universe@7: /*
universe@7:  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS HEADER.
universe@34:  *
universe@24:  * Copyright 2018 Mike Becker. All rights reserved.
universe@34:  *
universe@7:  * Redistribution and use in source and binary forms, with or without
universe@7:  * modification, are permitted provided that the following conditions are met:
universe@7:  *
universe@7:  *   1. Redistributions of source code must retain the above copyright
universe@7:  *      notice, this list of conditions and the following disclaimer.
universe@7:  *
universe@7:  *   2. Redistributions in binary form must reproduce the above copyright
universe@7:  *      notice, this list of conditions and the following disclaimer in the
universe@7:  *      documentation and/or other materials provided with the distribution.
universe@7:  *
universe@7:  * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
universe@7:  * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
universe@7:  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
universe@7:  * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE
universe@7:  * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
universe@7:  * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
universe@7:  * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
universe@7:  * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
universe@7:  * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
universe@7:  * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
universe@7:  * POSSIBILITY OF SUCH DAMAGE.
universe@34:  *
universe@7:  */
universe@7: package de.uapcore.lightpit;
universe@7: 
universe@38: import de.uapcore.lightpit.dao.DataAccessObjects;
universe@38: import de.uapcore.lightpit.dao.postgres.PGDataAccessObjects;
universe@33: import org.slf4j.Logger;
universe@33: import org.slf4j.LoggerFactory;
universe@33: 
universe@7: import javax.servlet.ServletException;
universe@7: import javax.servlet.http.HttpServlet;
universe@7: import javax.servlet.http.HttpServletRequest;
universe@7: import javax.servlet.http.HttpServletResponse;
universe@13: import javax.servlet.http.HttpSession;
universe@33: import java.io.IOException;
universe@33: import java.lang.reflect.Method;
universe@33: import java.lang.reflect.Modifier;
universe@38: import java.sql.Connection;
universe@38: import java.sql.SQLException;
universe@33: import java.util.*;
universe@7: 
universe@7: /**
universe@7:  * A special implementation of a HTTPServlet which is focused on implementing
universe@7:  * the necessary functionality for {@link LightPITModule}s.
universe@7:  */
universe@9: public abstract class AbstractLightPITServlet extends HttpServlet {
universe@34: 
universe@10:     private static final Logger LOG = LoggerFactory.getLogger(AbstractLightPITServlet.class);
universe@34: 
universe@13:     private static final String HTML_FULL_DISPATCHER = Functions.jspPath("html_full");
universe@33: 
universe@11:     /**
universe@11:      * The EL proxy is necessary, because the EL resolver cannot handle annotation properties.
universe@11:      */
universe@36:     private LightPITModule.ELProxy moduleInfo = null;
universe@33: 
universe@10:     /**
universe@11:      * Invocation mapping gathered from the {@link RequestMapping} annotations.
universe@34:      * <p>
universe@18:      * Paths in this map must always start with a leading slash, although
universe@18:      * the specification in the annotation must not start with a leading slash.
universe@34:      * <p>
universe@34:      * The reason for this is the different handling of empty paths in
universe@18:      * {@link HttpServletRequest#getPathInfo()}.
universe@11:      */
universe@39:     private final Map<HttpMethod, Map<String, Method>> mappings = new HashMap<>();
universe@11: 
universe@11:     /**
universe@10:      * Gives implementing modules access to the {@link ModuleManager}.
universe@33:      *
universe@10:      * @return the module manager
universe@10:      */
universe@10:     protected final ModuleManager getModuleManager() {
universe@10:         return (ModuleManager) getServletContext().getAttribute(ModuleManager.SC_ATTR_NAME);
universe@10:     }
universe@33: 
universe@38: 
universe@34:     /**
universe@38:      * Creates a set of data access objects for the specified connection.
universe@33:      *
universe@38:      * @param connection the SQL connection
universe@38:      * @return a set of data access objects
universe@17:      */
universe@38:     private DataAccessObjects createDataAccessObjects(Connection connection) throws SQLException {
universe@38:         final var df = (DatabaseFacade) getServletContext().getAttribute(DatabaseFacade.SC_ATTR_NAME);
universe@39:         if (df.getSQLDialect() == DatabaseFacade.Dialect.Postgres) {
universe@39:             return new PGDataAccessObjects(connection);
universe@38:         }
universe@39:         throw new AssertionError("Non-exhaustive if-else - this is a bug.");
universe@17:     }
universe@33: 
universe@38:     private ResponseType invokeMapping(Method method, HttpServletRequest req, HttpServletResponse resp, DataAccessObjects dao) throws IOException {
universe@11:         try {
universe@14:             LOG.trace("invoke {}#{}", method.getDeclaringClass().getName(), method.getName());
universe@38:             return (ResponseType) method.invoke(this, req, resp, dao);
universe@12:         } catch (ReflectiveOperationException | ClassCastException ex) {
universe@38:             LOG.error("invocation of method {} failed: {}", method.getName(), ex.getMessage());
universe@38:             LOG.debug("Details: ", ex);
universe@12:             resp.sendError(HttpServletResponse.SC_INTERNAL_SERVER_ERROR);
universe@12:             return ResponseType.NONE;
universe@11:         }
universe@11:     }
universe@11: 
universe@11:     @Override
universe@11:     public void init() throws ServletException {
universe@36:         moduleInfo = Optional.ofNullable(this.getClass().getAnnotation(LightPITModule.class))
universe@36:                 .map(LightPITModule.ELProxy::new).orElse(null);
universe@33: 
universe@33:         if (moduleInfo != null) {
universe@12:             scanForRequestMappings();
universe@12:         }
universe@33: 
universe@12:         LOG.trace("{} initialized", getServletName());
universe@12:     }
universe@12: 
universe@12:     private void scanForRequestMappings() {
universe@12:         try {
universe@11:             Method[] methods = getClass().getDeclaredMethods();
universe@11:             for (Method method : methods) {
universe@11:                 Optional<RequestMapping> mapping = Optional.ofNullable(method.getAnnotation(RequestMapping.class));
universe@11:                 if (mapping.isPresent()) {
universe@11:                     if (!Modifier.isPublic(method.getModifiers())) {
universe@11:                         LOG.warn("{} is annotated with {} but is not public",
universe@11:                                 method.getName(), RequestMapping.class.getSimpleName()
universe@11:                         );
universe@11:                         continue;
universe@11:                     }
universe@11:                     if (Modifier.isAbstract(method.getModifiers())) {
universe@11:                         LOG.warn("{} is annotated with {} but is abstract",
universe@11:                                 method.getName(), RequestMapping.class.getSimpleName()
universe@11:                         );
universe@11:                         continue;
universe@11:                     }
universe@12:                     if (!ResponseType.class.isAssignableFrom(method.getReturnType())) {
universe@12:                         LOG.warn("{} is annotated with {} but has the wrong return type - 'ResponseType' required",
universe@12:                                 method.getName(), RequestMapping.class.getSimpleName()
universe@12:                         );
universe@12:                         continue;
universe@12:                     }
universe@12: 
universe@11:                     Class<?>[] params = method.getParameterTypes();
universe@38:                     if (params.length == 3
universe@11:                             && HttpServletRequest.class.isAssignableFrom(params[0])
universe@38:                             && HttpServletResponse.class.isAssignableFrom(params[1])
universe@38:                             && DataAccessObjects.class.isAssignableFrom(params[2])) {
universe@34: 
universe@34:                         final String requestPath = "/" + mapping.get().requestPath();
universe@12: 
universe@39:                         if (mappings
universe@39:                                 .computeIfAbsent(mapping.get().method(), k -> new HashMap<>())
universe@39:                                 .putIfAbsent(requestPath, method) != null) {
universe@11:                             LOG.warn("{} {} has multiple mappings",
universe@11:                                     mapping.get().method(),
universe@11:                                     mapping.get().requestPath()
universe@11:                             );
universe@11:                         }
universe@12: 
universe@22:                         LOG.debug("{} {} maps to {}::{}",
universe@11:                                 mapping.get().method(),
universe@18:                                 requestPath,
universe@22:                                 getClass().getSimpleName(),
universe@11:                                 method.getName()
universe@11:                         );
universe@11:                     } else {
universe@40:                         LOG.warn("{} is annotated with {} but has the wrong parameters - (HttpServletRequest,HttpServletResponse,DataAccessObjects) required",
universe@11:                                 method.getName(), RequestMapping.class.getSimpleName()
universe@11:                         );
universe@11:                     }
universe@11:                 }
universe@11:             }
universe@12:         } catch (SecurityException ex) {
universe@12:             LOG.error("Scan for request mappings on declared methods failed.", ex);
universe@11:         }
universe@11:     }
universe@11: 
universe@11:     @Override
universe@11:     public void destroy() {
universe@11:         mappings.clear();
universe@11:         LOG.trace("{} destroyed", getServletName());
universe@11:     }
universe@34: 
universe@13:     /**
universe@13:      * Sets the name of the dynamic fragment.
universe@34:      * <p>
universe@13:      * It is sufficient to specify the name without any extension. The extension
universe@13:      * is added automatically if not specified.
universe@34:      * <p>
universe@13:      * The fragment must be located in the dynamic fragments folder.
universe@34:      *
universe@34:      * @param req          the servlet request object
universe@13:      * @param fragmentName the name of the fragment
universe@13:      * @see Constants#DYN_FRAGMENT_PATH_PREFIX
universe@13:      */
universe@13:     public void setDynamicFragment(HttpServletRequest req, String fragmentName) {
universe@13:         req.setAttribute(Constants.REQ_ATTR_FRAGMENT, Functions.dynFragmentPath(fragmentName));
universe@13:     }
universe@34: 
universe@11:     /**
universe@13:      * Specifies the name of an additional stylesheet used by the module.
universe@34:      * <p>
universe@13:      * Setting an additional stylesheet is optional, but quite common for HTML
universe@13:      * output.
universe@34:      * <p>
universe@13:      * It is sufficient to specify the name without any extension. The extension
universe@13:      * is added automatically if not specified.
universe@34:      *
universe@34:      * @param req        the servlet request object
universe@13:      * @param stylesheet the name of the stylesheet
universe@11:      */
universe@13:     public void setStylesheet(HttpServletRequest req, String stylesheet) {
universe@13:         req.setAttribute(Constants.REQ_ATTR_STYLESHEET, Functions.enforceExt(stylesheet, ".css"));
universe@10:     }
universe@34: 
universe@10:     private void forwardToFullView(HttpServletRequest req, HttpServletResponse resp)
universe@10:             throws IOException, ServletException {
universe@34: 
universe@36:         req.setAttribute(Constants.REQ_ATTR_MENU, getModuleManager().getMainMenu());
universe@13:         req.getRequestDispatcher(HTML_FULL_DISPATCHER).forward(req, resp);
universe@10:     }
universe@34: 
universe@39:     private Optional<Method> findMapping(HttpMethod method, HttpServletRequest req) {
universe@39:         return Optional.ofNullable(mappings.get(method))
universe@39:                 .map(rm -> rm.get(Optional.ofNullable(req.getPathInfo()).orElse("/"))
universe@39:                 );
universe@11:     }
universe@34: 
universe@34:     private void forwardAsSpecified(ResponseType type, HttpServletRequest req, HttpServletResponse resp)
universe@12:             throws ServletException, IOException {
universe@12:         switch (type) {
universe@34:             case NONE:
universe@34:                 return;
universe@12:             case HTML_FULL:
universe@12:                 forwardToFullView(req, resp);
universe@12:                 return;
universe@12:             // TODO: implement remaining response types
universe@12:             default:
universe@34:                 throw new AssertionError("ResponseType switch is not exhaustive - this is a bug!");
universe@12:         }
universe@12:     }
universe@34: 
universe@38:     private void doProcess(HttpMethod method, HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
universe@27: 
universe@13:         // choose the requested language as session language (if available) or fall back to english, otherwise
universe@20:         HttpSession session = req.getSession();
universe@13:         if (session.getAttribute(Constants.SESSION_ATTR_LANGUAGE) == null) {
universe@13:             Optional<List<String>> availableLanguages = Functions.availableLanguages(getServletContext()).map(Arrays::asList);
universe@13:             Optional<Locale> reqLocale = Optional.of(req.getLocale());
universe@13:             Locale sessionLocale = reqLocale.filter((rl) -> availableLanguages.map((al) -> al.contains(rl.getLanguage())).orElse(false)).orElse(Locale.ENGLISH);
universe@13:             session.setAttribute(Constants.SESSION_ATTR_LANGUAGE, sessionLocale);
universe@34:             LOG.debug("Setting language for new session {}: {}", session.getId(), sessionLocale.getDisplayLanguage());
universe@14:         } else {
universe@15:             Locale sessionLocale = (Locale) session.getAttribute(Constants.SESSION_ATTR_LANGUAGE);
universe@15:             resp.setLocale(sessionLocale);
universe@15:             LOG.trace("Continuing session {} with language {}", session.getId(), sessionLocale);
universe@13:         }
universe@34: 
universe@21:         // set some internal request attributes
universe@13:         req.setAttribute(Constants.REQ_ATTR_PATH, Functions.fullPath(req));
universe@13:         req.setAttribute(Constants.REQ_ATTR_MODULE_CLASSNAME, this.getClass().getName());
universe@36:         Optional.ofNullable(moduleInfo).ifPresent((proxy) -> req.setAttribute(Constants.REQ_ATTR_MODULE_INFO, proxy));
universe@34: 
universe@38:         // obtain a connection and create the data access objects
universe@38:         final var db = (DatabaseFacade) req.getServletContext().getAttribute(DatabaseFacade.SC_ATTR_NAME);
universe@38:         try (final var connection = db.getDataSource().getConnection()) {
universe@38:             final var dao = createDataAccessObjects(connection);
universe@39:             try {
universe@39:                 connection.setAutoCommit(false);
universe@39:                 // call the handler, if available, or send an HTTP 404 error
universe@39:                 final var mapping = findMapping(method, req);
universe@39:                 if (mapping.isPresent()) {
universe@39:                     forwardAsSpecified(invokeMapping(mapping.get(), req, resp, dao), req, resp);
universe@39:                 } else {
universe@39:                     resp.sendError(HttpServletResponse.SC_NOT_FOUND);
universe@39:                 }
universe@39:                 connection.commit();
universe@39:             } catch (SQLException ex) {
universe@39:                 LOG.warn("Database transaction failed (Code {}): {}", ex.getErrorCode(), ex.getMessage());
universe@39:                 LOG.debug("Details: ", ex);
universe@39:                 resp.sendError(HttpServletResponse.SC_INTERNAL_SERVER_ERROR, "Unhandled Transaction Error - Code:" + ex.getErrorCode());
universe@39:                 connection.rollback();
universe@38:             }
universe@38:         } catch (SQLException ex) {
universe@39:             LOG.error("Severe Database Exception (Code {}): {}", ex.getErrorCode(), ex.getMessage());
universe@38:             LOG.debug("Details: ", ex);
universe@38:             resp.sendError(HttpServletResponse.SC_INTERNAL_SERVER_ERROR, "Database Error - Code:" + ex.getErrorCode());
universe@12:         }
universe@12:     }
universe@34: 
universe@7:     @Override
universe@7:     protected final void doGet(HttpServletRequest req, HttpServletResponse resp)
universe@7:             throws ServletException, IOException {
universe@12:         doProcess(HttpMethod.GET, req, resp);
universe@7:     }
universe@7: 
universe@7:     @Override
universe@7:     protected final void doPost(HttpServletRequest req, HttpServletResponse resp)
universe@7:             throws ServletException, IOException {
universe@12:         doProcess(HttpMethod.POST, req, resp);
universe@7:     }
universe@7: }