/*
    * SPDX-FileCopyrightText: none
    * SPDX-License-Identifier: CC0-1.0
    */
   
   package dev.metaschema.core.model.constraint.impl;
   
   import java.util.ArrayList;
   import java.util.List;
  import java.util.Map;
  import java.util.concurrent.ConcurrentHashMap;
  import java.util.stream.Collectors;
  
  import dev.metaschema.core.metapath.item.node.INodeItem;
  import dev.metaschema.core.model.constraint.ConstraintInitializationException;
  import dev.metaschema.core.model.constraint.IIndex;
  import dev.metaschema.core.model.constraint.IIndexConstraint;
  import dev.metaschema.core.model.constraint.IIndexHasKeyConstraint;
  import dev.metaschema.core.model.constraint.IKeyField;
  import dev.metaschema.core.model.constraint.IUniqueConstraint;
  import dev.metaschema.core.util.CollectionUtil;
  import edu.umd.cs.findbugs.annotations.NonNull;
  
  /**
   * The default implementation of an index that can support the
   * {@link IIndexConstraint}, {@link IIndexHasKeyConstraint}, and
   * {@link IUniqueConstraint}.
   */
  public class DefaultIndex implements IIndex {
    @NonNull
    private final List<IKeyField> keyFields;
    @NonNull
    private final Map<List<String>, INodeItem> keyToItemMap = new ConcurrentHashMap<>();
  
    /**
     * Construct a new index.
     *
     * @param keyFields
     *          the key field components to use to generate keys by default
     */
    public DefaultIndex(@NonNull List<? extends IKeyField> keyFields) {
      this.keyFields = CollectionUtil.unmodifiableList(new ArrayList<>(keyFields));
    }
  
    @Override
    public List<IKeyField> getKeyFields() {
      return keyFields;
    }
  
    @Override
    public INodeItem put(@NonNull INodeItem item, @NonNull List<String> key) {
      INodeItem oldItem = null;
      if (!IIndex.isAllNulls(key)) {
        // only add keys with some information (values)
        oldItem = keyToItemMap.put(key, item);
      }
      return oldItem;
    }
  
    @Override
    public INodeItem get(List<String> key) {
      int requiredSize = getKeyFields().size();
      if (requiredSize != key.size()) {
        throw new ConstraintInitializationException(
            String.format("Provided key '%s' is not the size '%d' required by the index.",
                key.stream()
                    .map(value -> new StringBuilder().append('"').append(value).append('"').toString())
                    .collect(Collectors.joining(",", "{", "}")),
                requiredSize));
      }
      return keyToItemMap.get(key);
    }
  }