Gadgetbridge/app/src/main/java/nodomain/freeyourgadget/gadgetbridge/service/devices/huawei/ResponseManager.java

/*  Copyright (C) 2022 Gaignon Damien
    Copyright (C) 2022-2023 MartinJM

    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.huawei;

import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

import java.util.ArrayList;
import java.util.Collections;
import java.util.List;

import nodomain.freeyourgadget.gadgetbridge.devices.huawei.HuaweiPacket;
import nodomain.freeyourgadget.gadgetbridge.service.devices.huawei.requests.Request;

/**
 * Manages all response data.
 */
public class ResponseManager {
    private static final Logger LOG = LoggerFactory.getLogger(ResponseManager.class);

    private final List<Request> handlers = Collections.synchronizedList(new ArrayList<>());
    private HuaweiPacket receivedPacket;
    private final AsynchronousResponse asynchronousResponse;
    private final HuaweiSupportProvider support;

    public ResponseManager(HuaweiSupportProvider support) {
        this.asynchronousResponse = new AsynchronousResponse(support);
        this.support = support;
    }

    /**
     * Add a request to the response handler list
     * @param handler The request to handle responses
     */
    public void addHandler(Request handler) {
        synchronized (handlers) {
            handlers.add(handler);
        }
    }

    /**
     * Remove a request from the response handler list
     * @param handler The request to remove
     */
    public void removeHandler(Request handler) {
        synchronized (handlers) {
            handlers.remove(handler);
        }
    }

    /**
     * Parses the data into a Huawei Packet.
     * If the packet is complete, it will be handled by the first request that accepts it,
     * or as an asynchronous request otherwise.
     *
     * @param data The received data
     */
    public void handleData(byte[] data) {
        try {
            if (receivedPacket == null)
                receivedPacket = new HuaweiPacket(support.getParamsProvider()).parse(data);
            else
                receivedPacket = receivedPacket.parse(data);
        } catch (HuaweiPacket.ParseException e) {
            LOG.error("Packet parse exception", e);

            // Clean up so the next message may be parsed correctly
            this.receivedPacket = null;
            return;
        }

        if (receivedPacket.complete) {
            Request handler = null;
            synchronized (handlers) {
                for (Request req : handlers) {
                    if (req.handleResponse(receivedPacket)) {
                        handler = req;
                        break;
                    }
                }
            }

            if (handler == null) {
                LOG.debug("Service: " + Integer.toHexString(receivedPacket.serviceId & 0xff) + ", command: " + Integer.toHexString(receivedPacket.commandId & 0xff)  + ", asynchronous response.");

                // Asynchronous response
                asynchronousResponse.handleResponse(receivedPacket);
            } else {
                LOG.debug("Service: " + Integer.toHexString(receivedPacket.serviceId & 0xff)  + ", command: " + Integer.toHexString(receivedPacket.commandId & 0xff)  + ", handled by: " + handler.getClass());

                synchronized (handlers) {
                    handlers.remove(handler);
                }

                handler.handleResponse();
            }
            receivedPacket = null;
        }
    }
}