/*

 * Copyright (c) 2014, 2016, 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.

 */

/*

 * @test

 * @summary Verify correctnes of the random generator from Utility.java

 * @library /test/lib

 * @modules java.base/jdk.internal.misc

 *          java.management

 * @run driver RandomGeneratorTest SAME_SEED

 * @run driver RandomGeneratorTest NO_SEED

 * @run driver RandomGeneratorTest DIFFERENT_SEED

 */

import java.io.FileWriter;

import java.io.IOException;

import java.io.PrintWriter;

import java.util.ArrayList;

import java.util.List;

import java.util.Random;

import jdk.test.lib.process.OutputAnalyzer;

import jdk.test.lib.process.ProcessTools;

import jdk.test.lib.Utils;

/**

 * The test verifies correctness of work {@link jdk.test.lib.Utils#getRandomInstance()}.

 * Test works in three modes: same seed provided, no seed provided and

 * different seed provided. In the first case the test expects that all random numbers

 * will be repeated in all next iterations. For other two modes test expects that

 * randomly generated numbers differ from original.

 */

public class RandomGeneratorTest {

    private static final String SEED_VM_OPTION = "-D" + Utils.SEED_PROPERTY_NAME + "=";

    public static void main( String[] args) throws Throwable {

        if (args.length == 0) {

            throw new Error("TESTBUG: No test mode provided.");

        }

        SeedOption seedOpt = SeedOption.valueOf(args[0]);

        List<String> jvmArgs = new ArrayList<String>();

        String optStr = seedOpt.getSeedOption();

        if (optStr != null) {

            jvmArgs.add(optStr);

        }

        jvmArgs.add(RandomRunner.class.getName());

        String origFileName = seedOpt.name() + "_orig";

        jvmArgs.add(origFileName);

        int fileNameIndex = jvmArgs.size() - 1;

        String[] cmdLineArgs = jvmArgs.toArray(new String[jvmArgs.size()]);

        ProcessTools.executeTestJvm(cmdLineArgs).shouldHaveExitValue(0);

        String etalon = Utils.fileAsString(origFileName).trim();

        cmdLineArgs[fileNameIndex] = seedOpt.name();

        seedOpt.verify(etalon, cmdLineArgs);

    }

    /**

     * The utility enum helps to generate an appropriate string that should be passed

     * to the command line depends on the testing mode. It is also responsible for the result

     * validation.

     */

    private enum SeedOption {

        SAME_SEED {

            @Override

            public String getSeedOption() {

                return SEED_VM_OPTION + Utils.SEED;

            }

            @Override

            protected boolean isOutputExpected(String orig, String output) {

                return output.equals(orig);

            }

        },

        DIFFERENT_SEED {

            @Override

            public String getSeedOption() {

                return SEED_VM_OPTION + Utils.getRandomInstance().nextLong();

            }

            @Override

            public void verify(String orig, String[] cmdLine) {

                cmdLine[0] = getSeedOption();

                super.verify(orig, cmdLine);

            }

        },

        NO_SEED {

            @Override

            public String getSeedOption() {

                return null;

            }

        };

        /**

         * Generates a string to be added as a command line argument.

         * It contains "-D" prefix, system property name, '=' sign

         * and seed value.

         * @return command line argument

         */

        public abstract String getSeedOption();

        protected boolean isOutputExpected(String orig, String output) {

            return !output.equals(orig);

        }

        /**

         * Verifies that the original output meets expectations

         * depending on the test mode. It compares the output of second execution

         * to original one.

         * @param orig original output

         * @param cmdLine command line arguments

         * @throws Throwable - Throws an exception in case test failure.

         */

        public void verify(String orig, String[] cmdLine) {

            String output;

            OutputAnalyzer oa;

            try {

                oa = ProcessTools.executeTestJvm(cmdLine);

            } catch (Throwable t) {

                throw new Error("TESTBUG: Unexpedted exception during jvm execution.", t);

            }

            oa.shouldHaveExitValue(0);

            try {

                output = Utils.fileAsString(name()).trim();

            } catch (IOException ioe) {

                throw new Error("TESTBUG: Problem during IO operation with file: " + name(), ioe);

            }

            if (!isOutputExpected(orig, output)) {

                System.err.println("Initial output: " + orig);

                System.err.println("Second run output: " + output);

                throw new AssertionError("Unexpected random number sequence for mode: " + this.name());

            }

        }

    }

    /**

     * The helper class generates several random numbers

     * and put results to a file. The file name came as first

     * command line argument.

     */

    public static class RandomRunner {

        private static final int COUNT = 10;

        public static void main(String[] args) {

            StringBuilder sb = new StringBuilder();

            Random rng = Utils.getRandomInstance();

            for (int i = 0; i < COUNT; i++) {

                sb.append(rng.nextLong()).append(' ');

            }

            try (PrintWriter pw = new PrintWriter(new FileWriter(args[0]))) {

                pw.write(sb.toString());

            } catch (IOException ioe) {

                throw new Error("TESTBUG: Problem during IO operation with file: " + args[0], ioe);

            }

        }

    }

}