/*
    * SPDX-FileCopyrightText: none
    * SPDX-License-Identifier: CC0-1.0
    */
   
   package dev.metaschema.oscal.lib.profile.resolver.support;
   
   import java.util.Collections;
   import java.util.EnumSet;
  import java.util.Set;
  
  import dev.metaschema.core.metapath.IMetapathExpression;
  import dev.metaschema.core.metapath.item.node.IAssemblyNodeItem;
  import dev.metaschema.core.metapath.item.node.IDocumentNodeItem;
  import dev.metaschema.core.metapath.item.node.IRootAssemblyNodeItem;
  import dev.metaschema.core.util.CollectionUtil;
  import dev.metaschema.core.util.ObjectUtils;
  import dev.metaschema.oscal.lib.OscalBindingContext;
  import dev.metaschema.oscal.lib.OscalModelConstants;
  import edu.umd.cs.findbugs.annotations.NonNull;
  
  /**
   * Visits a catalog document and its children as designated.
   * <p>
   * This implementation is stateless. The {@code T} parameter can be used to
   * convey state as needed.
   *
   * @param <T>
   *          the state type
   * @param <R>
   *          the result type
   */
  public abstract class AbstractCatalogEntityVisitor<T, R>
      extends AbstractCatalogVisitor<T, R> {
    @NonNull
    public static final IMetapathExpression CHILD_PART_METAPATH
        = IMetapathExpression.compile("part|part//part",
            OscalBindingContext.OSCAL_STATIC_METAPATH_CONTEXT);
    @NonNull
    private static final IMetapathExpression BACK_MATTER_RESOURCES_METAPATH
        = IMetapathExpression.compile("back-matter/resource",
            OscalBindingContext.OSCAL_STATIC_METAPATH_CONTEXT);
    @NonNull
    private static final Set<IEntityItem.ItemType> GROUP_CONTAINER_TYPES
        = ObjectUtils.notNull(EnumSet.of(
            IEntityItem.ItemType.GROUP,
            IEntityItem.ItemType.CONTROL,
            IEntityItem.ItemType.PARAMETER,
            IEntityItem.ItemType.PART));
    @NonNull
    private static final Set<IEntityItem.ItemType> CONTROL_CONTAINER_TYPES
        = ObjectUtils.notNull(EnumSet.of(
            IEntityItem.ItemType.CONTROL,
            IEntityItem.ItemType.PARAMETER,
            IEntityItem.ItemType.PART));
    @NonNull
    private final Set<IEntityItem.ItemType> itemTypesToVisit;
  
    /**
     * Create a new visitor that will visit the item types identified by
     * {@code itemTypesToVisit}.
     *
     * @param itemTypesToVisit
     *          the item type the visitor will visit
     */
    public AbstractCatalogEntityVisitor(@NonNull Set<IEntityItem.ItemType> itemTypesToVisit) {
      this.itemTypesToVisit = CollectionUtil.unmodifiableSet(itemTypesToVisit);
    }
  
    public Set<IEntityItem.ItemType> getItemTypesToVisit() {
      return CollectionUtil.unmodifiableSet(itemTypesToVisit);
    }
  
    protected boolean isVisitedItemType(@NonNull IEntityItem.ItemType type) {
      return itemTypesToVisit.contains(type);
    }
  
    @Override
    public R visitCatalog(IDocumentNodeItem catalogDocument, T state) {
      R result = super.visitCatalog(catalogDocument, state);
  
      catalogDocument.modelItems().forEachOrdered(item -> {
        IRootAssemblyNodeItem root = ObjectUtils.requireNonNull((IRootAssemblyNodeItem) item);
        visitMetadata(root, state);
        visitBackMatter(root, state);
      });
      return result;
    }
  
    @Override
    protected R visitGroupContainer(IAssemblyNodeItem catalogOrGroup, R initialResult, T state) {
      R retval;
      if (Collections.disjoint(getItemTypesToVisit(), GROUP_CONTAINER_TYPES)) {
        retval = initialResult;
      } else {
        retval = super.visitGroupContainer(catalogOrGroup, initialResult, state);
      }
      return retval;
    }
 
   @Override
   protected R visitControlContainer(IAssemblyNodeItem catalogOrGroupOrControl, R initialResult, T state) {
     R retval;
     if (Collections.disjoint(getItemTypesToVisit(), CONTROL_CONTAINER_TYPES)) {
       retval = initialResult;
     } else {
       // first descend to all control container children
       retval = super.visitControlContainer(catalogOrGroupOrControl, initialResult, state);
 
       // handle parameters
       if (isVisitedItemType(IEntityItem.ItemType.PARAMETER)) {
         retval = catalogOrGroupOrControl.getModelItemsByName(OscalModelConstants.QNAME_PARAM).stream()
             .map(paramItem -> visitParameter(
                 ObjectUtils.requireNonNull((IAssemblyNodeItem) paramItem),
                 catalogOrGroupOrControl,
                 state))
             .reduce(retval, (first, second) -> aggregateResults(first, second, state));
       }
     }
     return retval;
   }
 
   protected void visitParts(@NonNull IAssemblyNodeItem groupOrControlItem, T state) {
     // handle parts
     if (isVisitedItemType(IEntityItem.ItemType.PART)) {
       CHILD_PART_METAPATH.evaluate(groupOrControlItem).stream()
           .map(item -> (IAssemblyNodeItem) item)
           .forEachOrdered(partItem -> {
             visitPart(ObjectUtils.requireNonNull(partItem), groupOrControlItem, state);
           });
     }
   }
 
   @Override
   protected R visitGroupInternal(@NonNull IAssemblyNodeItem item, R childResult, T state) {
     if (isVisitedItemType(IEntityItem.ItemType.PART)) {
       visitParts(item, state);
     }
 
     R retval = childResult;
     if (isVisitedItemType(IEntityItem.ItemType.GROUP)) {
       retval = visitGroup(item, retval, state);
     }
     return retval;
   }
 
   @Override
   protected R visitControlInternal(IAssemblyNodeItem item, R childResult, T state) {
     if (isVisitedItemType(IEntityItem.ItemType.PART)) {
       visitParts(item, state);
     }
 
     R retval = childResult;
     if (isVisitedItemType(IEntityItem.ItemType.CONTROL)) {
       retval = visitControl(item, retval, state);
     }
     return retval;
   }
 
   /**
    * Called when visiting a parameter.
    * <p>
    * Can be overridden by classes extending this interface to support processing
    * of the visited object.
    *
    * @param item
    *          the Metapath item for the parameter
    * @param catalogOrGroupOrControl
    *          the parameter's parent Metapath item
    * @param state
    *          the calling context information
    * @return a meaningful result of the given type
    */
   protected R visitParameter(
       @NonNull IAssemblyNodeItem item,
       @NonNull IAssemblyNodeItem catalogOrGroupOrControl,
       T state) {
     // do nothing
     return newDefaultResult(state);
   }
 
   /**
    * Called when visiting a part.
    * <p>
    * Can be overridden by classes extending this interface to support processing
    * of the visited object.
    *
    * @param item
    *          the Metapath item for the part
    * @param groupOrControl
    *          the part's parent Metapath item
    * @param state
    *          the calling context information
    */
   protected void visitPart( // NOPMD noop default
       @NonNull IAssemblyNodeItem item,
       @NonNull IAssemblyNodeItem groupOrControl,
       T state) {
     // do nothing
   }
 
   /**
    * Called when visiting the "metadata" section of an OSCAL document.
    * <p>
    * Visits each contained role, location, and party.
    *
    * @param rootItem
    *          the root Module node item containing the "metadata" node
    * @param state
    *          the calling context information
    */
   protected void visitMetadata(@NonNull IRootAssemblyNodeItem rootItem, T state) {
     rootItem.getModelItemsByName(OscalModelConstants.QNAME_METADATA).stream()
         .map(metadataItem -> (IAssemblyNodeItem) metadataItem)
         .forEach(metadataItem -> {
           if (isVisitedItemType(IEntityItem.ItemType.ROLE)) {
             metadataItem.getModelItemsByName(OscalModelConstants.QNAME_ROLE).stream()
                 .map(roleItem -> (IAssemblyNodeItem) roleItem)
                 .forEachOrdered(roleItem -> {
                   visitRole(ObjectUtils.requireNonNull(roleItem), metadataItem, state);
                 });
           }
 
           if (isVisitedItemType(IEntityItem.ItemType.LOCATION)) {
             metadataItem.getModelItemsByName(OscalModelConstants.QNAME_LOCATION).stream()
                 .map(locationItem -> (IAssemblyNodeItem) locationItem)
                 .forEachOrdered(locationItem -> {
                   visitLocation(ObjectUtils.requireNonNull(locationItem), metadataItem, state);
                 });
           }
 
           if (isVisitedItemType(IEntityItem.ItemType.PARTY)) {
             metadataItem.getModelItemsByName(OscalModelConstants.QNAME_PARTY).stream()
                 .map(partyItem -> (IAssemblyNodeItem) partyItem)
                 .forEachOrdered(partyItem -> {
                   visitParty(ObjectUtils.requireNonNull(partyItem), metadataItem, state);
                 });
           }
         });
   }
 
   /**
    * Called when visiting a role in the "metadata" section of an OSCAL document.
    * <p>
    * Can be overridden by classes extending this interface to support processing
    * of the visited object.
    *
    * @param item
    *          the role Module node item which is a child of the "metadata" node
    * @param metadataItem
    *          the "metadata" Module node item containing the role
    * @param state
    *          the calling context information
    */
   protected void visitRole( // NOPMD noop default
       @NonNull IAssemblyNodeItem item,
       @NonNull IAssemblyNodeItem metadataItem,
       T state) {
     // do nothing
   }
 
   /**
    * Called when visiting a location in the "metadata" section of an OSCAL
    * document.
    * <p>
    * Can be overridden by classes extending this interface to support processing
    * of the visited object.
    *
    * @param item
    *          the location Module node item which is a child of the "metadata"
    *          node
    * @param metadataItem
    *          the "metadata" Module node item containing the location
    * @param state
    *          the calling context information
    */
   protected void visitLocation( // NOPMD noop default
       @NonNull IAssemblyNodeItem item,
       @NonNull IAssemblyNodeItem metadataItem,
       T state) {
     // do nothing
   }
 
   /**
    * Called when visiting a party in the "metadata" section of an OSCAL document.
    * <p>
    * Can be overridden by classes extending this interface to support processing
    * of the visited object.
    *
    * @param item
    *          the party Module node item which is a child of the "metadata" node
    * @param metadataItem
    *          the "metadata" Module node item containing the party
    * @param state
    *          the calling context information
    */
   protected void visitParty( // NOPMD noop default
       @NonNull IAssemblyNodeItem item,
       @NonNull IAssemblyNodeItem metadataItem,
       T state) {
     // do nothing
   }
 
   /**
    * Called when visiting the "back-matter" section of an OSCAL document.
    * <p>
    * Visits each contained resource.
    *
    * @param rootItem
    *          the root Module node item containing the "back-matter" node
    * @param state
    *          the calling context information
    */
   protected void visitBackMatter(@NonNull IRootAssemblyNodeItem rootItem, T state) {
     if (isVisitedItemType(IEntityItem.ItemType.RESOURCE)) {
       BACK_MATTER_RESOURCES_METAPATH.evaluate(rootItem).stream()
           .map(item -> (IAssemblyNodeItem) item)
           .forEachOrdered(resourceItem -> {
             visitResource(ObjectUtils.requireNonNull(resourceItem), rootItem, state);
           });
     }
   }
 
   /**
    * Called when visiting a resource in the "back-matter" section of an OSCAL
    * document.
    * <p>
    * Can be overridden by classes extending this interface to support processing
    * of the visited object.
    *
    * @param resource
    *          the resource Module node item which is a child of the "metadata"
    *          node
    * @param backMatter
    *          the resource Module node item containing the party
    * @param state
    *          the calling context information
    */
   protected void visitResource( // NOPMD noop default
       @NonNull IAssemblyNodeItem resource,
       @NonNull IRootAssemblyNodeItem backMatter,
       T state) {
     // do nothing
   }
 }