/*
    * SPDX-FileCopyrightText: none
    * SPDX-License-Identifier: CC0-1.0
    */
   
   package dev.metaschema.core.metapath.cst.path;
   
   import dev.metaschema.core.metapath.DynamicContext;
   import dev.metaschema.core.metapath.IExpression;
  import dev.metaschema.core.metapath.cst.IExpressionVisitor;
  import dev.metaschema.core.metapath.item.ISequence;
  import dev.metaschema.core.metapath.item.ItemUtils;
  import dev.metaschema.core.util.CustomCollectors;
  import dev.metaschema.core.util.ObjectUtils;
  import edu.umd.cs.findbugs.annotations.NonNull;
  
  /**
   * An expression that finds a child of the document root using the {@code right}
   * expression.
   * <p>
   * Based on the XPath 3.1
   * <a href= "https://www.w3.org/TR/xpath-31/#id-path-operator">path
   * operator</a>.
   */
  public class RootSlashPath
      extends AbstractRootPathExpression {
  
    /**
     * Construct a new expression that finds a child of the document root using the
     * {@code node} expression.
     *
     * @param text
     *          the parsed text of the expression
     * @param node
     *          the path to evaluate relative to the document root
     */
    public RootSlashPath(@NonNull String text, @NonNull IExpression node) {
      super(text, node);
    }
  
    @Override
    public <RESULT, CONTEXT> RESULT accept(IExpressionVisitor<RESULT, CONTEXT> visitor, CONTEXT context) {
      return visitor.visitRootSlashPath(this, context);
    }
  
    @Override
    protected ISequence<?> evaluate(DynamicContext dynamicContext, ISequence<?> focus) {
      ISequence<?> roots = ObjectUtils.notNull(focus.stream()
          .map(item -> ItemUtils.checkItemIsNodeItem(dynamicContext, item))
          // the previous checks for a null instance
          .flatMap(item -> Axis.ANCESTOR_OR_SELF.execute(ObjectUtils.notNull(item)).limit(1))
          .collect(CustomCollectors.toSequence()));
      return getExpression().accept(dynamicContext, roots);
    }
  }