/*
 * 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
 *
 *      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.apache.wicket.settings;

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

import org.apache.wicket.Application;
import org.apache.wicket.Component;
import org.apache.wicket.IComponentAwareEventSink;
import org.apache.wicket.IDetachListener;
import org.apache.wicket.IEventDispatcher;
import org.apache.wicket.event.IEvent;
import org.apache.wicket.event.IEventSink;
import org.apache.wicket.serialize.ISerializer;
import org.apache.wicket.serialize.java.JavaSerializer;
import org.apache.wicket.util.lang.Args;
import org.apache.wicket.util.string.Strings;

/**
 * Framework settings for retrieving and configuring framework settings.
 *
 * @author Jonathan Locke
 * @author Chris Turner
 * @author Eelco Hillenius
 * @author Juergen Donnerstag
 * @author Johan Compagner
 * @author Igor Vaynberg (ivaynberg)
 * @author Martijn Dashorst
 * @author James Carman
 */
public class FrameworkSettings implements IEventDispatcher
{
        /**
         *  Does the standard delivery of events. Events can be disabled at application level by setting a <code>null</code>
         *  {@link IEventDispatcher} via {@link #setDefaultEventDispatcher(IEventDispatcher)} and setting  no additional
         *  {@link IEventDispatcher}s (via {@link #add(IEventDispatcher)}).
         */
        private static class DefaultEventDispatcher implements IEventDispatcher
        {
                @Override
                public void dispatchEvent(Object sink, IEvent<?> event, Component component)
                {
                        // direct delivery
                        if (component != null && sink instanceof IComponentAwareEventSink)
                        {
                                ((IComponentAwareEventSink)sink).onEvent(component, event);
                        }
                        else if (sink instanceof IEventSink)
                        {
                                ((IEventSink)sink).onEvent(event);
                        }
                }
        }
        private IDetachListener detachListener;

        private IEventDispatcher defaultEventDispatcher = new DefaultEventDispatcher();
        private List<IEventDispatcher> eventDispatchers = null;

        /**
         * The {@link ISerializer} that will be used to convert the pages to/from byte arrays
         */
        private ISerializer serializer;

        /**
         * Construct.
         * 
         * @param application
         */
        public FrameworkSettings(final Application application)
        {
                serializer = new JavaSerializer(application.getApplicationKey());
        }

        /**
         * Gets the Wicket version. The Wicket version is in the same format as the version element in
         * the pom.xml file (project descriptor). The version is generated by maven in the build/release
         * cycle and put in the /META-INF/MANIFEST.MF file located in the root folder of the Wicket jar.
         * <p>
         * The version usually follows one of the following formats:
         * <ul>
         * <li>major.minor[.bug] for stable versions. 1.1, 1.2, 1.2.1 are examples</li>
         * <li>major.minor-state for development versions. 1.2-beta2, 1.3-SNAPSHOT are examples</li>
         * </ul>
         *</p>
         *
         * @return the Wicket version
         */
        public String getVersion()
        {
                String implVersion = null;
                Package pkg = getClass().getPackage();
                if (pkg != null)
                {
                        implVersion = pkg.getImplementationVersion();
                }
                return Strings.isEmpty(implVersion) ? "n/a" : implVersion;
        }

        /**
         * @return detach listener or <code>null</code> if none
         */
        public IDetachListener getDetachListener()
        {
                return detachListener;
        }

        /**
         * Sets detach listener
         *
         * @param detachListener
         *            listener or <code>null</code> to remove
         * @return {@code this} object for chaining
         */
        public FrameworkSettings setDetachListener(IDetachListener detachListener)
        {
                this.detachListener = detachListener;
                return this;
        }

        /**
         * Registers a new event dispatcher
         *
         * @param dispatcher {@link IEventDispatcher}
         * @return {@code this} object for chaining
         */
        public FrameworkSettings add(IEventDispatcher dispatcher)
        {
                Args.notNull(dispatcher, "dispatcher");
                if (eventDispatchers == null)
                {
                        eventDispatchers = new ArrayList<>();
                }
                if (!eventDispatchers.contains(dispatcher))
                {
                        eventDispatchers.add(dispatcher);
                }
                return this;
        }

        /**
         * @return Returns <code>true</code> if there is at least one event dispatcher
         */
        public final boolean hasAnyEventDispatchers()
        {
                if (defaultEventDispatcher != null)
                {
                        return true;
                }
                return eventDispatchers != null && !eventDispatchers.isEmpty();
        }

        /**
         * Dispatches event to registered dispatchers
         * 
         * @see IEventDispatcher#dispatchEvent(Object, IEvent, Component)
         *
         */
        @Override
        public void dispatchEvent(Object sink, IEvent<?> event, Component component)
        {
                if (defaultEventDispatcher != null)
                {
                        defaultEventDispatcher.dispatchEvent(sink, event, component);
                }

                // additional dispatchers delivery
                if (eventDispatchers == null)
                {
                        return;
                }
                for (IEventDispatcher dispatcher : eventDispatchers)
                {
                        dispatcher.dispatchEvent(sink, event, component);
                }
        }

        /**
         * Allows to set the default events dispatcher
         *
         * @param defaultEventDispatcher
         *                      IEventDispatcher
         * @return {@code this} object for chaining
         */
        public FrameworkSettings setDefaultEventDispatcher(IEventDispatcher defaultEventDispatcher)
        {
                this.defaultEventDispatcher = defaultEventDispatcher;
                return this;
        }

        /**
         * Sets the {@link ISerializer} that will be used to convert objects to/from byte arrays
         *
         * @param serializer
         *            the {@link ISerializer} to use
         * @return {@code this} object for chaining
         */
        public FrameworkSettings setSerializer(ISerializer serializer)
        {
                this.serializer = Args.notNull(serializer, "serializer");
                return this;
        }

        /**
         * @return the {@link ISerializer} that will be used to convert objects to/from byte arrays
         */
        public ISerializer getSerializer()
        {
                return serializer;
        }
}