/*
    * SPDX-FileCopyrightText: none
    * SPDX-License-Identifier: CC0-1.0
    */
   
   package gov.nist.secauto.metaschema.core.metapath.impl;
   
   import gov.nist.secauto.metaschema.core.metapath.DynamicContext;
   import gov.nist.secauto.metaschema.core.metapath.IMetapathExpression;
  import gov.nist.secauto.metaschema.core.metapath.MetapathException;
  import gov.nist.secauto.metaschema.core.metapath.StaticContext;
  import gov.nist.secauto.metaschema.core.metapath.item.IItem;
  import gov.nist.secauto.metaschema.core.metapath.item.ISequence;
  import gov.nist.secauto.metaschema.core.util.ObjectUtils;
  
  import edu.umd.cs.findbugs.annotations.NonNull;
  import nl.talsmasoftware.lazy4j.Lazy;
  
  /**
   * An implementation of a Metapath expression that is compiled when evaluated.
   * <p>
   * Lazy compilation may cause additional {@link MetapathException} errors at
   * evaluation time, since compilation errors are not raised until evaluation.
   */
  public class LazyCompilationMetapathExpression implements IMetapathExpression {
    @NonNull
    private final String path;
    @NonNull
    private final StaticContext staticContext;
    @NonNull
    private final Lazy<IMetapathExpression> compiledMetapath;
  
    /**
     * Construct a new lazy-compiled Metapath expression.
     *
     * @param path
     *          the metapath expression
     * @param staticContext
     *          the static evaluation context
     */
    public LazyCompilationMetapathExpression(
        @NonNull String path,
        @NonNull StaticContext staticContext) {
      this.path = path;
      this.staticContext = staticContext;
      this.compiledMetapath = ObjectUtils.notNull(Lazy.lazy(() -> IMetapathExpression.compile(path, staticContext)));
    }
  
    @Override
    public String getPath() {
      return path;
    }
  
    @Override
    public StaticContext getStaticContext() {
      return staticContext;
    }
  
    @NonNull
    private IMetapathExpression getCompiledMetapath() {
      return ObjectUtils.notNull(compiledMetapath.get());
    }
  
    @Override
    public <T extends IItem> ISequence<T> evaluate(IItem focus, DynamicContext dynamicContext) {
      return getCompiledMetapath().evaluate(focus, dynamicContext);
    }
  
    @Override
    public String toString() {
      return getPath();
    }
  }