/*
 * Licensed to the Apache Software Foundation (ASF) under one
 * or more contributor license agreements.  See the NOTICE file
 * distributed with this work for additional information
 * regarding copyright ownership.  The ASF 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
 * <p/>
 * http://www.apache.org/licenses/LICENSE-2.0
 * <p/>
 * 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.apache.atlas.omrs.topicconnectors.inmemory;

import org.apache.atlas.ocf.ffdc.ConnectorCheckedException;
import org.apache.atlas.omrs.eventmanagement.events.v1.OMRSEventV1;
import org.apache.atlas.omrs.topicconnectors.OMRSTopicConnector;

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


/**
 * InMemoryOMRSTopicConnector provides a concrete implementation of the OMRSTopicConnector that
 * uses an in-memory list as the event/messaging infrastructure.
 */
public class InMemoryOMRSTopicConnector extends OMRSTopicConnector
{
    private volatile List<OMRSEventV1>   inMemoryOMRSTopic = new ArrayList<>();

    public InMemoryOMRSTopicConnector()
    {
        super();
    }

    /**
     * Supports putting events to the in memory OMRS Topic
     *
     * @param newEvent - event to publish
     */
    private synchronized void putEvent(OMRSEventV1  newEvent)
    {
        inMemoryOMRSTopic.add(newEvent);
    }


    /**
     * Returns all of the events found on the in memory OMRS Topic.
     *
     * @return list of received events.
     */
    private synchronized List<OMRSEventV1> getEvents()
    {
        List<OMRSEventV1>   receivedEvents = inMemoryOMRSTopic;
        inMemoryOMRSTopic = new ArrayList<>();

        return receivedEvents;
    }


    /**
     * Sends the supplied event to the topic.
     *
     * @param event - OMRSEvent object containing the event properties.
     */
    public void sendEvent(OMRSEventV1 event)
    {
        this.putEvent(event);

    }


    /**
     * Look to see if there is one of more new events to process.
     *
     * @return a list of received events or null
     */
    protected List<OMRSEventV1> checkForEvents()
    {
        return this.getEvents();
    }


    /**
     * Indicates that the connector is completely configured and can begin processing.
     *
     * @throws ConnectorCheckedException - there is a problem within the connector.
     */
    public void start() throws ConnectorCheckedException
    {
        super.start();
    }


    /**
     * Free up any resources held since the connector is no longer needed.
     *
     * @throws ConnectorCheckedException - there is a problem within the connector.
     */
    public  void disconnect() throws ConnectorCheckedException
    {
        super.disconnect();
    }
}
