/*

 * 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.functors;

import java.lang.reflect.Constructor;

import java.lang.reflect.InvocationTargetException;

import org.apache.commons.collections4.FunctorException;

import org.apache.commons.collections4.Transformer;

/**

 * Transformer implementation that creates a new object instance by reflection.

 * <p>

 * <b>WARNING:</b> from v4.1 onwards this class will <b>not</b> be serializable anymore

 * in order to prevent potential remote code execution exploits. Please refer to

 * <a href="https://issues.apache.org/jira/browse/COLLECTIONS-580">COLLECTIONS-580</a>

 * for more details.

 * </p>

 *

 * @since 3.0

 */

public class InstantiateTransformer<T> implements Transformer<Class<? extends T>, T> {

    /** Singleton instance that uses the no arg constructor */

    @SuppressWarnings("rawtypes")

    private static final Transformer NO_ARG_INSTANCE = new InstantiateTransformer<>();

    /** The constructor parameter types */

    private final Class<?>[] iParamTypes;

    /** The constructor arguments */

    private final Object[] iArgs;

    /**

     * Get a typed no-arg instance.

     *

     * @param <T>  the type of the objects to be created

     * @return Transformer<Class<? extends T>, T>

     */

    public static <T> Transformer<Class<? extends T>, T> instantiateTransformer() {

        return NO_ARG_INSTANCE;

    }

    /**

     * Transformer method that performs validation.

     *

     * @param <T>  the type of the objects to be created

     * @param paramTypes  the constructor parameter types

     * @param args  the constructor arguments

     * @return an instantiate transformer

     * @throws IllegalArgumentException if paramTypes does not match args

     */

    public static <T> Transformer<Class<? extends T>, T> instantiateTransformer(final Class<?>[] paramTypes,

                                                                                final Object[] args) {

        if (((paramTypes == null) && (args != null))

            || ((paramTypes != null) && (args == null))

            || ((paramTypes != null) && (args != null) && (paramTypes.length != args.length))) {

            throw new IllegalArgumentException("Parameter types must match the arguments");

        }

        if (paramTypes == null || paramTypes.length == 0) {

            return new InstantiateTransformer<>();

        }

        return new InstantiateTransformer<>(paramTypes, args);

    }

    /**

     * Constructor for no arg instance.

     */

    private InstantiateTransformer() {

        super();

        iParamTypes = null;

        iArgs = null;

    }

    /**

     * Constructor that performs no validation.

     * Use <code>instantiateTransformer</code> if you want that.

     * <p>

     * Note: from 4.0, the input parameters will be cloned

     *

     * @param paramTypes  the constructor parameter types

     * @param args  the constructor arguments

     */

    public InstantiateTransformer(final Class<?>[] paramTypes, final Object[] args) {

        super();

        iParamTypes = paramTypes != null ? paramTypes.clone() : null;

        iArgs = args != null ? args.clone() : null;

    }

    /**

     * Transforms the input Class object to a result by instantiation.

     *

     * @param input  the input object to transform

     * @return the transformed result

     */

    @Override

    public T transform(final Class<? extends T> input) {

        try {

            if (input == null) {

                throw new FunctorException(

                    "InstantiateTransformer: Input object was not an instanceof Class, it was a null object");

            }

            final Constructor<? extends T> con = input.getConstructor(iParamTypes);

            return con.newInstance(iArgs);

        } catch (final NoSuchMethodException ex) {

            throw new FunctorException("InstantiateTransformer: The constructor must exist and be public ");

        } catch (final InstantiationException ex) {

            throw new FunctorException("InstantiateTransformer: InstantiationException", ex);

        } catch (final IllegalAccessException ex) {

            throw new FunctorException("InstantiateTransformer: Constructor must be public", ex);

        } catch (final InvocationTargetException ex) {

            throw new FunctorException("InstantiateTransformer: Constructor threw an exception", ex);

        }

    }

}