/*
 * Copyright 2015 Open Networking Laboratory
 *
 * 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.
 */
package org.onosproject.intentperf;

import com.fasterxml.jackson.databind.node.ObjectNode;
import com.google.common.collect.ImmutableList;
import com.google.common.collect.ImmutableSet;
import org.apache.felix.scr.annotations.Activate;
import org.apache.felix.scr.annotations.Component;
import org.apache.felix.scr.annotations.Deactivate;
import org.apache.felix.scr.annotations.Reference;
import org.apache.felix.scr.annotations.ReferenceCardinality;
import org.onlab.osgi.ServiceDirectory;
import org.onosproject.intentperf.IntentPerfCollector.Sample;
import org.onosproject.ui.UiConnection;
import org.onosproject.ui.UiExtension;
import org.onosproject.ui.UiExtensionService;
import org.onosproject.ui.UiMessageHandler;
import org.onosproject.ui.UiView;

import java.util.Collection;
import java.util.HashSet;
import java.util.List;
import java.util.Set;

import static java.util.Collections.synchronizedSet;

/**
 * Mechanism to stream data to the GUI.
 */
@Component(immediate = true, enabled = false)
public class IntentPerfUi {

    @Reference(cardinality = ReferenceCardinality.MANDATORY_UNARY)
    protected UiExtensionService uiExtensionService;

    private final Set<StreamingControl> handlers = synchronizedSet(new HashSet<>());

    private List<UiView> views = ImmutableList.of(new UiView("intentPerf", "Intent Performance"));
    private UiExtension uiExtension = new UiExtension(views, this::newHandlers,
                                                      getClass().getClassLoader());

    @Activate
    protected void activate() {
        uiExtensionService.register(uiExtension);
    }

    @Deactivate
    protected void deactivate() {
        uiExtensionService.unregister(uiExtension);
    }

    /**
     * Reports a single sample of performance data.
     *
     * @param sample performance sample
     */
    public void reportSample(Sample sample) {
        synchronized (handlers) {
            handlers.forEach(h -> h.send(sample));
        }
    }

    // Creates and returns session specific message handler.
    private Collection<UiMessageHandler> newHandlers() {
        return ImmutableList.of(new StreamingControl());
    }

    // UI Message handlers for turning on/off reporting to a session.
    private class StreamingControl extends UiMessageHandler {

        private boolean streamingEnabled = false;

        protected StreamingControl() {
            super(ImmutableSet.of("intentPerfStart", "intentPerfStop"));
        }

        @Override
        public void process(ObjectNode message) {
            streamingEnabled = message.path("event").asText("unknown").equals("initPerfStart");
        }

        @Override
        public void init(UiConnection connection, ServiceDirectory directory) {
            super.init(connection, directory);
            handlers.add(this);
        }

        @Override
        public void destroy() {
            super.destroy();
            handlers.remove(this);
        }

        private void send(Sample sample) {
            // FIXME: finish this
            ObjectNode sn = mapper.createObjectNode()
                    .put("time", sample.time);
            connection().sendMessage("intentPerf", 0, sn);
        }
    }

}