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 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
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import java.nio.ByteBuffer;
import java.nio.ByteOrder;
import java.nio.CharBuffer;
import java.util.ArrayList;
import java.util.List;
import java.util.PrimitiveIterator.OfInt;
import java.util.Random;

import jdk.test.lib.RandomFactory;

import org.junit.jupiter.params.ParameterizedTest;
import org.junit.jupiter.params.provider.Arguments;
import org.junit.jupiter.params.provider.MethodSource;

import static org.junit.jupiter.api.Assertions.assertEquals;
import static org.junit.jupiter.api.Assertions.assertFalse;
import static org.junit.jupiter.api.Assertions.assertThrows;

/*
 * @test
 * @bug 8343110 8361299 8364345
 * @key randomness
 * @library /test/lib
 * @build jdk.test.lib.RandomFactory
 * @summary Tests CharBuffer implementations of CharSequence
 * @run junit CharBufferAsCharSequenceTest
 */
public class CharBufferAsCharSequenceTest {

    private static final Random RAND = RandomFactory.getRandom();
    private static final int SIZE = RAND.nextInt(128, 1153);

    private static char[] randomChars() {
        char[] chars = new char[SIZE];
        for (int i=0; i<SIZE; ++i) {
            chars[i] = (char) RAND.nextInt();
        }
        return chars;
    }

    /**
     * Randomly adjusts the position and limit such that the position will be in the
     * first 1/4th and the limit in the last half.
     */
    private static CharBuffer randomizeRange(CharBuffer cb) {
        int mid = cb.capacity() >>> 1;
        int start = RAND.nextInt(mid >> 1); // from 0 to 1/4
        int end = RAND.nextInt(mid + 1, cb.capacity()); // from mid to capacity
        cb.position(start);
        cb.limit(end);
        return cb;
    }

    /**
     * Generates random content to use for populating <i>cb</i> then calling through
     * to {@code addCases(String, char[], CharBuffer, List)}
     *
     * @param type  String description of the type of CharBuffer under test.
     * @param cb    CharBuffer instance to populate as base of creating cases.
     * @param cases The {@code List} to populate with the cases for use from
     *              {@link #charBufferArguments()}.
     */
    private static void populateAndAddCases(String type, CharBuffer cb, List<Arguments> cases) {
        assert cb.position() == 0 && cb.limit() == cb.capacity();
        char[] buf = randomChars();
        cb.put(buf);
        cb.clear();
        addCases(type, buf, cb, cases);
    }

    /**
     * Adds 4 cases to <i>cases</i>.
     * <ul>
     * <li>Full use of cb</li>.
     * <li>A duplicate of <i>cb</i> with a randomized position and limit. See
     * {@code randomizeRange(CharBuffer)}
     * <li>
     * <li>A {@link CharBuffer#slice() sliced} copy of randomized range.</li>
     * <li>A {@link CharBuffer#slice() sliced} copy of randomized range with a
     * randomized position and limit.</li>
     * </ul>
     */
    private static void addCases(String type, char[] buf, CharBuffer cb, List<Arguments> cases) {
        assert cb.position() == 0 && cb.limit() == cb.capacity();
        cases.add(Arguments.of(cb, buf, 0, buf.length, type + " full"));

        CharBuffer rndRange = randomizeRange(cb.duplicate());
        cases.add(Arguments.of(rndRange, buf, rndRange.position(), rndRange.limit(),
                type + " at " + rndRange.position() + " through " + rndRange.limit()));
        cases.add(Arguments.of(rndRange.slice(), buf, rndRange.position(), rndRange.limit(),
                type + " sliced at " + rndRange.position() + " through " + rndRange.limit()));

        CharBuffer rndSlicedRange = randomizeRange(rndRange.slice());
        cases.add(Arguments.of(rndSlicedRange,
                               buf,
                               rndRange.position() + rndSlicedRange.position(),
                               rndRange.position() + rndSlicedRange.limit(),
                               type + " sliced at " + rndRange.position() + " with position " +
                               rndSlicedRange.position() + " and limit " + rndSlicedRange.limit()));
    }

    /**
     * Returns a {@code List} of {@link Arguments}, with each entry representing a
     * test case scenario.
     * <ul>
     *   <li>CharBuffer - the instance to be tested</li>
     *   <li>char[] - the data expected to be backing the current state of the CharBuffer</li>
     *   <li>int start - index (inclusive) into char[] where the CharBuffer should be positioned</li>
     *   <li>int stop - index (exclusive) into char[] where the CharBuffer should be limited</li>
     *   <li>String - description of the test scenario</li>
     * </ul>
     *
     * Generates the following sets of arguments/test cases.
     * <ul>
     *   <li>See {@code populateAndAddCases(String, CharBuffer, List)} for the
     *       following types:
     *     <ul>
     *       <li>HeapCharBuffer</i>
     *       <li>HeapByteBuffer Big Endian</i>
     *       <li>HeapByteBuffer Little Endian</i>
     *       <li>DirectByteBuffer Big Endian</i>
     *       <li>DirectByteBuffer Little Endian</i>
     *     </ul>
     *   </li>
     *   <li>Randomly generated content into {@link CharBuffer#wrap(CharSequence)
     *       StringCharBuffer} - see {@code addCases(String, char[], CharBuffer, List)}.
     *     <ul>
     *       <li>StringCharBuffer wrapping a {@code CharBuffer} created from
     *           {@link CharBuffer#wrap(char[])}</li>
     *       <li>StringCharBuffer wrapping a {@code String}</li>
     *     </ul>
     *   </li>
     * </ul>
     */
    static List<Arguments> charBufferArguments() {
        List<Arguments> args = new ArrayList<>();

        populateAndAddCases("HeapCharBuffer", CharBuffer.allocate(SIZE), args);
        populateAndAddCases("HeapByteBuffer BE",
                ByteBuffer.allocate(SIZE * 2).order(ByteOrder.BIG_ENDIAN).asCharBuffer(), args);
        populateAndAddCases("HeapByteBuffer LE",
                ByteBuffer.allocate(SIZE * 2).order(ByteOrder.LITTLE_ENDIAN).asCharBuffer(), args);
        populateAndAddCases("DirectByteBuffer BE",
                ByteBuffer.allocateDirect(SIZE * 2).order(ByteOrder.BIG_ENDIAN).asCharBuffer(), args);
        populateAndAddCases("DirectByteBuffer LE",
                ByteBuffer.allocateDirect(SIZE * 2).order(ByteOrder.LITTLE_ENDIAN).asCharBuffer(), args);

        char[] randomChars = randomChars();
        CharBuffer cb = CharBuffer.wrap(randomChars);
        addCases("StringCharBuffer over CharBuffer", randomChars, CharBuffer.wrap(cb), args);

        addCases("StringCharBuffer over String", randomChars, CharBuffer.wrap(new String(randomChars)), args);

        return args;
    }

    @ParameterizedTest(name="{4}")
    @MethodSource("charBufferArguments")
    void testToString(CharSequence actual, char[] expected, int start, int stop, String description) {
        assertEquals(new String(expected, start, stop - start), actual.toString(), description);
    }

    @ParameterizedTest(name="{4}")
    @MethodSource("charBufferArguments")
    void testLength(CharSequence actual, char[] expected, int start, int stop, String description) {
        assertEquals(stop - start, actual.length(), description);
    }

    @ParameterizedTest(name="{4}")
    @MethodSource("charBufferArguments")
    void testGetCharsRange(CharSequence actual, char[] expected, int start, int stop, String description) {
        char[] val = new char[16];
        int length = Math.min(10, stop - start - 1);
        actual.getChars(1, length + 1, val, 3);

        for (int i = 0; i < length; ++i) {
            assertEquals(expected[i + start + 1], val[i + 3], "val at offset of " + i + " from " + description);
        }
        // test that calling getChars did not move the position
        assertEquals(expected[start], actual.charAt(0), "first char after calling getChars: " + description);
    }

    @ParameterizedTest(name="{4}")
    @MethodSource("charBufferArguments")
    void testGetCharsAll(CharSequence actual, char[] expected, int start, int stop, String description) {
        char[] val = new char[stop - start];
        actual.getChars(0, val.length, val, 0);

        for (int i = 0; i < val.length; ++i) {
            assertEquals(expected[i + start], val[i], "val at offset of " + i + " from " + description);
        }
        // test that calling getChars did not move the position
        assertEquals(expected[start], actual.charAt(0), "first char after calling getChars: " + description);
    }

    @ParameterizedTest(name="{4}")
    @MethodSource("charBufferArguments")
    void testGetCharsNegativeSrcBegin(CharSequence actual, char[] expected, int start, int stop, String description) {
        char[] val = new char[16];
        assertThrows(IndexOutOfBoundsException.class, () -> actual.getChars(-1, 4, val, 1));
    }

    @ParameterizedTest(name="{4}")
    @MethodSource("charBufferArguments")
    void testGetCharsNegativeSrcEnd(CharSequence actual, char[] expected, int start, int stop, String description) {
        char[] val = new char[16];
        assertThrows(IndexOutOfBoundsException.class, () -> actual.getChars(0, -4, val, 1));
    }

    @ParameterizedTest(name="{4}")
    @MethodSource("charBufferArguments")
    void testGetCharsSrcEndBeforeBegin(CharSequence actual, char[] expected, int start, int stop, String description) {
        char[] val = new char[16];
        assertThrows(IndexOutOfBoundsException.class, () -> actual.getChars(3, 2, val, 1));
    }

    @ParameterizedTest(name="{4}")
    @MethodSource("charBufferArguments")
    void testGetCharsNegativeDstBegin(CharSequence actual, char[] expected, int start, int stop, String description) {
        char[] val = new char[16];
        assertThrows(IndexOutOfBoundsException.class, () -> actual.getChars(1, 3, val, -1));
    }

    @ParameterizedTest(name="{4}")
    @MethodSource("charBufferArguments")
    void testGetCharsDstBeginOOB(CharSequence actual, char[] expected, int start, int stop, String description) {
        char[] val = new char[16];
        assertThrows(IndexOutOfBoundsException.class, () -> actual.getChars(1, 4, val, val.length + 1));
    }

    @ParameterizedTest(name="{4}")
    @MethodSource("charBufferArguments")
    void testGetCharsDstLengthOOB(CharSequence actual, char[] expected, int start, int stop, String description) {
        char[] val = new char[16];
        assertThrows(IndexOutOfBoundsException.class, () -> actual.getChars(1, 4, val, val.length - 2));
    }

    @ParameterizedTest(name="{4}")
    @MethodSource("charBufferArguments")
    void testGetCharsNullDst(CharSequence actual, char[] expected, int start, int stop, String description) {
        assertThrows(NullPointerException.class, () -> actual.getChars(0, 1, null, 0));
    }

    @ParameterizedTest(name="{4}")
    @MethodSource("charBufferArguments")
    void testCharAt(CharSequence actual, char[] expected, int start, int stop, String description) {
        for (int i = 0, j = stop - start; i < j; ++i) {
            assertEquals(expected[start + i], actual.charAt(i), "chart at " + i + ": " + description);
        }
    }

    @ParameterizedTest(name="{4}")
    @MethodSource("charBufferArguments")
    void testCharAtNegativePos(CharSequence actual, char[] expected, int start, int stop, String description) {
        assertThrows(IndexOutOfBoundsException.class, () -> actual.charAt(-1));
    }

    @ParameterizedTest(name="{4}")
    @MethodSource("charBufferArguments")
    void testCharAtPosOOB(CharSequence actual, char[] expected, int start, int stop, String description) {
        assertThrows(IndexOutOfBoundsException.class, () -> actual.charAt(stop - start + 1));
    }

    @ParameterizedTest(name="{4}")
    @MethodSource("charBufferArguments")
    void testChars(CharSequence actual, char[] expected, int start, int stop, String description) {
        OfInt chars = actual.chars().iterator();
        for (int i = 0, j = stop - start; i < j; ++i) {
            assertEquals(expected[start + i], (char) chars.nextInt(), "chart at " + i + ": " + description);
        }
        assertFalse(chars.hasNext(), "chars has more elements than expected " + description);
    }

    @ParameterizedTest(name="{4}")
    @MethodSource("charBufferArguments")
    void testCodePoints(CharSequence actual, char[] expected, int start, int stop, String description) {
        OfInt codePoints = actual.codePoints().iterator();
        for (int i = 0, j = stop - start; i < j; ++i) {
            char c1 = expected[start + i];
            int expectedCodePoint = c1;
            if (Character.isHighSurrogate(c1) && (i + 1) < j) {
                char c2 = expected[start + i + 1];
                if (Character.isLowSurrogate(c2)) {
                    expectedCodePoint = Character.toCodePoint(c1, c2);
                    ++i;
                }
            }
            assertEquals(expectedCodePoint, codePoints.nextInt(), "code point at " + i + ": " + description);
        }
        assertFalse(codePoints.hasNext(), "codePoints has more elements than expected " + description);
    }

    @ParameterizedTest(name="{4}")
    @MethodSource("charBufferArguments")
    void testSubSequence(CharSequence actual, char[] expected, int start, int stop, String description) {
        int maxTests = Math.min(7,  ((stop - start) >> 1) - 1);
        for (int i = 0; i < maxTests; ++i) {
            assertEquals(new String(expected, start + i, stop - start - (2 * i)),
                    actual.subSequence(i, actual.length() - i).toString(),
                    "subsequence at index " + i + " for " + description);
        }
    }
}