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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.online;

import com.rapidclipse.framework.server.webapi.JavascriptTemplate;
import com.vaadin.flow.component.ClientCallable;
import com.vaadin.flow.component.HasElement;
import com.vaadin.flow.component.Tag;
import com.vaadin.flow.component.UI;
import com.vaadin.flow.component.dependency.JsModule;
import com.vaadin.flow.function.SerializableConsumer;
import com.vaadin.flow.shared.Registration;


/**
 * With this class you can check the current online status of the device. More importantly you can register listeners
 * for when the device goes online or offline.
 *
 * @author XDEV Software
 * @since 10.02.00
 */
@JsModule("./webapi/online.ts")
@Tag("rap-online")
public class Online extends JavascriptTemplate
{
	public Online(final HasElement parent)
	{
		super(parent);
	}
	
	/**
	 * Register an online listener. This listener is triggered when the client comes back online after being
	 * offline or vice versa. To unregister this event you can either use the returned Registration or by calling
	 * {@link #unregisterAllOnlineListeners()}.
	 */
	public Registration addOnlineListener(final SerializableConsumer onOnline)
	{
		final Runnable firstAddedCallback  = () -> this.getElement().callJsFunction("registerOnlineListener");
		final Runnable lastRemovedCallback = () -> this.getElement().callJsFunction("unregisterOnlineListener");
		return this.registerConsumer(OnlineState.class, onOnline, firstAddedCallback, lastRemovedCallback);
	}
	
	/**
	 * This method can be used to unregister previously registered onOnLine listeners. This will also stop the client
	 * from sending more events to the server. To register an onOnLine listener
	 * you can call the {@link #addOnlineListener(SerializableConsumer)} method.
	 */
	public void unregisterAllOnlineListeners()
	{
		final Runnable unregisterCallback = () -> this.getElement().callJsFunction("unregisterOnlineListener");
		this.unregisterAllConsumers(OnlineState.class, unregisterCallback);
	}
	
	/**
	 * Get the current OnLine state of the device (The state can not be retrieved while the client is offline).
	 *
	 * @param onStateReceived
	 *            The callback triggered when the state is received. It consumes the current onLine state.
	 */
	public static void getOnlineState(final SerializableConsumer onStateReceived)
	{
		UI.getCurrent().getPage().executeJs("return navigator.onLine").then(Boolean.class,
			isOnline -> onStateReceived.accept(isOnline ? OnlineState.ONLINE : OnlineState.OFFLINE));
	}
	
	@ClientCallable
	private void onOnline()
	{
		this.notifyConsumers(OnlineState.class, OnlineState.ONLINE);
	}
	
	@ClientCallable
	private void onOffline()
	{
		this.notifyConsumers(OnlineState.class, OnlineState.OFFLINE);
	}
}