/*
    * 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.internal;
  
  import java.util.Arrays;
  import java.util.Objects;
  
  import org.apache.commons.jexl3.JexlContext;
  import org.apache.commons.jexl3.JexlOptions;
  import org.apache.commons.jexl3.parser.ASTJexlLambda;
  
  /**
   * A Script closure.
   */
  public class Closure extends Script {
      /** The frame. */
      protected final Frame frame;
      /** The options. */
      protected final JexlOptions options;
  
      /**
       * Creates a closure.
       * @param theCaller the calling interpreter
       * @param lambda the lambda
       */
      protected Closure(final Interpreter theCaller, final ASTJexlLambda lambda) {
          super(theCaller.jexl, null, lambda);
          frame = lambda.createFrame(theCaller.frame);
          final JexlOptions callerOptions = theCaller.options;
          options = callerOptions != null ? callerOptions.copy() :  null;
      }
  
      /**
       * Creates a curried version of a script.
       * @param base the base script
       * @param args the script arguments
       */
      protected Closure(final Script base, final Object[] args) {
          super(base.jexl, base.source, base.script);
          final Frame sf = base instanceof Closure ? ((Closure) base).frame :  null;
          frame = sf == null
                  ? script.createFrame(args)
                  : sf.assign(args);
          JexlOptions closureOptions = null;
          if (base instanceof Closure) {
              closureOptions = ((Closure) base).options;
          }
          options = closureOptions != null ? closureOptions.copy() :  null;
      }
  
      @Override
      public Callable callable(final JexlContext context, final Object... args) {
          final Frame local = frame != null ? frame.assign(args) : null;
          return new Callable(createInterpreter(context, local, options)) {
              @Override
              public Object interpret() {
                  return interpreter.runClosure(Closure.this);
              }
          };
      }
  
      /**
       * Enable lambda recursion.
       * <p>Assign this lambda in its own frame if the symbol it is assigned to in its definition scope
       * is captured in its body.</p>
       * <p>This done allow a locally defined function to "see" and call  itself as a local (captured) variable.</p>
       * Typical case is: <code>const f = (x)->x <= 0? 1 : x*f(x-1)</code>. Since assignment of f occurs after
       * the lambda creation, we need to patch the lambda frame to expose itself through the captured symbol.
       * @param parentFrame the parent calling frame
       * @param symbol the symbol index (in the caller of this closure)
       */
      void captureSelfIfRecursive(final Frame parentFrame, final int symbol) {
          if (script instanceof ASTJexlLambda) {
              final Scope parentScope = parentFrame != null ? parentFrame.getScope() : null;
              final Scope localScope = frame != null ? frame.getScope() : null;
              if (parentScope != null  && localScope != null && parentScope == localScope.getParent()) {
                  final Integer reg = localScope.getCaptured(symbol);
                  if (reg != null) {
                      frame.set(reg, this);
                  }
              }
          }
      }
  
      @Override
     public boolean equals(final Object obj) {
         if (obj == null) {
             return false;
         }
         if (getClass() != obj.getClass()) {
             return false;
         }
         final Closure other = (Closure) obj;
         if (this.jexl != other.jexl) {
             return false;
         }
         if (!Objects.equals(this.source, other.source)) {
             return false;
         }
         if (this.frame == other.frame) {
             return true;
         }
         return Arrays.deepEquals(
                 this.frame.nocycleStack(this),
                 other.frame.nocycleStack(other));
     }
 
     @Override
     public Object evaluate(final JexlContext context) {
         return execute(context, (Object[])null);
     }
 
     @Override
     public Object execute(final JexlContext context) {
         return execute(context, (Object[])null);
     }
 
     @Override
     public Object execute(final JexlContext context, final Object... args) {
         final Frame local = frame != null ? frame.assign(args) : null;
         final Interpreter interpreter = createInterpreter(context, local, options);
         return interpreter.runClosure(this);
     }
 
     @Override
     public String[] getUnboundParameters() {
         return frame.getUnboundParameters();
     }
 
     @Override
     public int hashCode() {
         // CSOFF: Magic number
         int hash = 17;
         hash = 31 * hash + Objects.hashCode(jexl);
         hash = 31 * hash + Objects.hashCode(source);
         hash = 31 * hash + (frame != null ? Arrays.deepHashCode(frame.nocycleStack(this)) : 0);
         // CSON: Magic number
         return hash;
     }
 
 }