/*
    * 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.collections4;
  
  import java.util.Collection;
  import java.util.Map;
  import java.util.Objects;
  
  import org.apache.commons.collections4.functors.ChainedClosure;
  import org.apache.commons.collections4.functors.EqualPredicate;
  import org.apache.commons.collections4.functors.ExceptionClosure;
  import org.apache.commons.collections4.functors.ForClosure;
  import org.apache.commons.collections4.functors.IfClosure;
  import org.apache.commons.collections4.functors.InvokerTransformer;
  import org.apache.commons.collections4.functors.NOPClosure;
  import org.apache.commons.collections4.functors.SwitchClosure;
  import org.apache.commons.collections4.functors.TransformerClosure;
  import org.apache.commons.collections4.functors.WhileClosure;
  
  /**
   * {@code ClosureUtils} provides reference implementations and utilities
   * for the Closure functor interface. The supplied closures are:
   * <ul>
   * <li>Invoker - invokes a method on the input object
   * <li>For - repeatedly calls a closure for a fixed number of times
   * <li>While - repeatedly calls a closure while a predicate is true
   * <li>Chained - chains two or more closures together
   * <li>If - calls one closure or another based on a predicate
   * <li>Switch - calls one closure based on one or more predicates
   * <li>SwitchMap - calls one closure looked up from a Map
   * <li>Transformer - wraps a Transformer as a Closure
   * <li>NOP - does nothing
   * <li>Exception - always throws an exception
   * </ul>
   * <p>
   * Since v4.1 only closures which are considered to be safe are
   * Serializable. Closures considered to be unsafe for serialization are:
   * </p>
   * <ul>
   * <li>Invoker
   * <li>For
   * <li>While
   * </ul>
   *
   * @since 3.0
   */
  public class ClosureUtils {
  
      /**
       * Creates a Closure that calls a Transformer each time it is called.
       * The transformer will be called using the closure's input object.
       * The transformer's result will be ignored.
       *
       * @see org.apache.commons.collections4.functors.TransformerClosure
       * @param <E>  the type that the closure acts on
       * @param transformer  the transformer to run each time in the closure, null means nop
       * @return the closure
       */
      public static <E> Closure<E> asClosure(final Transformer<? super E, ?> transformer) {
          return TransformerClosure.transformerClosure(transformer);
      }
  
      /**
       * Create a new Closure that calls each closure in turn, passing the
       * result into the next closure.
       *
       * @see org.apache.commons.collections4.functors.ChainedClosure
       * @param <E>  the type that the closure acts on
       * @param closures  an array of closures to chain
       * @return the {@code chained} closure
       * @throws NullPointerException if the closures array is null
       * @throws NullPointerException if any closure in the array is null
       */
      public static <E> Closure<E> chainedClosure(final Closure<? super E>... closures) {
          return ChainedClosure.chainedClosure(closures);
      }
  
      /**
       * Create a new Closure that calls each closure in turn, passing the
       * result into the next closure. The ordering is that of the iterator()
       * method on the collection.
       *
       * @see org.apache.commons.collections4.functors.ChainedClosure
       * @param <E>  the type that the closure acts on
       * @param closures  a collection of closures to chain
      * @return the {@code chained} closure
      * @throws NullPointerException if the closures collection is null
      * @throws NullPointerException if any closure in the collection is null
      */
     public static <E> Closure<E> chainedClosure(final Collection<? extends Closure<? super E>> closures) {
         return ChainedClosure.chainedClosure(closures);
     }
 
     /**
      * Creates a Closure that will call the closure once and then repeatedly
      * until the predicate returns false.
      *
      * @see org.apache.commons.collections4.functors.WhileClosure
      * @param <E>  the type that the closure acts on
      * @param closure  the closure to call repeatedly, not null
      * @param predicate  the predicate to use as an end of loop test, not null
      * @return the {@code do-while} closure
      * @throws NullPointerException if either argument is null
      */
     public static <E> Closure<E> doWhileClosure(final Closure<? super E> closure,
                                                 final Predicate<? super E> predicate) {
         return WhileClosure.<E>whileClosure(predicate, closure, true);
     }
 
     /**
      * Gets a Closure that always throws an exception.
      * This could be useful during testing as a placeholder.
      *
      * @param <E>  the type that the closure acts on
      * @return the closure
      * @see ExceptionClosure
      */
     public static <E> Closure<E> exceptionClosure() {
         return ExceptionClosure.<E>exceptionClosure();
     }
 
     /**
      * Creates a Closure that will call the closure {@code count} times.
      * <p>
      * A null closure or zero count returns the {@code NOPClosure}.
      *
      * @see org.apache.commons.collections4.functors.ForClosure
      * @param <E>  the type that the closure acts on
      * @param count  the number of times to loop
      * @param closure  the closure to call repeatedly
      * @return the {@code for} closure
      */
     public static <E> Closure<E> forClosure(final int count, final Closure<? super E> closure) {
         return ForClosure.forClosure(count, closure);
     }
 
     /**
      * Create a new Closure that calls another closure based on the
      * result of the specified predicate.
      *
      * @see org.apache.commons.collections4.functors.IfClosure
      * @param <E>  the type that the closure acts on
      * @param predicate  the validating predicate
      * @param trueClosure  the closure called if the predicate is true
      * @return the {@code if} closure
      * @throws NullPointerException if the predicate or closure is null
      * @since 3.2
      */
     public static <E> Closure<E> ifClosure(final Predicate<? super E> predicate,
                                            final Closure<? super E> trueClosure) {
         return IfClosure.<E>ifClosure(predicate, trueClosure);
     }
 
     /**
      * Create a new Closure that calls one of two closures depending
      * on the specified predicate.
      *
      * @see org.apache.commons.collections4.functors.IfClosure
      * @param <E>  the type that the closure acts on
      * @param predicate  the predicate to switch on
      * @param trueClosure  the closure called if the predicate is true
      * @param falseClosure  the closure called if the predicate is false
      * @return the {@code switch} closure
      * @throws NullPointerException if the predicate or either closure is null
      */
     public static <E> Closure<E> ifClosure(final Predicate<? super E> predicate,
                                            final Closure<? super E> trueClosure,
                                            final Closure<? super E> falseClosure) {
         return IfClosure.<E>ifClosure(predicate, trueClosure, falseClosure);
     }
 
     /**
      * Creates a Closure that will invoke a specific method on the closure's
      * input object by reflection.
      *
      * @see org.apache.commons.collections4.functors.InvokerTransformer
      * @see org.apache.commons.collections4.functors.TransformerClosure
      * @param <E>  the type that the closure acts on
      * @param methodName  the name of the method
      * @return the {@code invoker} closure
      * @throws NullPointerException if the method name is null
      */
     public static <E> Closure<E> invokerClosure(final String methodName) {
         // reuse transformer as it has caching - this is lazy really, should have inner class here
         return asClosure(InvokerTransformer.<E, Object>invokerTransformer(methodName));
     }
 
     /**
      * Creates a Closure that will invoke a specific method on the closure's
      * input object by reflection.
      *
      * @see org.apache.commons.collections4.functors.InvokerTransformer
      * @see org.apache.commons.collections4.functors.TransformerClosure
      * @param <E>  the type that the closure acts on
      * @param methodName  the name of the method
      * @param paramTypes  the parameter types
      * @param args  the arguments
      * @return the {@code invoker} closure
      * @throws NullPointerException if the method name is null
      * @throws IllegalArgumentException if the paramTypes and args don't match
      */
     public static <E> Closure<E> invokerClosure(final String methodName, final Class<?>[] paramTypes,
                                                 final Object[] args) {
         // reuse transformer as it has caching - this is lazy really, should have inner class here
         return asClosure(InvokerTransformer.<E, Object>invokerTransformer(methodName, paramTypes, args));
     }
 
     /**
      * Gets a Closure that will do nothing.
      * This could be useful during testing as a placeholder.
      *
      * @see org.apache.commons.collections4.functors.NOPClosure
      * @param <E>  the type that the closure acts on
      * @return the closure
      */
     public static <E> Closure<E> nopClosure() {
         return NOPClosure.<E>nopClosure();
     }
 
     /**
      * Create a new Closure that calls one of the closures depending
      * on the predicates.
      * <p>
      * The Map consists of Predicate keys and Closure values. A closure
      * is called if its matching predicate returns true. Each predicate is evaluated
      * until one returns true. If no predicates evaluate to true, the default
      * closure is called. The default closure is set in the map with a
      * null key. The ordering is that of the iterator() method on the entryset
      * collection of the map.
      * </p>
      *
      * @see org.apache.commons.collections4.functors.SwitchClosure
      * @param <E>  the type that the closure acts on
      * @param predicatesAndClosures  a map of predicates to closures
      * @return the {@code switch} closure
      * @throws NullPointerException if the map is null
      * @throws NullPointerException if any closure in the map is null
      * @throws ClassCastException  if the map elements are of the wrong type
      */
     public static <E> Closure<E> switchClosure(final Map<Predicate<E>, Closure<E>> predicatesAndClosures) {
         return SwitchClosure.switchClosure(predicatesAndClosures);
     }
 
     /**
      * Create a new Closure that calls one of the closures depending
      * on the predicates.
      * <p>
      * The closure at array location 0 is called if the predicate at array
      * location 0 returned true. Each predicate is evaluated
      * until one returns true.
      * </p>
      *
      * @see org.apache.commons.collections4.functors.SwitchClosure
      * @param <E>  the type that the closure acts on
      * @param predicates  an array of predicates to check, not null
      * @param closures  an array of closures to call, not null
      * @return the {@code switch} closure
      * @throws NullPointerException if either array is null
      * @throws NullPointerException if any element in the arrays is null
      * @throws IllegalArgumentException if the arrays have different sizes
      */
     public static <E> Closure<E> switchClosure(final Predicate<? super E>[] predicates,
                                                final Closure<? super E>[] closures) {
         return SwitchClosure.<E>switchClosure(predicates, closures, null);
     }
 
     /**
      * Create a new Closure that calls one of the closures depending
      * on the predicates.
      * <p>
      * The closure at array location 0 is called if the predicate at array
      * location 0 returned true. Each predicate is evaluated
      * until one returns true. If no predicates evaluate to true, the default
      * closure is called.
      * </p>
      *
      * @see org.apache.commons.collections4.functors.SwitchClosure
      * @param <E>  the type that the closure acts on
      * @param predicates  an array of predicates to check, not null
      * @param closures  an array of closures to call, not null
      * @param defaultClosure  the default to call if no predicate matches
      * @return the {@code switch} closure
      * @throws NullPointerException if either array is null
      * @throws NullPointerException if any element in the arrays is null
      * @throws IllegalArgumentException if the arrays are different sizes
      */
     public static <E> Closure<E> switchClosure(final Predicate<? super E>[] predicates,
                                                final Closure<? super E>[] closures,
                                                final Closure<? super E> defaultClosure) {
         return SwitchClosure.<E>switchClosure(predicates, closures, defaultClosure);
     }
 
     /**
      * Create a new Closure that uses the input object as a key to find the
      * closure to call.
      * <p>
      * The Map consists of object keys and Closure values. A closure
      * is called if the input object equals the key. If there is no match, the
      * default closure is called. The default closure is set in the map
      * using a null key.
      * </p>
      *
      * @see org.apache.commons.collections4.functors.SwitchClosure
      * @param <E>  the type that the closure acts on
      * @param objectsAndClosures  a map of objects to closures
      * @return the closure
      * @throws NullPointerException if the map is null
      * @throws NullPointerException if any closure in the map is null
      */
     @SuppressWarnings("unchecked")
     public static <E> Closure<E> switchMapClosure(final Map<? extends E, Closure<E>> objectsAndClosures) {
         Objects.requireNonNull(objectsAndClosures, "objectsAndClosures");
         final Closure<? super E> def = objectsAndClosures.remove(null);
         final int size = objectsAndClosures.size();
         final Closure<? super E>[] trs = new Closure[size];
         final Predicate<E>[] preds = new Predicate[size];
         int i = 0;
         for (final Map.Entry<? extends E, Closure<E>> entry : objectsAndClosures.entrySet()) {
             preds[i] = EqualPredicate.<E>equalPredicate(entry.getKey());
             trs[i] = entry.getValue();
             i++;
         }
         return ClosureUtils.<E>switchClosure(preds, trs, def);
     }
 
     /**
      * Creates a Closure that will call the closure repeatedly until the
      * predicate returns false.
      *
      * @see org.apache.commons.collections4.functors.WhileClosure
      * @param <E>  the type that the closure acts on
      * @param predicate  the predicate to use as an end of loop test, not null
      * @param closure  the closure to call repeatedly, not null
      * @return the {@code while} closure
      * @throws NullPointerException if either argument is null
      */
     public static <E> Closure<E> whileClosure(final Predicate<? super E> predicate, final Closure<? super E> closure) {
         return WhileClosure.<E>whileClosure(predicate, closure, false);
     }
 
     /**
      * Don't allow instances.
      */
     private ClosureUtils() {
         // empty
     }
 
 }