histogram";

    public static final ParseField NUM_BUCKETS_FIELD = new ParseField("buckets");

    private static final ObjectParser<AutoDateHistogramAggregationBuilder, Void> PARSER;
    static {
        PARSER = new ObjectParser<>(AutoDateHistogramAggregationBuilder.NAME);
        ValuesSourceParserHelper.declareNumericFields(PARSER, true, true, true);

        PARSER.declareInt(AutoDateHistogramAggregationBuilder::setNumBuckets, NUM_BUCKETS_FIELD);
    }

    public static AutoDateHistogramAggregationBuilder parse(String aggregationName, XContentParser parser) throws IOException {
        return PARSER.parse(parser, new AutoDateHistogramAggregationBuilder(aggregationName), null);
    }

    private int numBuckets = 10;

    /** Create a new builder with the given name. */
    public AutoDateHistogramAggregationBuilder(String name) {
        super(name, ValuesSourceType.NUMERIC, ValueType.DATE);
    }

    /** Read from a stream, for internal use only. */
    public AutoDateHistogramAggregationBuilder(StreamInput in) throws IOException {
        super(in, ValuesSourceType.NUMERIC, ValueType.DATE);
        numBuckets = in.readVInt();
    }

    protected AutoDateHistogramAggregationBuilder(AutoDateHistogramAggregationBuilder clone, Builder factoriesBuilder,
            Map<String, Object> metaData) {
        super(clone, factoriesBuilder, metaData);
        this.numBuckets = clone.numBuckets;
    }

    @Override
    protected AggregationBuilder shallowCopy(Builder factoriesBuilder, Map<String, Object> metaData) {
        return new AutoDateHistogramAggregationBuilder(this, factoriesBuilder, metaData);
    }

    @Override
    protected void innerWriteTo(StreamOutput out) throws IOException {
        out.writeVInt(numBuckets);
    }

    @Override
    public String getType() {
        return NAME;
    }

    public AutoDateHistogramAggregationBuilder setNumBuckets(int numBuckets) {
        if (numBuckets <= 0) {
            throw new IllegalArgumentException(NUM_BUCKETS_FIELD.getPreferredName() + " must be greater than 0 for [" + name + "]");
        }
        this.numBuckets = numBuckets;
        return this;
    }

    public int getNumBuckets() {
        return numBuckets;
    }

    @Override
    protected ValuesSourceAggregatorFactory<Numeric, ?> innerBuild(SearchContext context, ValuesSourceConfig<Numeric> config,
            AggregatorFactory<?> parent, Builder subFactoriesBuilder) throws IOException {
        RoundingInfo[] roundings = new RoundingInfo[6];
        roundings[0] = new RoundingInfo(createRounding(DateTimeUnit.SECOND_OF_MINUTE), 1000L, 1, 5, 10, 30);
        roundings[1] = new RoundingInfo(createRounding(DateTimeUnit.MINUTES_OF_HOUR), 60 * 1000L, 1, 5, 10, 30);
        roundings[2] = new RoundingInfo(createRounding(DateTimeUnit.HOUR_OF_DAY), 60 * 60 * 1000L, 1, 3, 12);
        roundings[3] = new RoundingInfo(createRounding(DateTimeUnit.DAY_OF_MONTH), 24 * 60 * 60 * 1000L, 1, 7);
        roundings[4] = new RoundingInfo(createRounding(DateTimeUnit.MONTH_OF_YEAR), 30 * 24 * 60 * 60 * 1000L, 1, 3);
        roundings[5] = new RoundingInfo(createRounding(DateTimeUnit.YEAR_OF_CENTURY), 365 * 24 * 60 * 60 * 1000L, 1, 5, 10, 20, 50, 100);

        int maxRoundingInterval = Arrays.stream(roundings,0, roundings.length-1)
            .map(rounding -> rounding.innerIntervals)
            .flatMapToInt(Arrays::stream)
            .boxed()
            .reduce(Integer::max).get();
        Settings settings = context.getQueryShardContext().getIndexSettings().getNodeSettings();
        int maxBuckets = MultiBucketConsumerService.MAX_BUCKET_SETTING.get(settings);
        int bucketCeiling = maxBuckets / maxRoundingInterval;
        if (numBuckets > bucketCeiling) {
            throw new IllegalArgumentException(NUM_BUCKETS_FIELD.getPreferredName()+
                " must be less than " + bucketCeiling);
        }
        return new AutoDateHistogramAggregatorFactory(name, config, numBuckets, roundings, context, parent, subFactoriesBuilder, metaData);
    }

    private Rounding createRounding(DateTimeUnit interval) {
        Rounding.Builder tzRoundingBuilder = Rounding.builder(interval);
        if (timeZone() != null) {
            tzRoundingBuilder.timeZone(timeZone());
        }
        Rounding rounding = tzRoundingBuilder.build();
        return rounding;
    }

    @Override
    protected XContentBuilder doXContentBody(XContentBuilder builder, Params params) throws IOException {
        builder.field(NUM_BUCKETS_FIELD.getPreferredName(), numBuckets);
        return builder;
    }

    @Override
    protected int innerHashCode() {
        return Objects.hash(numBuckets);
    }

    @Override
    protected boolean innerEquals(Object obj) {
        AutoDateHistogramAggregationBuilder other = (AutoDateHistogramAggregationBuilder) obj;
        return Objects.equals(numBuckets, other.numBuckets);
    }

    public static class RoundingInfo implements Writeable {
        final Rounding rounding;
        final int[] innerIntervals;
        final long roughEstimateDurationMillis;

        public RoundingInfo(Rounding rounding, long roughEstimateDurationMillis, int... innerIntervals) {
            this.rounding = rounding;
            this.roughEstimateDurationMillis = roughEstimateDurationMillis;
            this.innerIntervals = innerIntervals;
        }

        public RoundingInfo(StreamInput in) throws IOException {
            rounding = Rounding.Streams.read(in);
            roughEstimateDurationMillis = in.readVLong();
            innerIntervals = in.readIntArray();
        }

        @Override
        public void writeTo(StreamOutput out) throws IOException {
            Rounding.Streams.write(rounding, out);
            out.writeVLong(roughEstimateDurationMillis);
            out.writeIntArray(innerIntervals);
        }

        public int getMaximumInnerInterval() {
            return innerIntervals[innerIntervals.length - 1];
        }

        public long getRoughEstimateDurationMillis() {
            return roughEstimateDurationMillis;
        }

        @Override
        public int hashCode() {
            return Objects.hash(rounding, Arrays.hashCode(innerIntervals));
        }

        @Override
        public boolean equals(Object obj) {
            if (obj == null) {
                return false;
            }
            if (obj.getClass() != getClass()) {
                return false;
            }
            RoundingInfo other = (RoundingInfo) obj;
            return Objects.equals(rounding, other.rounding) &&
                    Objects.deepEquals(innerIntervals, other.innerIntervals);
        }
    }
}
