/*
 * Copyright Elasticsearch B.V. and/or licensed to Elasticsearch B.V. under one
 * or more contributor license agreements. Licensed under the Elastic License
 * 2.0 and the Server Side Public License, v 1; you may not use this file except
 * in compliance with, at your election, the Elastic License 2.0 or the Server
 * Side Public License, v 1.
 */

package org.elasticsearch.index.shard;

import org.elasticsearch.Version;
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.xcontent.ToXContentFragment;
import org.elasticsearch.common.xcontent.XContentBuilder;
import org.elasticsearch.index.store.StoreStats;

import java.io.IOException;

public class DocsStats implements Writeable, ToXContentFragment {

    private long count = 0;
    private long deleted = 0;
    private long totalSizeInBytes = 0;

    public DocsStats() {

    }

    public DocsStats(StreamInput in) throws IOException {
        count = in.readVLong();
        deleted = in.readVLong();
        if (in.getVersion().onOrAfter(Version.V_6_1_0)) {
            totalSizeInBytes = in.readVLong();
        } else {
            totalSizeInBytes = -1;
        }
    }

    public DocsStats(long count, long deleted, long totalSizeInBytes) {
        this.count = count;
        this.deleted = deleted;
        this.totalSizeInBytes = totalSizeInBytes;
    }

    public void add(DocsStats other) {
        if (other == null) {
            return;
        }
        if (this.totalSizeInBytes == -1) {
            this.totalSizeInBytes = other.totalSizeInBytes;
        } else if (other.totalSizeInBytes != -1) {
            this.totalSizeInBytes += other.totalSizeInBytes;
        }
        this.count += other.count;
        this.deleted += other.deleted;
    }

    public long getCount() {
        return this.count;
    }

    public long getDeleted() {
        return this.deleted;
    }

    /**
     * Returns the total size in bytes of all documents in this stats.
     * This value may be more reliable than {@link StoreStats#getSizeInBytes()} in estimating the index size.
     */
    public long getTotalSizeInBytes() {
        return totalSizeInBytes;
    }

    @Override
    public void writeTo(StreamOutput out) throws IOException {
        out.writeVLong(count);
        out.writeVLong(deleted);
        if (out.getVersion().onOrAfter(Version.V_6_1_0)) {
            out.writeVLong(totalSizeInBytes);
        }
    }

    @Override
    public XContentBuilder toXContent(XContentBuilder builder, Params params) throws IOException {
        builder.startObject(Fields.DOCS);
        builder.field(Fields.COUNT, count);
        builder.field(Fields.DELETED, deleted);
        builder.endObject();
        return builder;
    }

    static final class Fields {
        static final String DOCS = "docs";
        static final String COUNT = "count";
        static final String DELETED = "deleted";
    }
}
