/*
 * Copyright (c) 2015, 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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 * questions.
 */

import java.io.ByteArrayInputStream;
import java.io.IOException;
import java.io.InputStream;
import java.util.Arrays;
import java.util.Random;

/*
 * @test
 * @bug 8765432
 * @library /lib/testlibrary
 * @build jdk.testlibrary.*
 * @key randomness
 * @summary Basic test for InputStream.readNBytes
 */
public class ReadNBytes {

    // TODO: Improve test coverage...

    private static Random generator = RandomFactory.getRandom();

    public static void main(String[] args) throws IOException {
        test(new byte[]{1, 2, 3});
        test(createRandomBytes(1024));
        test(createRandomBytes((1 << 13) - 1));
        test(createRandomBytes((1 << 13)));
        test(createRandomBytes((1 << 13) + 1));
        test(createRandomBytes((1 << 15) - 1));
        test(createRandomBytes((1 << 15)));
        test(createRandomBytes((1 << 15) + 1));
        test(createRandomBytes((1 << 17) - 1));
        test(createRandomBytes((1 << 17)));
        test(createRandomBytes((1 << 17) + 1));
    }

    static void test(byte[] inputBytes) throws IOException {
        int length = inputBytes.length;
        InputStream in = new ByteArrayInputStream(inputBytes);
        byte[] readBytes = new byte[roundUp(length) >> 1];
        int nread = in.readNBytes(readBytes, 0, readBytes.length);

        int x;
        byte[] tmp;
        check(nread == readBytes.length,
                "Expected number of bytes read: " + readBytes.length + ", got: " + nread);
        check(Arrays.equals((tmp = Arrays.copyOf(inputBytes, nread)), readBytes),
              "Expected[" + tmp + "], got:[" + readBytes + "]");

        // Read again
        nread = in.readNBytes(readBytes, 0, readBytes.length);

        check(nread == length - readBytes.length,
              "Expected number of bytes read: " + (length - readBytes.length) + ", got: " + nread);
        check(Arrays.equals((tmp = Arrays.copyOfRange(inputBytes, readBytes.length, length)),
                            Arrays.copyOf(readBytes, nread)),
              "Expected[" + tmp + "], got:[" + readBytes + "]");
        // Expect end of stream
        check((x = in.read()) == -1,
              "Expected end of stream from read(), got " + x);
        check((x = in.read(tmp)) == -1,
              "Expected end of stream from read(byte[]), got " + x);
        check((x = in.read(tmp, 0, tmp.length)) == -1,
              "Expected end of stream from read(byte[], int, int), got " + x);
        check((x = in.readNBytes(tmp, 0, tmp.length)) == 0,
              "Expected end of stream, 0, from readNBytes(byte[], int, int), got " + x);
    }

    static byte[] createRandomBytes(int size) {
        byte[] bytes = new byte[size];
        generator.nextBytes(bytes);
        return bytes;
    }

    private static int roundUp(int size) {
        int x = Integer.highestOneBit(size);
        if (x != size)
            x = x << 1;
        return x;
    }

    static void check(boolean cond, Object ... failedArgs) {
        if (cond)
            return;
        StringBuilder sb = new StringBuilder();
        for (Object o : failedArgs)
            sb.append(o);
        throw new RuntimeException(sb.toString());
    }
}