/*
 * Copyright (c) 2016, 2018, Oracle and/or its affiliates. All rights reserved.
 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
 *
 * The Universal Permissive License (UPL), Version 1.0
 *
 * Subject to the condition set forth below, permission is hereby granted to any
 * person obtaining a copy of this software, associated documentation and/or
 * data (collectively the "Software"), free of charge and under any and all
 * copyright rights in the Software, and any and all patent rights owned or
 * freely licensable by each licensor hereunder covering either (i) the
 * unmodified Software as contributed to or provided by such licensor, or (ii)
 * the Larger Works (as defined below), to deal in both
 *
 * (a) the Software, and
 *
 * (b) any piece of software and/or hardware listed in the lrgrwrks.txt file if
 * one is included with the Software each a "Larger Work" to which the Software
 * is contributed by such licensors),
 *
 * without restriction, including without limitation the rights to copy, create
 * derivative works of, display, perform, and distribute the Software and make,
 * use, sell, offer for sale, import, export, have made, and have sold the
 * Software and the Larger Work(s), and to sublicense the foregoing rights on
 * either these or other terms.
 *
 * This license is subject to the following condition:
 *
 * The above copyright notice and either this complete permission notice or at a
 * minimum a reference to the UPL must be included in all copies or substantial
 * portions of the Software.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
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package com.oracle.truffle.api.test.host;

import java.io.ByteArrayOutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.lang.reflect.InvocationTargetException;
import java.net.URLClassLoader;

import org.junit.runners.BlockJUnit4ClassRunner;
import org.junit.runners.model.InitializationError;

public final class SeparateClassloaderTestRunner extends BlockJUnit4ClassRunner {
    public SeparateClassloaderTestRunner(Class<?> clazz) throws InitializationError {
        super(getFromTestClassloader(clazz));
    }

    private static final String JAVA_INTEROP_PACKAGE = "com.oracle.truffle.api.interop.java";

    private static final boolean JDK8OrEarlier = System.getProperty("java.specification.version").compareTo("1.9") < 0;

    private static Class<?> getFromTestClassloader(Class<?> clazz) throws InitializationError {
        try {
            ClassLoader testClassLoader = JDK8OrEarlier ? new PreJDK9TestClassLoader() : new JDK9TestClassLoader();
            return Class.forName(clazz.getName(), true, testClassLoader);
        } catch (ClassNotFoundException e) {
            throw new InitializationError(e);
        }
    }

    public static final class Theories extends org.junit.experimental.theories.Theories {
        public Theories(Class<?> clazz) throws InitializationError {
            super(getFromTestClassloader(clazz));
        }
    }

    private static class PreJDK9TestClassLoader extends URLClassLoader {
        PreJDK9TestClassLoader() {
            super(((URLClassLoader) getSystemClassLoader()).getURLs());
        }

        @Override
        public Class<?> loadClass(String name) throws ClassNotFoundException {
            if (name.startsWith(JAVA_INTEROP_PACKAGE)) {
                return super.findClass(name);
            }
            return super.loadClass(name);
        }
    }

    
As of JDK9, Truffle API is deployed in a module (possibly the unnamed module) so to retrieve
the class file bytes for separate class loading requires using module API. The latter is done
via reflection so that this class still compiles on JDK8.
/**
     * As of JDK9, Truffle API is deployed in a module (possibly the unnamed module) so to retrieve
     * the class file bytes for separate class loading requires using module API. The latter is done
     * via reflection so that this class still compiles on JDK8.
     */
    private static class JDK9TestClassLoader extends ClassLoader {

        @Override
        public Class<?> loadClass(String name) throws ClassNotFoundException {
            if (name.startsWith(JAVA_INTEROP_PACKAGE)) {
                return findClassInModule(name);
            }
            return super.loadClass(name);
        }

        
Reflective call to java.lang.Class.getModule(). /**
         * Reflective call to {@code java.lang.Class.getModule()}.
         */
        private static Object getModule(Class<?> cls) {
            try {
                return Class.class.getMethod("getModule").invoke(cls);
            } catch (IllegalAccessException | IllegalArgumentException | InvocationTargetException | NoSuchMethodException | SecurityException e) {
                throw new AssertionError(e);
            }
        }

        
Reflective call to java.lang.reflect.Module.getResourceAsStream(String name). /**
         * Reflective call to {@code java.lang.reflect.Module.getResourceAsStream(String name)}.
         */
        private static InputStream getResourceAsStream(Object module, String name) {
            try {
                return (InputStream) module.getClass().getMethod("getResourceAsStream", String.class).invoke(module, name);
            } catch (IllegalAccessException | IllegalArgumentException | InvocationTargetException | NoSuchMethodException | SecurityException e) {
                throw new AssertionError(e);
            }
        }

        protected Class<?> findClassInModule(String name) throws ClassNotFoundException {
            Class<?> classInModule = super.loadClass(name);
            Object module = getModule(classInModule);
            String res = name.replace('.', '/') + ".class";
            InputStream is = getResourceAsStream(module, res);
            if (is == null) {
                throw new ClassNotFoundException(name);
            }
            byte[] arr = readAllBytes(name, is);
            return defineClass(name, arr, 0, arr.length, getClass().getProtectionDomain());
        }
    }

    static byte[] readAllBytes(String name, InputStream is) throws ClassNotFoundException {
        ByteArrayOutputStream os = new ByteArrayOutputStream();
        byte[] arr = new byte[4096];
        for (;;) {
            int len;
            try {
                len = is.read(arr);
            } catch (IOException ex) {
                throw new ClassNotFoundException(name);
            }
            if (len < 0) {
                break;
            }
            os.write(arr, 0, len);
        }
        arr = os.toByteArray();
        return arr;
    }
}