/*
 * Copyright 2002-2017 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
 *
 *      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.springframework.web.socket.client.jetty;

import java.net.URI;
import java.security.Principal;
import java.util.List;
import java.util.Map;
import java.util.concurrent.Callable;
import java.util.concurrent.Future;

import org.eclipse.jetty.websocket.api.Session;
import org.eclipse.jetty.websocket.client.ClientUpgradeRequest;
import org.eclipse.jetty.websocket.client.WebSocketClient;

import org.springframework.context.Lifecycle;
import org.springframework.core.task.AsyncListenableTaskExecutor;
import org.springframework.core.task.SimpleAsyncTaskExecutor;
import org.springframework.core.task.TaskExecutor;
import org.springframework.http.HttpHeaders;
import org.springframework.lang.Nullable;
import org.springframework.util.concurrent.ListenableFuture;
import org.springframework.util.concurrent.ListenableFutureTask;
import org.springframework.web.socket.WebSocketExtension;
import org.springframework.web.socket.WebSocketHandler;
import org.springframework.web.socket.WebSocketSession;
import org.springframework.web.socket.adapter.jetty.JettyWebSocketHandlerAdapter;
import org.springframework.web.socket.adapter.jetty.JettyWebSocketSession;
import org.springframework.web.socket.adapter.jetty.WebSocketToJettyExtensionConfigAdapter;
import org.springframework.web.socket.client.AbstractWebSocketClient;
import org.springframework.web.util.UriComponents;
import org.springframework.web.util.UriComponentsBuilder;

/**
 * Initiates WebSocket requests to a WebSocket server programmatically
 * through the Jetty WebSocket API.
 *
 * <p>As of 4.1 this class implements {@link Lifecycle} rather than
 * {@link org.springframework.context.SmartLifecycle}. Use
 * {@link org.springframework.web.socket.client.WebSocketConnectionManager
 * WebSocketConnectionManager} instead to auto-start a WebSocket connection.
 *
 * @author Rossen Stoyanchev
 * @since 4.0
 */
public class JettyWebSocketClient extends AbstractWebSocketClient implements Lifecycle {

	private final org.eclipse.jetty.websocket.client.WebSocketClient client;

	private final Object lifecycleMonitor = new Object();

	@Nullable
	private AsyncListenableTaskExecutor taskExecutor = new SimpleAsyncTaskExecutor();


	/**
	 * Default constructor that creates an instance of
	 * {@link org.eclipse.jetty.websocket.client.WebSocketClient}.
	 */
	public JettyWebSocketClient() {
		this.client = new org.eclipse.jetty.websocket.client.WebSocketClient();
	}

	/**
	 * Constructor that accepts an existing
	 * {@link org.eclipse.jetty.websocket.client.WebSocketClient} instance.
	 */
	public JettyWebSocketClient(WebSocketClient client) {
		this.client = client;
	}


	/**
	 * Set an {@link AsyncListenableTaskExecutor} to use when opening connections.
	 * If this property is set to {@code null}, calls to any of the
	 * {@code doHandshake} methods will block until the connection is established.
	 * <p>By default an instance of {@code SimpleAsyncTaskExecutor} is used.
	 */
	public void setTaskExecutor(@Nullable AsyncListenableTaskExecutor taskExecutor) {
		this.taskExecutor = taskExecutor;
	}

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

	@Override
	public boolean isRunning() {
		synchronized (this.lifecycleMonitor) {
			return this.client.isStarted();
		}
	}

	@Override
	public void start() {
		synchronized (this.lifecycleMonitor) {
			if (!isRunning()) {
				try {
					if (logger.isInfoEnabled()) {
						logger.info("Starting Jetty WebSocketClient");
					}
					this.client.start();
				}
				catch (Exception ex) {
					throw new IllegalStateException("Failed to start Jetty client", ex);
				}
			}
		}
	}

	@Override
	public void stop() {
		synchronized (this.lifecycleMonitor) {
			if (isRunning()) {
				try {
					if (logger.isInfoEnabled()) {
						logger.info("Stopping Jetty WebSocketClient");
					}
					this.client.stop();
				}
				catch (Exception ex) {
					logger.error("Error stopping Jetty WebSocketClient", ex);
				}
			}
		}
	}

	@Override
	public ListenableFuture<WebSocketSession> doHandshake(WebSocketHandler webSocketHandler,
			String uriTemplate, Object... uriVars) {

		UriComponents uriComponents = UriComponentsBuilder.fromUriString(uriTemplate).buildAndExpand(uriVars).encode();
		return doHandshake(webSocketHandler, null, uriComponents.toUri());
	}

	@Override
	public ListenableFuture<WebSocketSession> doHandshakeInternal(WebSocketHandler wsHandler,
			HttpHeaders headers, final URI uri, List<String> protocols,
			List<WebSocketExtension> extensions,  Map<String, Object> attributes) {

		final ClientUpgradeRequest request = new ClientUpgradeRequest();
		request.setSubProtocols(protocols);

		for (WebSocketExtension e : extensions) {
			request.addExtensions(new WebSocketToJettyExtensionConfigAdapter(e));
		}

		for (String header : headers.keySet()) {
			request.setHeader(header, headers.get(header));
		}

		Principal user = getUser();
		final JettyWebSocketSession wsSession = new JettyWebSocketSession(attributes, user);
		final JettyWebSocketHandlerAdapter listener = new JettyWebSocketHandlerAdapter(wsHandler, wsSession);

		Callable<WebSocketSession> connectTask = () -> {
			Future<Session> future = client.connect(listener, uri, request);
			future.get();
			return wsSession;
		};

		if (this.taskExecutor != null) {
			return this.taskExecutor.submitListenable(connectTask);
		}
		else {
			ListenableFutureTask<WebSocketSession> task = new ListenableFutureTask<>(connectTask);
			task.run();
			return task;
		}
	}

	/**
	 * @return the user to make available through {@link WebSocketSession#getPrincipal()};
	 * 	by default this method returns {@code null}
	 */
	@Nullable
	protected Principal getUser() {
		return null;
	}

}
