/*

 * Copyright (c) 2014, Oracle and/or its affiliates. All rights reserved.

 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.

 *

 * This code is free software; you can redistribute it and/or modify it

 * under the terms of the GNU General Public License version 2 only, as

 * published by the Free Software Foundation.

 *

 * This code is distributed in the hope that it will be useful, but WITHOUT

 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or

 * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License

 * version 2 for more details (a copy is included in the LICENSE file that

 * accompanied this code).

 *

 * You should have received a copy of the GNU General Public License version

 * 2 along with this work; if not, write to the Free Software Foundation,

 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.

 *

 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA

 * or visit www.oracle.com if you need additional information or have any

 * questions.

 */

import java.io.*;

import java.net.URI;

import java.util.HashMap;

import java.util.Map;

import javax.tools.*;

import static java.util.Collections.unmodifiableMap;

/**

 * class for storing source/byte code in memory.

 */

public class InMemoryFileManager extends ForwardingJavaFileManager {

    private final Map<String, InMemoryJavaFile> classes = new HashMap<>();

    public InMemoryFileManager(JavaFileManager fileManager) {

        super(fileManager);

    }

    @Override

    public JavaFileObject getJavaFileForOutput(Location location, String className, JavaFileObject.Kind kind, FileObject sibling) throws IOException {

        InMemoryJavaFile javaFile = new InMemoryJavaFile(className);

        classes.put(className, javaFile);

        return javaFile;

    }

    @Override

    public ClassLoader getClassLoader(Location location) {

        return new ClassLoader(this.getClass().getClassLoader()) {

            @Override

            protected Class<?> findClass(String name) throws ClassNotFoundException {

                InMemoryJavaFile classData = classes.get(name);

                if (classData == null) throw new ClassNotFoundException(name);

                byte[] byteCode = classData.bos.toByteArray();

                return defineClass(name, byteCode, 0, byteCode.length);

            }

        };

    }

    public Map<String, ? extends JavaFileObject> getClasses() {

        return unmodifiableMap(classes);

    }

    private static class InMemoryJavaFile extends SimpleJavaFileObject {

        private final ByteArrayOutputStream bos =

                new ByteArrayOutputStream();

        protected InMemoryJavaFile(String name) {

            super(URI.create("mfm:///" + name.replace('.', '/') + Kind.CLASS.extension), Kind.CLASS);

        }

        @Override

        public OutputStream openOutputStream() throws IOException {

            return bos;

        }

        @Override

        public InputStream openInputStream() throws IOException {

            return new ByteArrayInputStream(bos.toByteArray());

        }

    }

}