public static String attributesToQidoPath()

in util/src/main/java/com/google/cloud/healthcare/imaging/dicomadapter/AttributesUtil.java [103:161]
51 lines of code
12 McCabe index (conditional complexity)

  public static String attributesToQidoPath(Attributes attrs, String... includeFields)
      throws DicomServiceException {
    HashSet<Integer> nonEmptyKeys = new HashSet<>();
    HashSet<String> includeFieldSet = new HashSet<>(Arrays.asList(includeFields));
    // SpecificCharacterSet is not supported, and passing it as param or include would be wrong
    attrs.remove(Tag.SpecificCharacterSet);
    for (int tag : attrs.tags()) {
      if (attrs.containsValue(tag)) {
        nonEmptyKeys.add(tag);
      } else {
        includeFieldSet.add(TagUtils.toHexString(tag));
      }
    }

    StringBuilder qidoPath = new StringBuilder();
    if (nonEmptyKeys.contains(Tag.QueryRetrieveLevel)) {
      switch (attrs.getString(Tag.QueryRetrieveLevel)) {
        case "STUDY":
          qidoPath.append("studies?limit=" + STUDIES_SERIES_LIMIT + "&");
          break;
        case "SERIES":
          qidoPath.append("series?limit=" + STUDIES_SERIES_LIMIT + "&");
          break;
        case "IMAGE":
          qidoPath.append("instances?limit=" + INSTANCES_LIMIT + "&");
          break;
        default:
          throw new DicomServiceException(Status.ProcessingFailure,
              "Invalid QueryRetrieveLevel specified");
      }
      nonEmptyKeys.remove(Tag.QueryRetrieveLevel);
    } else {
      throw new DicomServiceException(Status.ProcessingFailure, "No QueryRetrieveLevel specified");
    }

    if (includeFieldSet.size() > 0) {
      for (String includeField : includeFieldSet) {
        qidoPath.append("includefield=" + includeField + "&");
      }
    }

    for (int keyTag : nonEmptyKeys) {
      // non-string type search keys don't seem to exist
      // multiple values are valid for UID lists, but unsupported by api. Invalid for other VRs.
      String[] values = attrs.getStrings(keyTag);
      if (values.length > 1) {
        throw new DicomServiceException(Status.ProcessingFailure,
            "Multiple values per tag not supported, tag: " + TagUtils.toHexString(keyTag));
      }

      for (String value : values) {
        String encodedValue;
        encodedValue = URLEncoder.encode(value, StandardCharsets.UTF_8);
        qidoPath.append(TagUtils.toHexString(keyTag) + "=" + encodedValue + "&");
      }
    }

    return qidoPath.toString();
  }