static URI relativize()

in java/com/googlesource/gerrit/plugins/supermanifest/JiriUpdater.java [228:289]
49 lines of code
15 McCabe index (conditional complexity)

  static URI relativize(URI current, URI target) {
    // We only handle bare paths for now.
    if (!target.toString().equals(target.getPath())) {
      return target;
    }
    if (!current.toString().equals(current.getPath())) {
      return target;
    }

    String cur = current.normalize().getPath();
    String dest = target.normalize().getPath();

    if (cur.startsWith(SLASH) != dest.startsWith(SLASH)) {
      return target;
    }

    while (cur.startsWith(SLASH)) {
      cur = cur.substring(1);
    }
    while (dest.startsWith(SLASH)) {
      dest = dest.substring(1);
    }

    if (cur.indexOf('/') == -1 || dest.indexOf('/') == -1) {
      // Avoid having to special-casing in the next two ifs.
      String prefix = "prefix/";
      cur = prefix + cur;
      dest = prefix + dest;
    }

    if (!cur.endsWith(SLASH)) {
      // The current file doesn't matter.
      int lastSlash = cur.lastIndexOf('/');
      cur = cur.substring(0, lastSlash);
    }
    String destFile = "";
    if (!dest.endsWith(SLASH)) {
      // We always have to provide the destination file.
      int lastSlash = dest.lastIndexOf('/');
      destFile = dest.substring(lastSlash + 1, dest.length());
      dest = dest.substring(0, dest.lastIndexOf('/'));
    }

    String[] cs = cur.split(SLASH);
    String[] ds = dest.split(SLASH);

    int common = 0;
    while (common < cs.length && common < ds.length && cs[common].equals(ds[common])) {
      common++;
    }

    StringJoiner j = new StringJoiner(SLASH);
    for (int i = common; i < cs.length; i++) {
      j.add("..");
    }
    for (int i = common; i < ds.length; i++) {
      j.add(ds[i]);
    }

    j.add(destFile);
    return URI.create(j.toString());
  }