# AddNotificationFunctionProcessor.java

    /*
     * Copyright (c) 2018, 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.notification.mgt.Notification;
    import org.wso2.carbon.device.mgt.common.notification.mgt.NotificationManagementException;
    import org.wso2.carbon.device.mgt.common.notification.mgt.NotificationManagementService;
    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.query.processor.stream.function.StreamFunctionProcessor;
    import org.wso2.siddhi.query.api.definition.AbstractDefinition;
    import org.wso2.siddhi.query.api.definition.Attribute;
    import org.wso2.siddhi.query.api.exception.ExecutionPlanValidationException;

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

    public class AddNotificationFunctionProcessor extends StreamFunctionProcessor {

        private static final Log log = LogFactory.getLog(AddNotificationFunctionProcessor.class);

        /**
         * The init method of the StreamProcessor, this method will be called before other methods
         *
         * @param abstractDefinition           the incoming stream definition
         * @param attributeExpressionExecutors the executors of each function parameters
         * @param executionPlanContext         the context of the execution plan
         * @return the additional output attributes introduced by the function
         */
        @Override
        protected List<Attribute> init(AbstractDefinition abstractDefinition,
                                       ExpressionExecutor[] attributeExpressionExecutors,
                                       ExecutionPlanContext executionPlanContext) {
            if (attributeExpressionExecutors.length != 3) {
                throw new ExecutionPlanValidationException(
                        "Invalid no of arguments passed to device:addNotification() function, required 3 but found " +
                                attributeExpressionExecutors.length);
            }
            if (attributeExpressionExecutors[0].getReturnType() != Attribute.Type.STRING) {
                throw new ExecutionPlanValidationException(
                        "Invalid parameter type found for the first argument (deviceIdentifier) of device:addNotification() " +
                                "function, required " + Attribute.Type.STRING + " as deviceIdentifier, 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:addNotification() " +
                                "function, required " + Attribute.Type.STRING + " as deviceType, but found " +
                                attributeExpressionExecutors[1].getReturnType().toString());
            }
            if (attributeExpressionExecutors[2].getReturnType() != Attribute.Type.STRING) {
                throw new ExecutionPlanValidationException(
                        "Invalid parameter type found for the third argument (description) of device:addNotification() " +
                                "function, required " + Attribute.Type.STRING + " as description, but found " +
                                attributeExpressionExecutors[2].getReturnType().toString());
            }
            ArrayList<Attribute> attributes = new ArrayList<>();
            attributes.add(new Attribute("notified", Attribute.Type.BOOL));
            return attributes;
        }

        /**
         * The process method of the StreamFunction, used when more than one function parameters are provided
         *
         * @param data the data values for the function parameters
         * @return the data for additional output attributes introduced by the function
         */
        @Override
        protected Object[] process(Object[] data) {
            if (data[0] == null || data[1] == null || data[2] == null) {
                throw new ExecutionPlanRuntimeException("Invalid input given to device:addNotification() function. " +
                        "Neither of any three arguments cannot be null");
            }
            boolean isNotified = false;
            String deviceId = (String) data[0];
            String deviceType = (String) data[1];
            String description = (String) data[2];
            Notification notification = new Notification();
            notification.setStatus(Notification.Status.NEW.name());
            notification.setDeviceIdentifier(deviceId);
            notification.setDeviceType(deviceType);
            notification.setDescription(description);

            NotificationManagementService notificationManagementService = DeviceUtils.getNotificationManagementService();
            try {
                isNotified = notificationManagementService.addNotification(new DeviceIdentifier(deviceId, deviceType), notification);
            } catch (NotificationManagementException e) {
                // We are not throwing this exception to siddhi runtime as it will break the complete siddhi execution
                // flow for the event stream coming in.
                log.error("Error occurred while adding notification '" + notification.toString() + "' for " +
                        deviceType + " device with id " + deviceId, e);
            }

            return new Object[]{isNotified};
        }

        /**
         * The process method of the StreamFunction, used when zero or one function parameter is provided
         *
         * @param data null if the function parameter count is zero or runtime data value of the function parameter
         * @return the data for additional output attribute introduced by the function
         */
        @Override
        protected Object[] process(Object data) {
            return new Object[0];
        }

        /**
         * This will be called only once and this can be used to acquire
         * required resources for the processing element.
         * This will be called after initializing the system and before
         * starting to process the events.
         */
        @Override
        public void start() {

        }

        /**
         * This will be called only once and this can be used to release
         * the acquired resources for processing.
         * This will be called before shutting down the system.
         */
        @Override
        public void stop() {

        }

        /**
         * Used to collect the serializable state of the processing element, that need to be
         * persisted for the reconstructing the element to the same state on a different point of time
         *
         * @return stateful objects of the processing element as an array
         */
        @Override
        public Object[] currentState() {
            return new Object[0];
        }

        /**
         * Used to restore serialized state of the processing element, for reconstructing
         * the element to the same state as if was on a previous point of time.
         *
         * @param objects the stateful objects of the element as an array on
         *                the same order provided by currentState().
         */
        @Override
        public void restoreState(Object[] objects) {
            //Since there's no need to maintain a state, nothing needs to be done here.
        }
    }