/*
    * 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.metaschema.core.metapath.item.node;
  
  import gov.nist.secauto.metaschema.core.metapath.format.IPathFormatter;
  import gov.nist.secauto.metaschema.core.metapath.format.IPathSegment;
  import gov.nist.secauto.metaschema.core.metapath.item.IItem;
  import gov.nist.secauto.metaschema.core.util.ObjectUtils;
  
  import java.net.URI;
  import java.util.Collection;
  import java.util.List;
  import java.util.stream.Stream;
  
  import edu.umd.cs.findbugs.annotations.NonNull;
  import edu.umd.cs.findbugs.annotations.Nullable;
  
  /**
   * Represents a queryable Metapath model node.
   */
  public interface INodeItem extends IItem, IPathSegment, INodeItemVisitable {
  
    /**
     * Generate a path for this node in the directed node graph, using the provided
     * path formatter.
     */
    @Override
    String format(IPathFormatter formatter);
  
    /**
     * Gets the value of the provided node item.
     * <p>
     * If the provided node item is a document, this method get the first child node
     * item's value, since a document doesn't have a value.
     *
     * @param <CLASS>
     *          the type of the bound object to return
     * @param item
     *          the node item to get the value of
     * @return a bound object
     * @throws NullPointerException
     *           if the node item has no associated value
     */
    @SuppressWarnings("unchecked")
    @NonNull
    static <CLASS> CLASS toValue(@NonNull INodeItem item) {
      INodeItem valuedItem;
      if (item instanceof IDocumentNodeItem) {
        // get first child item, since the document has no value
        valuedItem = item.modelItems().findFirst().get();
      } else {
        valuedItem = item;
      }
      return ObjectUtils.requireNonNull((CLASS) valuedItem.getValue());
    }
  
    /**
     * Retrieve the parent node item if it exists.
     *
     * @return the parent node item, or {@code null} if this node item has no known
     *         parent
     */
    INodeItem getParentNodeItem();
  
    /**
     * Retrieve the parent content node item if it exists. A content node is a
     * non-document node.
     *
     * @return the parent content node item, or {@code null} if this node item has
     *         no known parent content node item
     */
    IModelNodeItem<?, ?> getParentContentNodeItem();
  
    /**
     * Get the type of node item this is.
    *
    * @return the node item's type
    */
   @NonNull
   NodeItemType getNodeItemType();
 
   /**
    * Retrieve the base URI of this node.
    * <p>
    * The base URI of a node will be in order of preference:
    * <ol>
    * <li>the base URI defined on the node</li>
    * <li>the base URI defined on the nearest ancestor node</li>
    * <li>the base URI defined on the document node</li>
    * <li>{@code null} if the document node is unknown</li>
    * </ol>
    *
    * @return the base URI or {@code null} if it is unknown
    */
   URI getBaseUri();
 
   /**
    * Get the path for this node item as a Metapath.
    *
    * @return the Metapath
    */
   @NonNull
   default String getMetapath() {
     return toPath(IPathFormatter.METAPATH_PATH_FORMATER);
   }
 
   @Override
   default Stream<? extends INodeItem> getPathStream() {
     INodeItem parent = getParentNodeItem();
     return ObjectUtils.notNull(
         parent == null ? Stream.of(this) : Stream.concat(getParentNodeItem().getPathStream(), Stream.of(this)));
   }
 
   /**
    * Get a stream of all ancestors of this node item. The stream is ordered from
    * closest to farthest ancestor.
    *
    * @return a stream of ancestor node items
    */
   @NonNull
   default Stream<? extends INodeItem> ancestor() {
     return ancestorsOf(this);
   }
 
   /**
    * Get a stream of this and all ancestors of this node item. The stream is
    * ordered from self, then closest to farthest ancestor.
    *
    * @return a stream of this node followed by all ancestor node items
    */
   @NonNull
   default Stream<? extends INodeItem> ancestorOrSelf() {
     return ObjectUtils.notNull(Stream.concat(Stream.of(this), ancestor()));
   }
 
   /**
    * Get a stream of the ancestors of the provided {@code item}. The stream is
    * ordered from the closest to farthest ancestor.
    *
    * @param item
    *          the target item to get ancestors for
    *
    * @return a stream of all ancestor node items
    */
   @NonNull
   static Stream<? extends INodeItem> ancestorsOf(@NonNull INodeItem item) {
     INodeItem parent = item.getParentNodeItem();
     return ObjectUtils.notNull(parent == null ? Stream.empty() : Stream.concat(Stream.of(parent), ancestorsOf(parent)));
   }
 
   /**
    * Get a stream of all descendant model items of this node item. The stream is
    * ordered from closest to farthest descendants in a depth-first order.
    *
    * @return a stream of descendant node items
    */
   @NonNull
   default Stream<? extends INodeItem> descendant() {
     return decendantsOf(this);
   }
 
   /**
    * Get a stream of all descendant model items of the provided {@code item}. The
    * stream is ordered from closest to farthest descendants in a depth-first
    * order.
    *
    * @param item
    *          the target item to get descendants for
    *
    * @return a stream of descendant node items
    */
   @NonNull
   static Stream<? extends INodeItem> decendantsOf(@NonNull INodeItem item) {
     Stream<? extends INodeItem> children = item.modelItems();
 
     return ObjectUtils.notNull(children.flatMap(child -> {
       assert child != null;
       return Stream.concat(Stream.of(child), decendantsOf(child));
     }));
   }
 
   /**
    * Get a stream of this node, followed by all descendant model items of this
    * node item. The stream is ordered from closest to farthest descendants in a
    * depth-first order.
    *
    * @return a stream of this node and descendant node items
    */
   @NonNull
   default Stream<? extends INodeItem> descendantOrSelf() {
     return ObjectUtils.notNull(Stream.concat(Stream.of(this), descendant()));
   }
 
   /**
    * Get the flags and value data associated this node. The resulting collection
    * is expected to be ordered, with the results in document order.
    * <p>
    * The resulting collection may be modified, but such modification is not thread
    * safe
    *
    * @return a collection of flags
    */
   @NonNull
   Collection<? extends IFlagNodeItem> getFlags();
 
   /**
    * Lookup a flag and value data on this node by it's effective name.
    *
    * @param name
    *          the effective name of the flag
    * @return the flag with the matching effective name or {@code null} if no match
    *         was found
    */
   @Nullable
   IFlagNodeItem getFlagByName(@NonNull String name);
 
   /**
    * Get the flags and value data associated with this node as a stream.
    *
    * @return the stream of flags or an empty stream if none exist
    */
   @SuppressWarnings("null")
   @NonNull
   default Stream<? extends IFlagNodeItem> flags() {
     return getFlags().stream();
   }
 
   /**
    * Get the model items (i.e., fields, assemblies) and value data associated this
    * node. A given model instance can be multi-valued, so the value of each
    * instance will be a list. The resulting collection is expected to be ordered,
    * with the results in document order.
    * <p>
    * The resulting collection may be modified, but such modification is not thread
    * safe
    *
    * @return a collection of list(s), with each list containing the items for a
    *         given model instance
    */
   @NonNull
   Collection<? extends List<? extends IModelNodeItem<?, ?>>> getModelItems();
 
   /**
    * Get the collection of model items associated with the instance having the
    * provided {@code name}.
    * <p>
    * The resulting collection may be modified, but such modification is not thread
    * safe
    *
    * @param name
    *          the instance name to get model items for
    * @return the sequence of items associated with the named model instance, or an
    *         empty list if an instance with that name is not present
    */
   @NonNull
   List<? extends IModelNodeItem<?, ?>> getModelItemsByName(@NonNull String name);
 
   /**
    * Get the model items (i.e., fields, assemblies) and value data associated this
    * node as a stream.
    *
    * @return the stream of model items or an empty stream if none exist
    */
   @SuppressWarnings("null")
   @NonNull
   default Stream<? extends IModelNodeItem<?, ?>> modelItems() {
     return getModelItems().stream().flatMap(list -> list.stream());
   }
 }