/*
    * Licensed to the Apache Software Foundation (ASF) under one or more
    * contributor license agreements.  See the NOTICE file distributed with
    * this work for additional information regarding copyright ownership.
    * The ASF licenses this file to You under the Apache License, Version 2.0
    * (the "License"); you may not use this file except in compliance with
    * the License.  You may obtain a copy of the License at
    *
    *      http://www.apache.org/licenses/LICENSE-2.0
   *
   * Unless required by applicable law or agreed to in writing, software
   * distributed under the License is distributed on an "AS IS" BASIS,
   * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
   * See the License for the specific language governing permissions and
   * limitations under the License.
   */
  package org.apache.commons.jexl3.jexl342;
  
  import org.apache.commons.jexl3.JexlEngine;
  import org.apache.commons.jexl3.JexlException;
  import org.apache.commons.jexl3.introspection.JexlMethod;
  
  /**
   * Wraps a reference or optional method executor.
   */
  public class ReferenceMethodExecutor implements JexlMethod {
      /** The reference handler. */
      private final ReferenceUberspect.ReferenceHandler handler;
      /** The method to delegate to. */
      private final JexlMethod method;
  
      /**
       * Creates an instance.
       * @param referenceHandler the reference handler
       * @param jexlMethod the method executor
       */
      public ReferenceMethodExecutor(final ReferenceUberspect.ReferenceHandler referenceHandler, final JexlMethod jexlMethod) {
          if (referenceHandler == null || jexlMethod == null) {
              throw new IllegalArgumentException("handler and method cant be null");
          }
          this.method = jexlMethod;
          this.handler = referenceHandler;
      }
  
      /**
       * Dereference an expected optional or reference .
       * @param opt the reference
       * @return the reference value
       */
      protected Object getReference(final Object opt) {
          return handler.callGet(opt);
      }
  
      @Override
      public Class<?> getReturnType() {
          return method != null ?  method.getReturnType() : null;
      }
  
      @Override
      public Object invoke(final Object ref, final Object... args) throws Exception {
          final Object obj = getReference(ref);
          return obj == null ? null : method.invoke(obj, args);
      }
  
      @Override
      public boolean isCacheable() {
          return method != null && method.isCacheable();
      }
  
      @Override
      public boolean tryFailed(final Object rval) {
          return method == null || method.tryFailed(rval);
      }
  
      @Override
      public Object tryInvoke(final String name, final Object ref, final Object... args) throws JexlException.TryFailed {
          final Object obj = getReference(ref);
          if (method == null) {
              return obj == null ? null : JexlEngine.TRY_FAILED;
          }
          if (obj == ref) {
              return JexlEngine.TRY_FAILED;
          }
          return method.tryInvoke(name, obj, args);
      }
  }