/*
 * JBoss, Home of Professional Open Source
 *
 * Distributable under LGPL license.
 * See terms of license at gnu.org.
 */
package javax.security.jacc;

/** The representation of a URLPattern in the WebResourcePermission and
 * WebUserDataPermission URLPatternSpecs.
 *  
 * @author Scott.Stark@jboss.org
 * @version $Revison:$
 */
class URLPattern
{
   /** the '/' pattern */
   static final int DEFAULT = 0;
   /** the '/*' pattern */
   static final int THE_PATH_PREFIX = 1;
   /** a '/.../*' pattern */
   static final int PATH_PREFIX = 2;
   /** a '*.xxx' pattern */
   static final int EXTENSION = 3;
   /** an exact pattern */
   static final int EXACT = 4;

   private String pattern;
   private String ext;
   private int length;
   private int type = -1;

   URLPattern(String pattern)
   {
      this.pattern = pattern;
      length = pattern.length();
      if( pattern.equals("/") )
         type = DEFAULT;
      else if( pattern.startsWith("/*") )
         type = THE_PATH_PREFIX;
      else if( length > 0 && pattern.charAt(0) == '/' && pattern.endsWith("/*") )
         type = PATH_PREFIX;
      else if( pattern.startsWith("*.") )
      {
         type = EXTENSION;
         ext = pattern.substring(1);
      }
      else
         type = EXACT;
   }

   /** The matching rules from the WebResourcePermission implies:

   1. their pattern values are String equivalent, or
   2. this pattern is the path-prefix pattern "/*", or
   3. this pattern is a path-prefix pattern (that is, it starts with "/" and ends
      with "/*") and the argument pattern starts with the substring of this
      pattern, minus its last 2 characters, and the next character of the
      argument pattern, if there is one, is "/", or
   4. this pattern is an extension pattern (that is, it starts with "*.") and the
      argument pattern ends with this pattern, or
   5. the reference pattern is the special default pattern, "/", which matches all
      argument patterns.
   */
   boolean matches(URLPattern url)
   {
      return matches(url.pattern);
   }

   boolean matches(String urlPattern)
   {
      // 2 or 5
      if( type == DEFAULT || type == THE_PATH_PREFIX )
         return true;

      // 4, extension pattern
      if( type == EXTENSION && urlPattern.endsWith(ext) )
         return true;

      // 3. a path-prefix pattern
      if( type == PATH_PREFIX )
      {
         if( urlPattern.regionMatches(0,pattern, 0, length-2) )
         {
            int last = length - 2;
            if( urlPattern.length() > last && urlPattern.charAt(last) != '/' )
               return false;
            return true;
         }
         return false;
      }

      // 1. pattern values are String equivalent for exact pattern
      if( pattern.equals(urlPattern) )
         return true;

      return false;
   }

   String getPattern()
   {
      return pattern;
   }
   boolean isDefault()
   {
      return type == DEFAULT;
   }
   boolean isExact()
   {
      return type == EXACT;
   }
   boolean isExtension()
   {
      return type == EXTENSION;
   }
   boolean isPrefix()
   {
      return type == THE_PATH_PREFIX || type == PATH_PREFIX;
   }

   public int hashCode()
   {
      return pattern.hashCode();
   }

   boolean equals(URLPattern p)
   {
      boolean equals = type == p.type;
      if( equals )
      {
         equals = pattern.equals(p.pattern);
      }
      return equals;
   }

}