modules/binding-rest-runtime/src/main/java/org/apache/tuscany/sca/binding/rest/provider/TuscanyRESTServlet.java

/*
 * 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.rest.provider;

import java.io.IOException;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.Calendar;
import java.util.Collections;
import java.util.Date;
import java.util.Enumeration;
import java.util.GregorianCalendar;
import java.util.List;
import java.util.Properties;
import java.util.logging.Level;
import java.util.logging.Logger;

import javax.servlet.FilterConfig;
import javax.servlet.ServletContext;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import javax.ws.rs.HttpMethod;
import javax.ws.rs.core.Application;
import javax.ws.rs.core.MediaType;

import org.apache.tuscany.sca.assembly.Binding;
import org.apache.tuscany.sca.binding.rest.RESTBinding;
import org.apache.tuscany.sca.common.http.HTTPCacheContext;
import org.apache.tuscany.sca.common.http.HTTPHeader;
import org.apache.tuscany.sca.core.ExtensionPointRegistry;
import org.apache.tuscany.sca.extensibility.ClassLoaderContext;
import org.apache.wink.common.internal.registry.ProvidersRegistry;
import org.apache.wink.common.internal.registry.metadata.MethodMetadata;
import org.apache.wink.server.handlers.HandlersChain;
import org.apache.wink.server.handlers.HandlersFactory;
import org.apache.wink.server.handlers.MessageContext;
import org.apache.wink.server.handlers.RequestHandler;
import org.apache.wink.server.handlers.ResponseHandler;
import org.apache.wink.server.internal.DeploymentConfiguration;
import org.apache.wink.server.internal.RequestProcessor;
import org.apache.wink.server.internal.handlers.CheckLocationHeaderHandler;
import org.apache.wink.server.internal.registry.ResourceRecord;
import org.apache.wink.server.internal.servlet.RestServlet;

/**
 *
 */
public class TuscanyRESTServlet extends RestServlet {
    private static final Logger logger = Logger.getLogger(TuscanyRESTServlet.class.getName());
    
    private static final long serialVersionUID = 89997233133964915L;
    private ExtensionPointRegistry registry;
    private RESTBinding binding;
    private Class<?> resourceClass;
    private boolean fixed;

    public TuscanyRESTServlet(ExtensionPointRegistry registry, Binding binding, Class<?> resourceClass) {
        super();
        this.registry = registry;
        this.binding = (RESTBinding) binding;
        this.resourceClass = resourceClass;
    }
    
    public void init() throws ServletException {
        ClassLoader cl =
            ClassLoaderContext.setContextClassLoader(Thread.currentThread().getContextClassLoader(),
                                                     registry.getServiceDiscovery(),
                                                     "/META-INF/server/wink-providers");
        try {
            super.init();
        } finally {
            if (cl != null) {
                // return previous classLoader
                Thread.currentThread().setContextClassLoader(cl);
            }
        }
    }
    
    /**
     * Create Tuscany own DeploymentConfiguration in order to be able to 
     * add ResponseHandler to the Wink HandlerChain
     */
    public DeploymentConfiguration createDeploymentConfiguration() throws ClassNotFoundException, InstantiationException, IllegalAccessException { 
        return new TuscanyDeploymentConfiguration();
    }

    @SuppressWarnings({"unchecked", "rawtypes"})
    @Override
    public DeploymentConfiguration getDeploymentConfiguration() throws ClassNotFoundException, InstantiationException,
        IllegalAccessException, IOException {


        // setup proper classLoader to work on OSGi environment
        ClassLoader cl =
            ClassLoaderContext.setContextClassLoader(Thread.currentThread().getContextClassLoader(),
                                                     registry.getServiceDiscovery(),
                                                     "javax.ws.rs.ext.RuntimeDelegate",
                                                     "/META-INF/wink-alternate-shortcuts.properties",
                                                     "/META-INF/server/wink-providers");

        DeploymentConfiguration config = null;
        try {
            config = super.getDeploymentConfiguration();
        } finally {
            if (cl != null) {
                // return previous classLoader
                Thread.currentThread().setContextClassLoader(cl);
            }
        }

        // [rfeng] FIXME: This is a hack to fool Apache wink to not remove the servlet path
        config.setFilterConfig(new FilterConfig() {

            public ServletContext getServletContext() {
                return getServletContext();
            }

            public Enumeration getInitParameterNames() {
                return getInitParameterNames();
            }

            public String getInitParameter(String arg0) {
                return getInitParameter(arg0);
            }

            public String getFilterName() {
                return getServletName();
            }
        });

        ProvidersRegistry providers = config.getProvidersRegistry();
        providers.addProvider(new DataBindingJAXRSReader(registry), 0.001, true);
        providers.addProvider(new DataBindingJAXRSWriter(registry), 0.001, true);
        
        return config;
    }

    private synchronized void fixMediaTypes(DeploymentConfiguration config) {
        if (fixed) {
            return;
        }
        // FIXME: A hacky workaround for https://issues.apache.org/jira/browse/TUSCANY-3572
        ResourceRecord record = config.getResourceRegistry().getRecord(resourceClass);

        for (MethodMetadata methodMetadata : record.getMetadata().getResourceMethods()) {
            String method = methodMetadata.getHttpMethod();
            if (HttpMethod.GET.equals(method) || HttpMethod.HEAD.equals(method) || HttpMethod.DELETE.equals(method)) {
                methodMetadata.addConsumes(MediaType.APPLICATION_OCTET_STREAM_TYPE);
                methodMetadata.addConsumes(MediaType.WILDCARD_TYPE);
            }
            if (HttpMethod.HEAD.equals(method) || HttpMethod.DELETE.equals(method)) {
                methodMetadata.addProduces(MediaType.APPLICATION_OCTET_STREAM_TYPE);
                methodMetadata.addConsumes(MediaType.WILDCARD_TYPE);
            }
        }
        for (MethodMetadata methodMetadata : record.getMetadata().getSubResourceMethods()) {
            String method = methodMetadata.getHttpMethod();
            if (HttpMethod.GET.equals(method) || HttpMethod.HEAD.equals(method) || HttpMethod.DELETE.equals(method)) {
                methodMetadata.addConsumes(MediaType.APPLICATION_OCTET_STREAM_TYPE);
                methodMetadata.addConsumes(MediaType.WILDCARD_TYPE);
            }
            if (HttpMethod.HEAD.equals(method) || HttpMethod.DELETE.equals(method)) {
                methodMetadata.addProduces(MediaType.APPLICATION_OCTET_STREAM_TYPE);
                methodMetadata.addConsumes(MediaType.WILDCARD_TYPE);
            }
        }
        fixed = true;
    }

    @Override
    public RequestProcessor getRequestProcessor() {
        RequestProcessor processor = super.getRequestProcessor();
        // The 1st call returns null
        if (processor != null) {
            fixMediaTypes(processor.getConfiguration());
        }
        return processor;
    }
    
    /**
     * TuscanyDeploymentConfiguration
     * 
     * Required to inject TuscanyResponseHandler to the HandlerChain
     */
    class TuscanyDeploymentConfiguration extends DeploymentConfiguration {
        
        @Override
        protected List<ResponseHandler> initResponseUserHandlers() {
            List<ResponseHandler> list = super.initResponseUserHandlers();
            list.add(new TuscanyResponseHandler());
            return list;
        }
    }
    
    /**
     * TuscanyResponseHandler
     * 
     * Required to support declartive HTTP Headers
     */
    class TuscanyResponseHandler implements ResponseHandler {
        public void handleResponse(MessageContext context, HandlersChain chain) throws Throwable {
            
            // assert response is not committed
            final HttpServletResponse httpResponse = context.getAttribute(HttpServletResponse.class);
            if (httpResponse.isCommitted()) {
                logger.log(Level.FINE, "The response is already committed. Nothing to do.");
                return;
            }
            
            //process declarative headers
            for(HTTPHeader header : binding.getHttpHeaders()) {                
                //treat special headers that need to be calculated
                if(header.getName().equalsIgnoreCase("Expires")) {
                    GregorianCalendar calendar = new GregorianCalendar();
                    calendar.setTime(new Date());

                    calendar.add(Calendar.HOUR, Integer.parseInt(header.getValue()));

                    httpResponse.setHeader("Expires", HTTPCacheContext.RFC822DateFormat.format( calendar.getTime() ));
                } else {
                    //default behaviour to pass the header value to HTTP response
                    httpResponse.setHeader(header.getName(), header.getValue());
                }
            }     

            chain.doChain(context);
        }

        public void init(Properties props) {

        }        
    }

}