BaseURLContextMenuStrategy-template.java

/*
 * gvNIX is an open source tool for rapid application development (RAD).
 * Copyright (C) 2010 Generalitat Valenciana
 *
 * This program is free software: you can redistribute it and/or modify it under
 * the terms of the GNU General Public License as published by the Free Software
 * Foundation, either version 3 of the License, or (at your option) any later
 * version.
 *
 * This program is distributed in the hope that it will be useful, but WITHOUT
 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS
 * FOR A PARTICULAR PURPOSE. See the GNU General Public License for more
 * details.
 *
 * You should have received a copy of the GNU General Public License along with
 * this program. If not, see <http://www.gnu.org/licenses/>.
 */
package __TOP_LEVEL_PACKAGE__.web.menu;

import java.util.Enumeration;
import java.util.HashMap;
import java.util.Iterator;
import java.util.Map;
import java.util.Set;
import java.util.Stack;
import java.util.TreeSet;
import java.util.regex.Pattern;

import javax.servlet.ServletContext;
import javax.servlet.http.HttpServletRequest;

/**
 * Base class for gvNIX Context menu Strategy based on URL matching.
 * <p>
 * This Abstract class provides the way to locate the menu item by comparing
 * current request URL with menu items.
 * <p>
 * This takes care if current URL if from internal forwarding. This method could be
 * used by layouts libraries (like apache Tiles).
 * <p>
 * If a item has a URL based in an <i>EL</i> Expression this will be evaluated
 * before compare it.
 *
 * @author <a href="http://www.disid.com">DISID Corporation S.L.</a> made for
 *         <a href="http://www.dgti.gva.es">General Directorate for Information Technologies (DGTI)</a>
 */
public abstract class BaseURLContextMenuStrategy implements ContextMenuStrategy {

  private static final Pattern EL_PATTERN = Pattern.compile(".*[$][{].*[}]");

  /**
   * Get current {@link MenuItem} based on the <code>request</code> URL
   *
   * @param request
   * @param jspContext
   * @param menu
   * @return current {@link MenuItem} or <code>null</code> if not match found.
   */
  protected MenuItem getItemFromCurrentURL(HttpServletRequest request,
                                           ServletContext jspContext, Menu menu) {

    // If request comes from a internal server forward we'll need original
    // request URI
    // See Servlert 2.4 specification, section SRV.8.4.2 for more
    // information
    String path = (String) request
        .getAttribute("javax.servlet.forward.request_uri");

    String contextPath;
    if (path == null) {
      // If isn't a forwarded request so we'll use the original URI
      path = request.getRequestURI();
      contextPath = request.getContextPath();
    }
    else {
      contextPath = (String) request
          .getAttribute("javax.servlet.forward.context_path");
    }

    if (path.startsWith(contextPath)) {
      path = path.substring(contextPath.length());
    }

    Enumeration<String> paramNamesEnum = request.getParameterNames();
    TreeSet<String> paramNames = new TreeSet<String>();

    // We create a new Map because request.getParameterMap() is a map of
    // String[].
    // In java 1.5 application will throw a ClassCastException if you try
    // set
    // ParameterMap's value into a String variable.
    // In java 1.6 works fine.
    Map<String, String> paramValues = new HashMap<String, String>(request
        .getParameterMap().size());
    String paramName;

    while (paramNamesEnum.hasMoreElements()) {
      paramName = paramNamesEnum.nextElement();
      paramNames.add(paramName);
      paramValues.put(paramName, request.getParameter(paramName));
    }

    class StackItem {

      Iterator<MenuItem> iterator;

      public StackItem(Iterator<MenuItem> childIterator) {
        this.iterator = childIterator;
      }
    }

    Stack<StackItem> stack = new Stack<StackItem>();

    stack.push(new StackItem(menu.getChildren().iterator()));
    StackItem curStackItem;
    MenuItem curItem;
    while (!stack.isEmpty()) {
      curStackItem = stack.pop();
      while (curStackItem.iterator.hasNext()) {
        curItem = curStackItem.iterator.next();
        if (isSameDestination(request, jspContext, path, paramNames,
            paramValues, curItem.getUrl())) {
          return curItem;
        }
        if (curItem.hasChildren()) {
          stack.push(curStackItem);
          stack.push(new StackItem(curItem.getChildren().iterator()));
          break;
        }
      }
    }

    return null;

  }

  /**
   * Compares request URL with {@link MenuItem}'s destination. This will ignore
   * parameters values if {@link MenuItem}'s destination if based on <i>EL</i>
   * expression. Inherit class could override this method to change compare
   * behavior.
   *
   * @param request
   * @param jspContext
   * @param path1
   * @param paramNames
   * @param paramValues
   * @param destination2 {@link MenuItem}'s destination
   * @return <code>true</code> if match
   */
  protected boolean isSameDestination(HttpServletRequest request,
                                      ServletContext jspContext, String path1,
                                      Set<String> paramNames,
                                      Map<String, String> paramValues,
                                      String destination2) {

    if (destination2 == null || destination2.isEmpty()) {
      return false;
    }

    int questionCharIndes2 = destination2.indexOf('?');

    // Url's files have the same size.
    String path2;
    String query2;
    if (questionCharIndes2 < 0) {
      path2 = destination2;
      query2 = null;
    }
    else {
      path2 = destination2.substring(0, questionCharIndes2);
      query2 = destination2.substring(questionCharIndes2 + 1);
    }

    if (path1.length() != path2.length()) {
      return false;
    }

    if (!path1.equalsIgnoreCase(path2)) {
      // Url's files are different
      return false;
    }

    // Compare parameters without values
    if (paramNames.isEmpty() && query2 != null) {
      return false;
    }
    else if (query2 == null && !paramNames.isEmpty()) {
      return false;
    }

    String[] paramTokens2 = new String[] {};
    if (query2 != null) {
    	paramTokens2 = query2.split("[&]");
    }

    Set<String> paramNames2 = new TreeSet<String>();
    Map<String, String> paramValues2 = new HashMap<String, String>();

    String paramName;
    String paramValue;
    int equalCharIndex;
    for (String paramToken : paramTokens2) {
      equalCharIndex = paramToken.indexOf('=');
      if (equalCharIndex < 0) {
        paramName = paramToken;
        paramValue = null;
      }
      else {
        paramName = paramToken.substring(0, equalCharIndex);
        paramValue = paramToken.substring(equalCharIndex + 1,
            paramToken.length());
      }
      // TODO case insensitive compare: check servlet specification
      paramNames2.add(paramName.toLowerCase());
      paramValues2.put(paramName, paramValue);
    }

    // check for duplicated parameters
    if (paramNames.size() != paramNames2.size()) {
      return false;
    }

    Iterator<String> iterParamNames1 = paramNames.iterator();
    Iterator<String> iterParamNames2 = paramNames2.iterator();

    String paramName2;
    String paramValue2;
    while (iterParamNames1.hasNext()) {
      paramName = iterParamNames1.next();
      paramName2 = iterParamNames2.next();
      if (!paramName.equals(paramName2)) {
        return false;
      }
      paramValue = paramValues.get(paramName);
      paramValue2 = paramValues2.get(paramName2);
      if (paramValue2 != null && EL_PATTERN.matcher(paramValue2).matches()) {
        continue;
      }
      if (!hasText(paramValue)) {
        if (hasText(paramValue2)) {
          return false;
        }
        continue;
      }
      if (!paramValue.equals(paramValue2)) {
        return false;
      }
    }
    return true;
  }

  private boolean hasText(String var) {
    if (var == null) {
      return false;
    }
    return var.trim().isEmpty();
  }
}