/*
 * Copyright 2002-2018 the original author or authors.
 *
 * 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
 *
 *      https://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.springframework.web.socket.client.standard;

import java.util.Arrays;
import java.util.List;

import javax.websocket.ClientEndpointConfig;
import javax.websocket.ClientEndpointConfig.Configurator;
import javax.websocket.ContainerProvider;
import javax.websocket.Decoder;
import javax.websocket.Encoder;
import javax.websocket.Endpoint;
import javax.websocket.Extension;
import javax.websocket.Session;
import javax.websocket.WebSocketContainer;

import org.springframework.beans.factory.BeanFactory;
import org.springframework.beans.factory.BeanFactoryAware;
import org.springframework.core.task.SimpleAsyncTaskExecutor;
import org.springframework.core.task.TaskExecutor;
import org.springframework.lang.Nullable;
import org.springframework.util.Assert;
import org.springframework.web.socket.client.ConnectionManagerSupport;
import org.springframework.web.socket.handler.BeanCreatingHandlerProvider;

/**
 * A WebSocket connection manager that is given a URI, an {@link Endpoint}, connects to a
 * WebSocket server through the {@link #start()} and {@link #stop()} methods. If
 * {@link #setAutoStartup(boolean)} is set to {@code true} this will be done automatically
 * when the Spring ApplicationContext is refreshed.
 *
 * @author Rossen Stoyanchev
 * @since 4.0
 * @see AnnotatedEndpointConnectionManager
 */
public class EndpointConnectionManager extends ConnectionManagerSupport implements BeanFactoryAware {

	@Nullable
	private final Endpoint endpoint;

	@Nullable
	private final BeanCreatingHandlerProvider<Endpoint> endpointProvider;

	private final ClientEndpointConfig.Builder configBuilder = ClientEndpointConfig.Builder.create();

	private WebSocketContainer webSocketContainer = ContainerProvider.getWebSocketContainer();

	private TaskExecutor taskExecutor = new SimpleAsyncTaskExecutor("EndpointConnectionManager-");

	@Nullable
	private volatile Session session;


	public EndpointConnectionManager(Endpoint endpoint, String uriTemplate, Object... uriVariables) {
		super(uriTemplate, uriVariables);
		Assert.notNull(endpoint, "endpoint must not be null");
		this.endpoint = endpoint;
		this.endpointProvider = null;
	}

	public EndpointConnectionManager(Class<? extends Endpoint> endpointClass, String uriTemplate, Object... uriVars) {
		super(uriTemplate, uriVars);
		Assert.notNull(endpointClass, "endpointClass must not be null");
		this.endpoint = null;
		this.endpointProvider = new BeanCreatingHandlerProvider<>(endpointClass);
	}


	public void setSupportedProtocols(String... protocols) {
		this.configBuilder.preferredSubprotocols(Arrays.asList(protocols));
	}

	public void setExtensions(Extension... extensions) {
		this.configBuilder.extensions(Arrays.asList(extensions));
	}

	public void setEncoders(List<Class<? extends Encoder>> encoders) {
		this.configBuilder.encoders(encoders);
	}

	public void setDecoders(List<Class<? extends Decoder>> decoders) {
		this.configBuilder.decoders(decoders);
	}

	public void setConfigurator(Configurator configurator) {
		this.configBuilder.configurator(configurator);
	}

	public void setWebSocketContainer(WebSocketContainer webSocketContainer) {
		this.webSocketContainer = webSocketContainer;
	}

	public WebSocketContainer getWebSocketContainer() {
		return this.webSocketContainer;
	}

	@Override
	public void setBeanFactory(BeanFactory beanFactory) {
		if (this.endpointProvider != null) {
			this.endpointProvider.setBeanFactory(beanFactory);
		}
	}

	/**
	 * Set a {@link TaskExecutor} to use to open connections.
	 * By default {@link SimpleAsyncTaskExecutor} is used.
	 */
	public void setTaskExecutor(TaskExecutor taskExecutor) {
		Assert.notNull(taskExecutor, "TaskExecutor must not be null");
		this.taskExecutor = taskExecutor;
	}

	/**
	 * Return the configured {@link TaskExecutor}.
	 */
	public TaskExecutor getTaskExecutor() {
		return this.taskExecutor;
	}


	@Override
	protected void openConnection() {
		this.taskExecutor.execute(() -> {
			try {
				if (logger.isInfoEnabled()) {
					logger.info("Connecting to WebSocket at " + getUri());
				}
				Endpoint endpointToUse = this.endpoint;
				if (endpointToUse == null) {
					Assert.state(this.endpointProvider != null, "No endpoint set");
					endpointToUse = this.endpointProvider.getHandler();
				}
				ClientEndpointConfig endpointConfig = this.configBuilder.build();
				this.session = getWebSocketContainer().connectToServer(endpointToUse, endpointConfig, getUri());
				logger.info("Successfully connected to WebSocket");
			}
			catch (Throwable ex) {
				logger.error("Failed to connect to WebSocket", ex);
			}
		});
	}

	@Override
	protected void closeConnection() throws Exception {
		try {
			Session session = this.session;
			if (session != null && session.isOpen()) {
				session.close();
			}
		}
		finally {
			this.session = null;
		}
	}

	@Override
	protected boolean isConnected() {
		Session session = this.session;
		return (session != null && session.isOpen());
	}

}
