/*
 * Copyright 2006 - 2013
 *     Stefan Balev     <stefan.balev@graphstream-project.org>
 *     Julien Baudry    <julien.baudry@graphstream-project.org>
 *     Antoine Dutot    <antoine.dutot@graphstream-project.org>
 *     Yoann Pigné      <yoann.pigne@graphstream-project.org>
 *     Guilhelm Savin   <guilhelm.savin@graphstream-project.org>
 * 
 * This file is part of GraphStream <http://graphstream-project.org>.
 * 
 * GraphStream is a library whose purpose is to handle static or dynamic
 * graph, create them from scratch, file or any source and display them.
 * 
 * This program is free software distributed under the terms of two licenses, the
 * CeCILL-C license that fits European law, and the GNU Lesser General Public
 * License. You can  use, modify and/ or redistribute the software under the terms
 * of the CeCILL-C license as circulated by CEA, CNRS and INRIA at the following
 * URL <http://www.cecill.info> or under the terms of the GNU LGPL as published by
 * the Free Software Foundation, either version 3 of the License, or (at your
 * option) any later version.
 * 
 * This program is distributed in the hope that it will be useful, but WITHOUT ANY
 * WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A
 * PARTICULAR PURPOSE.  See the GNU Lesser General Public License for more details.
 * 
 * You should have received a copy of the GNU Lesser General Public License
 * along with this program.  If not, see <http://www.gnu.org/licenses/>.
 * 
 * The fact that you are presently reading this means that you have had
 * knowledge of the CeCILL-C and LGPL licenses and that you accept their terms.
 */
package org.graphstream.stream.thread;

import java.util.LinkedList;
import java.util.concurrent.TimeUnit;
import java.util.concurrent.locks.Condition;
import java.util.concurrent.locks.ReentrantLock;

import org.graphstream.graph.Graph;
import org.graphstream.stream.ProxyPipe;
import org.graphstream.stream.Replayable;
import org.graphstream.stream.Replayable.Controller;
import org.graphstream.stream.Sink;
import org.graphstream.stream.Source;
import org.graphstream.stream.SourceBase;

/**
 * Filter that allows to pass graph events between two threads without explicit
 * synchronization.
 * 
 * <p>
 * This filter allows to register it as an output for some source of events in a
 * source thread (hereafter called the input thread) and to register listening
 * outputs in a destination thread (hereafter called the sink thread).
 * </p>
 * 
 * <pre>
 *                       |
 *   Source ---> ThreadProxyFilter ----> Sink
 *  Thread 1             |              Thread 2
 *                       |
 * </pre>
 * 
 * <p>
 * In other words, this class allows to listen in a sink thread graph events
 * that are produced in another source thread without any explicit
 * synchronization on the source of events.
 * </p>
 * 
 * <p>
 * The only restriction is that the sink thread must regularly call the
 * {@link #pump()} method to dispatch events coming from the source to all sinks
 * registered (see the explanation in {@link org.graphstream.stream.ProxyPipe}).
 * </p>
 * 
 * <p>
 * You can register any kind of input as source of event, but if the input is a
 * graph, then you can choose to "replay" all the content of the graph so that
 * at the other end of the filter, all outputs receive the complete content of
 * the graph. This is the default behavior if this filter is constructed with a
 * graph as input.
 * </p>
 */
public class ThreadProxyPipe extends SourceBase implements ProxyPipe {

        /**
         * Proxy id.
         */
        protected String id;

        /**
         * The event sender name, usually the graph name.
         */
        protected String from;

        /**
         * The message box used to exchange messages between the two threads.
         */
        protected LinkedList<GraphEvents> events;
        protected LinkedList<Object[]> eventsData;

        protected ReentrantLock lock;
        protected Condition notEmpty;

        /**
         * Used only to remove the listener. We ensure this is done in the source
         * thread.
         */
        protected Source input;

        /**
         * Signals that this proxy must be removed from the source input.
         */
        protected boolean unregisterWhenPossible = false;

        public ThreadProxyPipe() {
                this.events = new LinkedList<GraphEvents>();
                this.eventsData = new LinkedList<Object[]>();
                this.lock = new ReentrantLock();
                this.notEmpty = this.lock.newCondition();
                this.from = "<in>";
                this.input = null;
        }

        /**
         * 
         * @param input
         *            The source of events we listen at.
         * 
         * @deprecated Use the default constructor and then call the
         *             {@link #init(Source)} method.
         */
        @Deprecated
        public ThreadProxyPipe(Source input) {
                this(input, null, input instanceof Replayable);
        }

        /**
         * 
         * @param input
         * @param replay
         * 
         * @deprecated Use the default constructor and then call the
         *             {@link #init(Source)} method.
         */
        @Deprecated
        public ThreadProxyPipe(Source input, boolean replay) {
                this(input, null, replay);
        }

        /**
         * 
         * @param input
         * @param initialListener
         * @param replay
         * 
         * @deprecated Use the default constructor and then call the
         *             {@link #init(Source)} method.
         */
        @Deprecated
        public ThreadProxyPipe(Source input, Sink initialListener, boolean replay) {
                this();

                if (initialListener != null)
                        addSink(initialListener);

                init(input, replay);
        }

        public void init() {
                init(null, false);
        }

        /**
         * Init the proxy. If there are previous events, they will be cleared.
         * 
         * @param source
         *            source of the events
         */
        public void init(Source source) {
                init(source, source instanceof Replayable);
        }

        /**
         * Init the proxy. If there are previous events, they will be cleared.
         * 
         * @param source
         *            source of the events
         * @param replay
         *            true if the source should be replayed. You need a
         *            {@link org.graphstream.stream.Replayable} source to enable
         *            replay, else nothing happens.
         */
        public void init(Source source, boolean replay) {
                lock.lock();

                try {
                        if (this.input != null)
                                this.input.removeSink(this);

                        this.input = source;

                        this.events.clear();
                        this.eventsData.clear();
                } finally {
                        lock.unlock();
                }

                if (source != null) {
                        if (source instanceof Graph)
                                this.from = ((Graph) source).getId();

                        this.input.addSink(this);

                        if (replay && source instanceof Replayable) {
                                Replayable r = (Replayable) source;
                                Controller rc = r.getReplayController();

                                rc.addSink(this);
                                rc.replay();
                        }
                }
        }

        @Override
        public String toString() {
                String dest = "nil";

                if (attrSinks.size() > 0)
                        dest = attrSinks.get(0).toString();

                return String.format("thread-proxy(from %s to %s)", from, dest);
        }

        /**
         * Ask the proxy to unregister from the event input source (stop receive
         * events) as soon as possible (when the next event will occur in the
         * graph).
         */
        public void unregisterFromSource() {
                unregisterWhenPossible = true;
        }

        /**
         * This method must be called regularly in the output thread to check if the
         * input source sent events. If some event occurred, the listeners will be
         * called.
         */
        public void pump() {
                GraphEvents e = null;
                Object[] data = null;

                do {
                        lock.lock();

                        try {
                                e = events.poll();
                                data = eventsData.poll();
                        } finally {
                                lock.unlock();
                        }

                        if (e != null)
                                processMessage(e, data);
                } while (e != null);
        }

        /*
         * (non-Javadoc)
         * 
         * @see org.graphstream.stream.ProxyPipe#blockingPump()
         */
        public void blockingPump() throws InterruptedException {
                blockingPump(0);
        }

        public void blockingPump(long timeout) throws InterruptedException {
                GraphEvents e;
                Object[] data;

                lock.lock();

                try {
                        if (timeout > 0)
                                while (events.size() == 0)
                                        notEmpty.await(timeout, TimeUnit.MILLISECONDS);
                        else
                                while (events.size() == 0)
                                        notEmpty.await();
                } finally {
                        lock.unlock();
                }

                do {
                        lock.lock();

                        try {
                                e = events.poll();
                                data = eventsData.poll();
                        } finally {
                                lock.unlock();
                        }

                        if (e != null)
                                processMessage(e, data);
                } while (e != null);
        }

        public boolean hasPostRemaining() {
                boolean r = true;
                lock.lock();

                try {
                        r = events.size() > 0;
                } finally {
                        lock.unlock();
                }

                return r;
        }

        /**
         * Set of events sent via the message box.
         */
        protected static enum GraphEvents {
                ADD_NODE, DEL_NODE, ADD_EDGE, DEL_EDGE, STEP, CLEARED, ADD_GRAPH_ATTR, CHG_GRAPH_ATTR, DEL_GRAPH_ATTR, ADD_NODE_ATTR, CHG_NODE_ATTR, DEL_NODE_ATTR, ADD_EDGE_ATTR, CHG_EDGE_ATTR, DEL_EDGE_ATTR
        };

        protected boolean maybeUnregister() {
                if (unregisterWhenPossible) {
                        if (input != null)
                                input.removeSink(this);
                        return true;
                }

                return false;
        }

        protected void post(GraphEvents e, Object... data) {
                lock.lock();

                try {
                        events.add(e);
                        eventsData.add(data);

                        notEmpty.signal();
                } finally {
                        lock.unlock();
                }
        }

        public void edgeAttributeAdded(String graphId, long timeId, String edgeId,
                        String attribute, Object value) {
                if (maybeUnregister())
                        return;

                post(GraphEvents.ADD_EDGE_ATTR, graphId, timeId, edgeId, attribute,
                                value);
        }

        public void edgeAttributeChanged(String graphId, long timeId,
                        String edgeId, String attribute, Object oldValue, Object newValue) {
                if (maybeUnregister())
                        return;

                post(GraphEvents.CHG_EDGE_ATTR, graphId, timeId, edgeId, attribute,
                                oldValue, newValue);
        }

        public void edgeAttributeRemoved(String graphId, long timeId,
                        String edgeId, String attribute) {
                if (maybeUnregister())
                        return;

                post(GraphEvents.DEL_EDGE_ATTR, graphId, timeId, edgeId, attribute);
        }

        public void graphAttributeAdded(String graphId, long timeId,
                        String attribute, Object value) {
                if (maybeUnregister())
                        return;

                post(GraphEvents.ADD_GRAPH_ATTR, graphId, timeId, attribute, value);
        }

        public void graphAttributeChanged(String graphId, long timeId,
                        String attribute, Object oldValue, Object newValue) {
                if (maybeUnregister())
                        return;

                post(GraphEvents.CHG_GRAPH_ATTR, graphId, timeId, attribute, oldValue,
                                newValue);
        }

        public void graphAttributeRemoved(String graphId, long timeId,
                        String attribute) {
                if (maybeUnregister())
                        return;

                post(GraphEvents.DEL_GRAPH_ATTR, graphId, timeId, attribute);
        }

        public void nodeAttributeAdded(String graphId, long timeId, String nodeId,
                        String attribute, Object value) {
                if (maybeUnregister())
                        return;

                post(GraphEvents.ADD_NODE_ATTR, graphId, timeId, nodeId, attribute,
                                value);
        }

        public void nodeAttributeChanged(String graphId, long timeId,
                        String nodeId, String attribute, Object oldValue, Object newValue) {
                if (maybeUnregister())
                        return;

                post(GraphEvents.CHG_NODE_ATTR, graphId, timeId, nodeId, attribute,
                                oldValue, newValue);
        }

        public void nodeAttributeRemoved(String graphId, long timeId,
                        String nodeId, String attribute) {
                if (maybeUnregister())
                        return;

                post(GraphEvents.DEL_NODE_ATTR, graphId, timeId, nodeId, attribute);
        }

        public void edgeAdded(String graphId, long timeId, String edgeId,
                        String fromNodeId, String toNodeId, boolean directed) {
                if (maybeUnregister())
                        return;

                post(GraphEvents.ADD_EDGE, graphId, timeId, edgeId, fromNodeId,
                                toNodeId, directed);
        }

        public void edgeRemoved(String graphId, long timeId, String edgeId) {
                if (maybeUnregister())
                        return;

                post(GraphEvents.DEL_EDGE, graphId, timeId, edgeId);
        }

        public void graphCleared(String graphId, long timeId) {
                if (maybeUnregister())
                        return;

                post(GraphEvents.CLEARED, graphId, timeId);
        }

        public void nodeAdded(String graphId, long timeId, String nodeId) {
                if (maybeUnregister())
                        return;

                post(GraphEvents.ADD_NODE, graphId, timeId, nodeId);
        }

        public void nodeRemoved(String graphId, long timeId, String nodeId) {
                if (maybeUnregister())
                        return;

                post(GraphEvents.DEL_NODE, graphId, timeId, nodeId);
        }

        public void stepBegins(String graphId, long timeId, double step) {
                if (maybeUnregister())
                        return;

                post(GraphEvents.STEP, graphId, timeId, step);
        }

        // MBoxListener

        public void processMessage(GraphEvents e, Object[] data) {
                String graphId, elementId, attribute;
                Long timeId;
                Object newValue, oldValue;

                switch (e) {
                case ADD_NODE:
                        graphId = (String) data[0];
                        timeId = (Long) data[1];
                        elementId = (String) data[2];

                        sendNodeAdded(graphId, timeId, elementId);
                        break;
                case DEL_NODE:
                        graphId = (String) data[0];
                        timeId = (Long) data[1];
                        elementId = (String) data[2];

                        sendNodeRemoved(graphId, timeId, elementId);
                        break;
                case ADD_EDGE:
                        graphId = (String) data[0];
                        timeId = (Long) data[1];
                        elementId = (String) data[2];

                        String fromId = (String) data[3];
                        String toId = (String) data[4];
                        boolean directed = (Boolean) data[5];

                        sendEdgeAdded(graphId, timeId, elementId, fromId, toId, directed);
                        break;
                case DEL_EDGE:
                        graphId = (String) data[0];
                        timeId = (Long) data[1];
                        elementId = (String) data[2];

                        sendEdgeRemoved(graphId, timeId, elementId);
                        break;
                case STEP:
                        graphId = (String) data[0];
                        timeId = (Long) data[1];

                        double step = (Double) data[2];

                        sendStepBegins(graphId, timeId, step);
                        break;
                case ADD_GRAPH_ATTR:
                        graphId = (String) data[0];
                        timeId = (Long) data[1];
                        attribute = (String) data[2];
                        newValue = data[3];

                        sendGraphAttributeAdded(graphId, timeId, attribute, newValue);
                        break;
                case CHG_GRAPH_ATTR:
                        graphId = (String) data[0];
                        timeId = (Long) data[1];
                        attribute = (String) data[2];
                        oldValue = data[3];
                        newValue = data[4];

                        sendGraphAttributeChanged(graphId, timeId, attribute, oldValue,
                                        newValue);
                        break;
                case DEL_GRAPH_ATTR:
                        graphId = (String) data[0];
                        timeId = (Long) data[1];
                        attribute = (String) data[2];

                        sendGraphAttributeRemoved(graphId, timeId, attribute);
                        break;
                case ADD_EDGE_ATTR:
                        graphId = (String) data[0];
                        timeId = (Long) data[1];
                        elementId = (String) data[2];
                        attribute = (String) data[3];
                        newValue = data[4];

                        sendEdgeAttributeAdded(graphId, timeId, elementId, attribute,
                                        newValue);
                        break;
                case CHG_EDGE_ATTR:
                        graphId = (String) data[0];
                        timeId = (Long) data[1];
                        elementId = (String) data[2];
                        attribute = (String) data[3];
                        oldValue = data[4];
                        newValue = data[5];

                        sendEdgeAttributeChanged(graphId, timeId, elementId, attribute,
                                        oldValue, newValue);
                        break;
                case DEL_EDGE_ATTR:
                        graphId = (String) data[0];
                        timeId = (Long) data[1];
                        elementId = (String) data[2];
                        attribute = (String) data[3];

                        sendEdgeAttributeRemoved(graphId, timeId, elementId, attribute);
                        break;
                case ADD_NODE_ATTR:
                        graphId = (String) data[0];
                        timeId = (Long) data[1];
                        elementId = (String) data[2];
                        attribute = (String) data[3];
                        newValue = data[4];

                        sendNodeAttributeAdded(graphId, timeId, elementId, attribute,
                                        newValue);
                        break;
                case CHG_NODE_ATTR:
                        graphId = (String) data[0];
                        timeId = (Long) data[1];
                        elementId = (String) data[2];
                        attribute = (String) data[3];
                        oldValue = data[4];
                        newValue = data[5];

                        sendNodeAttributeChanged(graphId, timeId, elementId, attribute,
                                        oldValue, newValue);
                        break;
                case DEL_NODE_ATTR:
                        graphId = (String) data[0];
                        timeId = (Long) data[1];
                        elementId = (String) data[2];
                        attribute = (String) data[3];

                        sendNodeAttributeRemoved(graphId, timeId, elementId, attribute);
                        break;
                case CLEARED:
                        graphId = (String) data[0];
                        timeId = (Long) data[1];

                        sendGraphCleared(graphId, timeId);
                        break;
                default:
                        System.err.printf("ThreadProxy : Unknown message %s !!%n", e);
                        break;
                }
        }
}