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/*
 * Firebird Open Source JDBC Driver
 *
 * Distributable under LGPL license.
 * You may obtain a copy of the License at http://www.gnu.org/copyleft/lgpl.html
 *
 * This program 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
 * LGPL License for more details.
 *
 * This file was created by members of the firebird development team.
 * All individual contributions remain the Copyright (C) of those
 * individuals.  Contributors to this file are either listed here or
 * can be obtained from a source control history command.
 *
 * All rights reserved.
 */
package org.firebirdsql.gds.ng;

import org.firebirdsql.gds.JaybirdErrorCodes;
import org.firebirdsql.gds.ServiceParameterBuffer;
import org.firebirdsql.gds.ServiceRequestBuffer;
import org.firebirdsql.gds.ng.listeners.ServiceListener;
import org.firebirdsql.gds.ng.listeners.ServiceListenerDispatcher;

import java.nio.charset.StandardCharsets;
import java.sql.SQLException;

import static org.firebirdsql.gds.ISCConstants.*;
import static org.firebirdsql.gds.VaxEncoding.iscVaxInteger2;

/**
 * Abstract service implementation.
 *
 * @author Mark Rotteveel
 * @since 3.0
 */
public abstract class AbstractFbService>
        extends AbstractFbAttachment implements FbService {

    private static final System.Logger log = System.getLogger(AbstractFbService.class.getName());
    protected final ServiceListenerDispatcher serviceListenerDispatcher = new ServiceListenerDispatcher();
    private final WarningMessageCallback serviceWarningCallback =
            warning -> serviceListenerDispatcher.warningReceived(AbstractFbService.this, warning);

    protected AbstractFbService(T connection, DatatypeCoder datatypeCoder) {
        super(connection, datatypeCoder);
    }

    @Override
    public final  R getServiceInfo(ServiceParameterBuffer serviceParameterBuffer,
            ServiceRequestBuffer serviceRequestBuffer, int bufferLength, InfoProcessor infoProcessor)
            throws SQLException {
        final byte[] responseBuffer = getServiceInfo(serviceParameterBuffer, serviceRequestBuffer, bufferLength);
        try {
            return infoProcessor.process(responseBuffer);
        } catch (SQLException e) {
            exceptionListenerDispatcher.errorOccurred(e);
            throw e;
        }
    }

    @Override
    public final void addServiceListener(ServiceListener listener) {
        serviceListenerDispatcher.addListener(listener);
    }

    @Override
    public final void removeServiceListener(ServiceListener listener) {
        serviceListenerDispatcher.removeListener(listener);
    }

    /**
     * Actual implementation of service detach.
     * 
     * Implementations of this method should only be called from {@link #close()}, and should not
     * notify service listeners of the service {@link ServiceListener#detaching(FbService)} and
     * {@link ServiceListener#detached(FbService)} events.
     * 
     */
    protected abstract void internalDetach() throws SQLException;

    /**
     * {@inheritDoc}
     * 
     * Implementation note: Calls {@link #checkConnected()} and notifies service listeners of the detaching event, then
     * calls {@link #internalDetach()} and finally notifies service listeners of database detach and removes all
     * listeners.
     * 
     */
    @Override
    public final void close() throws SQLException {
        try (LockCloseable ignored = withLock()) {
            checkConnected();
            serviceListenerDispatcher.detaching(this);
            try {
                internalDetach();
            } finally {
                serviceListenerDispatcher.detached(this);
                serviceListenerDispatcher.shutdown();
            }
        } catch (SQLException e) {
            exceptionListenerDispatcher.errorOccurred(e);
            throw e;
        } finally {
            exceptionListenerDispatcher.shutdown();
        }
    }

    /**
     * @return The warning callback for this service.
     */
    protected final WarningMessageCallback getServiceWarningCallback() {
        return serviceWarningCallback;
    }

    protected ServiceRequestBuffer getDescribeServiceRequestBuffer() {
        ServiceRequestBuffer srb = createServiceRequestBuffer();
        srb.addArgument(isc_info_svc_server_version);
        return srb;
    }

    protected InfoProcessor getServiceInformationProcessor() {
        return new ServiceInformationProcessor();
    }

    private class ServiceInformationProcessor implements InfoProcessor {
        @Override
        public FbService process(byte[] info) throws SQLException {
            if (info.length == 0) {
                throw FbExceptionBuilder.forException(JaybirdErrorCodes.jb_infoResponseEmpty)
                        .messageParameter("service")
                        .toSQLException();
            }
            int len;
            int i = 0;
            while (info[i] != isc_info_end) {
                switch (info[i++]) {
                case isc_info_svc_server_version -> {
                    len = iscVaxInteger2(info, i);
                    i += 2;
                    String firebirdVersion = new String(info, i, len, StandardCharsets.UTF_8);
                    i += len;
                    setServerVersion(firebirdVersion);
                }
                case isc_info_truncated -> {
                    log.log(System.Logger.Level.DEBUG, "Received isc_info_truncated");
                    return AbstractFbService.this;
                }
                default -> throw FbExceptionBuilder.forException(isc_infunk).toSQLException();
                }
            }
            return AbstractFbService.this;
        }
    }
}