/*

  * Copyright 2006-2011 The Kuali Foundation

  *

  * Licensed under the Educational Community 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.opensource.org/licenses/ecl2.php

  *

  * 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.kuali.rice.kew.web;

 import org.apache.log4j.Logger;

 import org.kuali.rice.core.api.config.property.Config;

 import org.kuali.rice.core.api.config.property.ConfigContext;

 import org.kuali.rice.core.api.reflect.ObjectDefinition;

 import org.kuali.rice.core.api.resourceloader.GlobalResourceLoader;

 import org.kuali.rice.core.api.util.ClassLoaderUtils;

 import javax.servlet.Filter;

 import javax.servlet.FilterChain;

 import javax.servlet.FilterConfig;

 import javax.servlet.ServletContext;

 import javax.servlet.ServletException;

 import javax.servlet.ServletRequest;

 import javax.servlet.ServletResponse;

 import javax.servlet.http.HttpServletRequest;

 import java.io.IOException;

 import java.util.Collections;

 import java.util.Enumeration;

 import java.util.HashMap;

 import java.util.Iterator;

 import java.util.LinkedList;

 import java.util.List;

 import java.util.Map;

 import java.util.SortedSet;

 import java.util.TreeSet;

 /**

  * A filter which at runtime reads a series of filter configurations, constructs

  * and initializes those filters, and invokes them when it is invoked. This

  * allows runtime user configuration of arbitrary filters in the webapp context.

  *

  * @author Kuali Rice Team (rice.collab@kuali.org)

  */

 public class BootstrapFilter implements Filter {

         private static final Logger LOG = Logger.getLogger(BootstrapFilter.class);

         private static final String FILTER_PREFIX = "filter.";

         private static final String CLASS_SUFFIX = ".class";

         private static final String FILTER_MAPPING_PREFIX = "filtermapping.";

         private FilterConfig config;

         private final Map<String, Filter> filters = new HashMap<String, Filter>();

         private final SortedSet<FilterMapping> filterMappings = new TreeSet<FilterMapping>();

         private boolean initted = false;

         public void init(FilterConfig cfg) throws ServletException {

                 this.config = cfg;

         }

         private void addFilter(String name, String classname, Map<String, String> props) throws ServletException {

                 LOG.debug("Adding filter: " + name + "=" + classname);

                 Object filterObject = GlobalResourceLoader.getResourceLoader().getObject(new ObjectDefinition(classname));

                 if (filterObject == null) {

                         throw new ServletException("Filter '" + name + "' class not found: " + classname);

                 }

                 if (!(filterObject instanceof Filter)) {

                         LOG.error("Class '" + filterObject.getClass() + "' does not implement servlet javax.servlet.Filter");

                         return;

                 }

                 Filter filter = (Filter) filterObject;

                 BootstrapFilterConfig fc = new BootstrapFilterConfig(config.getServletContext(), name);

                 for (Map.Entry<String, String> entry : props.entrySet()) {

                         String key = entry.getKey().toString();

                         final String prefix = FILTER_PREFIX + name + ".";

                         if (!key.startsWith(prefix) || key.equals(FILTER_PREFIX + name + CLASS_SUFFIX)) {

                                 continue;

                         }

                         String paramName = key.substring(prefix.length());

                         fc.addInitParameter(paramName, entry.getValue());

                 }

                 try {

                         filter.init(fc);

                         filters.put(name, filter);

                 } catch (ServletException se) {

                         LOG.error("Error initializing filter: " + name + " [" + classname + "]", se);

                 }

         }

         private void addFilterMapping(String filterName, String orderNumber, String value) {

                 filterMappings.add(new FilterMapping(filterName, orderNumber, value));

         }

         private synchronized void init() throws ServletException {

                 if (initted) {

                         return;

                 }

                 LOG.debug("initializing...");

                 Config cfg = ConfigContext.getCurrentContextConfig();

                 @SuppressWarnings({ "unchecked", "rawtypes" })

                 final Map<String, String> p = new HashMap<String, String>((Map) cfg.getProperties());

                 for (Map.Entry<String, String> entry : p.entrySet()) {

                         String key = entry.getKey().toString();

                         if (key.startsWith(FILTER_MAPPING_PREFIX)) {

                                 String[] values = key.split("\\.");

                                 if (values.length != 2 && values.length != 3) {

                                         throw new ServletException("Invalid filter mapping defined.  Should contain 2 or 3 pieces in the form of filtermapping.<<filter name>>.<<order number>> with the last piece optional.");

                                 }

                                 String filterName = values[1];

                                 String orderNumber = (values.length == 2 ? "0" : values[2]);

                                 String value = entry.getValue();

                                 addFilterMapping(filterName, orderNumber, value);

                         } else if (key.startsWith(FILTER_PREFIX) && key.endsWith(CLASS_SUFFIX)) {

                                 String name = key.substring(FILTER_PREFIX.length(), key.length() - CLASS_SUFFIX.length());

                                 String value = entry.getValue();

                                 // ClassLoader cl =

                                 // SpringServiceLocator.getPluginRegistry().getInstitutionPlugin().getClassLoader();

                                 // addFilter(name, value, cl, p);

                                 addFilter(name, value, p);

                         }

                 }

                 // do a diff log a warn if any filter has no mappings

                 for (String filterName : filters.keySet()) {

                         if (!hasFilterMapping(filterName)) {

                                 LOG.warn("NO FILTER MAPPING DETECTED.  Filter " + filterName + " has no mapping and will not be called.");

                         }

                 }

                 initted = true;

         }

         private boolean hasFilterMapping(String filterName) {

                 for (FilterMapping filterMapping : filterMappings) {

                         if (filterMapping.getFilterName().equals(filterName)) {

                                 return true;

                         }

                 }

                 return false;

         }

         public void doFilter(ServletRequest request, ServletResponse response, FilterChain chain) throws IOException, ServletException {

             LOG.debug("Begin BootstrapFilter...");

                 init();

                 // build the filter chain and execute it

                 if (!filterMappings.isEmpty() && request instanceof HttpServletRequest) {

                         chain = buildChain((HttpServletRequest) request, chain);

                 }

                 LOG.debug("...ending BootstrapFilter preperation, executing BootstrapFilter Chain.");

                 chain.doFilter(request, response);

         }

         private FilterChain buildChain(HttpServletRequest request, FilterChain targetChain) {

                 BootstrapFilterChain chain = new BootstrapFilterChain(targetChain, ClassLoaderUtils.getDefaultClassLoader());

                 String requestPath = request.getServletPath();

                 for (FilterMapping mapping : filterMappings) {

                         Filter filter = filters.get(mapping.getFilterName());

                         if (!chain.containsFilter(filter) && matchFiltersURL(mapping.getUrlPattern(), requestPath)) {

                                 chain.addFilter(filter);

                         }

                 }

                 return chain;

         }

         public void destroy() {

                 for (Filter filter : filters.values()) {

                         try {

                                 filter.destroy();

                         } catch (Exception e) {

                                 LOG.error("Error destroying filter: " + filter, e);

                         }

                 }

         }

         /**

          * This method was borrowed from the Tomcat codebase.

          */

         private boolean matchFiltersURL(String urlPattern, String requestPath) {

                 if (requestPath == null) {

                         return (false);

                 }

                 // Match on context relative request path

                 if (urlPattern == null) {

                         return (false);

                 }

                 // Case 1 - Exact Match

                 if (urlPattern.equals(requestPath)) {

                         return (true);

                 }

                 // Case 2 - Path Match ("/.../*")

                 if (urlPattern.equals("/*") || urlPattern.equals("*")) {

                         return (true);

                 }

                 if (urlPattern.endsWith("/*")) {

                         if (urlPattern.regionMatches(0, requestPath, 0, urlPattern.length() - 2)) {

                                 if (requestPath.length() == (urlPattern.length() - 2)) {

                                         return (true);

                                 } else if ('/' == requestPath.charAt(urlPattern.length() - 2)) {

                                         return (true);

                                 }

                         }

                         return (false);

                 }

                 // Case 3 - Extension Match

                 if (urlPattern.startsWith("*.")) {

                         int slash = requestPath.lastIndexOf('/');

                         int period = requestPath.lastIndexOf('.');

                         if ((slash >= 0) && (period > slash) && (period != requestPath.length() - 1) && ((requestPath.length() - period) == (urlPattern.length() - 1))) {

                                 return (urlPattern.regionMatches(2, requestPath, period + 1, urlPattern.length() - 2));

                         }

                 }

                 // Case 4 - "Default" Match

                 return (false); // NOTE - Not relevant for selecting filters

         }

 }

 /**

  * A filter chain that invokes a series of filters with which it was

  * initialized, and then delegates to a target filterchain.

  *

  * @author Kuali Rice Team (rice.collab@kuali.org)

  */

 class BootstrapFilterChain implements FilterChain {

         private final List<Filter> filters = new LinkedList<Filter>();

         private final FilterChain target;

         private Iterator<Filter> filterIterator;

         private ClassLoader originalClassLoader;

         public BootstrapFilterChain(FilterChain target, ClassLoader originalClassLoader) {

                 this.target = target;

                 this.originalClassLoader = originalClassLoader;

         }

         public void doFilter(ServletRequest request, ServletResponse response) throws IOException, ServletException {

                 if (filterIterator == null) {

                         filterIterator = filters.iterator();

                 }

                 if (filterIterator.hasNext()) {

                         (filterIterator.next()).doFilter(request, response, this);

                 } else {

                         // reset the CCL to the original classloader before calling the non

                         // workflow configured filter - this makes it so our

                         // CCL is the webapp classloader in workflow action classes and the

                         // code they call

                         Thread.currentThread().setContextClassLoader(originalClassLoader);

                         target.doFilter(request, response);

                 }

         }

         public void addFilter(Filter filter) {

                 filters.add(filter);

         }

         public boolean containsFilter(Filter filter) {

                 return filters.contains(filter);

         }

         public boolean isEmpty() {

                 return filters.isEmpty();

         }

 }

 /**

  * Borrowed from spring-mock.

  *

  * @author Kuali Rice Team (rice.collab@kuali.org)

  */

 class BootstrapFilterConfig implements FilterConfig {

         private final ServletContext servletContext;

         private final String filterName;

         private final Map<String, String> initParameters = new HashMap<String, String>();

         public BootstrapFilterConfig() {

                 this(null, "");

         }

         public BootstrapFilterConfig(String filterName) {

                 this(null, filterName);

         }

         public BootstrapFilterConfig(ServletContext servletContext) {

                 this(servletContext, "");

         }

         public BootstrapFilterConfig(ServletContext servletContext, String filterName) {

                 this.servletContext = servletContext;

                 this.filterName = filterName;

         }

         public String getFilterName() {

                 return filterName;

         }

         public ServletContext getServletContext() {

                 return servletContext;

         }

         public void addInitParameter(String name, String value) {

                 this.initParameters.put(name, value);

         }

         public String getInitParameter(String name) {

                 return this.initParameters.get(name);

         }

         public Enumeration<String> getInitParameterNames() {

                 return Collections.enumeration(this.initParameters.keySet());

         }

 }

 class FilterMapping implements Comparable<FilterMapping> {

         private String filterName;

         private String orderValue;

         private String urlPattern;

         public FilterMapping(String filterName, String orderValue, String urlPattern) {

                 this.filterName = filterName;

                 this.orderValue = orderValue;

                 this.urlPattern = urlPattern;

         }

         public int compareTo(FilterMapping object) {

                 return orderValue.compareTo(object.orderValue);

         }

         public String getFilterName() {

                 return filterName;

         }

         public String getOrderValue() {

                 return orderValue;

         }

         public String getUrlPattern() {

                 return urlPattern;

         }

 }