/*
 * 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.BufferedInputStream;
import java.io.ByteArrayOutputStream;
import java.io.IOException;
import java.util.concurrent.Callable;
import java.util.Random;

import com.oracle.java.testlibrary.Asserts;
import com.oracle.java.testlibrary.ByteCodeLoader;
import com.oracle.java.testlibrary.InfiniteLoop;
import com.oracle.java.testlibrary.Utils;
import sun.hotspot.WhiteBox;

public abstract class Helper {
    public static final WhiteBox WB = WhiteBox.getWhiteBox();
    public static final Random R = Utils.getRandomInstance();

    private static final long THRESHOLD = WB.getIntxVMFlag("CompileThreshold");
    private static byte[] CLASS_DATA;
    static {
        try {
            CLASS_DATA = loadClassData(TestCaseImpl.class.getName());
        } catch (IOException e) {
            throw new Error("TESTBUG: cannot load class byte code", e);
        }
    }

    public static void startInfiniteLoopThread(Runnable action) {
        startInfiniteLoopThread(action, 0L);
    }

    public static void startInfiniteLoopThread(Runnable action, long millis) {
        Thread t = new Thread(new InfiniteLoop(action, millis));
        t.setDaemon(true);
        t.start();
    }

    public static int callMethod(Callable<Integer> callable) {
        int result = 0;
        for (int i = 0; i < THRESHOLD; ++i) {
            try {
                result = callable.call();
            } catch (Exception e) {
                throw new AssertionError(
                        "Exception occurred during test method execution", e);
            }
            Asserts.assertEQ(result, TestCaseImpl.EXPECTED_VALUE,
                    "Method returns unexpected value");
        }
        return result;
    }

    private static byte[] loadClassData(String name) throws IOException {
        try (BufferedInputStream in = new BufferedInputStream(
                ClassLoader.getSystemResourceAsStream(name.replace(".", "/")
                        + ".class"))) {
            ByteArrayOutputStream result = new ByteArrayOutputStream();
            byte[] buffer = new byte[1024];
            int read;
            while ((read = in.read(buffer)) != -1) {
                result.write(buffer, 0, read);
            }
            return result.toByteArray();
        }
    }

    public interface TestCase {

        public static TestCase get() {
            String className = TestCaseImpl.class.getName();
            try {
                Class clazz = ByteCodeLoader.load(className, CLASS_DATA);
                return (TestCase) clazz.newInstance();
            } catch (ReflectiveOperationException e) {
                throw new Error("TESTBUG: error while creating " + className
                        + " instance from reloaded class", e);
            }
        }

        Callable<Integer> getCallable();
        int method();
    }

    public static class TestCaseImpl implements TestCase {
        private static final int RETURN_VALUE = 42;
        private static final int RECURSION_DEPTH = 10;
        public static final int EXPECTED_VALUE = RETURN_VALUE * RECURSION_DEPTH;
        private volatile int i;
        public TestCaseImpl() {
        }

        @Override
        public Callable<Integer> getCallable() {
            return () -> {
                i = 0;
                return method();
            };
        }

        @Override
        public int method() {
            ++i;
            int result = RETURN_VALUE;
            if (i < RECURSION_DEPTH) {
                return result + method();
            }
            return result;
        }

    }

}