/*
    * SPDX-FileCopyrightText: none
    * SPDX-License-Identifier: CC0-1.0
    */
   
   package dev.metaschema.core.metapath.cst.logic;
   
   import java.util.List;
   
  import dev.metaschema.core.metapath.DynamicContext;
  import dev.metaschema.core.metapath.IExpression;
  import dev.metaschema.core.metapath.cst.AbstractExpression;
  import dev.metaschema.core.metapath.cst.IExpressionVisitor;
  import dev.metaschema.core.metapath.function.library.FnBoolean;
  import dev.metaschema.core.metapath.item.ISequence;
  import dev.metaschema.core.metapath.item.atomic.IBooleanItem;
  import dev.metaschema.core.util.ObjectUtils;
  import edu.umd.cs.findbugs.annotations.NonNull;
  
  /**
   * An implementation of
   * <a href="https://www.w3.org/TR/xpath-31/#doc-xpath31-IfExpr">If
   * expression</a> supporting conditional evaluation.
   */
  public class If
      extends AbstractExpression {
    private final IExpression testExpression;
    private final IExpression thenExpression;
    private final IExpression elseExpression;
  
    /**
     * Construct a new conditional expression.
     *
     * @param text
     *          the parsed text of the expression
     * @param testExpression
     *          the first expression to evaluate
     * @param thenExpression
     *          the expression to evaluate if the test is {@code true}
     * @param elseExpression
     *          the expression to evaluate if the test is {@code false}
     */
    public If(
        @NonNull String text,
        @NonNull IExpression testExpression,
        @NonNull IExpression thenExpression,
        @NonNull IExpression elseExpression) {
      super(text);
      this.testExpression = testExpression;
      this.thenExpression = thenExpression;
      this.elseExpression = elseExpression;
    }
  
    /**
     * Get the "test" expression.
     *
     * @return the expression
     */
    protected IExpression getTestExpression() {
      return testExpression;
    }
  
    /**
     * Get the "then" expression.
     *
     * @return the expression
     */
    protected IExpression getThenExpression() {
      return thenExpression;
    }
  
    /**
     * Get the "else" expression.
     *
     * @return the expression
     */
    protected IExpression getElseExpression() {
      return elseExpression;
    }
  
    @Override
    public List<IExpression> getChildren() {
      return ObjectUtils.notNull(List.of(testExpression, thenExpression, elseExpression));
    }
  
    @Override
    protected ISequence<?> evaluate(DynamicContext dynamicContext, ISequence<?> focus) {
      ISequence<?> result = getTestExpression().accept(dynamicContext, focus);
  
      ISequence<?> retval;
      IBooleanItem effectiveResult = FnBoolean.fnBoolean(result);
      if (effectiveResult.toBoolean()) {
        retval = getThenExpression().accept(dynamicContext, focus);
      } else {
        retval = getElseExpression().accept(dynamicContext, focus);
      }
      return retval;
    }
  
   @Override
   public <RESULT, CONTEXT> RESULT accept(IExpressionVisitor<RESULT, CONTEXT> visitor, CONTEXT context) {
     return visitor.visitIf(this, context);
   }
 }