/*
 * Copyright 2014-2020 Real Logic Limited.
 *
 * 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
 *
 * https://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.agrona.generation;

import javax.tools.FileObject;
import javax.tools.ForwardingJavaFileManager;
import javax.tools.JavaFileManager;
import javax.tools.JavaFileObject;
import java.security.SecureClassLoader;
import java.util.HashMap;
import java.util.Map;

/**
 * {@link ForwardingJavaFileManager} for storing class files which can be looked up by name.
 *
 * @param <M> the kind of file manager forwarded to by this object.
 */
public class ClassFileManager<M extends JavaFileManager> extends ForwardingJavaFileManager<M>
{
    private final Map<String, JavaClassObject> classObjectByNameMap = new HashMap<>();

    public ClassFileManager(final M standardManager)
    {
        super(standardManager);
    }

    /**
     * {@inheritDoc}
     */
    public ClassLoader getClassLoader(final Location location)
    {
        return new SecureClassLoader()
        {
            protected Class<?> findClass(final String name)
            {
                final byte[] buffer = classObjectByNameMap.get(name).getBytes();
                return super.defineClass(name, buffer, 0, buffer.length);
            }
        };
    }

    /**
     * {@inheritDoc}
     */
    public JavaFileObject getJavaFileForOutput(
        final Location location, final String className, final JavaFileObject.Kind kind, final FileObject sibling)
    {
        final JavaClassObject javaClassObject = new JavaClassObject(className, kind);
        classObjectByNameMap.put(className, javaClassObject);

        return javaClassObject;
    }
}