/*
 *  Copyright 2012 Anyware Services
 *
 *  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.ametys.runtime.servlet;

import java.io.File;
import java.io.FileInputStream;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;
import java.net.URL;
import java.nio.file.Files;
import java.nio.file.Path;
import java.time.ZonedDateTime;
import java.util.Arrays;
import java.util.Collection;
import java.util.Enumeration;
import java.util.Map;
import java.util.Properties;
import java.util.UUID;
import java.util.regex.Pattern;

import javax.servlet.ServletConfig;
import javax.servlet.ServletContext;
import javax.servlet.ServletException;
import javax.servlet.ServletOutputStream;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import javax.servlet.http.HttpSession;
import javax.xml.XMLConstants;
import javax.xml.parsers.SAXParserFactory;
import javax.xml.transform.OutputKeys;
import javax.xml.transform.TransformerFactory;
import javax.xml.transform.sax.SAXTransformerFactory;
import javax.xml.transform.sax.TransformerHandler;
import javax.xml.transform.stream.StreamResult;
import javax.xml.transform.stream.StreamSource;
import javax.xml.validation.Schema;
import javax.xml.validation.SchemaFactory;

import org.apache.avalon.excalibur.logger.LoggerManager;
import org.apache.avalon.framework.configuration.Configuration;
import org.apache.avalon.framework.configuration.ConfigurationException;
import org.apache.avalon.framework.configuration.DefaultConfigurationBuilder;
import org.apache.avalon.framework.container.ContainerUtil;
import org.apache.avalon.framework.context.DefaultContext;
import org.apache.cocoon.Cocoon;
import org.apache.cocoon.ConnectionResetException;
import org.apache.cocoon.Constants;
import org.apache.cocoon.ResourceNotFoundException;
import org.apache.cocoon.environment.http.HttpContext;
import org.apache.cocoon.environment.http.HttpEnvironment;
import org.apache.cocoon.servlet.multipart.MultipartHttpServletRequest;
import org.apache.cocoon.servlet.multipart.RequestFactory;
import org.apache.cocoon.util.ClassUtils;
import org.apache.cocoon.util.log.SLF4JLoggerAdapter;
import org.apache.cocoon.util.log.SLF4JLoggerManager;
import org.apache.cocoon.xml.XMLUtils;
import org.apache.commons.collections.EnumerationUtils;
import org.apache.commons.io.FileUtils;
import org.apache.commons.io.IOUtils;
import org.apache.commons.lang3.StringUtils;
import org.apache.commons.lang3.exception.ExceptionUtils;
import org.apache.commons.lang3.time.StopWatch;
import org.apache.log4j.Appender;
import org.apache.log4j.LogManager;
import org.apache.log4j.xml.DOMConfigurator;
import org.apache.xml.serializer.OutputPropertiesFactory;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.slf4j.MDC;
import org.xml.sax.SAXException;
import org.xml.sax.XMLReader;

import org.ametys.core.ObservationConstants;
import org.ametys.core.authentication.AuthenticateAction;
import org.ametys.core.migration.MigrationExtensionPoint;
import org.ametys.core.observation.Event;
import org.ametys.core.observation.ObservationManager;
import org.ametys.core.user.CurrentUserProvider;
import org.ametys.core.user.UserIdentity;
import org.ametys.core.util.DateUtils;
import org.ametys.runtime.config.Config;
import org.ametys.runtime.config.ConfigManager;
import org.ametys.runtime.data.AmetysHomeLock;
import org.ametys.runtime.data.AmetysHomeLockException;
import org.ametys.runtime.log.MemoryAppender;
import org.ametys.runtime.plugin.Init;
import org.ametys.runtime.plugin.InitExtensionPoint;
import org.ametys.runtime.plugin.PluginsManager;
import org.ametys.runtime.plugin.PluginsManager.Status;
import org.ametys.runtime.plugin.component.PluginsComponentManager;
import org.ametys.runtime.plugins.admin.jvmstatus.ActiveSessionListener;
import org.ametys.runtime.request.RequestListener;
import org.ametys.runtime.request.RequestListenerManager;
import org.ametys.runtime.util.AmetysHomeHelper;

/**
 * Main entry point for applications.<br>
 * Overrides the CocoonServlet to add some initialization.<br>
 */
public class RuntimeServlet extends HttpServlet
{
    /** Constant for storing the {@link ServletConfig} in the Avalon context  */
    public static final String CONTEXT_SERVLET_CONFIG = "servlet-config";
    
    /** Constant for storing the servlet context URL in the Avalon context  */
    public static final String CONTEXT_CONTEXT_ROOT = "context-root";
    
    /** The cocoon.xconf URL */
    public static final String COCOON_CONF_URL = "/org/ametys/runtime/cocoon/cocoon.xconf";
    
    /** Default max upload size (10 Mb) */
    public static final int DEFAULT_MAX_UPLOAD_SIZE = 10 * 1024 * 1024;

    /** The maintenance file name */
    public static final String MAINTENANCE_FILENAME = "maintenance.xml";
    
    /** The config file name */
    public static final String CONFIG_FILE_NAME = "config.xml";
    
    /** Name of the servlet initialization parameter for the ametys home property */
    public static final String AMETYS_HOME_PROPERTY = "ametys.home.property";
    
    /** The default ametys home path (relative to the servlet context)  */
    public static final String AMETYS_HOME_DEFAULT = "/WEB-INF/data";
    
    /** The optional location (relative to application context) of the file that configures the list of plugins/workspaces/kernel to get somewhere else */
    public static final String EXTERNAL_LOCATIONS = "WEB-INF/param/external-locations.xml";

    /** File name in the administrator folder of the ametys home */
    public static final String INSTANCE_FILENAME = "instance-info.xml";
    
    /** The run modes */
    public enum RunMode
    {
        /** Application is currently starting */
        STARTING,
        /** Application is currently migrating */
        MIGRATING,
        /** Running init methods */
        INITIALIZING,
        /** Normal execution mode */
        NORMAL,
        /** Maintenance mode (See #getMaintenanceStatus) */
        MAINTENANCE,
        /** Safe mode (See PluginsManager#getStatus) */
        SAFEMODE,
        /** Fatal error during startup */
        FATALERROR,
        /** Application is currently stopping */
        STOPPING
    }
    
    /** The maintenance status of Ametys */
    public enum MaintenanceStatus
    {
        /** No maintenance activated */
        NONE,
        /** The maintenance was automatically switched on at startup due to a failed migration */
        AUTOMATIC,
        /** The maintenance was manually switched on */
        FORCED
    }
    /** Informations about the maintenance status when forced 
     * @param comment The comment to explain why the maintenance was started
     * @param initiator The user that started the maintenance
     * @param since The date the maintenance was stated */
    public record ForcedMainteanceInformations(String comment, UserIdentity initiator, ZonedDateTime since) { /* empty */ }
    
    private static RunMode _runMode = RunMode.STARTING;
    private static MaintenanceStatus _maintenanceStatus;
    private static ForcedMainteanceInformations _forcedMainteanceInformations;
    private static Logger _logger;
    private static ServletContext _servletContext;
    
    private String _servletContextPath;
    private URL _servletContextURL;
    private File _ametysHome;
    
    private DefaultContext _avalonContext;
    private HttpContext _context;
    private Cocoon _cocoon;
    private RequestFactory _requestFactory;
    private File _workDir;
    
    private int _maxUploadSize = DEFAULT_MAX_UPLOAD_SIZE;
    private File _uploadDir;
    private File _cacheDir;
    
    private AmetysHomeLock _ametysHomeLock;
    
    private LoggerManager _loggerManager;
    
    private Throwable _exception;
    
    private Collection<Pattern> _allowedURLPattern = Arrays.asList(Pattern.compile("_admin($|/.*)"), Pattern.compile("plugins/[^/]+/resources/.*"));
    
    @Override
    public void init() throws ServletException 
    {
        try
        {
            // Set this property in order to avoid a System.err.println (CatalogManager.java)
            if (System.getProperty("xml.catalog.ignoreMissing") == null)
            {
                System.setProperty("xml.catalog.ignoreMissing", "true");
            }
            
            _servletContext = getServletContext();
            _servletContext.addListener(ActiveSessionListener.class);
            _servletContextPath = _servletContext.getRealPath("/");
            
            _avalonContext = new DefaultContext();
            _context = new HttpContext(_servletContext);
            _avalonContext.put(Constants.CONTEXT_ENVIRONMENT_CONTEXT, _context);
            _avalonContext.put(Constants.CONTEXT_DEFAULT_ENCODING, "UTF-8");
            _avalonContext.put(CONTEXT_SERVLET_CONFIG, getServletConfig());
            
            _servletContextURL = new File(_servletContextPath).toURI().toURL();
            _avalonContext.put(CONTEXT_CONTEXT_ROOT, _servletContextURL);
        
            URL configFile = getClass().getResource(COCOON_CONF_URL);
            _avalonContext.put(Constants.CONTEXT_CONFIG_URL, configFile);
            
            _workDir = new File((File) _servletContext.getAttribute("javax.servlet.context.tempdir"), "cocoon-files");
            _workDir.mkdirs();
            _avalonContext.put(Constants.CONTEXT_WORK_DIR, _workDir);
            
            _cacheDir = new File(_workDir, "cache-dir");
            _cacheDir.mkdirs();
            _avalonContext.put(Constants.CONTEXT_CACHE_DIR, _cacheDir);
    
            // Create temp dir if it does not exist
            File tmpDir = new File(System.getProperty("java.io.tmpdir"));
            if (!tmpDir.exists())
            {
                FileUtils.forceMkdir(tmpDir);
            }
            
            // Init the Ametys home directory and lock before setting the logger.
            // The log folder is located in the Ametys home directory.
            _initAmetysHome();
            
            // Configuration file
            File config = FileUtils.getFile(_ametysHome, AmetysHomeHelper.AMETYS_HOME_CONFIG_DIR, CONFIG_FILE_NAME);
            final String fileName = config.getCanonicalPath();
            Config.setFilename(fileName);
            
            // Init logger
            _initLogger();
            
            _initAmetys();
        }
        catch (Throwable t)
        {
            setRunMode(RunMode.FATALERROR);
            
            if (_logger != null)
            {
                _logger.error("Error while loading Ametys. Entering in error mode.", t);
            }
            else
            {
                System.out.println("Error while loading Ametys. Entering in error mode.");
                t.printStackTrace();
            }

            _exception = t;
            
            _disposeCocoon();
        }
    }
    
    private void _initAmetysHome() throws AmetysHomeLockException
    {
        String ametysHomePath = null;
        
        boolean hasAmetysHomeProp = EnumerationUtils.toList(getInitParameterNames()).contains(AMETYS_HOME_PROPERTY);
        if (!hasAmetysHomeProp)
        {
            System.out.println(String.format("[INFO] The '%s' servlet initialization parameter was not found. The Ametys home directory default value will be used '%s'",
                    AMETYS_HOME_PROPERTY, AMETYS_HOME_DEFAULT));
        }
        else
        {
            String ametysHomeEnv = getInitParameter(AMETYS_HOME_PROPERTY);
            if (StringUtils.isEmpty(ametysHomeEnv))
            {
                System.out.println(String.format("[WARN] The '%s' servlet initialization parameter appears to be empty. Ametys home directory default value will be used '%s'",
                        AMETYS_HOME_PROPERTY, AMETYS_HOME_DEFAULT));
            }
            else
            {
                ametysHomePath = System.getenv(ametysHomeEnv);
                if (StringUtils.isEmpty(ametysHomePath))
                {
                    System.out.println(String.format(
                            "[WARN] The '%s' environment variable was not found or was empty. Ametys home directory default value will be used '%s'",
                            ametysHomeEnv, AMETYS_HOME_DEFAULT));
                }
            }
        }
        
        if (StringUtils.isEmpty(ametysHomePath))
        {
            ametysHomePath = _servletContext.getRealPath(AMETYS_HOME_DEFAULT);
        }
        
        System.out.println("Acquiring lock on " + ametysHomePath);
        
        // Acquire the lock on Ametys home
        _ametysHome = new File(ametysHomePath);
        _ametysHome.mkdirs();
        
        _ametysHomeLock = new AmetysHomeLock(_ametysHome);
        _ametysHomeLock.acquire();
    }

    /**
     * Get the instance identifier
     * @return The UUID of the Ametys instance or null if the id could not be generated at startup
     * @throws IllegalStateException If the file cannot be read
     */
    public static String getInstanceId()
    {
        Path statisticsFile = AmetysHomeHelper.getAmetysHome().toPath().resolve(INSTANCE_FILENAME);

        if (Files.exists(statisticsFile))
        {
            try (InputStream is = Files.newInputStream(statisticsFile))
            {
                Configuration configuration = new DefaultConfigurationBuilder().build(is);
                return configuration.getChild("unique-id").getValue();
            }
            catch (Exception e)
            {
                throw new IllegalStateException("Cannot read the ametys-home://" + INSTANCE_FILENAME + " file. Consider remove it and restart Ametys to recreate it", e);
            }
        }
        
        throw new IllegalStateException("The file ametys-home://" + INSTANCE_FILENAME + " does not exist while it should have created at startup");
    }

    private static void _createInstanceId()
    {
        try
        {
            Path statisticsFile = AmetysHomeHelper.getAmetysHome().toPath().resolve(INSTANCE_FILENAME);
    
            if (Files.exists(statisticsFile))
            {
                return;
            }
            
            String newId = UUID.randomUUID().toString();
            
            Files.createDirectories(statisticsFile.getParent());
            try (OutputStream os = Files.newOutputStream(statisticsFile))
            {
                // create a transformer for saving sax into a file
                TransformerHandler th = ((SAXTransformerFactory) TransformerFactory.newInstance()).newTransformerHandler();
                
                StreamResult result = new StreamResult(os);
                th.setResult(result);
    
                // create the format of result
                Properties format = new Properties();
                format.put(OutputKeys.METHOD, "xml");
                format.put(OutputKeys.INDENT, "yes");
                format.put(OutputKeys.ENCODING, "UTF-8");
                format.put(OutputPropertiesFactory.S_KEY_INDENT_AMOUNT, "2");
                th.getTransformer().setOutputProperties(format);
    
                th.startDocument();
                XMLUtils.startElement(th, "instance");
                XMLUtils.createElement(th, "unique-id", newId);
                XMLUtils.endElement(th, "instance");
                th.endDocument();
            }
        }
        catch (Exception e)
        {
            _logger.error("Cannot create the instance id", e);
        }
    }

    private void _initAmetys() throws Exception
    {
        setRunMode(RunMode.STARTING);
        _maintenanceStatus = null;
        _exception = null;

        // WEB-INF/param/runtime.xml loading
        _loadRuntimeConfig();

        _createCocoon();
        
        // Upload initialization
        _maxUploadSize = DEFAULT_MAX_UPLOAD_SIZE;
        _uploadDir = new File(RuntimeConfig.getInstance().getAmetysHome(), "uploads");
        
        if (ConfigManager.getInstance().isComplete())
        {
            Long maxUploadSizeParam = Config.getInstance().getValue("runtime.upload.max-size");
            if (maxUploadSizeParam != null)
            {
                // if the feature core/runtime.upload is deactivated, use the default value (10 Mb)
                _maxUploadSize = maxUploadSizeParam.intValue();
            }
        }

        _uploadDir.mkdirs();
        _avalonContext.put(Constants.CONTEXT_UPLOAD_DIR, _uploadDir);
        
        _requestFactory = new RequestFactory(true, _uploadDir, false, true, _maxUploadSize, "UTF-8");
        
        // Generate the instance-info file
        _createInstanceId();

        PluginsComponentManager pluginCM = (PluginsComponentManager) _servletContext.getAttribute("PluginsComponentManager");
        if (doMigrationAndInit(pluginCM))
        {
            restartCocoon(null);
        }
        else
        {
            if (PluginsManager.getInstance().isSafeMode())
            {
                setRunMode(RunMode.SAFEMODE);
            }
            else if (getMaintenanceStatus() != MaintenanceStatus.NONE)
            {
                setRunMode(RunMode.MAINTENANCE);
            }
            else
            {
                setRunMode(RunMode.NORMAL);
            }
        }
    }
    
    private void _initLogger() 
    {
        // Configure Log4j
        String logj4fFile = _servletContext.getRealPath("/WEB-INF/log4j.xml");
        
        // Hack to have context-relative log files, because of lack in configuration capabilities in log4j.
        // If there are more than one Ametys in the same JVM, the property will be successively set for each instance, 
        // so we heavily rely on DOMConfigurator beeing synchronous.
        System.setProperty("ametys.home.dir", _ametysHome.getAbsolutePath());
        DOMConfigurator.configure(logj4fFile);
        System.clearProperty("ametys.home.dir");
        
        Appender appender = new MemoryAppender(); 
        appender.setName(org.ametys.plugins.core.ui.log.LogManager.MEMORY_APPENDER_NAME);
        LogManager.getRootLogger().addAppender(appender); 
        Enumeration<org.apache.log4j.Logger> categories = LogManager.getCurrentLoggers(); 
        while (categories.hasMoreElements()) 
        { 
            org.apache.log4j.Logger logger = categories.nextElement(); 
            logger.addAppender(appender); 
        } 
        
        _loggerManager = new SLF4JLoggerManager();
        _logger = LoggerFactory.getLogger(getClass());
    }
    
    private void _createCocoon() throws Exception
    {
        _avalonContext.put(Constants.CONTEXT_CLASS_LOADER, getClass().getClassLoader());
        _avalonContext.put(Constants.CONTEXT_CLASSPATH, "");
        
        URL configFile = (URL) _avalonContext.get(Constants.CONTEXT_CONFIG_URL);
        
        _logger.info("Reloading from: {}", configFile.toExternalForm());
        
        Cocoon c = (Cocoon) ClassUtils.newInstance("org.apache.cocoon.Cocoon");
        ContainerUtil.enableLogging(c, new SLF4JLoggerAdapter(_logger));
        c.setLoggerManager(_loggerManager);
        ContainerUtil.contextualize(c, _avalonContext);
        ContainerUtil.initialize(c);

        _cocoon = c;
    }

    /**
     * Init migration and plugins
     * @param pluginCM Plugins Component Manager
     * @return true if a server restart is required
     * @throws Exception Something went wrong
     */
    public static boolean doMigrationAndInit(PluginsComponentManager pluginCM) throws Exception
    {
        if (_initMigration(pluginCM))
        {
            return true;
        }

        _initPlugins(pluginCM);
        
        return false;
    }
    
    private static void _initPlugins(PluginsComponentManager pluginCM) throws Exception
    {
        setRunMode(RunMode.INITIALIZING);

        // If we're in safe mode 
        if (!PluginsManager.getInstance().isSafeMode())
        {
            // Plugins Init class execution
            InitExtensionPoint initExtensionPoint = (InitExtensionPoint) pluginCM.lookup(InitExtensionPoint.ROLE);
            for (String id : initExtensionPoint.getExtensionsIds())
            {
                Init init = initExtensionPoint.getExtension(id);
                init.init();
            }
            
            // Application Init class execution if available
            if (pluginCM.hasComponent(Init.ROLE))
            {
                Init init = (Init) pluginCM.lookup(Init.ROLE);
                init.init();
            }
        }
    }
    
    private static boolean _initMigration(PluginsComponentManager pluginCM) throws Exception
    {
        setRunMode(RunMode.MIGRATING);

        MigrationExtensionPoint migrationEP = (MigrationExtensionPoint) pluginCM.lookup(MigrationExtensionPoint.ROLE);
        return migrationEP.doMigration();
    }
    
    private void _loadRuntimeConfig() throws ServletException
    {
        Configuration runtimeConf = null;
        try
        {
            // XML Schema validation
            SAXParserFactory factory = SAXParserFactory.newInstance();
            factory.setNamespaceAware(true);
            
            URL schemaURL = getClass().getResource("runtime-4.1.xsd");
            Schema schema = SchemaFactory.newInstance(XMLConstants.W3C_XML_SCHEMA_NS_URI).newSchema(schemaURL);
            factory.setSchema(schema);
            
            XMLReader reader = factory.newSAXParser().getXMLReader();
            DefaultConfigurationBuilder runtimeConfBuilder = new DefaultConfigurationBuilder(reader);
            
            File runtimeConfigFile = new File(_servletContextPath, "WEB-INF/param/runtime.xml");
            try (InputStream runtime = new FileInputStream(runtimeConfigFile))
            {
                runtimeConf = runtimeConfBuilder.build(runtime, runtimeConfigFile.getAbsolutePath());
            }
        }
        catch (Exception e)
        {
            _logger.error("Unable to load runtime file at 'WEB-INF/param/runtime.xml'. PluginsManager will enter in safe mode.", e);
        }
        
        Configuration externalConf = null;
        try
        {
            DefaultConfigurationBuilder externalConfBuilder = new DefaultConfigurationBuilder();

            File externalConfigFile = new File(_servletContextPath, EXTERNAL_LOCATIONS);
            if (externalConfigFile.exists())
            {
                try (InputStream external = new FileInputStream(externalConfigFile))
                {
                    externalConf = externalConfBuilder.build(external, externalConfigFile.getAbsolutePath());
                }
            }
        }
        catch (Exception e)
        {
            _logger.error("Unable to load external locations values at " + EXTERNAL_LOCATIONS, e);
            throw new ServletException("Unable to load external locations values at " + EXTERNAL_LOCATIONS, e);
        }
        
        RuntimeConfig.configure(runtimeConf, externalConf, _ametysHome, _servletContextPath);
    }

    @Override
    public void destroy() 
    {
        setRunMode(RunMode.STOPPING);
        
        if (_cocoon != null) 
        {
            _logger.debug("Servlet destroyed - disposing Cocoon");
            _disposeCocoon();
        }
        
        if (_ametysHomeLock != null)
        {
            _ametysHomeLock.release();
            _ametysHomeLock = null;
        }
        
        _avalonContext = null;
        _logger = null;
        _loggerManager = null;
    }

    
    private final void _disposeCocoon() 
    {
        if (_cocoon != null) 
        {
            ContainerUtil.dispose(_cocoon);
            _cocoon = null;
        }
    }

    @Override
    public final void service(HttpServletRequest req, HttpServletResponse res) throws ServletException, IOException
    {
        req.setCharacterEncoding("UTF-8");

        // add the cocoon header timestamp
        res.addHeader("X-Cocoon-Version", Constants.VERSION);
        
        // Error mode
        if (_exception != null)
        {
            _renderError(req, res, _exception, "An error occured during Ametys initialization.");
            return;
        }
        
        // Restarting
        if (_cocoon == null)
        {
            _renderError(req, res, null, "Ametys is restarting. Please try again later.");
            return;
        }
        
        String uri = _retrieveUri(req);
        
        if (PluginsManager.getInstance().isSafeMode())
        {
            // safe mode
            String finalUri = uri;
            boolean allowed = _allowedURLPattern.stream().anyMatch(p -> p.matcher(finalUri).matches());
            if (!allowed) 
            {
                res.addHeader("X-Ametys-SafeMode", "true");

                Status status = PluginsManager.getInstance().getStatus();
                
                if (status == Status.NO_CONFIG)
                {
                    res.sendRedirect(req.getContextPath() + "/_admin/public/first-start.html");
                    return;
                }
                else if (status == Status.CONFIG_INCOMPLETE)
                {
                    res.sendRedirect(req.getContextPath() + "/_admin/public/load-config.html");
                    return;
                }
                else
                {
                    res.sendRedirect(req.getContextPath() + "/_admin/public/safe-mode.html");
                    return;
                }
            }
        }

        UserIdentity authenticatedUser = null;
        HttpSession session = req.getSession(false); 
        if (session != null) 
        { 
            authenticatedUser = (UserIdentity) session.getAttribute(AuthenticateAction.SESSION_USERIDENTITY); 
        }
        
        MDC.remove("user"); 
                
        if (authenticatedUser != null) 
        { 
            MDC.put("user", UserIdentity.userIdentityToString(authenticatedUser));
        }
        
        MDC.put("requestURI", req.getRequestURI());

        StopWatch stopWatch = new StopWatch();
        HttpServletRequest request = null;
        try 
        {
            // used for timing the processing
            stopWatch.start();

            _fireRequestStarted(req);
            
            // get the request (wrapped if contains multipart-form data)
            request = _requestFactory.getServletRequest(req);
            
            // Process the request
            HttpEnvironment env = new HttpEnvironment(uri, _servletContextURL.toExternalForm(), request, res, _servletContext, _context, "UTF-8", "UTF-8");
            env.enableLogging(new SLF4JLoggerAdapter(_logger));
            
            if (!_cocoon.process(env)) 
            {
                // We reach this when there is nothing in the processing change that matches
                // the request. For example, no matcher matches.
                _logger.error("The Cocoon engine failed to process the request.");
                _renderError(request, res, null, "Cocoon engine failed to process the request");
            }
        } 
        catch (ResourceNotFoundException | ConnectionResetException | IOException e) 
        {
            _logger.warn(e.toString());
            _renderError(request, res, e, e.getMessage());
        } 
        catch (Throwable e) 
        {
            _logger.error("Internal Cocoon Problem", e);
            _renderError(request, res, e, "Internal Cocoon Problem");
        }
        finally 
        {
            stopWatch.stop();
            _logger.info("'{}' processed in {} ms.", uri, stopWatch.getTime());
            
            try
            {
                if (request instanceof MultipartHttpServletRequest) 
                {
                    _logger.debug("Deleting uploaded file(s).");
                    ((MultipartHttpServletRequest) request).cleanup();
                }
            } 
            catch (IOException e)
            {
                _logger.error("Cocoon got an Exception while trying to cleanup the uploaded files.", e);
            }
        }

        _fireRequestEnded(req);

        if (Boolean.TRUE.equals(req.getAttribute("org.ametys.runtime.reload")))
        {
            restartCocoon(req);
        }
    }
    
    /**
     * Restart cocoon
     * @param req The http servlet request, used to read safeMode and normalMode
     *            request attribute if possible. If null, safe mode will be
     *            forced only if it was already forced.
     */
    public void restartCocoon(HttpServletRequest req)
    {
        try
        {
            ConfigManager.getInstance().dispose();
            _disposeCocoon(); 
            _servletContext.removeAttribute("PluginsComponentManager");
            
            // By default force safe mode if it was already forced
            boolean wasForcedSafeMode = PluginsManager.getInstance().getStatus() == PluginsManager.Status.SAFE_MODE_FORCED;
            boolean forceSafeMode = wasForcedSafeMode;
            if (req != null)
            {
                // Also, checks if there is some specific request attributes
                // Force safe mode if is explicitly requested
                // Or force safe mode it was already forced unless normal mode is explicitly requested 
                forceSafeMode = Boolean.TRUE.equals(req.getAttribute("org.ametys.runtime.reload.safeMode"));
                if (!forceSafeMode)
                {
                    forceSafeMode = wasForcedSafeMode && !Boolean.TRUE.equals(req.getAttribute("org.ametys.runtime.reload.normalMode"));
                }
            }
            
            _servletContext.setAttribute("org.ametys.runtime.forceSafeMode", forceSafeMode);
            
            _initAmetys();
        }
        catch (Exception e)
        {
            setRunMode(RunMode.FATALERROR);

            _logger.error("Error while reloading Ametys. Entering in error mode.", e);
            _exception = e;
        }
    }
    
    private String _retrieveUri(HttpServletRequest req)
    {
        String uri = req.getServletPath();
        
        String pathInfo = req.getPathInfo();
        if (pathInfo != null) 
        {
            uri += pathInfo;
        }
        
        if (uri.length() > 0 && uri.charAt(0) == '/') 
        {
            uri = uri.substring(1);
        }
        return uri;
    }
    
    @SuppressWarnings("unchecked")
    private void _fireRequestStarted(HttpServletRequest req)
    {
        Collection< ? extends RequestListener> listeners = (Collection< ? extends RequestListener>) _servletContext.getAttribute(RequestListenerManager.CONTEXT_ATTRIBUTE_REQUEST_LISTENERS);

        if (listeners == null)
        {
            return;
        }

        for (RequestListener listener : listeners)
        {
            listener.requestStarted(req);
        }
    }

    @SuppressWarnings("unchecked")
    private void _fireRequestEnded(HttpServletRequest req)
    {
        Collection<? extends RequestListener> listeners = (Collection< ? extends RequestListener>) _servletContext.getAttribute(RequestListenerManager.CONTEXT_ATTRIBUTE_REQUEST_LISTENERS);

        if (listeners == null)
        {
            return;
        }

        for (RequestListener listener : listeners)
        {
            listener.requestEnded(req);
        }
    }
    
    /**
     * Set the maintenance status
     * @param maintenanceStatus The new maintenance status. Cannot be null.
     * @param forcedMainteanceInformations The informations if the mode is FORCED. Can be null.
     */
    public static void setMaintenanceStatus(MaintenanceStatus maintenanceStatus, ForcedMainteanceInformations forcedMainteanceInformations)
    {
        if (_maintenanceStatus != maintenanceStatus)
        {
            LoggerFactory.getLogger(Runtime.class).debug("Switching maintenance status from " + _maintenanceStatus + " to " + maintenanceStatus);
        }

        ForcedMainteanceInformations fixedForcedMainteanceInformations = null;
        if (forcedMainteanceInformations != null)
        {
            fixedForcedMainteanceInformations = new ForcedMainteanceInformations(StringUtils.defaultString(forcedMainteanceInformations.comment).replaceAll("\r?\n", "<br/>"), forcedMainteanceInformations.initiator, forcedMainteanceInformations.since);
        }
        
        try
        {
            File maintenanceFile = FileUtils.getFile(AmetysHomeHelper.getAmetysHome(), AmetysHomeHelper.AMETYS_HOME_ADMINISTRATOR_DIR, MAINTENANCE_FILENAME);
            if (maintenanceStatus != MaintenanceStatus.FORCED)
            {
                if (maintenanceFile.exists())
                {
                    FileUtils.delete(maintenanceFile);
                }
            }
            else 
            {
                // create the result where to write
                maintenanceFile.getParentFile().mkdirs();
                
                try (OutputStream os = new FileOutputStream(maintenanceFile))
                {
                    // create a transformer for saving sax into a file
                    TransformerHandler th = ((SAXTransformerFactory) TransformerFactory.newInstance()).newTransformerHandler();
                    
                    StreamResult result = new StreamResult(os);
                    th.setResult(result);
    
                    // create the format of result
                    Properties format = new Properties();
                    format.put(OutputKeys.METHOD, "xml");
                    format.put(OutputKeys.INDENT, "yes");
                    format.put(OutputKeys.ENCODING, "UTF-8");
                    format.put(OutputPropertiesFactory.S_KEY_INDENT_AMOUNT, "2");
                    th.getTransformer().setOutputProperties(format);
    
                    th.startDocument();
                    XMLUtils.startElement(th, "maintenance");
                    if (fixedForcedMainteanceInformations != null)
                    {
                        XMLUtils.createElement(th, "comment", StringUtils.defaultString(fixedForcedMainteanceInformations.comment));
                        XMLUtils.createElement(th, "initiator", StringUtils.defaultString(UserIdentity.userIdentityToString(fixedForcedMainteanceInformations.initiator)));
                        if (fixedForcedMainteanceInformations.since != null)
                        {
                            XMLUtils.createElement(th, "since", DateUtils.zonedDateTimeToString(fixedForcedMainteanceInformations.since));
                        }
                    }
                    XMLUtils.endElement(th, "maintenance");
                    th.endDocument();
                }
            }
        }
        catch (Exception e)
        {
            throw new RuntimeException("Cannot change maintenance status", e);
        }

        _maintenanceStatus = maintenanceStatus;
        _forcedMainteanceInformations = fixedForcedMainteanceInformations;
        
        try
        {
            PluginsComponentManager pluginCM = (PluginsComponentManager) _servletContext.getAttribute("PluginsComponentManager");
            ObservationManager observationManager = (ObservationManager) pluginCM.lookup(ObservationManager.ROLE);
            CurrentUserProvider currentUserProvider = (CurrentUserProvider) pluginCM.lookup(CurrentUserProvider.ROLE);
            if (observationManager != null)
            {
                observationManager.notify(new Event(ObservationConstants.EVENT_RUNTIME_MAINTENANCE, currentUserProvider.getUser(), Map.of()));
            }
        }
        catch (Exception e)
        {
            // Safe mode
        }
    }
    
    /**
     * Get the current maintenance status
     * @return The maintenance status
     */
    public static MaintenanceStatus getMaintenanceStatus()
    {
        if (_maintenanceStatus == null)
        {
            File maintenanceFile = FileUtils.getFile(AmetysHomeHelper.getAmetysHome(), AmetysHomeHelper.AMETYS_HOME_ADMINISTRATOR_DIR, MAINTENANCE_FILENAME);
            
            if (!maintenanceFile.exists())
            {
                _maintenanceStatus = MaintenanceStatus.NONE;
            }
            else
            {
                _maintenanceStatus = MaintenanceStatus.FORCED;
                try
                {
                    Configuration configuration = new DefaultConfigurationBuilder().buildFromFile(maintenanceFile);
                    _forcedMainteanceInformations = new ForcedMainteanceInformations(configuration.getChild("comment").getValue(""), 
                                                                                    UserIdentity.stringToUserIdentity(configuration.getChild("initiator").getValue(null)),
                                                                                    DateUtils.parseZonedDateTime(configuration.getChild("since").getValue(null)));
                }
                catch (ConfigurationException | SAXException | IOException e)
                {
                    _logger.error("Cannot read the maintenance status file", e);
                    _forcedMainteanceInformations = null;
                }
            }
        }
        return _maintenanceStatus; 
    }
    
    /**
     * When maintenance status is forced, this comment may explains why
     * @return The comment. Can be null even in forced mode.
     */
    public static ForcedMainteanceInformations getMaintenanceStatusForcedInformations()
    {
        return _forcedMainteanceInformations;
    }

    /**
     * Set the run mode
     * @param mode the running mode
     */
    public static void setRunMode(RunMode mode)
    {
        if (_runMode != mode)
        {
            LoggerFactory.getLogger(RuntimeServlet.class).debug("Switching run mode from " + _runMode + " to " + mode);
        }
        
        _runMode = mode;
    }

    /**
     * Get the run mode
     * @return the current run mode
     */
    public static RunMode getRunMode()
    {
        return _runMode;
    }

    private void _renderError(HttpServletRequest req, HttpServletResponse res, Throwable throwable, String message) throws ServletException
    {
        ServletConfig config = getServletConfig();

        if (config == null)
        {
            throw new ServletException("Cannot access to ServletConfig");
        }

        try
        {
            ServletOutputStream os = res.getOutputStream();
            String path = req.getRequestURI().substring(req.getContextPath().length());
    
            // Favicon associated with the error page.
            if (path.equals("/favicon.ico"))
            {
                try (InputStream is = getClass().getResourceAsStream("favicon.ico"))
                {
                    res.setStatus(200);
                    res.setContentType(config.getServletContext().getMimeType("favicon.ico"));
                    
                    IOUtils.copy(is, os);
                    
                    return;
                }
            }
    
            res.setStatus(500);
            res.setContentType("text/html; charset=UTF-8");
    
            SAXTransformerFactory saxFactory = (SAXTransformerFactory) TransformerFactory.newInstance();
            TransformerHandler th;
            
            try (InputStream is = getClass().getResourceAsStream("fatal.xsl"))
            {
                StreamSource errorSource = new StreamSource(is);
                th = saxFactory.newTransformerHandler(errorSource);
            }
            
            Properties format = new Properties();
            format.put(OutputKeys.METHOD, "xml");
            format.put(OutputKeys.ENCODING, "UTF-8");
            format.put(OutputKeys.DOCTYPE_SYSTEM, "about:legacy-compat");
    
            th.getTransformer().setOutputProperties(format);
    
            th.getTransformer().setParameter("code", 500);
            th.getTransformer().setParameter("realPath", config.getServletContext().getRealPath("/"));
            th.getTransformer().setParameter("contextPath", req.getContextPath());
            
            StreamResult result = new StreamResult(os);
            th.setResult(result);
    
            th.startDocument();
    
            XMLUtils.startElement(th, "http://apache.org/cocoon/exception/1.0", "exception-report");
            XMLUtils.startElement(th, "http://apache.org/cocoon/exception/1.0", "message");
            XMLUtils.data(th, message);
            XMLUtils.endElement(th, "http://apache.org/cocoon/exception/1.0", "message");
            
            XMLUtils.startElement(th, "http://apache.org/cocoon/exception/1.0", "stacktrace");
            if (throwable != null)
            {
                XMLUtils.data(th, ExceptionUtils.getStackTrace(throwable));
            }
            XMLUtils.endElement(th, "http://apache.org/cocoon/exception/1.0", "stacktrace");
            XMLUtils.endElement(th, "http://apache.org/cocoon/exception/1.0", "ex:exception-report");
    
            th.endDocument();
        }
        catch (Exception e)
        {
            // Nothing we can do anymore ...
            throw new ServletException(e);
        }
    }

    /*
     * private void _runMaintenanceMode(HttpServletRequest req, HttpServletResponse res) throws ServletException, IOException { ServletConfig config = getServletConfig(); if (config == null) { throw new ServletException("Cannot access to ServletConfig"); } ServletOutputStream os = res.getOutputStream(); if (req.getRequestURI().startsWith("/WEB-INF/error/")) { // Service des fichiers statiques de la page d'erreur File f = new File(config.getServletContext().getRealPath(req.getRequestURI())); if (f.exists()) { res.setStatus(200); InputStream is = new FileInputStream(f); SourceUtil.copy(is, os); is.close(); } else { res.setStatus(404); } return; } res.setStatus(500); SAXTransformerFactory saxFactory = (SAXTransformerFactory) TransformerFactory.newInstance(); InputStream is; File errorXSL = new File(config.getServletContext().getRealPath("/WEB-INF/error/error.xsl")); if (errorXSL.exists()) { is = new FileInputStream(errorXSL); } else { is = getClass().getResourceAsStream("/org/ametys/runtime/kernel/pages/error/error.xsl"); } try { StreamSource errorSource = new StreamSource(is); Templates templates = saxFactory.newTemplates(errorSource); TransformerHandler th = saxFactory.newTransformerHandler(templates); is.close(); StreamResult result = new StreamResult(os); th.setResult(result); th.startDocument(); th.startElement("", "error", "error", new AttributesImpl()); saxMaintenanceMessage(th); th.endElement("", "error", "error"); th.endDocument(); } catch (Exception ex) { throw new ServletException("Unable to send maintenance page", ex); } }
     */

    /**
     * In maintenance mode, send error information as SAX events.<br>
     * 
     * @param ch the contentHandler receiving the message
     * @throws SAXException if an error occured while send SAX events
     */
    /*
     * protected void saxMaintenanceMessage(ContentHandler ch) throws SAXException { String maintenanceMessage = "The application is under maintenance. Please retry later."; ch.characters(maintenanceMessage.toCharArray(), 0, maintenanceMessage.length()); } private boolean _accept(HttpServletRequest req) { // FIX ME à ne pas mettre en dur return req.getRequestURI().startsWith("_admin"); }
     */
}