/**
 * Copyright 2012 International Business Machines Corp.
 * <p/>
 * See the NOTICE file distributed with this work for additional information
 * regarding copyright ownership. Licensed 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
 * <p/>
 * http://www.apache.org/licenses/LICENSE-2.0
 * <p/>
 * 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.batchee.container.util;

import java.io.IOException;
import java.io.InputStream;
import java.io.ObjectInputStream;
import java.io.ObjectStreamClass;
import java.lang.reflect.Proxy;

public class TCCLObjectInputStream extends ObjectInputStream {
    private static final BlacklistClassResolver BLACKLIST_CLASSES = new BlacklistClassResolver(
        toArray(System.getProperty(
            "batchee.serialization.class.blacklist",
            "org.codehaus.groovy.runtime.,org.apache.commons.collections.functors.,org.apache.xalan")),
        toArray(System.getProperty("batchee.serialization.class.whitelist")));

    private final ClassLoader tccl;

    public TCCLObjectInputStream(final InputStream in) throws IOException {
        super(in);
        tccl = Thread.currentThread().getContextClassLoader();
    }

    @Override
    protected Class<?> resolveClass(final ObjectStreamClass desc) throws ClassNotFoundException {
        return Class.forName(BLACKLIST_CLASSES.check(desc.getName()), false, tccl);
    }

    @Override
    protected Class resolveProxyClass(final String[] interfaces) throws IOException, ClassNotFoundException {
        final Class[] cinterfaces = new Class[interfaces.length];
        for (int i = 0; i < interfaces.length; i++) {
            cinterfaces[i] = Class.forName(interfaces[i], false, tccl);
        }

        try {
            return Proxy.getProxyClass(tccl, cinterfaces);
        } catch (IllegalArgumentException e) {
            throw new ClassNotFoundException(null, e);
        }
    }

    private static String[] toArray(final String property) {
        return property == null ? null : property.split(" *, *");
    }

    private static class BlacklistClassResolver {
        private final String[] blacklist;
        private final String[] whitelist;

        protected BlacklistClassResolver(final String[] blacklist, final String[] whitelist) {
            this.whitelist = whitelist;
            this.blacklist = blacklist;
        }

        protected boolean isBlacklisted(final String name) {
            return (whitelist != null && !contains(whitelist, name)) || contains(blacklist, name);
        }

        public final String check(final String name) {
            if (isBlacklisted(name)) {
                throw new SecurityException(name + " is not whitelisted as deserialisable, prevented before loading.");
            }
            return name;
        }

        private static String[] toArray(final String property) {
            return property == null ? null : property.split(" *, *");
        }

        private static boolean contains(final String[] list, String name) {
            if (list != null) {
                for (final String white : list) {
                    if (name.startsWith(white)) {
                        return true;
                    }
                }
            }
            return false;
        }
    }
}
