/*
    * 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.beanutils2;
  
  import java.lang.reflect.Array;
  import java.lang.reflect.Constructor;
  import java.lang.reflect.InvocationTargetException;
  import java.lang.reflect.Modifier;
  
  /**
   * <p>
   * Utility reflection methods focused on constructors, modeled after {@link MethodUtils}.
   * </p>
   *
   * <h2>Known Limitations</h2>
   * <h3>Accessing Public Constructors In A Default Access Superclass</h3>
   * <p>
   * There is an issue when invoking public constructors contained in a default access superclass. Reflection locates these constructors fine and correctly
   * assigns them as public. However, an {@code IllegalAccessException} is thrown if the constructors is invoked.
   * </p>
   *
   * <p>
   * {@code ConstructorUtils} contains a workaround for this situation. It will attempt to call {@code setAccessible} on this constructor. If this call succeeds,
   * then the method can be invoked as normal. This call will only succeed when the application has sufficient security privileges. If this call fails then a
   * warning will be logged and the method may fail.
   * </p>
   */
  public class ConstructorUtils {
  
      /**
       * Returns a constructor with single argument.
       *
       * @param <T>           the type of the constructor
       * @param klass         the class to be constructed
       * @param parameterType The constructor parameter type
       * @return null if matching accessible constructor cannot be found.
       * @see Class#getConstructor
       * @see #getAccessibleConstructor(java.lang.reflect.Constructor)
       */
      public static <T> Constructor<T> getAccessibleConstructor(final Class<T> klass, final Class<?> parameterType) {
  
          final Class<?>[] parameterTypes = { parameterType };
          return getAccessibleConstructor(klass, parameterTypes);
      }
  
      /**
       * Returns a constructor given a class and signature.
       *
       * @param <T>            the type to be constructed
       * @param klass          the class to be constructed
       * @param parameterTypes the parameter array
       * @return null if matching accessible constructor cannot be found
       * @see Class#getConstructor
       * @see #getAccessibleConstructor(java.lang.reflect.Constructor)
       */
      public static <T> Constructor<T> getAccessibleConstructor(final Class<T> klass, final Class<?>[] parameterTypes) {
  
          try {
              return getAccessibleConstructor(klass.getConstructor(parameterTypes));
          } catch (final NoSuchMethodException e) {
              return null;
          }
      }
  
      /**
       * Returns accessible version of the given constructor.
       *
       * @param <T>  the type of the constructor
       * @param ctor prototype constructor object.
       * @return {@code null} if accessible constructor cannot be found.
       * @see SecurityManager
       */
      public static <T> Constructor<T> getAccessibleConstructor(final Constructor<T> ctor) {
  
          // Make sure we have a method to check
          if (ctor == null) {
              return null;
          }
  
          // If the requested method is not public we cannot call it
          if (!Modifier.isPublic(ctor.getModifiers())) {
              return null;
          }
  
         // If the declaring class is public, we are done
         final Class<T> clazz = ctor.getDeclaringClass();
         if (Modifier.isPublic(clazz.getModifiers())) {
             return ctor;
         }
 
         // what else can we do?
         return null;
     }
 
     /**
      * <p>
      * Find an accessible constructor with compatible parameters. Compatible parameters mean that every method parameter is assignable from the given
      * parameters. In other words, it finds constructor that will take the parameters given.
      * </p>
      *
      * <p>
      * First it checks if there is constructor matching the exact signature. If no such, all the constructors of the class are tested if their signatures are
      * assignment compatible with the parameter types. The first matching constructor is returned.
      * </p>
      *
      * @param <T>            the type of the class to be inspected
      * @param clazz          find constructor for this class
      * @param parameterTypes find method with compatible parameters
      * @return a valid Constructor object. If there's no matching constructor, returns {@code null}.
      */
     private static <T> Constructor<T> getMatchingAccessibleConstructor(final Class<T> clazz, final Class<?>[] parameterTypes) {
         // see if we can find the method directly
         // most of the time this works and it's much faster
         try {
             final Constructor<T> ctor = clazz.getConstructor(parameterTypes);
             try {
                 //
                 // XXX Default access superclass workaround
                 //
                 // When a public class has a default access superclass
                 // with public methods, these methods are accessible.
                 // Calling them from compiled code works fine.
                 //
                 // Unfortunately, using reflection to invoke these methods
                 // seems to (wrongly) to prevent access even when the method
                 // modifier is public.
                 //
                 // The following workaround solves the problem but will only
                 // work from sufficiently privileges code.
                 //
                 // Better workarounds would be gratefully accepted.
                 //
                 ctor.setAccessible(true);
             } catch (final SecurityException se) {
                 /* SWALLOW, if workaround fails don't fret. */
             }
             return ctor;
 
         } catch (final NoSuchMethodException e) { /* SWALLOW */
         }
 
         // search through all methods
         final int paramSize = parameterTypes.length;
         final Constructor<?>[] ctors = clazz.getConstructors();
         for (final Constructor<?> ctor2 : ctors) {
             // compare parameters
             final Class<?>[] ctorParams = ctor2.getParameterTypes();
             final int ctorParamSize = ctorParams.length;
             if (ctorParamSize == paramSize) {
                 boolean match = true;
                 for (int n = 0; n < ctorParamSize; n++) {
                     if (!MethodUtils.isAssignmentCompatible(ctorParams[n], parameterTypes[n])) {
                         match = false;
                         break;
                     }
                 }
 
                 if (match) {
                     // get accessible version of method
                     final Constructor<?> ctor = getAccessibleConstructor(ctor2);
                     if (ctor != null) {
                         try {
                             ctor.setAccessible(true);
                         } catch (final SecurityException se) {
                             /*
                              * Swallow SecurityException TODO: Why?
                              */
                         }
                         // Class.getConstructors() actually returns constructors
                         // of type T, so it is safe to cast.
                         return (Constructor<T>) ctor;
                     }
                 }
             }
         }
 
         return null;
     }
 
     /**
      * <p>
      * Convenience method returning new instance of {@code klazz} using a single argument constructor. The formal parameter type is inferred from the actual
      * values of {@code arg}. See {@link #invokeExactConstructor(Class, Object[], Class[])} for more details.
      * </p>
      *
      * <p>
      * The signatures should be assignment compatible.
      * </p>
      *
      * @param <T>   the type of the object to be constructed
      * @param klass the class to be constructed.
      * @param arg   the actual argument. May be null (this will result in calling the default constructor).
      * @return new instance of {@code klazz}
      * @throws NoSuchMethodException     If the constructor cannot be found
      * @throws IllegalAccessException    If an error occurs accessing the constructor
      * @throws InvocationTargetException If an error occurs invoking the constructor
      * @throws InstantiationException    If an error occurs instantiating the class
      * @see #invokeConstructor(Class, Object[], Class[])
      */
     public static <T> T invokeConstructor(final Class<T> klass, final Object arg)
             throws NoSuchMethodException, IllegalAccessException, InvocationTargetException, InstantiationException {
 
         final Object[] args = toArray(arg);
         return invokeConstructor(klass, args);
     }
 
     /**
      * <p>
      * Returns new instance of {@code klazz</code> created using the actual arguments <code>args}. The formal parameter types are inferred from the actual
      * values of {@code args}. See {@link #invokeExactConstructor(Class, Object[], Class[])} for more details.
      * </p>
      *
      * <p>
      * The signatures should be assignment compatible.
      * </p>
      *
      * @param <T>   the type of the object to be constructed
      * @param klass the class to be constructed.
      * @param args  actual argument array. May be null (this will result in calling the default constructor).
      * @return new instance of {@code klazz}
      * @throws NoSuchMethodException     If the constructor cannot be found
      * @throws IllegalAccessException    If an error occurs accessing the constructor
      * @throws InvocationTargetException If an error occurs invoking the constructor
      * @throws InstantiationException    If an error occurs instantiating the class
      * @see #invokeConstructor(Class, Object[], Class[])
      */
     public static <T> T invokeConstructor(final Class<T> klass, Object[] args)
             throws NoSuchMethodException, IllegalAccessException, InvocationTargetException, InstantiationException {
 
         if (null == args) {
             args = BeanUtils.EMPTY_OBJECT_ARRAY;
         }
         final int arguments = args.length;
         final Class<?>[] parameterTypes = new Class<?>[arguments];
         for (int i = 0; i < arguments; i++) {
             parameterTypes[i] = args[i].getClass();
         }
         return invokeConstructor(klass, args, parameterTypes);
     }
 
     /**
      * <p>
      * Returns new instance of {@code klazz} created using constructor with signature {@code parameterTypes</code> and actual arguments <code>args}.
      * </p>
      *
      * <p>
      * The signatures should be assignment compatible.
      * </p>
      *
      * @param <T>            the type of the object to be constructed
      * @param klass          the class to be constructed.
      * @param args           actual argument array. May be null (this will result in calling the default constructor).
      * @param parameterTypes parameter types array
      * @return new instance of {@code klazz}
      * @throws NoSuchMethodException     if matching constructor cannot be found
      * @throws IllegalAccessException    thrown on the constructor's invocation
      * @throws InvocationTargetException thrown on the constructor's invocation
      * @throws InstantiationException    thrown on the constructor's invocation
      * @see Constructor#newInstance
      */
     public static <T> T invokeConstructor(final Class<T> klass, Object[] args, Class<?>[] parameterTypes)
             throws NoSuchMethodException, IllegalAccessException, InvocationTargetException, InstantiationException {
 
         if (parameterTypes == null) {
             parameterTypes = BeanUtils.EMPTY_CLASS_ARRAY;
         }
         if (args == null) {
             args = BeanUtils.EMPTY_OBJECT_ARRAY;
         }
 
         final Constructor<T> ctor = getMatchingAccessibleConstructor(klass, parameterTypes);
         if (null == ctor) {
             throw new NoSuchMethodException("No such accessible constructor on object: " + klass.getName());
         }
         return ctor.newInstance(args);
     }
 
     /**
      * <p>
      * Convenience method returning new instance of {@code klazz} using a single argument constructor. The formal parameter type is inferred from the actual
      * values of {@code arg}. See {@link #invokeExactConstructor(Class, Object[], Class[])} for more details.
      * </p>
      *
      * <p>
      * The signatures should match exactly.
      * </p>
      *
      * @param <T>   the type of the object to be constructed
      * @param klass the class to be constructed.
      * @param arg   the actual argument. May be null (this will result in calling the default constructor).
      * @return new instance of {@code klazz}
      * @throws NoSuchMethodException     If the constructor cannot be found
      * @throws IllegalAccessException    If an error occurs accessing the constructor
      * @throws InvocationTargetException If an error occurs invoking the constructor
      * @throws InstantiationException    If an error occurs instantiating the class
      * @see #invokeExactConstructor(Class, Object[], Class[])
      */
     public static <T> T invokeExactConstructor(final Class<T> klass, final Object arg)
             throws NoSuchMethodException, IllegalAccessException, InvocationTargetException, InstantiationException {
 
         final Object[] args = toArray(arg);
         return invokeExactConstructor(klass, args);
     }
 
     /**
      * <p>
      * Returns new instance of {@code klazz</code> created using the actual arguments <code>args}. The formal parameter types are inferred from the actual
      * values of {@code args}. See {@link #invokeExactConstructor(Class, Object[], Class[])} for more details.
      * </p>
      *
      * <p>
      * The signatures should match exactly.
      * </p>
      *
      * @param <T>   the type of the object to be constructed
      * @param klass the class to be constructed.
      * @param args  actual argument array. May be null (this will result in calling the default constructor).
      * @return new instance of {@code klazz}
      * @throws NoSuchMethodException     If the constructor cannot be found
      * @throws IllegalAccessException    If an error occurs accessing the constructor
      * @throws InvocationTargetException If an error occurs invoking the constructor
      * @throws InstantiationException    If an error occurs instantiating the class
      * @see #invokeExactConstructor(Class, Object[], Class[])
      */
     public static <T> T invokeExactConstructor(final Class<T> klass, Object[] args)
             throws NoSuchMethodException, IllegalAccessException, InvocationTargetException, InstantiationException {
 
         if (null == args) {
             args = BeanUtils.EMPTY_OBJECT_ARRAY;
         }
         final int arguments = args.length;
         final Class<?>[] parameterTypes = new Class[arguments];
         for (int i = 0; i < arguments; i++) {
             parameterTypes[i] = args[i].getClass();
         }
         return invokeExactConstructor(klass, args, parameterTypes);
     }
 
     /**
      * <p>
      * Returns new instance of {@code klazz} created using constructor with signature {@code parameterTypes} and actual arguments {@code args}.
      * </p>
      *
      * <p>
      * The signatures should match exactly.
      * </p>
      *
      * @param <T>            the type of the object to be constructed
      * @param klass          the class to be constructed.
      * @param args           actual argument array. May be null (this will result in calling the default constructor).
      * @param parameterTypes parameter types array
      * @return new instance of {@code klazz}
      * @throws NoSuchMethodException     if matching constructor cannot be found
      * @throws IllegalAccessException    thrown on the constructor's invocation
      * @throws InvocationTargetException thrown on the constructor's invocation
      * @throws InstantiationException    thrown on the constructor's invocation
      * @see Constructor#newInstance
      */
     public static <T> T invokeExactConstructor(final Class<T> klass, Object[] args, Class<?>[] parameterTypes)
             throws NoSuchMethodException, IllegalAccessException, InvocationTargetException, InstantiationException {
 
         if (args == null) {
             args = BeanUtils.EMPTY_OBJECT_ARRAY;
         }
 
         if (parameterTypes == null) {
             parameterTypes = BeanUtils.EMPTY_CLASS_ARRAY;
         }
 
         final Constructor<T> ctor = getAccessibleConstructor(klass, parameterTypes);
         if (null == ctor) {
             throw new NoSuchMethodException("No such accessible constructor on object: " + klass.getName());
         }
         return ctor.newInstance(args);
     }
 
     /**
      * Delegates to {@link Array#newInstance(Class, int)}.
      *
      * @param <T>           Component type.
      * @param componentType See {@link Array#newInstance(Class, int)}.
      * @param length        See {@link Array#newInstance(Class, int)}.
      * @return See {@link Array#newInstance(Class, int)}.
      */
     @SuppressWarnings("unchecked")
     public static <T> T[] newArray(final Class<T> componentType, final int length) {
         return (T[]) Array.newInstance(componentType, length);
     }
 
     private static Object[] toArray(final Object arg) {
         Object[] args = null;
         if (arg != null) {
             args = new Object[] { arg };
         }
         return args;
     }
 
 }