/*
 * Copyright (c) 2020, 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
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/*
 * @test
 * @run testng TestRebase
 */

import jdk.incubator.foreign.MemoryAddress;
import jdk.incubator.foreign.MemoryLayouts;
import jdk.incubator.foreign.MemorySegment;
import org.testng.annotations.DataProvider;
import org.testng.annotations.Test;

import java.lang.invoke.VarHandle;
import java.util.ArrayList;
import java.util.List;
import java.util.function.IntFunction;

import static org.testng.Assert.assertEquals;
import static org.testng.Assert.assertTrue;
import static org.testng.Assert.fail;

public class TestRebase {

    static VarHandle BYTE_VH = MemoryLayouts.JAVA_BYTE.varHandle(byte.class);

    @Test(dataProvider = "slices")
    public void testRebase(SegmentSlice s1, SegmentSlice s2) {
        if (s1.contains(s2)) {
            //check that an address and its rebased counterpart point to same element
            MemoryAddress base = s2.segment.baseAddress();
            MemoryAddress rebased = base.rebase(s1.segment);
            for (int i = 0; i < s2.size(); i++) {
                int expected = (int) BYTE_VH.get(base.addOffset(i));
                int found = (int) BYTE_VH.get(rebased.addOffset(i));
                assertEquals(found, expected);
            }
        } else if (s1.kind != s2.kind) {
            // check that rebase s1 to s2 fails
            try {
                s1.segment.baseAddress().rebase(s2.segment);
                fail("Rebase unexpectedly passed!");
            } catch (IllegalArgumentException ex) {
                assertTrue(true);
            }
        } else if (!s2.contains(s1)) {
            //disjoint segments - check that rebased address is out of bounds
            MemoryAddress base = s2.segment.baseAddress();
            MemoryAddress rebased = base.rebase(s1.segment);
            for (int i = 0; i < s2.size(); i++) {
                BYTE_VH.get(base.addOffset(i));
                try {
                    BYTE_VH.get(rebased.addOffset(i));
                    fail("Rebased address on a disjoint segment is not out of bounds!");
                } catch (IndexOutOfBoundsException ex) {
                    assertTrue(true);
                }
            }
        }
    }

    static class SegmentSlice {

        enum Kind {
            NATIVE(MemorySegment::allocateNative),
            ARRAY(i -> MemorySegment.ofArray(new byte[i]));

            final IntFunction<MemorySegment> segmentFactory;

            Kind(IntFunction<MemorySegment> segmentFactory) {
                this.segmentFactory = segmentFactory;
            }

            MemorySegment makeSegment(int elems) {
                return segmentFactory.apply(elems);
            }
        }

        final Kind kind;
        final int first;
        final int last;
        final MemorySegment segment;

        public SegmentSlice(Kind kind, int first, int last, MemorySegment segment) {
            this.kind = kind;
            this.first = first;
            this.last = last;
            this.segment = segment;
        }

        boolean contains(SegmentSlice other) {
            return kind == other.kind &&
                    first <= other.first &&
                    last >= other.last;
        }

        int size() {
            return last - first + 1;
        }
    }

    @DataProvider(name = "slices")
    static Object[][] slices() {
        int[] sizes = { 16, 8, 4, 2, 1 };
        List<SegmentSlice> slices = new ArrayList<>();
        for (SegmentSlice.Kind kind : SegmentSlice.Kind.values()) {
            //init root segment
            MemorySegment segment = kind.makeSegment(16);
            for (int i = 0 ; i < 16 ; i++) {
                BYTE_VH.set(segment.baseAddress().addOffset(i), (byte)i);
            }
            //compute all slices
            for (int size : sizes) {
                for (int index = 0 ; index < 16 ; index += size) {
                    MemorySegment slice = segment.asSlice(index, size);
                    slices.add(new SegmentSlice(kind, index, index + size - 1, slice));
                }
            }
        }
        Object[][] sliceArray = new Object[slices.size() * slices.size()][];
        for (int i = 0 ; i < slices.size() ; i++) {
            for (int j = 0 ; j < slices.size() ; j++) {
                sliceArray[i * slices.size() + j] = new Object[] { slices.get(i), slices.get(j) };
            }
        }
        return sliceArray;
    }
}