Gadgetbridge/app/src/main/java/nodomain/freeyourgadget/gadgetbridge/service/devices/withingssteelhr/communication/notification/NotificationAttribute.java

/*  Copyright (C) 2021 Frank Ertl

    This file is part of Gadgetbridge.

    Gadgetbridge is free software: you can redistribute it and/or modify
    it under the terms of the GNU Affero General Public License as published
    by the Free Software Foundation, either version 3 of the License, or
    (at your option) any later version.

    Gadgetbridge is distributed in the hope that it will be useful,
    but WITHOUT ANY WARRANTY; without even the implied warranty of
    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
    GNU Affero General Public License for more details.

    You should have received a copy of the GNU Affero General Public License
    along with this program.  If not, see <http://www.gnu.org/licenses/>. */
package nodomain.freeyourgadget.gadgetbridge.service.devices.withingssteelhr.communication.notification;

import java.nio.ByteBuffer;
import java.nio.ByteOrder;
import java.nio.charset.StandardCharsets;

import nodomain.freeyourgadget.gadgetbridge.util.GB;
import nodomain.freeyourgadget.gadgetbridge.util.StringUtils;

public class NotificationAttribute {
    private byte attributeID;
    private short attributeLength;
    private short attributeMaxLength;
    private String value;

    public void setAttributeMaxLength(short attributeMaxLength) {
        this.attributeMaxLength = attributeMaxLength;
    }

    public byte getAttributeID() {
        return attributeID;
    }

    public void setAttributeID(byte attributeID) {
        this.attributeID = attributeID;
    }

    public short getAttributeLength() {
        short length = (short)(value != null? value.getBytes(StandardCharsets.UTF_8).length : 0);
        if (attributeMaxLength > 0 && length >  attributeMaxLength) {
            length = attributeMaxLength;
        }

        return length;
    }

    public String getValue() {
        return value;
    }

    public void setValue(String value) {
        this.value = value;
    }

    public byte[] serialize() {
        attributeLength = getAttributeLength();
        int length = attributeLength + 3;
        ByteBuffer buffer = ByteBuffer.allocate(length);
        buffer.put(attributeID);
        buffer.order(ByteOrder.LITTLE_ENDIAN);
        buffer.putShort(attributeLength);
        if (value != null) {
            buffer.order(ByteOrder.BIG_ENDIAN);
            buffer.put(value.getBytes(StandardCharsets.UTF_8), 0, attributeLength);
        }

        return buffer.array();
    }

    public void deserialize(byte[] rawData) {
        ByteBuffer buffer = ByteBuffer.wrap(rawData);
        attributeID = buffer.get();
        buffer.order(ByteOrder.LITTLE_ENDIAN);
        attributeLength = buffer.getShort();
        buffer.order(ByteOrder.BIG_ENDIAN);
        if (attributeLength > 0) {
            byte[] rawValue = new byte[attributeLength];
            buffer.get(rawValue);
            value = new String(rawValue, StandardCharsets.UTF_8);
        }
    }
}