/*

 * Copyright (c) 2012, 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 7121314

 * @summary AbstractCollection.toArray(T[]) doesn't return the given array

 *           in concurrent modification.

 * @author Ulf Zibis, David Holmes

 */

import java.util.AbstractCollection;

import java.util.Arrays;

import java.util.Iterator;

public class ToArrayTest {

    static class TestCollection<E> extends AbstractCollection<E> {

        private final E[] elements;

        private int[] sizes;

        private int nextSize;

        public TestCollection(E[] elements) {

            this.elements = elements;

            setSizeSequence(new int[] { elements.length });

        }

        /*

         * Sets the values that size() will return on each use. The next

         * call to size will return sizes[0], then sizes[1] etc. This allows us

         * to emulate a concurrent change to the contents of the collection

         * without having to perform concurrent changes. If sizes[n+1] contains

         * a larger value, the collection will appear to have shrunk when

         * iterated; if a smaller value then the collection will appear to have

         * grown when iterated.

         */

        void setSizeSequence(int... sizes) {

            this.sizes = sizes;

            nextSize = 0;

        }

        /* can change collection's size after each invocation */

        @Override

        public int size() {

            return sizes[nextSize == sizes.length - 1 ? nextSize : nextSize++];

        }

        @Override

        public Iterator<E> iterator() {

            return new Iterator<E>() {

                int pos = 0;

                public boolean hasNext() {

                    return pos < sizes[nextSize];

                }

                public E next() {

                    return elements[pos++];

                }

                public void remove() {

                    throw new UnsupportedOperationException(

                            "Not supported yet.");

                }

            };

        }

    }

    static final Object[] OBJECTS = { new Object(), new Object(), new Object() };

    static final TestCollection<?> CANDIDATE = new TestCollection<Object>(OBJECTS);

    static final int CAP = OBJECTS.length; // capacity of the CANDIDATE

    static final int LAST = CAP - 1; // last possible array index

    Object[] a;

    Object[] res;

    int last() {

        return a.length - 1;

    }

    protected void test() throws Throwable {

        // Check array type conversion

        res = new TestCollection<>(new Object[] { "1", "2" }).toArray(new String[0]);

        check(res instanceof String[]);

        check(res.length == 2);

        check(res[1] == "2");

        // Check incompatible type of target array

        try {

            res = CANDIDATE.toArray(new String[CAP]);

            check(false);

        } catch (Throwable t) {

            check(t instanceof ArrayStoreException);

        }

        // Check more elements than a.length

        a = new Object[CAP - 1]; // appears too small

        res = CANDIDATE.toArray(a);

        check(res != a);

        check(res[LAST] != null);

        // Check equal elements as a.length

        a = new Object[CAP]; // appears to match

        res = CANDIDATE.toArray(a);

        check(res == a);

        check(res[last()] != null);

        // Check equal elements as a.length

        a = new Object[CAP + 1]; // appears too big

        res = CANDIDATE.toArray(a);

        check(res == a);

        check(res[last()] == null);

        // Check less elements than expected, but more than a.length

        a = new Object[CAP - 2]; // appears too small

        CANDIDATE.setSizeSequence(CAP, CAP - 1);

        res = CANDIDATE.toArray(a);

        check(res != a);

        check(res.length == CAP - 1);

        check(res[LAST - 1] != null);

        // Check less elements than expected, but equal as a.length

        a = Arrays.copyOf(OBJECTS, CAP); // appears to match

        CANDIDATE.setSizeSequence(CAP, CAP - 1);

        res = CANDIDATE.toArray(a);

        check(res == a);

        check(res[last()] == null);

        // Check more elements than expected and more than a.length

        a = new Object[CAP - 1]; // appears to match

        CANDIDATE.setSizeSequence(CAP - 1, CAP);

        res = CANDIDATE.toArray(a);

        check(res != a);

        check(res[LAST] != null);

        // Check more elements than expected, but equal as a.length

        a = new Object[CAP - 1]; // appears to match

        CANDIDATE.setSizeSequence(CAP - 2, CAP - 1);

        res = CANDIDATE.toArray(a);

        check(res == a);

        check(res[last()] != null);

        // Check more elements than expected, but less than a.length

        a = Arrays.copyOf(OBJECTS, CAP); // appears to match

        CANDIDATE.setSizeSequence(CAP - 2, CAP - 1);

        res = CANDIDATE.toArray(a);

        check(res == a);

        check(res[last()] == null);

        test_7121314();

    }

    /*

     * Major target of this testcase, bug 7121314.

     */

    protected void test_7121314() throws Throwable {

        // Check equal elements as a.length, but less than expected

        a = new Object[CAP - 1]; // appears too small

        CANDIDATE.setSizeSequence(CAP, CAP - 1);

        res = CANDIDATE.toArray(a);

        check(res == a);

        check(res[last()] != null);

        // Check less elements than a.length and less than expected

        a = Arrays.copyOf(OBJECTS, CAP - 1); // appears too small

        CANDIDATE.setSizeSequence(CAP, CAP - 2);

        res = CANDIDATE.toArray(a);

        check(res == a);

        check(res[last()] == null);

    }

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

        ToArrayTest testcase = new ToArrayTest();

        try {

            testcase.test();

        } catch (Throwable t) {

            unexpected(t);

        }

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

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

    }

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

    static volatile int passed = 0, failed = 0;

    static void pass() { passed++; }

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

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

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

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

    static void equal(Object x, Object y) {

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

        else {System.out.println(x + " not equal to " + y); fail(); }

    }

}