/*
    * VelocityMenuDisplayer.java
    *
    * Created on December 7, 2002, 12:35 AM
    */
   package net.sf.navigator.displayer;
   
   import net.sf.navigator.menu.MenuComponent;
   import org.apache.commons.lang.StringUtils;
  import org.apache.commons.logging.Log;
  import org.apache.commons.logging.LogFactory;
  import org.apache.velocity.Template;
  import org.apache.velocity.VelocityContext;
  import org.apache.velocity.app.VelocityEngine;
  import org.apache.velocity.app.tools.VelocityFormatter;
  import org.apache.velocity.runtime.RuntimeConstants;
  import org.apache.velocity.tools.view.servlet.ServletLogger;
  import org.apache.velocity.tools.view.servlet.WebappLoader;
  
  import javax.servlet.ServletContext;
  import javax.servlet.http.HttpServletRequest;
  import javax.servlet.jsp.JspException;
  import javax.servlet.jsp.PageContext;
  import java.io.IOException;
  import java.io.StringWriter;
  import java.util.*;
  
  /**
   * @author  <a href="mailto:matt@raibledesigns.com">Matt Raible</a>
   * @version 1.0
   */
  public class VelocityMenuDisplayer extends MessageResourcesMenuDisplayer {
      protected static final Log log = LogFactory.getLog(VelocityMenuDisplayer.class);
      private static VelocityEngine velocityEngine = new VelocityEngine();
      private PageContext pageContext = null;
  
      public static void initialize(ServletContext context) {
          velocityEngine.setApplicationAttribute(ServletContext.class.getName(), context);
  
          // default to servletlogger, which logs to the servlet engines log
          velocityEngine.setProperty(RuntimeConstants.RUNTIME_LOG_LOGSYSTEM_CLASS,
                               ServletLogger.class.getName());
  
          // by default, load resources with webapp resource loader
          velocityEngine.setProperty(RuntimeConstants.RESOURCE_LOADER, "webapp");
          velocityEngine.setProperty("webapp.resource.loader.class", WebappLoader.class.getName());
  
          // now all is ready - init Velocity
          try {
              Properties props = new Properties();
              ResourceBundle defaults = ResourceBundle.getBundle("net.sf.navigator.displayer.velocity");
              for (Enumeration keys = defaults.getKeys(); keys.hasMoreElements();) {
                  String key = (String) keys.nextElement();
                  props.put(key, defaults.getString(key));
              }
  
              // look to see if the user has overridden velocity.properties by
              // placing velocity.properties in WEB-INF/classes
              ResourceBundle custom = null;
  
              try {
                  custom = ResourceBundle.getBundle("velocity");
                  for (Enumeration keys = custom.getKeys(); keys.hasMoreElements();) {
                      String key = (String) keys.nextElement();
                      props.put(key, custom.getString(key));
                  }
              } catch (MissingResourceException mre) {
                  log.debug("No velocity.properties found in classpath, using default settings");
              }
  
              velocityEngine.init(props);
          } catch (Exception e) {
              log.error("Error initializing Velocity: " + e.getMessage());
              e.printStackTrace();
          }
      }
  
      //~ Methods ================================================================
  
      public void init(PageContext pageContext, MenuDisplayerMapping mapping) {
          super.init(pageContext, mapping);
          this.pageContext = pageContext;
      }
  
      public void display(MenuComponent menu) throws JspException, IOException {
          if (isAllowed(menu)) {
              displayComponents(menu);
          }
      }
  
      protected void displayComponents(MenuComponent menu)
      throws JspException, IOException {
          HttpServletRequest request = (HttpServletRequest) pageContext.getRequest();
          Template t;
  
          try {
              String template = getConfig();
  
              if (template == null) {
                 throw new JspException("You must specify a template using the 'config' attribute.");
             } else {
                 log.debug("using template: " + template);
             }
 
             t = velocityEngine.getTemplate(template);
         } catch (Exception e) {
             String msg = "Error initializing Velocity: " + e.toString();
             log.error(msg, e);
             throw new JspException(msg, e);
         }
 
         StringWriter sw = new StringWriter();
         VelocityContext context = new VelocityContext();
 
         context.put("formatter", new VelocityFormatter(context));
         context.put("now", Calendar.getInstance().getTime());
         context.put("ctxPath", request.getContextPath());
         // add a helper class for string manipulation
         context.put("stringUtils", new StringUtils());
 
         // add a Map for use by the Expandable List Menu
         context.put("map", new HashMap());
 
         // see if a name and property were passed in
         if (!StringUtils.isEmpty(name)) {
             Object val1 = pageContext.findAttribute(name);
 
             if (val1 != null) {
                 context.put(name, val1);
             }
         }
 
         // request-scope attributes
         Enumeration e = request.getAttributeNames();
 
         while (e.hasMoreElements()) {
             String name = (String) e.nextElement();
             Object value = request.getAttribute(name);
             context.put(name, value);
         }
 
         context.put("request", request);
         context.put("session", request.getSession(false));
 
         if (pageContext.getAttribute("menuId") != null) {
             context.put("menuId", pageContext.getAttribute("menuId"));
         }
         context.put("menu", menu);
         context.put("displayer", this);
 
         try {
             t.merge(context, sw);
         } catch (Exception ex) {
             ex.printStackTrace();
             throw new JspException(ex);
         }
 
         String result = sw.getBuffer().toString();
 
         // Print this element to our output writer
         pageContext.getOut().print(result);
     }
 
     public void end(PageContext context) {
         this.pageContext = null;
     }
 }