/*
    * Portions of this software was developed by employees of the National Institute
    * of Standards and Technology (NIST), an agency of the Federal Government and is
    * being made available as a public service. Pursuant to title 17 United States
    * Code Section 105, works of NIST employees are not subject to copyright
    * protection in the United States. This software may be subject to foreign
    * copyright. Permission in the United States and in foreign countries, to the
    * extent that NIST may hold copyright, to use, copy, modify, create derivative
    * works, and distribute this software and its documentation without fee is hereby
   * granted on a non-exclusive basis, provided that this notice and disclaimer
   * of warranty appears in all copies.
   *
   * THE SOFTWARE IS PROVIDED 'AS IS' WITHOUT ANY WARRANTY OF ANY KIND, EITHER
   * EXPRESSED, IMPLIED, OR STATUTORY, INCLUDING, BUT NOT LIMITED TO, ANY WARRANTY
   * THAT THE SOFTWARE WILL CONFORM TO SPECIFICATIONS, ANY IMPLIED WARRANTIES OF
   * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE, AND FREEDOM FROM
   * INFRINGEMENT, AND ANY WARRANTY THAT THE DOCUMENTATION WILL CONFORM TO THE
   * SOFTWARE, OR ANY WARRANTY THAT THE SOFTWARE WILL BE ERROR FREE.  IN NO EVENT
   * SHALL NIST BE LIABLE FOR ANY DAMAGES, INCLUDING, BUT NOT LIMITED TO, DIRECT,
   * INDIRECT, SPECIAL OR CONSEQUENTIAL DAMAGES, ARISING OUT OF, RESULTING FROM,
   * OR IN ANY WAY CONNECTED WITH THIS SOFTWARE, WHETHER OR NOT BASED UPON WARRANTY,
   * CONTRACT, TORT, OR OTHERWISE, WHETHER OR NOT INJURY WAS SUSTAINED BY PERSONS OR
   * PROPERTY OR OTHERWISE, AND WHETHER OR NOT LOSS WAS SUSTAINED FROM, OR AROSE OUT
   * OF THE RESULTS OF, OR USE OF, THE SOFTWARE OR SERVICES PROVIDED HEREUNDER.
   */
  
  package gov.nist.secauto.oscal.lib.profile.resolver.support;
  
  import gov.nist.secauto.metaschema.model.common.metapath.MetapathExpression;
  import gov.nist.secauto.metaschema.model.common.metapath.MetapathExpression.ResultType;
  import gov.nist.secauto.metaschema.model.common.metapath.item.INodeItem;
  import gov.nist.secauto.metaschema.model.common.metapath.item.IRequiredValueModelNodeItem;
  import gov.nist.secauto.metaschema.model.common.util.CustomCollectors;
  import gov.nist.secauto.metaschema.model.common.util.ObjectUtils;
  import gov.nist.secauto.oscal.lib.profile.resolver.support.IEntityItem.ItemType;
  
  import org.apache.logging.log4j.Level;
  import org.apache.logging.log4j.LogManager;
  import org.apache.logging.log4j.Logger;
  
  import java.util.Collection;
  import java.util.HashSet;
  import java.util.Map;
  import java.util.Set;
  import java.util.UUID;
  import java.util.function.Function;
  import java.util.function.Predicate;
  import java.util.stream.Stream;
  
  import edu.umd.cs.findbugs.annotations.NonNull;
  import edu.umd.cs.findbugs.annotations.Nullable;
  
  public interface IIndexer {
    enum SelectionStatus {
      SELECTED,
      UNSELECTED,
      UNKNOWN;
    }
  
    MetapathExpression HAS_PROP_KEEP_METAPATH = MetapathExpression
        .compile("prop[@name='keep' and has-oscal-namespace('http://csrc.nist.gov/ns/oscal')]/@value = 'always'");
  
    Predicate<IEntityItem> KEEP_ENTITY_PREDICATE = new Predicate<>() {
  
      @Override
      public boolean test(IEntityItem entity) {
        return entity.getReferenceCount() > 0
            || (Boolean) ObjectUtils
                .notNull(IIndexer.HAS_PROP_KEEP_METAPATH.evaluateAs(entity.getInstance(), ResultType.BOOLEAN));
      }
  
    };
  
    static boolean isReferencedEntity(@NonNull IEntityItem entity) {
      return KEEP_ENTITY_PREDICATE.test(entity);
    }
  
    /**
     * Keep entities that have a reference count greater than zero or are required
     * to be kept based on the "keep"="always property.
     *
     * @param entities
     *          the entity items to filter
     * @return the entities that pass the filter
     */
    static Stream<IEntityItem> getReferencedEntitiesAsStream(@NonNull Collection<IEntityItem> entities) {
      return entities.stream().filter(KEEP_ENTITY_PREDICATE);
    }
  
    /**
     * Keep entities that have a reference count of zero or are not required to be
     * kept based on the "keep"="always property.
     *
     * @param entities
     *          the entity items to filter
     * @return the entities that pass the filter
     */
    static Stream<IEntityItem> getUnreferencedEntitiesAsStream(@NonNull Collection<IEntityItem> entities) {
      return entities.stream().filter(KEEP_ENTITY_PREDICATE.negate());
   }
 
   /**
    * Generates a stream of distinct items that have a reference count greater than
    * zero or are required to be kept based on the "keep"="always property.
    * <p>
    * Distinct items are determined based on the item's key using the provided
    * {@code keyMapper}.
    *
    * @param <T>
    *          the item type
    * @param <K>
    *          the key type
    * @param resolvedItems
    *          a series of previously resolved items to add to prepend to the
    *          stream
    * @param importedEntityItems
    *          a collection of new items to filter then append to the stream
    * @param keyMapper
    *          the key mapping function to determine the item's key
    * @return the resulting series of items with duplicate items with the same key
    *         removed
    */
   // TODO: Is this the right name for this method?
   static <T, K> Stream<T> filterDistinct(
       @NonNull Stream<T> resolvedItems,
       @NonNull Collection<IEntityItem> importedEntityItems,
       @NonNull Function<? super T, ? extends K> keyMapper) {
     @SuppressWarnings("unchecked") Stream<T> importedStream = getReferencedEntitiesAsStream(importedEntityItems)
         .map(entity -> (T) entity.getInstanceValue());
 
     return CustomCollectors.distinctByKey(
         ObjectUtils.notNull(Stream.concat(resolvedItems, importedStream)),
         keyMapper,
         (key, value1, value2) -> value2);
   }
 
   static void logIndex(@NonNull IIndexer indexer, @NonNull Level logLevel) {
     Logger logger = LogManager.getLogger();
 
     Set<INodeItem> indexedItems = new HashSet<>();
     if (logger.isEnabled(logLevel)) {
       for (ItemType itemType : ItemType.values()) {
         assert itemType != null;
         for (IEntityItem item : indexer.getEntitiesByItemType(itemType)) {
           INodeItem nodeItem = item.getInstance();
           indexedItems.add(nodeItem);
           logger.atLevel(logLevel).log("{} {}: selected: {}, reference count: {}",
               itemType.name(),
               item.isIdentifierReassigned() ? item.getIdentifier() + "(" + item.getOriginalIdentifier() + ")"
                   : item.getIdentifier(),
               indexer.getSelectionStatus(nodeItem),
               item.getReferenceCount());
         }
       }
     }
 
     for (Map.Entry<INodeItem, SelectionStatus> entry : indexer.getSelectionStatusMap().entrySet()) {
       INodeItem nodeItem = entry.getKey();
       if (!indexedItems.contains(nodeItem)) {
         Object value = nodeItem.getValue();
         logger.atLevel(logLevel).log("{}: {}", value == null ? "(null)" : value.getClass().getName(), entry.getValue());
       }
     }
   }
 
   @NonNull
   IEntityItem addRole(@NonNull IRequiredValueModelNodeItem role);
 
   @NonNull
   IEntityItem addLocation(@NonNull IRequiredValueModelNodeItem location);
 
   @NonNull
   IEntityItem addParty(@NonNull IRequiredValueModelNodeItem party);
 
   @Nullable
   IEntityItem addGroup(@NonNull IRequiredValueModelNodeItem group);
 
   @NonNull
   IEntityItem addControl(@NonNull IRequiredValueModelNodeItem control);
 
   @NonNull
   IEntityItem addParameter(@NonNull IRequiredValueModelNodeItem parameter);
 
   @Nullable
   IEntityItem addPart(@NonNull IRequiredValueModelNodeItem part);
 
   @NonNull
   IEntityItem addResource(@NonNull IRequiredValueModelNodeItem resource);
 
   @NonNull
   Collection<IEntityItem> getEntitiesByItemType(@NonNull IEntityItem.ItemType itemType);
 
   @Nullable
   default IEntityItem getEntity(@NonNull IEntityItem.ItemType itemType, @NonNull UUID identifier) {
     return getEntity(itemType, ObjectUtils.notNull(identifier.toString()), false);
   }
 
   /**
    * Lookup an item of the given {@code itemType} having the given
    * {@code identifier}.
    * <p>
    * Will normalize the case of a UUID-based identifier.
    *
    * @param itemType
    *          the type of item to search for
    * @param identifier
    *          the identifier to lookup
    * @return the matching item or {@code null} if no match was found
    */
   @Nullable
   default IEntityItem getEntity(@NonNull IEntityItem.ItemType itemType, @NonNull String identifier) {
     return getEntity(itemType, identifier, itemType.isUuid());
   }
 
   /**
    * Lookup an item of the given {@code itemType} having the given
    * {@code identifier}.
    * <p>
    * Will normalize the case of a UUID-based the identifier when requested.
    *
    * @param itemType
    *          the type of item to search for
    * @param identifier
    *          the identifier to lookup
    * @param normalize
    *          {@code true} if the identifier case should be normalized or
    *          {@code false} otherwise
    * @return the matching item or {@code null} if no match was found
    */
   @Nullable
   IEntityItem getEntity(@NonNull IEntityItem.ItemType itemType, @NonNull String identifier, boolean normalize);
 
   boolean removeItem(@NonNull IEntityItem entity);
 
   boolean isSelected(@NonNull IEntityItem entity);
 
   Map<INodeItem, SelectionStatus> getSelectionStatusMap();
 
   @NonNull
   SelectionStatus getSelectionStatus(@NonNull INodeItem item);
 
   void setSelectionStatus(@NonNull INodeItem item, @NonNull SelectionStatus selectionStatus);
 
   void resetSelectionStatus();
 
   void append(@NonNull IIndexer result);
 
   /**
    * Get a copy of the entity map.
    *
    * @return the copy
    */
   @NonNull
   Map<ItemType, Map<String, IEntityItem>> getEntities();
 }