/*
 * Copyright 2009 Red Hat, Inc.
 *
 * Red Hat 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.jboss.netty.handler.codec.serialization;

import java.io.EOFException;
import java.io.IOException;
import java.io.InputStream;
import java.io.ObjectInputStream;
import java.io.ObjectStreamClass;
import java.io.StreamCorruptedException;
import java.util.HashMap;
import java.util.Map;

/**
 * @author <a href="http://www.jboss.org/netty/">The Netty Project</a>
 * @author <a href="http://gleamynode.net/">Trustin Lee</a>
 *
 * @version $Rev: 2080 $, $Date: 2010-01-26 18:04:19 +0900 (Tue, 26 Jan 2010) $
 *
 */
class CompactObjectInputStream extends ObjectInputStream {

    private final Map<String, Class<?>> classCache = new HashMap<String, Class<?>>();
    private final ClassLoader classLoader;

    CompactObjectInputStream(InputStream in) throws IOException {
        this(in, null);
    }

    CompactObjectInputStream(InputStream in, ClassLoader classLoader) throws IOException {
        super(in);
        this.classLoader = classLoader;
    }

    @Override
    protected void readStreamHeader() throws IOException,
            StreamCorruptedException {
        int version = readByte() & 0xFF;
        if (version != STREAM_VERSION) {
            throw new StreamCorruptedException(
                    "Unsupported version: " + version);
        }
    }

    @Override
    protected ObjectStreamClass readClassDescriptor()
            throws IOException, ClassNotFoundException {
        int type = read();
        if (type < 0) {
            throw new EOFException();
        }
        switch (type) {
        case CompactObjectOutputStream.TYPE_FAT_DESCRIPTOR:
            return super.readClassDescriptor();
        case CompactObjectOutputStream.TYPE_THIN_DESCRIPTOR:
            String className = readUTF();
            Class<?> clazz = loadClass(className);
            return ObjectStreamClass.lookupAny(clazz);
        default:
            throw new StreamCorruptedException(
                    "Unexpected class descriptor type: " + type);
        }
    }

    @Override
    protected Class<?> resolveClass(ObjectStreamClass desc) throws IOException, ClassNotFoundException {
        // Query the cache first.
        String className = desc.getName();
        Class<?> clazz = classCache.get(className);
        if (clazz != null) {
            return clazz;
        }

        // And then try to resolve.
        try {
            clazz = loadClass(className);
        } catch (ClassNotFoundException ex) {
            clazz = super.resolveClass(desc);
        }

        classCache.put(className, clazz);
        return clazz;
    }

    protected Class<?> loadClass(String className) throws ClassNotFoundException {
        // Query the cache first.
        Class<?> clazz;
        clazz = classCache.get(className);
        if (clazz != null) {
            return clazz;
        }

        // And then try to load.
        ClassLoader classLoader = this.classLoader;
        if (classLoader == null) {
            classLoader = Thread.currentThread().getContextClassLoader();
        }

        if (classLoader != null) {
            clazz = classLoader.loadClass(className);
        } else {
            clazz = Class.forName(className);
        }

        classCache.put(className, clazz);
        return clazz;
    }
}
