# IsEnrolledFunctionExecutor.java

    /*
     * Copyright (c) 2017, WSO2 Inc. (http://www.wso2.org) All Rights Reserved.
     *
     * WSO2 Inc. licenses this file to you under the Apache License,
     * Version 2.0 (the "License"); you may not use this file except
     * in compliance with the License.
     * You may obtain a copy of the License at
     *
     * http://www.apache.org/licenses/LICENSE-2.0
     *
     * Unless required by applicable law or agreed to in writing,
     * software distributed under the License is distributed on an
     * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
     * KIND, either express or implied. See the License for the
     * specific language governing permissions and limitations
     * under the License.
     */

    package org.wso2.extension.siddhi.device;

    import org.apache.commons.logging.Log;
    import org.apache.commons.logging.LogFactory;
    import org.wso2.carbon.device.mgt.common.DeviceIdentifier;
    import org.wso2.carbon.device.mgt.common.DeviceManagementException;
    import org.wso2.carbon.device.mgt.common.group.mgt.GroupManagementException;
    import org.wso2.carbon.device.mgt.core.service.DeviceManagementProviderService;
    import org.wso2.carbon.device.mgt.core.service.GroupManagementProviderService;
    import org.wso2.extension.siddhi.device.utils.DeviceUtils;
    import org.wso2.siddhi.core.config.ExecutionPlanContext;
    import org.wso2.siddhi.core.exception.ExecutionPlanRuntimeException;
    import org.wso2.siddhi.core.executor.ExpressionExecutor;
    import org.wso2.siddhi.core.executor.function.FunctionExecutor;
    import org.wso2.siddhi.query.api.definition.Attribute;
    import org.wso2.siddhi.query.api.exception.ExecutionPlanValidationException;

    /**
     * isEnrolled(deviceId, deviceType)
     * Returns true if device enrolled.
     * Accept Type(s): (STRING, STRING)
     * Return Type(s): (BOOL)
     */
    public class IsEnrolledFunctionExecutor extends FunctionExecutor {

        private static Log log = LogFactory.getLog(IsEnrolledFunctionExecutor.class);
        private Attribute.Type returnType = Attribute.Type.BOOL;

        @Override
        protected void init(ExpressionExecutor[] attributeExpressionExecutors,
                ExecutionPlanContext executionPlanContext) {
            if (attributeExpressionExecutors.length != 2) {
                throw new ExecutionPlanValidationException(
                        "Invalid no of arguments passed to device:isEnrolled() function, required 2, but found "
                                + attributeExpressionExecutors.length);
            }
            if (attributeExpressionExecutors[0].getReturnType()!= Attribute.Type.STRING) {
                throw new ExecutionPlanValidationException(
                        "Invalid parameter type found for the first argument (deviceId) of device:isEnrolled() " +
                        "function, required " + Attribute.Type.STRING + ", but found " +
                        attributeExpressionExecutors[0].getReturnType().toString());
            }
            if (attributeExpressionExecutors[1].getReturnType() != Attribute.Type.STRING) {
                throw new ExecutionPlanValidationException(
                        "Invalid parameter type found for the second argument (deviceType) of device:isEnrolled() " +
                        "function, required " + Attribute.Type.STRING + ", but found " +
                        attributeExpressionExecutors[1].getReturnType().toString());
            }
        }

        @Override
        protected Object execute(Object[] data) {
            if (data[0] == null) {
                throw new ExecutionPlanRuntimeException("Invalid input given to device:isEnrolled() function. " +
                                                        "First argument cannot be null");
            }
            if (data[1] == null) {
                throw new ExecutionPlanRuntimeException("Invalid input given to device:isEnrolled() function. " +
                                                        "Second argument cannot be null");
            }

            String deviceId = (String) data[0];
            String deviceType = (String) data[1];

            DeviceIdentifier deviceIdentifier = new DeviceIdentifier(deviceId, deviceType);
            try {
                DeviceManagementProviderService deviceManagementService = DeviceUtils.getDeviceManagementProviderService();
                return deviceManagementService.isEnrolled(deviceIdentifier);
            } catch (DeviceManagementException e) {
                log.error("Error occurred while checking device is enrolled.", e);
            }
            return false;
        }

        @Override
        protected Object execute(Object data) {
            return null;  //Since the getDevicesOfUser function takes in 2 parameters, this method does not get called. Hence,not implemented.
        }

        @Override
        public void start() {
            //Nothing to start
        }

        @Override
        public void stop() {
            //Nothing to stop
        }

        @Override
        public Attribute.Type getReturnType() {
            return returnType;
        }

        @Override
        public Object[] currentState() {
            return null;    //No need to maintain a state.
        }

        @Override
        public void restoreState(Object[] state) {
            //Since there's no need to maintain a state, nothing needs to be done here.
        }
    }