package e4s.tutorial;

import e4s.application.E4PermissionRegistry;
import e4s.db.systabledef.*;
import e4s.html.*;
import e4s.servlet.E4ModuleImplementation;


/**
 * Show how to define, register and deal with permissions. They also can be combined.
 * 
 * {@tutorial Example_Permission}
 */
public class Example_Permission extends E4ModuleImplementation
{
   public static E4Method start = null;

   private final static E4Permission PERMISSION_VIEW_DATA = E4Permission.getInstance("TUTORIAL.VIEW.DATA");
   private final static E4Permission PERMISSION_EDIT_DATA = E4Permission.getInstance("TUTORIAL.EDIT.DATA");
   private final static E4Permission PERMISSION_DELETE_DATA = E4Permission.getInstance("TUTORIAL.DELETE.DATA");
   
   static
   {
      // first, once register the permission to make them editable in the permission dialog
      E4PermissionRegistry.addPermission(PERMISSION_DELETE_DATA,"delete something");
      E4PermissionRegistry.addPermission(PERMISSION_EDIT_DATA,"edit something");
      E4PermissionRegistry.addPermission(PERMISSION_VIEW_DATA,"view something");
   }

   public void start( HTML html )
   {
      if (canDo(PERMISSION_VIEW_DATA))
         html.print("This user may view data");
      else
         html.print("This user may NOT view data");
      
      html.BR();

      html.B().I().print("(Note: the following exception is expected here)");
      
      E4PermissionAnd permission_modify = new E4PermissionAnd(PERMISSION_EDIT_DATA,PERMISSION_DELETE_DATA);
      E4PermissionOr permission_do_anything = new E4PermissionOr(permission_modify,PERMISSION_VIEW_DATA);

      try
      {
         if (! canDo(permission_do_anything))
            throw new E4PermissionException(permission_do_anything);
      }
      catch( E4PermissionException pe)
      {
         // show the error
         html.SystemError(pe);
      }
   }
   
   
}