001/*
002 * Portions of this software was developed by employees of the National Institute
003 * of Standards and Technology (NIST), an agency of the Federal Government and is
004 * being made available as a public service. Pursuant to title 17 United States
005 * Code Section 105, works of NIST employees are not subject to copyright
006 * protection in the United States. This software may be subject to foreign
007 * copyright. Permission in the United States and in foreign countries, to the
008 * extent that NIST may hold copyright, to use, copy, modify, create derivative
009 * works, and distribute this software and its documentation without fee is hereby
010 * granted on a non-exclusive basis, provided that this notice and disclaimer
011 * of warranty appears in all copies.
012 *
013 * THE SOFTWARE IS PROVIDED 'AS IS' WITHOUT ANY WARRANTY OF ANY KIND, EITHER
014 * EXPRESSED, IMPLIED, OR STATUTORY, INCLUDING, BUT NOT LIMITED TO, ANY WARRANTY
015 * THAT THE SOFTWARE WILL CONFORM TO SPECIFICATIONS, ANY IMPLIED WARRANTIES OF
016 * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE, AND FREEDOM FROM
017 * INFRINGEMENT, AND ANY WARRANTY THAT THE DOCUMENTATION WILL CONFORM TO THE
018 * SOFTWARE, OR ANY WARRANTY THAT THE SOFTWARE WILL BE ERROR FREE.  IN NO EVENT
019 * SHALL NIST BE LIABLE FOR ANY DAMAGES, INCLUDING, BUT NOT LIMITED TO, DIRECT,
020 * INDIRECT, SPECIAL OR CONSEQUENTIAL DAMAGES, ARISING OUT OF, RESULTING FROM,
021 * OR IN ANY WAY CONNECTED WITH THIS SOFTWARE, WHETHER OR NOT BASED UPON WARRANTY,
022 * CONTRACT, TORT, OR OTHERWISE, WHETHER OR NOT INJURY WAS SUSTAINED BY PERSONS OR
023 * PROPERTY OR OTHERWISE, AND WHETHER OR NOT LOSS WAS SUSTAINED FROM, OR AROSE OUT
024 * OF THE RESULTS OF, OR USE OF, THE SOFTWARE OR SERVICES PROVIDED HEREUNDER.
025 */
026
027package gov.nist.secauto.oscal.lib.profile.resolver;
028
029import gov.nist.secauto.metaschema.model.common.util.CollectionUtil;
030
031import java.util.Collections;
032import java.util.LinkedHashMap;
033import java.util.List;
034import java.util.Map;
035import java.util.Objects;
036import java.util.function.Function;
037import java.util.stream.Collectors;
038import java.util.stream.Stream;
039
040import edu.umd.cs.findbugs.annotations.NonNull;
041import edu.umd.cs.findbugs.annotations.Nullable;
042
043public final class ModifyPhaseUtils {
044  private ModifyPhaseUtils() {
045    // disable construction
046  }
047
048  public static <T> Function<? super T, String> identityKey() {
049    return (item) -> Integer.toString(Objects.hashCode(item));
050  }
051
052  public static <T, R> Function<? super T, String> identifierKey(@NonNull Function<T, R> identifierFunction) {
053    return (item) -> {
054      R identifier = identifierFunction.apply(item);
055      String retval;
056      if (identifier == null) {
057        retval = Integer.toString(Objects.hashCode(item));
058      } else {
059        retval = identifier.toString();
060      }
061      return retval;
062    };
063  }
064
065  @SuppressWarnings("PMD.OnlyOneReturn") // readability
066  public static <T> T mergeItem(@Nullable T original, @Nullable T additional) {
067    if (additional == null) {
068      return original;
069    }
070
071    return additional;
072  }
073
074  @SuppressWarnings("PMD.OnlyOneReturn") // readability
075  public static <T> List<T> merge(@Nullable List<T> original, @Nullable List<T> additional,
076      Function<? super T, String> keyFunction) {
077    if (additional == null || additional.isEmpty()) {
078      return original;
079    }
080
081    if (original == null || original.isEmpty()) {
082      return additional;
083    }
084
085    // reverse the stream
086    List<T> reversed = Stream.concat(
087        CollectionUtil.listOrEmpty(original).stream(),
088        CollectionUtil.listOrEmpty(additional).stream())
089        .collect(Collectors.collectingAndThen(
090            Collectors.toList(),
091            l -> {
092              Collections.reverse(l);
093              return l;
094            }));
095
096    // build a map of each unique identity
097    Map<String, List<T>> identityMap = reversed.stream()
098        .collect(Collectors.groupingBy(keyFunction, LinkedHashMap::new, Collectors.toList()));
099
100    // build a reversed list of items, using the first item
101    return identityMap.values().stream()
102        .map(list -> list.stream().findFirst().get())
103        .collect(Collectors.collectingAndThen(
104            Collectors.toList(),
105            l -> {
106              Collections.reverse(l);
107              return l;
108            }));
109  }
110}