/*
    * SPDX-FileCopyrightText: none
    * SPDX-License-Identifier: CC0-1.0
    */
   
   package dev.metaschema.core.metapath.cst;
   
   import java.util.List;
   
  import dev.metaschema.core.metapath.DynamicContext;
  import dev.metaschema.core.metapath.IExpression;
  import dev.metaschema.core.metapath.function.IFunction;
  import dev.metaschema.core.metapath.item.ISequence;
  import dev.metaschema.core.qname.IEnhancedQName;
  import dev.metaschema.core.util.CollectionUtil;
  import edu.umd.cs.findbugs.annotations.NonNull;
  
  /**
   * The CST node for a Metapath
   * <a href="https://www.w3.org/TR/xpath-31/#id-named-function-ref">named
   * function reference</a>.
   */
  public class NamedFunctionReference
      extends AbstractExpression {
    @NonNull
    private final IEnhancedQName name;
    private final int arity;
  
    /**
     * Construct a new Metapath named function reference CST node.
     *
     * @param text
     *          the parsed text of the expression
     * @param name
     *          the function name
     * @param arity
     *          the number of function arguments
     */
    public NamedFunctionReference(
        @NonNull String text,
        @NonNull IEnhancedQName name, int arity) {
      super(text);
      this.name = name;
      this.arity = arity;
    }
  
    /**
     * Get the function name.
     *
     * @return the name of the referenced function
     */
    @NonNull
    public IEnhancedQName getName() {
      return name;
    }
  
    /**
     * Get the expected number of function arguments for this lookup.
     *
     * @return the number of arguments
     */
    public int getArity() {
      return arity;
    }
  
    @Override
    public List<? extends IExpression> getChildren() {
      return CollectionUtil.emptyList();
    }
  
    @SuppressWarnings("null")
    @Override
    public String toCSTString() {
      return String.format("%s[name=%s, arity=%d]", getClass().getName(), name, arity);
    }
  
    @Override
    public <RESULT, CONTEXT> RESULT accept(IExpressionVisitor<RESULT, CONTEXT> visitor, CONTEXT context) {
      return visitor.visitNamedFunctionReference(this, context);
    }
  
    @Override
    protected ISequence<?> evaluate(DynamicContext dynamicContext, ISequence<?> focus) {
      IFunction function = dynamicContext.lookupFunction(name, arity);
      return ISequence.of(function);
    }
  }