/*
 * JBoss, Home of Professional Open Source.
 * Copyright 2011, Red Hat, Inc., and individual contributors
 * as indicated by the @author tags. See the copyright.txt file in the
 * distribution for a full listing of individual contributors.
 *
 * This is free software; you can redistribute it and/or modify it
 * under the terms of the GNU Lesser General Public License as
 * published by the Free Software Foundation; either version 2.1 of
 * the License, or (at your option) any later version.
 *
 * This software 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
 * Lesser General Public License for more details.
 *
 * You should have received a copy of the GNU Lesser General Public
 * License along with this software; if not, write to the Free
 * Software Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA
 * 02110-1301 USA, or see the FSF site: http://www.fsf.org.
 */
package org.jboss.as.clustering.jgroups.subsystem;

import static org.jboss.as.clustering.controller.PropertiesTestUtil.checkMapModels;
import static org.jboss.as.clustering.controller.PropertiesTestUtil.checkMapResults;
import static org.jboss.as.clustering.controller.PropertiesTestUtil.executeOpInBothControllersWithAttachments;
import static org.jboss.as.controller.descriptions.ModelDescriptionConstants.COMPOSITE;
import static org.jboss.as.controller.descriptions.ModelDescriptionConstants.MODULE;
import static org.jboss.as.controller.descriptions.ModelDescriptionConstants.OP;
import static org.jboss.as.controller.descriptions.ModelDescriptionConstants.OP_ADDR;
import static org.jboss.as.controller.descriptions.ModelDescriptionConstants.STEPS;
import static org.jboss.as.controller.descriptions.ModelDescriptionConstants.SUBSYSTEM;

import java.util.List;

import org.jboss.as.clustering.controller.CommonUnaryRequirement;
import org.jboss.as.clustering.subsystem.AdditionalInitialization;
import org.jboss.as.controller.ModelVersion;
import org.jboss.as.controller.PathAddress;
import org.jboss.as.controller.descriptions.ModelDescriptionConstants;
import org.jboss.as.controller.operations.common.Util;
import org.jboss.as.controller.transform.OperationTransformer.TransformedOperation;
import org.jboss.as.model.test.FailedOperationTransformationConfig;
import org.jboss.as.model.test.ModelTestControllerVersion;
import org.jboss.as.model.test.ModelTestUtils;
import org.jboss.as.subsystem.test.KernelServices;
import org.jboss.as.subsystem.test.KernelServicesBuilder;
import org.jboss.dmr.ModelNode;
import org.jgroups.conf.ClassConfigurator;
import org.junit.Assert;
import org.junit.Test;

/**
 * Test cases for transformers used in the JGroups subsystem.
 *
 * @author <a href="tomaz.cerar@redhat.com">Tomaz Cerar</a>
 * @author Richard Achmatowicz (c) 2011 Red Hat Inc.
 * @author Radoslav Husar
 */
public class JGroupsTransformersTestCase extends OperationTestCaseBase {

    private static String formatEAP6SubsystemArtifact(ModelTestControllerVersion version) {
        return formatArtifact("org.jboss.as:jboss-as-clustering-jgroups:%s", version);
    }

    private static String formatEAP7SubsystemArtifact(ModelTestControllerVersion version) {
        return formatArtifact("org.jboss.eap:wildfly-clustering-jgroups-extension:%s", version);
    }

    private static String formatArtifact(String pattern, ModelTestControllerVersion version) {
        return String.format(pattern, version.getMavenGavVersion());
    }

    private static JGroupsModel getModelVersion(ModelTestControllerVersion controllerVersion) {
        switch (controllerVersion) {
            case EAP_6_4_0:
            case EAP_6_4_7:
                return JGroupsModel.VERSION_1_3_0;
            case EAP_7_0_0:
                return JGroupsModel.VERSION_4_0_0;
            case EAP_7_1_0:
                return JGroupsModel.VERSION_5_0_0;
            case EAP_7_2_0:
                return JGroupsModel.VERSION_6_0_0;
            default:
                throw new IllegalArgumentException();
        }
    }

    private static String[] getDependencies(ModelTestControllerVersion version) {
        switch (version) {
            case EAP_6_4_0:
            case EAP_6_4_7:
                return new String[] {
                        formatEAP6SubsystemArtifact(version),
                };
            case EAP_7_0_0:
            case EAP_7_1_0:
            case EAP_7_2_0:
                return new String[] {
                        formatEAP7SubsystemArtifact(version),
                        formatArtifact("org.jboss.eap:wildfly-clustering-common:%s", version),
                        formatArtifact("org.jboss.eap:wildfly-clustering-jgroups-spi:%s", version),
                        formatArtifact("org.jboss.eap:wildfly-clustering-service:%s", version),
                        formatArtifact("org.jboss.eap:wildfly-clustering-spi:%s", version),
                };
            default:
                throw new IllegalArgumentException();
        }
    }

    private static org.jboss.as.subsystem.test.AdditionalInitialization createAdditionalInitialization() {
        return new AdditionalInitialization()
                .require(CommonUnaryRequirement.SOCKET_BINDING, "jgroups-tcp", "jgroups-udp", "jgroups-udp-fd", "some-binding", "client-binding", "jgroups-diagnostics", "jgroups-mping", "jgroups-tcp-fd", "jgroups-client-fd", "jgroups-state-xfr")
                ;
    }

    @Test
    public void testTransformerEAP640() throws Exception {
        testTransformation(ModelTestControllerVersion.EAP_6_4_0);
    }

    @Test
    public void testTransformerEAP700() throws Exception {
        testTransformation(ModelTestControllerVersion.EAP_7_0_0);
    }

    @Test
    public void testTransformerEAP710() throws Exception {
        testTransformation(ModelTestControllerVersion.EAP_7_1_0);
    }

    @Test
    public void testTransformerEAP720() throws Exception {
        testTransformation(ModelTestControllerVersion.EAP_7_2_0);
    }

    /**
     * Tests transformation of model from current version into specified version.
     */
    private void testTransformation(final ModelTestControllerVersion controller) throws Exception {
        final ModelVersion version = getModelVersion(controller).getVersion();
        final String[] dependencies = getDependencies(controller);
        final String subsystemXmlResource = String.format("subsystem-jgroups-transform-%d_%d_%d.xml", version.getMajor(), version.getMinor(), version.getMicro());

        // create builder for current subsystem version
        KernelServicesBuilder builder = createKernelServicesBuilder(createAdditionalInitialization())
                .setSubsystemXmlResource(subsystemXmlResource);

        // initialize the legacy services and add required jars
        builder.createLegacyKernelServicesBuilder(createAdditionalInitialization(), controller, version)
                .addMavenResourceURL(dependencies)
                .addSingleChildFirstClass(AdditionalInitialization.class)
                // workaround IllegalArgumentException: key 1100 (org.jboss.as.clustering.jgroups.auth.BinaryAuthToken) is already in magic map; make sure that all keys are unique
                .addSingleChildFirstClass(ClassConfigurator.class)
                .skipReverseControllerCheck()
                .dontPersistXml();

        KernelServices services = builder.build();

        Assert.assertTrue(services.isSuccessfulBoot());
        Assert.assertTrue(services.getLegacyServices(version).isSuccessfulBoot());

        // check that both versions of the legacy model are the same and valid
        checkSubsystemModelTransformation(services, version, null, false);

        if (JGroupsModel.VERSION_3_0_0.requiresTransformation(version)) {
            // Test properties operations
            propertiesMapOperationsTest(services, version);

            testNonMapTransformersWork(services, version);
        }
    }

    private static void propertiesMapOperationsTest(KernelServices services, ModelVersion version) throws Exception {
        ////////////////////////////////////////////////////////////////////////////////////
        // Check individual operations

        // Check operations on /transport=*
        executeOpInBothControllersWithAttachments(services, version, getTransportUndefinePropertiesOperation("maximal", "TCP"));
        checkMapModels(services, version, getTransportAddress("maximal", "TCP"));

        executeOpInBothControllersWithAttachments(services, version, getTransportPutPropertyOperation("maximal", "TCP", "tcp_nodelay", "true"));
        checkMapResults(services, new ModelNode("true"), version, getTransportGetPropertyOperation("maximal", "TCP", "tcp_nodelay"));
        checkMapModels(services, version, getTransportAddress("maximal", "TCP"), "tcp_nodelay", "true");

        executeOpInBothControllersWithAttachments(services, version, getTransportPutPropertyOperation("maximal", "TCP", "loopback", "false"));
        checkMapResults(services, new ModelNode("true"), version, getTransportGetPropertyOperation("maximal", "TCP", "tcp_nodelay"));
        checkMapResults(services, new ModelNode("false"), version, getTransportGetPropertyOperation("maximal", "TCP", "loopback"));
        checkMapModels(services, version, getTransportAddress("maximal", "TCP"), "tcp_nodelay", "true", "loopback", "false");

        executeOpInBothControllersWithAttachments(services, version, getTransportPutPropertyOperation("maximal", "TCP", "loopback", "true"));
        checkMapResults(services, new ModelNode("true"), version, getTransportGetPropertyOperation("maximal", "TCP", "tcp_nodelay"));
        checkMapResults(services, new ModelNode("true"), version, getTransportGetPropertyOperation("maximal", "TCP", "loopback"));
        checkMapModels(services, version, getTransportAddress("maximal", "TCP"), "tcp_nodelay", "true", "loopback", "true");

        executeOpInBothControllersWithAttachments(services, version, getTransportRemovePropertyOperation("maximal", "TCP", "tcp_nodelay"));
        checkMapResults(services, new ModelNode(), version, getTransportGetPropertyOperation("maximal", "TCP", "tcp_nodelay"));
        checkMapResults(services, new ModelNode("true"), version, getTransportGetPropertyOperation("maximal", "TCP", "loopback"));
        checkMapModels(services, version, getTransportAddress("maximal", "TCP"), "loopback", "true");

        executeOpInBothControllersWithAttachments(services, version, getTransportPutPropertyOperation("maximal", "TCP", "tcp_nodelay", "false"));
        checkMapResults(services, new ModelNode("false"), version, getTransportGetPropertyOperation("maximal", "TCP", "tcp_nodelay"));
        checkMapResults(services, new ModelNode("true"), version, getTransportGetPropertyOperation("maximal", "TCP", "loopback"));
        checkMapModels(services, version, getTransportAddress("maximal", "TCP"), "tcp_nodelay", "false", "loopback", "true");

        executeOpInBothControllersWithAttachments(services, version, getTransportClearPropertiesOperation("maximal", "TCP"));
        checkMapResults(services, new ModelNode(), version, getTransportGetPropertyOperation("maximal", "TCP", "tcp_nodelay"));
        checkMapResults(services, new ModelNode(), version, getTransportGetPropertyOperation("maximal", "TCP", "loopback"));
        checkMapModels(services, version, getTransportAddress("maximal", "TCP"));

        // Check operations on /protocol=*
        executeOpInBothControllersWithAttachments(services, version, getProtocolUndefinePropertiesOperation("maximal", "MPING"));
        checkMapModels(services, version, getProtocolAddress("maximal", "MPING"));

        executeOpInBothControllersWithAttachments(services, version, getProtocolPutPropertyOperation("maximal", "MPING", "send_on_all_interfaces", "true"));
        checkMapResults(services, new ModelNode("true"), version, getProtocolGetPropertyOperation("maximal", "MPING", "send_on_all_interfaces"));
        checkMapModels(services, version, getProtocolAddress("maximal", "MPING"), "send_on_all_interfaces", "true");

        executeOpInBothControllersWithAttachments(services, version, getProtocolPutPropertyOperation("maximal", "MPING", "receive_on_all_interfaces", "false"));
        checkMapResults(services, new ModelNode("true"), version, getProtocolGetPropertyOperation("maximal", "MPING", "send_on_all_interfaces"));
        checkMapResults(services, new ModelNode("false"), version, getProtocolGetPropertyOperation("maximal", "MPING", "receive_on_all_interfaces"));
        checkMapModels(services, version, getProtocolAddress("maximal", "MPING"), "send_on_all_interfaces", "true", "receive_on_all_interfaces", "false");

        executeOpInBothControllersWithAttachments(services, version, getProtocolRemovePropertyOperation("maximal", "MPING", "receive_on_all_interfaces"));
        checkMapResults(services, new ModelNode("true"), version, getProtocolGetPropertyOperation("maximal", "MPING", "send_on_all_interfaces"));
        checkMapResults(services, new ModelNode(), version, getProtocolGetPropertyOperation("maximal", "MPING", "receive_on_all_interfaces"));
        checkMapModels(services, version, getProtocolAddress("maximal", "MPING"), "send_on_all_interfaces", "true");

        executeOpInBothControllersWithAttachments(services, version, getProtocolRemovePropertyOperation("maximal", "MPING", "send_on_all_interfaces"));
        checkMapResults(services, new ModelNode(), version, getProtocolGetPropertyOperation("maximal", "MPING", "send_on_all_interfaces"));
        checkMapModels(services, version, getProtocolAddress("maximal", "MPING"));

        executeOpInBothControllersWithAttachments(services, version, getProtocolPutPropertyOperation("maximal", "MPING", "receive_on_all_interfaces", "true"));
        checkMapResults(services, new ModelNode("true"), version, getProtocolGetPropertyOperation("maximal", "MPING", "receive_on_all_interfaces"));
        checkMapModels(services, version, getProtocolAddress("maximal", "MPING"), "receive_on_all_interfaces", "true");

        executeOpInBothControllersWithAttachments(services, version, getProtocolPutPropertyOperation("maximal", "MPING", "receive_on_all_interfaces", "false"));
        checkMapResults(services, new ModelNode("false"), version, getProtocolGetPropertyOperation("maximal", "MPING", "receive_on_all_interfaces"));
        checkMapModels(services, version, getProtocolAddress("maximal", "MPING"), "receive_on_all_interfaces", "false");

        executeOpInBothControllersWithAttachments(services, version, getProtocolClearPropertiesOperation("maximal", "MPING"));
        checkMapModels(services, version, getProtocolAddress("maximal", "MPING"));

        ////////////////////////////////////////////////////////////////////////////////////
        // Check composite operations
        ModelNode composite = new ModelNode();
        composite.get(OP).set(COMPOSITE);
        composite.get(OP_ADDR).setEmptyList();
        composite.get(STEPS).add(getProtocolPutPropertyOperation("maximal", "MPING", "send_on_all_interfaces", "false"));
        composite.get(STEPS).add(getProtocolPutPropertyOperation("maximal", "MPING", "receive_on_all_interfaces", "true"));
        composite.get(STEPS).add(getTransportPutPropertyOperation("maximal", "TCP", "tcp_nodelay", "true"));
        executeOpInBothControllersWithAttachments(services, version, composite);
        // Reread values back
        checkMapResults(services, new ModelNode("false"), version, getProtocolGetPropertyOperation("maximal", "MPING", "send_on_all_interfaces"));
        checkMapResults(services, new ModelNode("true"), version, getProtocolGetPropertyOperation("maximal", "MPING", "receive_on_all_interfaces"));
        checkMapResults(services, new ModelNode("true"), version, getTransportGetPropertyOperation("maximal", "TCP", "tcp_nodelay"));

        composite.get(STEPS).setEmptyList();
        composite.get(STEPS).add(getProtocolPutPropertyOperation("maximal", "MPING", "send_on_all_interfaces", "true"));
        composite.get(STEPS).add(getProtocolPutPropertyOperation("maximal", "MPING", "receive_on_all_interfaces", "false"));
        composite.get(STEPS).add(getTransportPutPropertyOperation("maximal", "TCP", "tcp_nodelay", "false"));
        executeOpInBothControllersWithAttachments(services, version, composite);
        // Reread values back
        checkMapResults(services, new ModelNode("true"), version, getProtocolGetPropertyOperation("maximal", "MPING", "send_on_all_interfaces"));
        checkMapResults(services, new ModelNode("false"), version, getProtocolGetPropertyOperation("maximal", "MPING", "receive_on_all_interfaces"));
        checkMapResults(services, new ModelNode("false"), version, getTransportGetPropertyOperation("maximal", "TCP", "tcp_nodelay"));
        checkMapModels(services, version, getProtocolAddress("maximal", "MPING"), "send_on_all_interfaces", "true", "receive_on_all_interfaces", "false");
        checkMapModels(services, version, getTransportAddress("maximal", "TCP"), "tcp_nodelay", "false");

        composite.get(STEPS).setEmptyList();
        composite.get(STEPS).add(getProtocolRemovePropertyOperation("maximal", "MPING", "send_on_all_interfaces"));
        composite.get(STEPS).add(getProtocolRemovePropertyOperation("maximal", "MPING", "receive_on_all_interfaces"));
        composite.get(STEPS).add(getTransportPutPropertyOperation("maximal", "TCP", "loopback", "false"));
        composite.get(STEPS).add(getTransportRemovePropertyOperation("maximal", "TCP", "tcp_nodelay"));
        executeOpInBothControllersWithAttachments(services, version, composite);
        // Reread values back
        checkMapResults(services, new ModelNode(), version, getProtocolGetPropertyOperation("maximal", "MPING", "send_on_all_interfaces"));
        checkMapResults(services, new ModelNode(), version, getProtocolGetPropertyOperation("maximal", "MPING", "receive_on_all_interfaces"));
        checkMapResults(services, new ModelNode(), version, getTransportGetPropertyOperation("maximal", "TCP", "tcp_nodelay"));
        checkMapResults(services, new ModelNode("false"), version, getTransportGetPropertyOperation("maximal", "TCP", "loopback"));
        checkMapModels(services, version, getProtocolAddress("maximal", "MPING"));
        checkMapModels(services, version, getTransportAddress("maximal", "TCP"), "loopback", "false");

        composite.get(STEPS).setEmptyList();
        composite.get(STEPS).add(getProtocolPutPropertyOperation("maximal", "MPING", "send_on_all_interfaces", "false"));
        composite.get(STEPS).add(getProtocolPutPropertyOperation("maximal", "MPING", "receive_on_all_interfaces", "true"));
        composite.get(STEPS).add(getTransportRemovePropertyOperation("maximal", "TCP", "loopback"));
        executeOpInBothControllersWithAttachments(services, version, composite);
        checkMapResults(services, new ModelNode("false"), version, getProtocolGetPropertyOperation("maximal", "MPING", "send_on_all_interfaces"));
        checkMapResults(services, new ModelNode("true"), version, getProtocolGetPropertyOperation("maximal", "MPING", "receive_on_all_interfaces"));
        checkMapResults(services, new ModelNode(), version, getTransportGetPropertyOperation("maximal", "TCP", "loopback"));
        checkMapModels(services, version, getProtocolAddress("maximal", "MPING"), "send_on_all_interfaces", "false", "receive_on_all_interfaces", "true");
        checkMapModels(services, version, getTransportAddress("maximal", "TCP"));
    }

    private void testNonMapTransformersWork(KernelServices services, ModelVersion version) throws Exception {
        final PathAddress stackAddr = PathAddress.pathAddress(SUBSYSTEM, getMainSubsystemName()).append("stack", "test");
        ModelNode addStack = Util.createAddOperation(stackAddr);
        executeOpInBothControllersWithAttachments(services, version, addStack);

        final PathAddress transportAddr = stackAddr.append("transport", "tcp");
        ModelNode addTransport = Util.createAddOperation(transportAddr);
        addTransport.get(MulticastProtocolResourceDefinition.Attribute.SOCKET_BINDING.getName()).set("some-binding");
        addTransport.get(MODULE).set("do.reject");
        TransformedOperation op = services.executeInMainAndGetTheTransformedOperation(addTransport, version);
        Assert.assertTrue(op.rejectOperation(success()));

        final PathAddress protocolAddr = stackAddr.append("protocol", "PING");
        ModelNode addProtocol = Util.createAddOperation(protocolAddr);
        addProtocol.get(MODULE).set("do.reject");
        op = services.executeInMainAndGetTheTransformedOperation(addProtocol, version);
        Assert.assertTrue(op.rejectOperation(success()));

        op = services.executeInMainAndGetTheTransformedOperation(Util.getWriteAttributeOperation(transportAddr, MODULE, "reject.this"), version);
        Assert.assertTrue(op.rejectOperation(success()));

        op = services.executeInMainAndGetTheTransformedOperation(Util.getWriteAttributeOperation(protocolAddr, MODULE, "reject.this"), version);
        Assert.assertTrue(op.rejectOperation(success()));
    }

    @Test
    public void testRejectionsEAP640() throws Exception {
        testRejections(ModelTestControllerVersion.EAP_6_4_0);
    }

    @Test
    public void testRejectionsEAP700() throws Exception {
        testRejections(ModelTestControllerVersion.EAP_7_0_0);
    }

    @Test
    public void testRejectionsEAP710() throws Exception {
        testRejections(ModelTestControllerVersion.EAP_7_1_0);
    }

    @Test
    public void testRejectionsEAP720() throws Exception {
        testRejections(ModelTestControllerVersion.EAP_7_2_0);
    }

    private void testRejections(final ModelTestControllerVersion controller) throws Exception {
        final ModelVersion version = getModelVersion(controller).getVersion();
        final String[] dependencies = getDependencies(controller);

        // create builder for current subsystem version
        KernelServicesBuilder builder = createKernelServicesBuilder(createAdditionalInitialization());

        // initialize the legacy services and add required jars
        builder.createLegacyKernelServicesBuilder(createAdditionalInitialization(), controller, version)
                .addSingleChildFirstClass(AdditionalInitialization.class)
                .addMavenResourceURL(dependencies)
                // workaround IllegalArgumentException: key 1100 (org.jboss.as.clustering.jgroups.auth.BinaryAuthToken) is already in magic map; make sure that all keys are unique
                .addSingleChildFirstClass(ClassConfigurator.class)
                .dontPersistXml();

        KernelServices services = builder.build();
        Assert.assertTrue(services.isSuccessfulBoot());
        KernelServices legacyServices = services.getLegacyServices(version);
        Assert.assertNotNull(legacyServices);
        Assert.assertTrue(legacyServices.isSuccessfulBoot());

        List<ModelNode> operations = builder.parseXmlResource("subsystem-jgroups-transform-reject.xml");
        ModelTestUtils.checkFailedTransformedBootOperations(services, version, operations, createFailedOperationTransformationConfig(version));
    }

    private static FailedOperationTransformationConfig createFailedOperationTransformationConfig(ModelVersion version) {
        FailedOperationTransformationConfig config = new FailedOperationTransformationConfig();

        PathAddress subsystemAddress = PathAddress.pathAddress(JGroupsSubsystemResourceDefinition.PATH);

        if (JGroupsModel.VERSION_7_0_0.requiresTransformation(version)) {
            config.addFailedAttribute(subsystemAddress.append(StackResourceDefinition.WILDCARD_PATH).append(TransportResourceDefinition.pathElement("TCP_NIO2")), FailedOperationTransformationConfig.REJECTED_RESOURCE);
            config.addFailedAttribute(subsystemAddress.append(StackResourceDefinition.WILDCARD_PATH).append(ProtocolResourceDefinition.pathElement("FD_SOCK")), FailedOperationTransformationConfig.REJECTED_RESOURCE);
        }

        if (JGroupsModel.VERSION_3_0_0.requiresTransformation(version)) {
            // Channel resource in a typical configuration would be not rejected, but since we don't have infinispan subsystem setup (because
            // that would create a cyclical dependency) it has to be rejected in this subsystem test
            config.addFailedAttribute(subsystemAddress.append(ChannelResourceDefinition.WILDCARD_PATH), FailedOperationTransformationConfig.REJECTED_RESOURCE);
            config.addFailedAttribute(subsystemAddress.append(StackResourceDefinition.WILDCARD_PATH).append(TransportResourceDefinition.pathElement("TCP")).append(ThreadPoolResourceDefinition.WILDCARD_PATH), FailedOperationTransformationConfig.REJECTED_RESOURCE);
        }

        if (JGroupsModel.VERSION_2_0_0.requiresTransformation(version)) {
            PathAddress stackAddress = subsystemAddress.append(StackResourceDefinition.WILDCARD_PATH);
            PathAddress relayAddress = stackAddress.append(RelayResourceDefinition.PATH);
            config.addFailedAttribute(relayAddress, FailedOperationTransformationConfig.REJECTED_RESOURCE);
            config.addFailedAttribute(relayAddress.append(RemoteSiteResourceDefinition.WILDCARD_PATH), FailedOperationTransformationConfig.REJECTED_RESOURCE);
        }

        return config;
    }


    private static ModelNode success() {
        final ModelNode result = new ModelNode();
        result.get(ModelDescriptionConstants.OUTCOME).set(ModelDescriptionConstants.SUCCESS);
        result.get(ModelDescriptionConstants.RESULT);
        return result;
    }

}
