/*
    * SPDX-FileCopyrightText: none
    * SPDX-License-Identifier: CC0-1.0
    */
   
   package gov.nist.secauto.metaschema.core.model;
   
   import org.apache.logging.log4j.LogManager;
   import org.apache.logging.log4j.Logger;
  
  import java.util.Collection;
  import java.util.LinkedHashSet;
  import java.util.Objects;
  import java.util.Set;
  import java.util.function.Function;
  
  import edu.umd.cs.findbugs.annotations.NonNull;
  import edu.umd.cs.findbugs.annotations.SuppressFBWarnings;
  
  /**
   * Supports walking a portion of a metaschema model collecting a set of
   * definitions that match the provided filter. For a definition to be collected,
   * the filter must return {@code true}.
   */
  public abstract class DefinitionCollectingModelWalker
      extends ModelWalker<Void> {
    private static final Logger LOGGER = LogManager.getLogger(DefinitionCollectingModelWalker.class);
  
    private final Function<IDefinition, Boolean> filter;
    @NonNull
    private final Set<IDefinition> definitions = new LinkedHashSet<>();
  
    @Override
    protected Void getDefaultData() { // NOPMD - intentional
      return null;
    }
  
    /**
     * Construct a new walker using the provided filter.
     *
     * @param filter
     *          the filter to match definitions against
     */
    protected DefinitionCollectingModelWalker(Function<IDefinition, Boolean> filter) {
      Objects.requireNonNull(filter, "filter");
      this.filter = filter;
    }
  
    /**
     * Retrieves the filter used for matching.
     *
     * @return the filter
     */
    protected Function<IDefinition, Boolean> getFilter() {
      return filter;
    }
  
    /**
     * Return the collection of definitions matching the configured filter.
     *
     * @return the collection of definitions
     */
    @NonNull
    @SuppressFBWarnings(value = "EI_EXPOSE_REP", justification = "interface doesn't allow modification")
    public Collection<? extends IDefinition> getDefinitions() {
      return definitions;
    }
  
    @Override
    protected void visit(IFlagDefinition def, Void data) {
      if (LOGGER.isTraceEnabled()) {
        LOGGER.trace("visiting flag definition '{}'", def.toCoordinates());
      }
      if (getFilter().apply(def)) {
        definitions.add(def);
      }
    }
  
    @Override
    protected boolean visit(IFieldDefinition def, Void data) {
      if (LOGGER.isTraceEnabled()) {
        LOGGER.trace("visiting field definition '{}'", def.toCoordinates());
      }
      boolean retval;
      if (definitions.contains(def)) {
        // no need to visit, since this has already been seen
        retval = false;
      } else {
        if (getFilter().apply(def)) {
          definitions.add(def);
        }
        retval = true;
      }
      return retval;
    }
  
    @Override
    protected boolean visit(IAssemblyDefinition def, Void data) {
      if (LOGGER.isTraceEnabled()) {
       LOGGER.trace("visiting assembly definition '{}'", def.toCoordinates());
     }
     boolean retval;
     if (definitions.contains(def)) {
       // no need to visit, since this has already been seen
       retval = false;
     } else {
       if (getFilter().apply(def)) {
         definitions.add(def);
       }
       retval = true;
     }
     return retval;
   }
 }