/*

 * Copyright (c) 2007, 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

 * @bug     6359979

 * @summary Compare List implementations for identical behavior

 * @author  Martin Buchholz

 */

import java.io.*;

import java.util.*;

import java.util.concurrent.*;

import static java.util.Collections.*;

@SuppressWarnings("unchecked")

public class LockStep {

    final int DEFAULT_SIZE = 5;

    int size;           // Running time is O(size**2)

    int intArg(String[] args, int i, int defaultValue) {

        return args.length > i ? Integer.parseInt(args[i]) : defaultValue;

    }

    boolean maybe(int n) { return rnd.nextInt(n) == 0; }

    void test(String[] args) {

        size = intArg(args, 0, DEFAULT_SIZE);

        lockSteps(new ArrayList(),

                  new LinkedList(),

                  new Vector());

    }

    void equalLists(List... lists) {

        for (List list : lists)

            equalLists(list, lists[0]);

    }

    void equalLists(List x, List y) {

        equal(x, y);

        equal(y, x);

        equal(x.size(),     y.size());

        equal(x.isEmpty(),  y.isEmpty());

        equal(x.hashCode(), y.hashCode());

        equal(x.toString(), y.toString());

        equal(x.toArray(),  y.toArray());

    }

    void lockSteps(List... lists) {

        for (int i = 0; i < lists.length; i++)

            if (maybe(4)) lists[i] = serialClone(lists[i]);

        for (final List list : lists)

            testEmptyList(list);

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

            ListFrobber adder = randomAdder();

            for (final List list : lists) {

                adder.frob(list);

                equal(list.size(), i+1);

            }

            equalLists(lists);

        }

        {

            final ListFrobber adder = randomAdder();

            final ListFrobber remover = randomRemover();

            for (final List list : lists) {

                THROWS(ConcurrentModificationException.class,

                       new F(){void f(){

                           Iterator it = list.iterator();

                           adder.frob(list);

                           it.next();}},

                       new F(){void f(){

                           Iterator it = asSubList(list).iterator();

                           remover.frob(list);

                           it.next();}},

                       new F(){void f(){

                           Iterator it = asSubList(asSubList(list)).iterator();

                           adder.frob(list);

                           it.next();}},

                       new F(){void f(){

                           List subList = asSubList(list);

                           remover.frob(list);

                           subList.get(0);}},

                       new F(){void f(){

                           List sl = asSubList(list);

                           List ssl = asSubList(sl);

                           adder.frob(sl);

                           ssl.get(0);}},

                       new F(){void f(){

                           List sl = asSubList(list);

                           List ssl = asSubList(sl);

                           remover.frob(sl);

                           ssl.get(0);}});

            }

        }

        for (final List l : lists) {

            final List sl = asSubList(l);

            final List ssl = asSubList(sl);

            ssl.add(0, 42);

            equal(ssl.get(0), 42);

            equal(sl.get(0), 42);

            equal(l.get(0), 42);

            final int s = l.size();

            final int rndIndex = rnd.nextInt(l.size());

            THROWS(IndexOutOfBoundsException.class,

                   new F(){void f(){l.subList(rndIndex, rndIndex).get(0);}},

                   new F(){void f(){l.subList(s/2, s).get(s/2 + 1);}},

                   new F(){void f(){l.subList(s/2, s).get(-1);}}

                   );

            THROWS(IllegalArgumentException.class,

                   new F(){void f(){  l.subList(1, 0);}},

                   new F(){void f(){ sl.subList(1, 0);}},

                   new F(){void f(){ssl.subList(1, 0);}});

        }

        equalLists(lists);

        for (final List list : lists) {

            equalLists(list, asSubList(list));

            equalLists(list, asSubList(asSubList(list)));

        }

        for (final List list : lists)

            System.out.println(list);

        for (int i = lists[0].size(); i > 0; i--) {

            ListFrobber remover = randomRemover();

            for (final List list : lists)

                remover.frob(list);

            equalLists(lists);

        }

    }

    <T> List<T> asSubList(List<T> list) {

        return list.subList(0, list.size());

    }

    void testEmptyCollection(Collection<?> c) {

        check(c.isEmpty());

        equal(c.size(), 0);

        equal(c.toString(),"[]");

        equal(c.toArray().length, 0);

        equal(c.toArray(new Object[0]).length, 0);

        Object[] a = new Object[1]; a[0] = Boolean.TRUE;

        equal(c.toArray(a), a);

        equal(a[0], null);

    }

    void testEmptyList(List list) {

        testEmptyCollection(list);

        equal(list.hashCode(), 1);

        equal(list, Collections.emptyList());

    }

    final Random rnd = new Random();

    abstract class ListFrobber { abstract void frob(List l); }

    ListFrobber randomAdder() {

        final Integer e = rnd.nextInt(1024);

        final int subListCount = rnd.nextInt(3);

        final boolean atBeginning = rnd.nextBoolean();

        final boolean useIterator = rnd.nextBoolean();

        final boolean simpleIterator = rnd.nextBoolean();

        return new ListFrobber() {void frob(List l) {

            final int s = l.size();

            List ll = l;

            for (int i = 0; i < subListCount; i++)

                ll = asSubList(ll);

            if (! useIterator) {

                if (atBeginning) {

                    switch (rnd.nextInt(3)) {

                    case 0: ll.add(0, e); break;

                    case 1: ll.subList(0, rnd.nextInt(s+1)).add(0, e); break;

                    case 2: ll.subList(0, rnd.nextInt(s+1)).subList(0,0).add(0,e); break;

                    default: throw new Error();

                    }

                } else {

                    switch (rnd.nextInt(3)) {

                    case 0: check(ll.add(e)); break;

                    case 1: ll.subList(s/2, s).add(s - s/2, e); break;

                    case 2: ll.subList(s, s).subList(0, 0).add(0, e); break;

                    default: throw new Error();

                    }

                }

            } else {

                if (atBeginning) {

                    ListIterator it = ll.listIterator();

                    equal(it.nextIndex(), 0);

                    check(! it.hasPrevious());

                    it.add(e);

                    equal(it.previousIndex(), 0);

                    equal(it.nextIndex(), 1);

                    check(it.hasPrevious());

                } else {

                    final int siz = ll.size();

                    ListIterator it = ll.listIterator(siz);

                    equal(it.previousIndex(), siz-1);

                    check(! it.hasNext());

                    it.add(e);

                    equal(it.previousIndex(), siz);

                    equal(it.nextIndex(), siz+1);

                    check(! it.hasNext());

                    check(it.hasPrevious());

                }

            }}};

    }

    ListFrobber randomRemover() {

        final int position = rnd.nextInt(3);

        final int subListCount = rnd.nextInt(3);

        return new ListFrobber() {void frob(List l) {

            final int s = l.size();

            List ll = l;

            for (int i = 0; i < subListCount; i++)

                ll = asSubList(ll);

            switch (position) {

            case 0: // beginning

                switch (rnd.nextInt(3)) {

                case 0: ll.remove(0); break;

                case 1: {

                    final Iterator it = ll.iterator();

                    check(it.hasNext());

                    THROWS(IllegalStateException.class,

                           new F(){void f(){it.remove();}});

                    it.next();

                    it.remove();

                    THROWS(IllegalStateException.class,

                           new F(){void f(){it.remove();}});

                    break;}

                case 2: {

                    final ListIterator it = ll.listIterator();

                    check(it.hasNext());

                    THROWS(IllegalStateException.class,

                           new F(){void f(){it.remove();}});

                    it.next();

                    it.remove();

                    THROWS(IllegalStateException.class,

                           new F(){void f(){it.remove();}});

                    break;}

                default: throw new Error();

                }

                break;

            case 1: // midpoint

                switch (rnd.nextInt(3)) {

                case 0: ll.remove(s/2); break;

                case 1: {

                    final ListIterator it = ll.listIterator(s/2);

                    it.next();

                    it.remove();

                    break;

                }

                case 2: {

                    final ListIterator it = ll.listIterator(s/2+1);

                    it.previous();

                    it.remove();

                    break;

                }

                default: throw new Error();

                }

                break;

            case 2: // end

                switch (rnd.nextInt(3)) {

                case 0: ll.remove(s-1); break;

                case 1: ll.subList(s-1, s).clear(); break;

                case 2:

                    final ListIterator it = ll.listIterator(s);

                    check(! it.hasNext());

                    check(it.hasPrevious());

                    THROWS(IllegalStateException.class,

                           new F(){void f(){it.remove();}});

                    it.previous();

                    equal(it.nextIndex(), s-1);

                    check(it.hasNext());

                    it.remove();

                    equal(it.nextIndex(), s-1);

                    check(! it.hasNext());

                    THROWS(IllegalStateException.class,

                           new F(){void f(){it.remove();}});

                    break;

                default: throw new Error();

                }

                break;

            default: throw new Error();

            }}};

    }

    //--------------------- Infrastructure ---------------------------

    volatile int passed = 0, failed = 0;

    void pass() {passed++;}

    void fail() {failed++; Thread.dumpStack();}

    void fail(String msg) {System.err.println(msg); fail();}

    void unexpected(Throwable t) {failed++; t.printStackTrace();}

    void check(boolean cond) {if (cond) pass(); else fail();}

    void equal(Object x, Object y) {

        if (x == null ? y == null : x.equals(y)) pass();

        else fail(x + " not equal to " + y);}

    <T> void equal(T[] x, T[] y) {check(Arrays.equals(x,y));}

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

        new LockStep().instanceMain(args);}

    void instanceMain(String[] args) throws Throwable {

        try {test(args);} catch (Throwable t) {unexpected(t);}

        System.out.printf("%nPassed = %d, failed = %d%n%n", passed, failed);

        if (failed > 0) throw new AssertionError("Some tests failed");}

    abstract class F {abstract void f() throws Throwable;}

    void THROWS(Class<? extends Throwable> k, F... fs) {

        for (F f : fs)

            try {f.f(); fail("Expected " + k.getName() + " not thrown");}

            catch (Throwable t) {

                if (k.isAssignableFrom(t.getClass())) pass();

                else unexpected(t);}}

    static byte[] serializedForm(Object obj) {

        try {

            ByteArrayOutputStream baos = new ByteArrayOutputStream();

            new ObjectOutputStream(baos).writeObject(obj);

            return baos.toByteArray();

        } catch (IOException e) { throw new RuntimeException(e); }}

    static Object readObject(byte[] bytes)

        throws IOException, ClassNotFoundException {

        InputStream is = new ByteArrayInputStream(bytes);

        return new ObjectInputStream(is).readObject();}

    @SuppressWarnings("unchecked")

    static <T> T serialClone(T obj) {

        try { return (T) readObject(serializedForm(obj)); }

        catch (Exception e) { throw new RuntimeException(e); }}

}