/*
 * 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.monitor.process;

import org.opensearch.common.unit.TimeValue;
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.common.unit.ByteSizeValue;
import org.opensearch.core.xcontent.ToXContentFragment;
import org.opensearch.core.xcontent.XContentBuilder;

import java.io.IOException;

/**
 * Holds stats for the process
 *
 * @opensearch.internal
 */
public class ProcessStats implements Writeable, ToXContentFragment {

    private final long timestamp;
    private final long openFileDescriptors;
    private final long maxFileDescriptors;
    private final Cpu cpu;
    private final Mem mem;

    public ProcessStats(long timestamp, long openFileDescriptors, long maxFileDescriptors, Cpu cpu, Mem mem) {
        this.timestamp = timestamp;
        this.openFileDescriptors = openFileDescriptors;
        this.maxFileDescriptors = maxFileDescriptors;
        this.cpu = cpu;
        this.mem = mem;
    }

    public ProcessStats(StreamInput in) throws IOException {
        timestamp = in.readVLong();
        openFileDescriptors = in.readLong();
        maxFileDescriptors = in.readLong();
        cpu = in.readOptionalWriteable(Cpu::new);
        mem = in.readOptionalWriteable(Mem::new);
    }

    @Override
    public void writeTo(StreamOutput out) throws IOException {
        out.writeVLong(timestamp);
        out.writeLong(openFileDescriptors);
        out.writeLong(maxFileDescriptors);
        out.writeOptionalWriteable(cpu);
        out.writeOptionalWriteable(mem);
    }

    public long getTimestamp() {
        return timestamp;
    }

    public long getOpenFileDescriptors() {
        return openFileDescriptors;
    }

    public long getMaxFileDescriptors() {
        return maxFileDescriptors;
    }

    public Cpu getCpu() {
        return cpu;
    }

    public Mem getMem() {
        return mem;
    }

    static final class Fields {
        static final String PROCESS = "process";
        static final String TIMESTAMP = "timestamp";
        static final String OPEN_FILE_DESCRIPTORS = "open_file_descriptors";
        static final String MAX_FILE_DESCRIPTORS = "max_file_descriptors";

        static final String CPU = "cpu";
        static final String PERCENT = "percent";
        static final String TOTAL = "total";
        static final String TOTAL_IN_MILLIS = "total_in_millis";

        static final String MEM = "mem";
        static final String TOTAL_VIRTUAL = "total_virtual";
        static final String TOTAL_VIRTUAL_IN_BYTES = "total_virtual_in_bytes";
    }

    @Override
    public XContentBuilder toXContent(XContentBuilder builder, Params params) throws IOException {
        builder.startObject(Fields.PROCESS);
        builder.field(Fields.TIMESTAMP, timestamp);
        builder.field(Fields.OPEN_FILE_DESCRIPTORS, openFileDescriptors);
        builder.field(Fields.MAX_FILE_DESCRIPTORS, maxFileDescriptors);
        if (cpu != null) {
            builder.startObject(Fields.CPU);
            builder.field(Fields.PERCENT, cpu.percent);
            builder.humanReadableField(Fields.TOTAL_IN_MILLIS, Fields.TOTAL, new TimeValue(cpu.total));
            builder.endObject();
        }
        if (mem != null) {
            builder.startObject(Fields.MEM);
            builder.humanReadableField(Fields.TOTAL_VIRTUAL_IN_BYTES, Fields.TOTAL_VIRTUAL, new ByteSizeValue(mem.totalVirtual));
            builder.endObject();
        }
        builder.endObject();
        return builder;
    }

    /**
     * Process memory information.
     *
     * @opensearch.internal
     */
    public static class Mem implements Writeable {

        private final long totalVirtual;

        public Mem(long totalVirtual) {
            this.totalVirtual = totalVirtual;
        }

        public Mem(StreamInput in) throws IOException {
            totalVirtual = in.readLong();
        }

        @Override
        public void writeTo(StreamOutput out) throws IOException {
            out.writeLong(totalVirtual);
        }

        public ByteSizeValue getTotalVirtual() {
            return new ByteSizeValue(totalVirtual);
        }
    }

    /**
     * Process CPU information.
     *
     * @opensearch.internal
     */
    public static class Cpu implements Writeable {

        private final short percent;
        private final long total;

        public Cpu(short percent, long total) {
            this.percent = percent;
            this.total = total;
        }

        public Cpu(StreamInput in) throws IOException {
            percent = in.readShort();
            total = in.readLong();
        }

        @Override
        public void writeTo(StreamOutput out) throws IOException {
            out.writeShort(percent);
            out.writeLong(total);
        }

        /**
         * Get the Process cpu usage.
         * <p>
         * Supported Platforms: All.
         */
        public short getPercent() {
            return percent;
        }

        /**
         * Get the Process cpu time (sum of User and Sys).
         * <p>
         * Supported Platforms: All.
         */
        public TimeValue getTotal() {
            return new TimeValue(total);
        }
    }
}
