/*
 * Licensed to the Apache Software Foundation (ASF) under one
 * or more contributor license agreements.  See the NOTICE file
 * distributed with this work for additional information
 * regarding copyright ownership.  The ASF licenses this file
 * to you 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.apache.tuscany.sca.binding.comet.runtime;

import java.util.HashMap;
import java.util.Map;

import org.apache.tuscany.sca.host.http.ServletHost;
import org.apache.tuscany.sca.interfacedef.Operation;
import org.apache.tuscany.sca.runtime.RuntimeEndpoint;
import org.atmosphere.cpr.AtmosphereServlet;

/**
 * This class is used to create two servlets: one exposing all the comet
 * services, the other one exposing the javascript toolkit.
 * 
 * Exposing all comet services through a single servlet is needed as the
 * browsers are undergone by the two http connection limit so all comet services
 * should send their responses via the same http connection to the same client.
 * 
 * Dispatching to the corresponding endpoint and operation is done internally
 * using Jersey RESTful Web Services integration with the AtmosphereServlet.
 * 
 * The Javascript toolkit servlet is unique as it is not tied to any of the
 * services - it offers a global API.
 */
public class ServletFactory {

	/**
	 * Init-param key for the AtmosphereServlet defining where to look for
	 * Jersey classes.
	 */
	private static final String PACKAGE_KEY = "com.sun.jersey.config.property.packages";

	/**
	 * Package of the class handling dispatching to endpoints.
	 */
	private static final String PACKAGE_VALUE = "org.apache.tuscany.sca.binding.comet.runtime.handler";

	/**
	 * Package of the class handling Javascript toolkit retrieval.
	 */
	private static final String JS_PACKAGE_VALUE = "org.apache.tuscany.sca.binding.comet.runtime.javascript";

	/**
	 * Property in the ServletContext where endpoints are added incrementally as
	 * the Tuscany runtime calls the CometServiceBindingProvider for each comet
	 * service.
	 */
	public static final String ENDPOINTS_KEY = "org.apache.tuscany.sca.binding.comet.endpoints";

	/**
	 * Property in the ServletContext where operations are added incrementally
	 * as the CometServiceBindingProvider is calling the registerServlet method
	 * for each comet service method.
	 */
	public static final String OPERATIONS_KEY = "org.apache.tuscany.sca.binding.comet.operations";

	/**
	 * Path where services will be exposed.
	 */
	public static final String PATH = "/tuscany-comet/*";

	/**
	 * Path where Javascript toolkit will be exposed.
	 */
	public static final String JS_PATH = "/org.apache.tuscany.sca.cometComponentContext.js/*";

	/**
	 * The servlet that is exposing the comet services.
	 */
	private static AtmosphereServlet cometServlet = null;

	/**
	 * The servlet that is exposing the Javascript toolkit.
	 */
	private static AtmosphereServlet javascriptServlet = null;

	/**
	 * Method called by CometServiceBindingProvider for each endpoint operation
	 * in order to create the two servlets and keep track of all the endpoints
	 * and their operations.
	 * 
	 * @param servletHost
	 *            the underlying servlet host
	 * @param endpoint
	 *            the endpoint
	 * @param operation
	 *            the operation
	 */
	public static synchronized void registerServlet(ServletHost servletHost,
			RuntimeEndpoint endpoint, Operation operation) {
		if (cometServlet == null) {
			cometServlet = new AtmosphereServlet();
			cometServlet.addInitParameter(PACKAGE_KEY, PACKAGE_VALUE);
			servletHost.addServletMapping(PATH, cometServlet);
			// store operations and corresponding endpoint in the ServletContext
			// so that they can be retrieved from inside the web service methods
			Map<String, RuntimeEndpoint> endpoints = new HashMap<String, RuntimeEndpoint>();
			cometServlet.getServletContext().setAttribute(ENDPOINTS_KEY,
					endpoints);
			Map<String, Operation> operations = new HashMap<String, Operation>();
			cometServlet.getServletContext().setAttribute(OPERATIONS_KEY,
					operations);
		}
		// add current operation to ServletContext
		String url = "/" + endpoint.getService().getName() + "/"
				+ operation.getName();
		Map<String, RuntimeEndpoint> endpoints = (Map<String, RuntimeEndpoint>) cometServlet
				.getServletContext().getAttribute(ENDPOINTS_KEY);
		endpoints.put(url, endpoint);
		Map<String, Operation> operations = (Map<String, Operation>) cometServlet
				.getServletContext().getAttribute(OPERATIONS_KEY);
		operations.put(url, operation);

		if (javascriptServlet == null) {
			javascriptServlet = new AtmosphereServlet();
			javascriptServlet.addInitParameter(PACKAGE_KEY, JS_PACKAGE_VALUE);
			servletHost.addServletMapping(JS_PATH, javascriptServlet);
		}
	}

}