/*

 * 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 final class Helper {

    public static final WhiteBox WHITE_BOX = WhiteBox.getWhiteBox();

    public static final Random RNG = Utils.getRandomInstance();

    private static final long THRESHOLD = WHITE_BOX.getIntxVMFlag("CompileThreshold");

    private static final String TEST_CASE_IMPL_CLASS_NAME = "Helper$TestCaseImpl";

    private static byte[] CLASS_DATA;

    static {

        try {

            CLASS_DATA = loadClassData(TEST_CASE_IMPL_CLASS_NAME);

        } catch (IOException e) {

            throw new Error("TESTBUG: cannot load class byte code", e);

        }

    }

    private Helper() {

    }

    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 expected) {

        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, expected, "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() {

            try {

                Class clazz = ByteCodeLoader.load(

                        TEST_CASE_IMPL_CLASS_NAME, CLASS_DATA);

                return (TestCase) clazz.newInstance();

            } catch (ReflectiveOperationException e) {

                throw new Error(String.format(

                        "TESTBUG: error while creating %s instance from reloaded class",

                        TEST_CASE_IMPL_CLASS_NAME), e);

            }

        }

        Callable<Integer> getCallable();

        int method();

        int expectedValue();

    }

    public static class TestCaseImpl implements TestCase {

        private static final int RETURN_VALUE = 42;

        private static final int RECURSION_DEPTH = 10;

        private volatile int i;

        @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;

        }

        @Override

        public int expectedValue() {

            return RETURN_VALUE * RECURSION_DEPTH;

        }

    }

}