[BOT.1] Add a class ForwardedStats in TetheringUtils

 */

package android.net.util;

import android.net.TetherStatsParcel;

import android.net.TetheringRequestParcel;

import androidx.annotation.NonNull;

import java.io.FileDescriptor;

import java.net.SocketException;

import java.util.Objects;

/**

 * Native methods for tethering utilization.

 * The classes and the methods for tethering utilization.

 *

 * {@hide}

 */

public class TetheringUtils {

    /**

     *  The object which records offload Tx/Rx forwarded bytes/packets.

     *  TODO: Replace the inner class ForwardedStats of class OffloadHardwareInterface with

     *  this class as well.

     */

    public static class ForwardedStats {

        public final long rxBytes;

        public final long rxPackets;

        public final long txBytes;

        public final long txPackets;

        public ForwardedStats() {

            rxBytes = 0;

            rxPackets = 0;

            txBytes = 0;

            txPackets = 0;

        }

        public ForwardedStats(long rxBytes, long txBytes) {

            this.rxBytes = rxBytes;

            this.rxPackets = 0;

            this.txBytes = txBytes;

            this.txPackets = 0;

        }

        public ForwardedStats(long rxBytes, long rxPackets, long txBytes, long txPackets) {

            this.rxBytes = rxBytes;

            this.rxPackets = rxPackets;

            this.txBytes = txBytes;

            this.txPackets = txPackets;

        }

        public ForwardedStats(@NonNull TetherStatsParcel tetherStats) {

            rxBytes = tetherStats.rxBytes;

            rxPackets = tetherStats.rxPackets;

            txBytes = tetherStats.txBytes;

            txPackets = tetherStats.txPackets;

        }

        public ForwardedStats(@NonNull ForwardedStats other) {

            rxBytes = other.rxBytes;

            rxPackets = other.rxPackets;

            txBytes = other.txBytes;

            txPackets = other.txPackets;

        }

        /** Add Tx/Rx bytes/packets and return the result as a new object. */

        @NonNull

        public ForwardedStats add(@NonNull ForwardedStats other) {

            return new ForwardedStats(rxBytes + other.rxBytes, rxPackets + other.rxPackets,

                    txBytes + other.txBytes, txPackets + other.txPackets);

        }

        /** Subtract Tx/Rx bytes/packets and return the result as a new object. */

        @NonNull

        public ForwardedStats subtract(@NonNull ForwardedStats other) {

            // TODO: Perhaps throw an exception if any negative difference value just in case.

            final long rxBytesDiff = Math.max(rxBytes - other.rxBytes, 0);

            final long rxPacketsDiff = Math.max(rxPackets - other.rxPackets, 0);

            final long txBytesDiff = Math.max(txBytes - other.txBytes, 0);

            final long txPacketsDiff = Math.max(txPackets - other.txPackets, 0);

            return new ForwardedStats(rxBytesDiff, rxPacketsDiff, txBytesDiff, txPacketsDiff);

        }

        /** Returns the string representation of this object. */

        @NonNull

        public String toString() {

            return String.format("ForwardedStats(rxb: %d, rxp: %d, txb: %d, txp: %d)", rxBytes,

                    rxPackets, txBytes, txPackets);

        }

    }

    /**

     * Configures a socket for receiving ICMPv6 router solicitations and sending advertisements.

     * @param fd the socket's {@link FileDescriptor}.