/*
 * Copyright 2002-2013 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.server.support;

import java.io.IOException;
import java.util.ArrayList;
import java.util.HashMap;
import java.util.List;
import java.util.Map;

import javax.servlet.ServletException;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

import org.springframework.http.server.ServerHttpRequest;
import org.springframework.http.server.ServerHttpResponse;
import org.springframework.http.server.ServletServerHttpRequest;
import org.springframework.http.server.ServletServerHttpResponse;
import org.springframework.util.Assert;
import org.springframework.web.HttpRequestHandler;
import org.springframework.web.socket.WebSocketHandler;
import org.springframework.web.socket.server.DefaultHandshakeHandler;
import org.springframework.web.socket.server.HandshakeFailureException;
import org.springframework.web.socket.server.HandshakeHandler;
import org.springframework.web.socket.server.HandshakeInterceptor;
import org.springframework.web.socket.support.ExceptionWebSocketHandlerDecorator;
import org.springframework.web.socket.support.LoggingWebSocketHandlerDecorator;

/**
 * A {@link HttpRequestHandler} for processing WebSocket handshake requests.
 *
 * <p>This is the main class to use when configuring a server WebSocket at a specific URL.
 * It is a very thin wrapper around a {@link HandshakeHandler} and a
 * {@link WebSocketHandler} instance also adapting the {@link HttpServletRequest} and
 * {@link HttpServletResponse} to {@link ServerHttpRequest} and {@link ServerHttpResponse}
 * respectively.
 *
 * <p>The {@link #applyDefaultDecorators(WebSocketHandler)} method decorates the given
 * WebSocketHandler with a logging and exception handling decorators. This method can
 * be overridden to change that.
 *
 * @author Rossen Stoyanchev
 * @since 4.0
 */
public class WebSocketHttpRequestHandler implements HttpRequestHandler {

	private final HandshakeHandler handshakeHandler;

	private final WebSocketHandler wsHandler;

	private final List<HandshakeInterceptor> interceptors = new ArrayList<HandshakeInterceptor>();


	public WebSocketHttpRequestHandler(WebSocketHandler webSocketHandler) {
		this(webSocketHandler, new DefaultHandshakeHandler());
	}

	public WebSocketHttpRequestHandler(WebSocketHandler wsHandler, HandshakeHandler handshakeHandler) {
		Assert.notNull(wsHandler, "wsHandler must not be null");
		Assert.notNull(handshakeHandler, "handshakeHandler must not be null");
		this.wsHandler = new ExceptionWebSocketHandlerDecorator(new LoggingWebSocketHandlerDecorator(wsHandler));
		this.handshakeHandler = handshakeHandler;
	}


	/**
	 * Configure one or more WebSocket handshake request interceptors.
	 */
	public void setHandshakeInterceptors(List<HandshakeInterceptor> interceptors) {
		this.interceptors.clear();
		if (interceptors != null) {
			this.interceptors.addAll(interceptors);
		}
	}

	/**
	 * Return the configured WebSocket handshake request interceptors.
	 */
	public List<HandshakeInterceptor> getHandshakeInterceptors() {
		return this.interceptors;
	}

	@Override
	public void handleRequest(HttpServletRequest servletRequest, HttpServletResponse servletResponse)
			throws ServletException, IOException {

		ServerHttpRequest request = new ServletServerHttpRequest(servletRequest);
		ServerHttpResponse response = new ServletServerHttpResponse(servletResponse);

		HandshakeInterceptorChain chain = new HandshakeInterceptorChain(this.interceptors, this.wsHandler);
		HandshakeFailureException failure = null;

		try {
			Map<String, Object> attributes = new HashMap<String, Object>();
			if (!chain.applyBeforeHandshake(request, response, attributes)) {
				return;
			}
			this.handshakeHandler.doHandshake(request, response, this.wsHandler, attributes);
			chain.applyAfterHandshake(request, response, null);
			response.close();
		}
		catch (HandshakeFailureException ex) {
			failure = ex;
		}
		catch (Throwable t) {
			failure = new HandshakeFailureException("Uncaught failure for request " + request.getURI(), t);
		}
		finally {
			if (failure != null) {
				chain.applyAfterHandshake(request, response, failure);
				throw failure;
			}
		}
	}

}