/*
    * Portions of this software was developed by employees of the National Institute
    * of Standards and Technology (NIST), an agency of the Federal Government and is
    * being made available as a public service. Pursuant to title 17 United States
    * Code Section 105, works of NIST employees are not subject to copyright
    * protection in the United States. This software may be subject to foreign
    * copyright. Permission in the United States and in foreign countries, to the
    * extent that NIST may hold copyright, to use, copy, modify, create derivative
    * works, and distribute this software and its documentation without fee is hereby
   * granted on a non-exclusive basis, provided that this notice and disclaimer
   * of warranty appears in all copies.
   *
   * THE SOFTWARE IS PROVIDED 'AS IS' WITHOUT ANY WARRANTY OF ANY KIND, EITHER
   * EXPRESSED, IMPLIED, OR STATUTORY, INCLUDING, BUT NOT LIMITED TO, ANY WARRANTY
   * THAT THE SOFTWARE WILL CONFORM TO SPECIFICATIONS, ANY IMPLIED WARRANTIES OF
   * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE, AND FREEDOM FROM
   * INFRINGEMENT, AND ANY WARRANTY THAT THE DOCUMENTATION WILL CONFORM TO THE
   * SOFTWARE, OR ANY WARRANTY THAT THE SOFTWARE WILL BE ERROR FREE.  IN NO EVENT
   * SHALL NIST BE LIABLE FOR ANY DAMAGES, INCLUDING, BUT NOT LIMITED TO, DIRECT,
   * INDIRECT, SPECIAL OR CONSEQUENTIAL DAMAGES, ARISING OUT OF, RESULTING FROM,
   * OR IN ANY WAY CONNECTED WITH THIS SOFTWARE, WHETHER OR NOT BASED UPON WARRANTY,
   * CONTRACT, TORT, OR OTHERWISE, WHETHER OR NOT INJURY WAS SUSTAINED BY PERSONS OR
   * PROPERTY OR OTHERWISE, AND WHETHER OR NOT LOSS WAS SUSTAINED FROM, OR AROSE OUT
   * OF THE RESULTS OF, OR USE OF, THE SOFTWARE OR SERVICES PROVIDED HEREUNDER.
   */
  
  package gov.nist.secauto.metaschema.core.metapath;
  
  import gov.nist.secauto.metaschema.core.metapath.function.FunctionService;
  import gov.nist.secauto.metaschema.core.metapath.function.IFunction;
  import gov.nist.secauto.metaschema.core.metapath.item.IItem;
  import gov.nist.secauto.metaschema.core.util.ObjectUtils;
  
  import java.util.List;
  import java.util.Objects;
  import java.util.stream.Collectors;
  
  import edu.umd.cs.findbugs.annotations.NonNull;
  
  class FunctionCall implements IExpression {
    @NonNull
    private final String name;
    @NonNull
    private final List<IExpression> arguments;
    private IFunction function;
  
    /**
     * Construct a new function call expression.
     *
     * @param name
     *          the function name
     * @param arguments
     *          the expressions used to provide arguments to the function call
     */
    protected FunctionCall(@NonNull String name, @NonNull List<IExpression> arguments) {
      this.name = Objects.requireNonNull(name, "name");
      this.arguments = Objects.requireNonNull(arguments, "arguments");
    }
  
    /**
     * Retrieve the associated function.
     *
     * @return the function or {@code null} if no function matched the defined name
     *         and arguments
     * @throws StaticMetapathException
     *           if the function was not found
     */
    public IFunction getFunction() {
      synchronized (this) {
        if (function == null) {
          function = FunctionService.getInstance().getFunction(name, arguments);
        }
        return function;
      }
    }
  
    @Override
    public List<IExpression> getChildren() {
      return arguments;
    }
  
    @Override
    public Class<? extends IItem> getBaseResultType() {
      Class<? extends IItem> retval = getFunction().getResult().getType();
      if (retval == null) {
        retval = IItem.class;
      }
      return retval;
    }
  
    @SuppressWarnings("null")
    @Override
    public String toASTString() {
      return String.format("%s[name=%s]", getClass().getName(), getFunction().getName());
    }
  
    @Override
    public <RESULT, CONTEXT> RESULT accept(IExpressionVisitor<RESULT, CONTEXT> visitor, CONTEXT context) {
      return visitor.visitFunctionCall(this, context);
   }
 
   @Override
   public ISequence<?> accept(DynamicContext dynamicContext, ISequence<?> focus) {
     List<ISequence<?>> arguments = ObjectUtils.notNull(getChildren().stream().map(expression -> {
       @NonNull ISequence<?> result = expression.accept(dynamicContext, focus);
       return result;
     }).collect(Collectors.toList()));
 
     IFunction function = getFunction();
     return function.execute(arguments, dynamicContext, focus);
   }
 }