/*
    * Copyright (C) 2005-2015 Schlichtherle IT Services.
    * All rights reserved. Use is subject to license terms.
    */
   package net.java.truevfs.access;
   
   import java.net.URI;
   import java.net.URISyntaxException;
   import javax.annotation.concurrent.ThreadSafe;
  import net.java.truecommons.shed.Paths;
  import net.java.truecommons.shed.QuotedUriSyntaxException;
  import net.java.truecommons.shed.UriBuilder;
  import static net.java.truevfs.kernel.spec.FsNodeName.*;
  
  /**
   * Utility functions for {@link URI}s which represent file system path names.
   *
   * @author Christian Schlichtherle
   */
  @ThreadSafe
  final class TUriHelper {
      static final URI SEPARATOR_URI = URI.create(SEPARATOR);
      static final URI DOT_URI = URI.create(".");
      static final URI DOT_DOT_URI = URI.create("..");
  
      static int pathPrefixLength(final URI uri) {
          final String ssp = uri.getSchemeSpecificPart();
          final String a = uri.getAuthority();
          final int al = null == a ? 0 : 2 + a.length();
          final int pl = Paths.prefixLength(ssp, SEPARATOR_CHAR, true) - al;
          return pl >= 0 ? pl : Paths.prefixLength(uri.getPath(), SEPARATOR_CHAR, false);
      }
  
      static URI check(final URI uri) throws URISyntaxException {
          if (null != uri.getFragment())
              throw new QuotedUriSyntaxException(uri, "Fragment component defined");
          return uri;
      }
  
      /**
       * Eventually recreates the given URI to work around
       * <a href="http://bugs.sun.com/bugdatabase/view_bug.do?bug_id=7198297">http://bugs.sun.com/bugdatabase/view_bug.do?bug_id=7198297</a>:
       * <pre>
       * {@code assert null == new URI("x/").resolve("..").getSchemeSpecificPart();}
       * </pre>
       *
       * @param  uri the URI to fix.
       * @return A fixed URI or {@code uri} if it doesn't need fixing.
       */
      static URI fix(final URI uri) {
          final String ssp = uri.getSchemeSpecificPart();
          final String a = uri.getAuthority();
          // Workaround for http://bugs.sun.com/bugdatabase/view_bug.do?bug_id=7198297 :
          // assert null == new URI("foo/").resolve(new URI("..")).getRawSchemeSpecificPart();
          if (null == ssp
                  || null == a && ssp.startsWith(SEPARATOR + SEPARATOR)) // empty authority
              return new UriBuilder(uri).toUri();
          return uri;
      }
  
      /**
       * Returns whether or not the given {@code uri} has an absolute path.
       * A URI has an absolute path if it doesn't need to be combined with
       * other path information in order to locate a file.
       *
       * @param  uri the URI to test.
       * @return Whether or not the given URI has an absolute path.
       */
      static boolean hasAbsolutePath(URI uri) {
          return !uri.isOpaque() && Paths.isAbsolute(
                  uri.getSchemeSpecificPart(), SEPARATOR_CHAR);
      }
  
      private TUriHelper() { }
  }