/*
 * 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.index.engine;

import org.apache.lucene.search.Sort;
import org.apache.lucene.search.SortedNumericSelector;
import org.apache.lucene.search.SortedNumericSortField;
import org.apache.lucene.search.SortedSetSortField;
import org.apache.lucene.search.SortedSetSelector;
import org.apache.lucene.search.SortField;
import org.apache.lucene.util.Version;
import org.opensearch.common.io.stream.BytesStreamOutput;
import org.opensearch.core.common.io.stream.StreamInput;
import org.opensearch.test.OpenSearchTestCase;

import java.io.IOException;
import java.util.Collections;
import java.util.Objects;

public class SegmentTests extends OpenSearchTestCase {
    static SortField randomSortField() {
        if (randomBoolean()) {
            SortedNumericSortField field = new SortedNumericSortField(
                randomAlphaOfLengthBetween(1, 10),
                SortField.Type.INT,
                randomBoolean(),
                randomBoolean() ? SortedNumericSelector.Type.MAX : SortedNumericSelector.Type.MIN
            );
            if (randomBoolean()) {
                field.setMissingValue(randomInt());
            }
            return field;
        } else {
            SortedSetSortField field = new SortedSetSortField(
                randomAlphaOfLengthBetween(1, 10),
                randomBoolean(),
                randomBoolean() ? SortedSetSelector.Type.MAX : SortedSetSelector.Type.MIN
            );
            if (randomBoolean()) {
                field.setMissingValue(randomBoolean() ? SortedSetSortField.STRING_FIRST : SortedSetSortField.STRING_LAST);
            }
            return field;
        }
    }

    static Sort randomIndexSort() {
        if (randomBoolean()) {
            return null;
        }
        int size = randomIntBetween(1, 5);
        SortField[] fields = new SortField[size];
        for (int i = 0; i < size; i++) {
            fields[i] = randomSortField();
        }
        return new Sort(fields);
    }

    static Segment randomSegment() {
        Segment segment = new Segment(randomAlphaOfLength(10));
        segment.committed = randomBoolean();
        segment.search = randomBoolean();
        segment.sizeInBytes = randomNonNegativeLong();
        segment.docCount = randomIntBetween(1, Integer.MAX_VALUE);
        segment.delDocCount = randomIntBetween(0, segment.docCount);
        segment.version = Version.LUCENE_8_0_0;
        segment.compound = randomBoolean();
        segment.mergeId = randomAlphaOfLengthBetween(1, 10);
        segment.segmentSort = randomIndexSort();
        if (randomBoolean()) {
            segment.attributes = Collections.singletonMap("foo", "bar");
        }
        return segment;
    }

    public void testSerialization() throws IOException {
        for (int i = 0; i < 20; i++) {
            Segment segment = randomSegment();
            BytesStreamOutput output = new BytesStreamOutput();
            segment.writeTo(output);
            output.flush();
            StreamInput input = output.bytes().streamInput();
            Segment deserialized = new Segment(input);
            assertTrue(isSegmentEquals(deserialized, segment));
        }
    }

    static boolean isSegmentEquals(Segment seg1, Segment seg2) {
        return seg1.docCount == seg2.docCount
            && seg1.delDocCount == seg2.delDocCount
            && seg1.committed == seg2.committed
            && seg1.search == seg2.search
            && Objects.equals(seg1.version, seg2.version)
            && Objects.equals(seg1.compound, seg2.compound)
            && seg1.sizeInBytes == seg2.sizeInBytes
            && seg1.getGeneration() == seg2.getGeneration()
            && seg1.getName().equals(seg2.getName())
            && seg1.getMergeId().equals(seg2.getMergeId())
            && Objects.equals(seg1.segmentSort, seg2.segmentSort);
    }
}