/**
 *
 *  Copyright 2005 The Apache Software Foundation or its licensors, as applicable.
 *
 *  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.apache.tuscany.core.webapp;

import org.apache.tuscany.core.context.CompositeContext;
import org.apache.tuscany.core.context.event.HttpSessionBound;
import org.apache.tuscany.core.context.event.RequestStart;
import org.apache.tuscany.core.context.event.RequestEnd;
import org.osoa.sca.CurrentModuleContext;
import org.osoa.sca.ModuleContext;

import javax.servlet.http.HttpServletRequest;
import javax.servlet.Filter;
import javax.servlet.ServletContext;
import javax.servlet.ServletException;
import javax.servlet.FilterConfig;
import javax.servlet.ServletResponse;
import javax.servlet.FilterChain;
import javax.servlet.ServletRequest;
import java.io.IOException;

/**
 * Notifies the {@link org.apache.tuscany.core.context.CompositeContext} of web request start and end events as well as setting up the
 * current session context. The latter is done using lazy Servlet-based session retrieval. The filter fires a session
 * start event, passing a <tt>LazyServletSessionId</tt> as the session id. The <tt>LazyServletSessionId</tt> is a
 * wrapper for the servlet request which may be called by the <tt>ModuleContext</tt> to retrieve the session id
 * lazily.
 * 
 * @version $Rev: 379957 $ $Date: 2006-02-22 14:58:24 -0800 (Wed, 22 Feb 2006) $
 */
public class TuscanyRequestFilter implements Filter {
    private CompositeContext moduleContext;

    public TuscanyRequestFilter() {
    }

    public void init(FilterConfig filterConfig) throws ServletException {
        ServletContext servletContext = filterConfig.getServletContext();
        moduleContext = (CompositeContext) servletContext.getAttribute(TuscanyServletListener.MODULE_COMPONENT_NAME);
    }

    public void destroy() {
    }

    public void doFilter(ServletRequest request, ServletResponse response, FilterChain filterChain) throws ServletException, IOException {
        ModuleContext oldContext = CurrentModuleContext.getContext();
        try {
            // Set the current module context
            ContextBinder.BINDER.setContext((ModuleContext) moduleContext);

            // Handle a request
            if (request instanceof HttpServletRequest) {
                if (((HttpServletRequest) request).getSession(false) != null) {

                    // A session is already active
                    moduleContext.publish(new HttpSessionBound(this, ((HttpServletRequest) request).getSession(true)));
                } else {
                    // Create a lazy wrapper since a session is not yet active
                    moduleContext.publish(new HttpSessionBound(this, new LazyHTTPSessionId((HttpServletRequest) request)));
                }
            } else {
                moduleContext.publish(new HttpSessionBound(this, request));
            }
            // Start processing the request
            moduleContext.publish(new RequestStart(this, request));
            // Dispatch to the next filter
            filterChain.doFilter(request, response);
        } catch (Exception e) {
            throw new ServletException(e);

        } finally {
            try {
                // End processing the request
                moduleContext.publish(new RequestEnd(this, request));
            } catch (Exception e) {
                throw new ServletException(e);
            }
            ContextBinder.BINDER.setContext(oldContext);
        }
    }

}