/*
 * ============LICENSE_START=======================================================
 * policy-endpoints
 * ================================================================================
 * Copyright (C) 2017-2018 AT&T Intellectual Property. All rights reserved.
 * ================================================================================
 * Licensed 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.
 * ============LICENSE_END=========================================================
 */

package org.onap.policy.common.endpoints.event.comm.bus;

import java.util.ArrayList;
import java.util.Arrays;
import java.util.HashMap;
import java.util.List;
import java.util.Properties;

import org.onap.policy.common.endpoints.properties.PolicyEndPointProperties;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

/**
 * Noop Topic Sink Factory.
 */
public interface NoopTopicSinkFactory {

    /**
     * Creates noop topic sinks based on properties files.
     * 
     * @param properties Properties containing initialization values
     * 
     * @return a noop topic sink
     * @throws IllegalArgumentException if invalid parameters are present
     */
    List<NoopTopicSink> build(Properties properties);

    /**
     * builds a noop sink.
     * 
     * @param servers list of servers
     * @param topic topic name
     * @param managed is this sink endpoint managed?
     * @return a noop topic sink
     * @throws IllegalArgumentException if invalid parameters are present
     */
    NoopTopicSink build(List<String> servers, String topic, boolean managed);

    /**
     * Destroys a sink based on the topic.
     * 
     * @param topic topic name
     * @throws IllegalArgumentException if invalid parameters are present
     */
    void destroy(String topic);

    /**
     * Destroys all sinks.
     */
    void destroy();

    /**
     * gets a sink based on topic name.
     * 
     * @param topic the topic name
     * 
     * @return a sink with topic name
     * @throws IllegalArgumentException if an invalid topic is provided
     * @throws IllegalStateException if the sink is in an incorrect state
     */
    NoopTopicSink get(String topic);

    /**
     * Provides a snapshot of the UEB Topic Writers.
     * 
     * @return a list of the UEB Topic Writers
     */
    List<NoopTopicSink> inventory();

}


/* ------------- implementation ----------------- */

/**
 * Factory of noop sinks.
 */
class IndexedNoopTopicSinkFactory implements NoopTopicSinkFactory {
    private static final String MISSING_TOPIC = "A topic must be provided";

    /**
     * Logger.
     */
    private static Logger logger = LoggerFactory.getLogger(IndexedNoopTopicSinkFactory.class);

    /**
     * noop topic sinks map.
     */
    protected HashMap<String, NoopTopicSink> noopTopicSinks = new HashMap<>();

    @Override
    public List<NoopTopicSink> build(Properties properties) {

        final String sinkTopics = properties.getProperty(PolicyEndPointProperties.PROPERTY_NOOP_SINK_TOPICS);
        if (sinkTopics == null || sinkTopics.isEmpty()) {
            logger.info("{}: no topic for noop sink", this);
            return new ArrayList<>();
        }

        final List<String> sinkTopicList = new ArrayList<>(Arrays.asList(sinkTopics.split("\\s*,\\s*")));
        final List<NoopTopicSink> newSinks = new ArrayList<>();
        synchronized (this) {
            for (final String topic : sinkTopicList) {
                if (this.noopTopicSinks.containsKey(topic)) {
                    newSinks.add(this.noopTopicSinks.get(topic));
                    continue;
                }

                String servers = properties.getProperty(PolicyEndPointProperties.PROPERTY_NOOP_SINK_TOPICS + "." + topic
                        + PolicyEndPointProperties.PROPERTY_TOPIC_SERVERS_SUFFIX);

                if (servers == null || servers.isEmpty()) {
                    servers = "noop";
                }

                final List<String> serverList = new ArrayList<>(Arrays.asList(servers.split("\\s*,\\s*")));

                final String managedString = properties.getProperty(PolicyEndPointProperties.PROPERTY_NOOP_SINK_TOPICS
                        + "." + topic + PolicyEndPointProperties.PROPERTY_MANAGED_SUFFIX);
                boolean managed = true;
                if (managedString != null && !managedString.isEmpty()) {
                    managed = Boolean.parseBoolean(managedString);
                }

                final NoopTopicSink noopSink = this.build(serverList, topic, managed);
                newSinks.add(noopSink);
            }
            return newSinks;
        }
    }

    @Override
    public NoopTopicSink build(List<String> servers, String topic, boolean managed) {

        List<String> noopSinkServers = servers;
        if (noopSinkServers == null || noopSinkServers.isEmpty()) {
            noopSinkServers = Arrays.asList("noop");
        }

        if (topic == null || topic.isEmpty()) {
            throw new IllegalArgumentException(MISSING_TOPIC);
        }

        synchronized (this) {
            if (this.noopTopicSinks.containsKey(topic)) {
                return this.noopTopicSinks.get(topic);
            }

            final NoopTopicSink sink = new NoopTopicSink(noopSinkServers, topic);

            if (managed) {
                this.noopTopicSinks.put(topic, sink);
            }

            return sink;
        }
    }

    @Override
    public void destroy(String topic) {
        if (topic == null || topic.isEmpty()) {
            throw new IllegalArgumentException(MISSING_TOPIC);
        }

        NoopTopicSink noopSink;
        synchronized (this) {
            if (!this.noopTopicSinks.containsKey(topic)) {
                return;
            }

            noopSink = this.noopTopicSinks.remove(topic);
        }

        noopSink.shutdown();
    }

    @Override
    public void destroy() {
        final List<NoopTopicSink> sinks = this.inventory();
        for (final NoopTopicSink sink : sinks) {
            sink.shutdown();
        }

        synchronized (this) {
            this.noopTopicSinks.clear();
        }
    }

    @Override
    public NoopTopicSink get(String topic) {
        if (topic == null || topic.isEmpty()) {
            throw new IllegalArgumentException(MISSING_TOPIC);
        }

        synchronized (this) {
            if (this.noopTopicSinks.containsKey(topic)) {
                return this.noopTopicSinks.get(topic);
            } else {
                throw new IllegalStateException("DmaapTopicSink for " + topic + " not found");
            }
        }
    }

    @Override
    public List<NoopTopicSink> inventory() {
        return new ArrayList<>(this.noopTopicSinks.values());
    }
}