/*
 * Copyright (c) 2018, 2019, 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.
 */


package org.graalvm.compiler.core.test;

import java.lang.invoke.MethodHandles;
import java.lang.reflect.Method;
import java.security.ProtectionDomain;

import org.graalvm.compiler.serviceprovider.JavaVersionUtil;
import org.objectweb.asm.Opcodes;

import sun.misc.Unsafe;

public abstract class CustomizedBytecodePatternTest extends GraalCompilerTest implements Opcodes {

    protected Class<?> getClass(String className) throws ClassNotFoundException {
        return new CachedLoader(CustomizedBytecodePatternTest.class.getClassLoader(), className).findClass(className);
    }

    /**
     * @param className
     * @param lookUp lookup object with boot class load capability (required for jdk 9 and above)
     * @return loaded class
     * @throws ClassNotFoundException
     */
    protected Class<?> getClassBL(String className, MethodHandles.Lookup lookUp) throws ClassNotFoundException {
        byte[] gen = generateClass(className.replace('.', '/'));
        Method defineClass = null;
        Class<?> loadedClass = null;
        try {
            if (JavaVersionUtil.JAVA_SPEC <= 8) {
                defineClass = Unsafe.class.getDeclaredMethod("defineClass", String.class, byte[].class, int.class, int.class, ClassLoader.class, ProtectionDomain.class);
                loadedClass = (Class<?>) defineClass.invoke(UNSAFE, className, gen, 0, gen.length, null, null);
            } else {
                defineClass = MethodHandles.lookup().getClass().getDeclaredMethod("defineClass", byte[].class);
                loadedClass = (Class<?>) defineClass.invoke(lookUp, gen);
            }
        } catch (Exception e) {
            throw new ClassNotFoundException(className, e);
        }
        return loadedClass;
    }

    private class CachedLoader extends ClassLoader {

        final String className;
        Class<?> loaded;

        CachedLoader(ClassLoader parent, String className) {
            super(parent);
            this.className = className;
        }

        @Override
        protected Class<?> findClass(String name) throws ClassNotFoundException {
            if (name.equals(className)) {
                if (loaded == null) {
                    byte[] gen = generateClass(name.replace('.', '/'));
                    loaded = defineClass(name, gen, 0, gen.length);
                }
                return loaded;
            } else {
                return super.findClass(name);
            }
        }

    }

    protected abstract byte[] generateClass(String internalClassName);

}