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/*
 * Copyright (C) 2013-2023 by XDEV Software, All Rights Reserved.
 *
 * This file is part of the RapidClipse Application Platform (RAP).
 *
 * This program is free software: you can redistribute it and/or modify
 * it under the terms of the GNU Affero General Public License 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 Affero General Public License for more details.
 *
 * You should have received a copy of the GNU Affero General Public License
 * along with this program.  If not, see .
 *
 * SPDX-License-Identifier: AGPL-3.0-or-later
 *
 * Contributors:
 *     XDEV Software - initial API and implementation
 */
package com.rapidclipse.framework.server.webapi;

import java.io.Serializable;
import java.util.HashMap;
import java.util.HashSet;
import java.util.Map;
import java.util.Optional;
import java.util.Set;

import com.vaadin.flow.component.HasElement;
import com.vaadin.flow.component.littemplate.LitTemplate;
import com.vaadin.flow.function.SerializableConsumer;
import com.vaadin.flow.shared.Registration;


/**
 * This class allows subclasses to register consumers for various javascript events. These are distinguished by their
 * consumed type.
 *
 * @author XDEV Software
 * @since 10.02.00
 */
public abstract class JavascriptTemplate extends LitTemplate
{
	private final Map, Set>> consumers = new HashMap<>();

	protected JavascriptTemplate()
	{
		super();
	}
	
	protected JavascriptTemplate(final HasElement parent)
	{
		super();
		
		parent.getElement().appendVirtualChild(this.getElement());
	}

	/**
	 * Add a new consumer to the set of consumers for the specified type.
	 * The consumer can be remove with the returned registration.
	 *
	 * @param type
	 *            Class type of the consumed value.
	 * @param consumer
	 *            The consumer that should be added to the consumer set.
	 */
	protected  Registration
		registerConsumer(final Class type, final SerializableConsumer consumer)
	{
		return registerConsumer(type, consumer, null, null);
	}

	/**
	 * Add a new consumer to the set of consumers for the specified type.
	 * The consumer can be remove with the returned registration.
	 *
	 * @param type
	 *            Class type of the consumed value.
	 * @param firstAddedCallback
	 *            called before the first consumer for the type is registered
	 * @param lastRemovedCallback
	 *            called after the last consumer for the type was removed
	 * @param consumer
	 *            The consumer that should be added to the consumer set.
	 */
	@SuppressWarnings("unchecked")
	protected  Registration registerConsumer(
		final Class type,
		final SerializableConsumer consumer,
		final Runnable firstAddedCallback,
		final Runnable lastRemovedCallback)
	{
		synchronized(this.consumers)
		{
			((Set>)this.consumers.computeIfAbsent(type, t -> {
				if(firstAddedCallback != null)
				{
					firstAddedCallback.run();
				}
				return new HashSet<>();
			})).add(consumer);
		}
		return () -> {
			synchronized(this.consumers)
			{
				final Set> consumers = this.consumers.get(type);
				if(consumers != null)
				{
					consumers.remove(consumer);
					if(consumers.isEmpty())
					{
						this.consumers.remove(type);
						if(lastRemovedCallback != null)
						{
							lastRemovedCallback.run();
						}
					}
				}
			}
		};
	}

	protected  void unregisterAllConsumers(final Class type)
	{
		unregisterAllConsumers(type, null);
	}

	protected  void
		unregisterAllConsumers(final Class type, final Runnable unregisterCallback)
	{
		synchronized(this.consumers)
		{
			final Set> consumers = this.consumers.get(type);
			if(consumers != null && !consumers.isEmpty())
			{
				consumers.clear();
				this.consumers.remove(type);
				if(unregisterCallback != null)
				{
					unregisterCallback.run();
				}
			}
		}
	}

	/**
	 * Notify all the consumers of the given class type to consume the given value.
	 *
	 * @param type
	 *            The class type of the consumers that should be notified.
	 * @param object
	 *            The object that should be consumed by the consumers.
	 */
	@SuppressWarnings("unchecked")
	protected  void notifyConsumers(final Class type, final T object)
	{
		synchronized(this.consumers)
		{
			Optional.ofNullable(this.consumers.get(type))
				.ifPresent(set -> ((Set>)set).forEach(c -> c.accept(object)));
		}
	}

	/**
	 * Clear the consumers map.
	 */
	protected void clearConsumers()
	{
		this.consumers.clear();
	}
}