/*

 * 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.Factory;

import org.apache.commons.collections4.FunctorException;

/**

 * Factory 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 InstantiateFactory<T> implements Factory<T> {

    /** The class to create */

    private final Class<T> iClassToInstantiate;

    /** The constructor parameter types */

    private final Class<?>[] iParamTypes;

    /** The constructor arguments */

    private final Object[] iArgs;

    /** The constructor */

    private transient Constructor<T> iConstructor = null;

    /**

     * Factory method that performs validation.

     *

     * @param <T>  the type the factory creates

     * @param classToInstantiate  the class to instantiate, not null

     * @param paramTypes  the constructor parameter types, cloned

     * @param args  the constructor arguments, cloned

     * @return a new instantiate factory

     * @throws NullPointerException if classToInstantiate is null

     * @throws IllegalArgumentException if paramTypes does not match args

     */

    public static <T> Factory<T> instantiateFactory(final Class<T> classToInstantiate,

                                                    final Class<?>[] paramTypes,

                                                    final Object[] args) {

        if (classToInstantiate == null) {

            throw new NullPointerException("Class to instantiate must not be null");

        }

        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 InstantiateFactory<>(classToInstantiate);

        }

        return new InstantiateFactory<>(classToInstantiate, paramTypes, args);

    }

    /**

     * Constructor that performs no validation.

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

     *

     * @param classToInstantiate  the class to instantiate

     */

    public InstantiateFactory(final Class<T> classToInstantiate) {

        super();

        iClassToInstantiate = classToInstantiate;

        iParamTypes = null;

        iArgs = null;

        findConstructor();

    }

    /**

     * Constructor that performs no validation.

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

     *

     * @param classToInstantiate  the class to instantiate

     * @param paramTypes  the constructor parameter types, cloned

     * @param args  the constructor arguments, cloned

     */

    public InstantiateFactory(final Class<T> classToInstantiate, final Class<?>[] paramTypes, final Object[] args) {

        super();

        iClassToInstantiate = classToInstantiate;

        iParamTypes = paramTypes.clone();

        iArgs = args.clone();

        findConstructor();

    }

    /**

     * Find the Constructor for the class specified.

     */

    private void findConstructor() {

        try {

            iConstructor = iClassToInstantiate.getConstructor(iParamTypes);

        } catch (final NoSuchMethodException ex) {

            throw new IllegalArgumentException("InstantiateFactory: The constructor must exist and be public ");

        }

    }

    /**

     * Creates an object using the stored constructor.

     *

     * @return the new object

     */

    @Override

    public T create() {

        // needed for post-serialization

        if (iConstructor == null) {

            findConstructor();

        }

        try {

            return iConstructor.newInstance(iArgs);

        } catch (final InstantiationException ex) {

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

        } catch (final IllegalAccessException ex) {

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

        } catch (final InvocationTargetException ex) {

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

        }

    }

}