/*
    * SPDX-FileCopyrightText: none
    * SPDX-License-Identifier: CC0-1.0
    */
   
   package gov.nist.secauto.metaschema.core.metapath.cst;
   
   import gov.nist.secauto.metaschema.core.metapath.DynamicContext;
   import gov.nist.secauto.metaschema.core.metapath.ISequence;
  import gov.nist.secauto.metaschema.core.metapath.function.library.FnData;
  import gov.nist.secauto.metaschema.core.metapath.item.atomic.IStringItem;
  import gov.nist.secauto.metaschema.core.util.ObjectUtils;
  
  import java.util.List;
  
  import edu.umd.cs.findbugs.annotations.NonNull;
  
  public class StringConcat
      extends AbstractNAryExpression {
  
    /**
     * Create a new expression that concatenates the results of evaluating the
     * provided {@code expressions} as strings.
     *
     * @param expressions
     *          the expressions to evaluate
     */
    public StringConcat(@NonNull List<IExpression> expressions) {
      super(expressions);
    }
  
    @Override
    public Class<IStringItem> getBaseResultType() {
      return IStringItem.class;
    }
  
    @Override
    public Class<IStringItem> getStaticResultType() {
      return getBaseResultType();
    }
  
    @Override
    public <RESULT, CONTEXT> RESULT accept(IExpressionVisitor<RESULT, CONTEXT> visitor, CONTEXT context) {
      return visitor.visitStringConcat(this, context);
    }
  
    @Override
    public ISequence<?> accept(DynamicContext dynamicContext, ISequence<?> focus) {
      // TODO: replace with concat function when implemented
      StringBuilder builder = new StringBuilder();
      for (IExpression child : getChildren()) {
        ISequence<?> result = child.accept(dynamicContext, focus);
        FnData.fnData(result).stream()
            .forEachOrdered(item -> {
              builder.append(item.asString());
            });
      }
      return ISequence.of(IStringItem.valueOf(ObjectUtils.notNull(builder.toString())));
    }
  }