private CodeOwnerSet parsePerFileLine()

in java/com/google/gerrit/plugins/codeowners/backend/findowners/FindOwnersCodeOwnerConfigParser.java [242:306]
55 lines of code
9 McCabe index (conditional complexity)

    private CodeOwnerSet parsePerFileLine(String line) {
      Matcher perFileMatcher = PAT_PER_FILE.matcher(line);
      if (!perFileMatcher.matches() || !isGlobs(perFileMatcher.group(1).trim())) {
        return null;
      }

      String matchedGroup2 = perFileMatcher.group(2).trim();
      if (!PAT_PER_FILE_OWNERS.matcher(matchedGroup2).matches()) {
        if (PAT_PER_FILE_INCLUDE.matcher(matchedGroup2).matches()) {
          error(
              ValidationError.create(
                  String.format(
                      "keyword 'include' is not supported for per file imports: %s", line)));

          // return an empty code owner set to avoid that the line will be reported as invalid once
          // more
          return CodeOwnerSet.builder().build();
        }
        return null;
      }

      String[] globsAndOwners =
          new String[] {
            removeExtraSpaces(perFileMatcher.group(1)), removeExtraSpaces(perFileMatcher.group(2))
          };
      ImmutableSet<String> dirGlobs = splitGlobs(globsAndOwners[0]);
      String directive = globsAndOwners[1];
      if (directive.equals(TOK_SET_NOPARENT)) {
        return CodeOwnerSet.builder()
            .setIgnoreGlobalAndParentCodeOwners()
            .setPathExpressions(dirGlobs)
            .build();
      }

      CodeOwnerConfigReference codeOwnerConfigReference;
      if ((codeOwnerConfigReference = parseInclude(directive)) != null) {
        return CodeOwnerSet.builder()
            .addImport(codeOwnerConfigReference)
            .setPathExpressions(dirGlobs)
            .build();
      }

      List<String> ownerEmails = Arrays.asList(directive.split(COMMA, -1));

      // Get the comment part of the line (the first '#' and everything that follows).
      String comment = perFileMatcher.group(3);
      Set<CodeOwnerAnnotation> annotations = new HashSet<>();
      if (comment != null) {
        Matcher annotationMatcher = PAT_ANNOTATION.matcher(comment);
        while (annotationMatcher.find()) {
          String annotation = annotationMatcher.group(1);
          annotations.add(CodeOwnerAnnotation.create(annotation));
        }
      }

      CodeOwnerSet.Builder codeOwnerSet =
          CodeOwnerSet.builder()
              .setPathExpressions(dirGlobs)
              .setCodeOwners(
                  ownerEmails.stream().map(CodeOwnerReference::create).collect(toImmutableSet()));
      ownerEmails.stream()
          .forEach(
              email -> codeOwnerSet.addAnnotations(CodeOwnerReference.create(email), annotations));
      return codeOwnerSet.build();
    }