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import jdk.test.lib.RandomFactory;
import org.junit.jupiter.api.Test;

import java.nio.CharBuffer;
import java.util.List;
import java.util.Random;
import java.util.regex.MatchResult;
import java.util.regex.Matcher;
import java.util.regex.Pattern;

import static org.junit.jupiter.api.Assertions.assertEquals;
import static org.junit.jupiter.api.Assertions.assertTrue;

/*
 * @test
 * @bug 8132995
 * @key randomness
 *
 * @summary Tests to exercise the optimization described in the bug report.
 * @library /test/lib
 * @run junit ImmutableMatchResultTest
 */

public class ImmutableMatchResultTest {

    private static final int prefixLen;
    private static final int infixLen;
    private static final int suffixLen;
    private static final String group1 = "abc";
    private static final String group2 = "wxyz";
    private static final String group0;
    private static final String in;
    private static final String groupResults = "(([a-z]+)([0-9]*))";
    private static final String inResults;
    private static final String letters1 = "abcd";
    private static final String digits1 = "12";
    private static final String letters2 = "pqr";
    private static final String digits2 = "";

    static {
        Random rnd = RandomFactory.getRandom();
        prefixLen = rnd.nextInt(10);
        infixLen = rnd.nextInt(10);
        suffixLen = rnd.nextInt(10);
        group0 = group1 + "-".repeat(infixLen) + group2;
        in = "-".repeat(prefixLen) + group0 + "-".repeat(suffixLen);
        inResults = " ".repeat(prefixLen) + letters1 + digits1 + " ".repeat(infixLen) + letters2 + digits2 + " ".repeat(suffixLen);
    }

    private static void test(CharSequence cs) {
        Matcher m = Pattern.compile("(" + group1 + ")-*(" + group2 + ")").matcher(cs);
        assertTrue(m.find());

        assertEquals(prefixLen, m.start());
        assertEquals(prefixLen + group0.length(), m.end());
        assertEquals(group0, m.toMatchResult().group());

        assertEquals(prefixLen, m.start(1));
        assertEquals(prefixLen + group1.length(), m.end(1));
        assertEquals(group1, m.toMatchResult().group(1));

        assertEquals(prefixLen + group1.length() + infixLen, m.start(2));
        assertEquals(prefixLen + group1.length() + infixLen + group2.length(), m.end(2));
        assertEquals(group2, m.toMatchResult().group(2));
    }

    @Test
    void testString() {
        test(in);
    }

    @Test
    void testStringBuilder() {
        test(new StringBuilder(in));
    }

    @Test
    void testStringBuffer() {
        test(new StringBuffer(in));
    }

    @Test
    void testCharBuffer() {
        test(CharBuffer.wrap(in));
    }

    private static void testResultsStream(CharSequence cs) {
        Matcher m = Pattern.compile(groupResults).matcher(cs);
        List<MatchResult> results = m.results().toList();
        assertEquals(2, results.size());

        int startLetters1 = prefixLen;
        int endLetters1 = startLetters1 + letters1.length();
        int startDigits1 = endLetters1;
        int endDigits1 = startDigits1 + digits1.length();

        assertEquals(startLetters1, results.get(0).start());
        assertEquals(startLetters1, results.get(0).start(0));
        assertEquals(startLetters1, results.get(0).start(1));
        assertEquals(startLetters1, results.get(0).start(2));
        assertEquals(startDigits1, results.get(0).start(3));

        assertEquals(endDigits1, results.get(0).end());
        assertEquals(endDigits1, results.get(0).end(0));
        assertEquals(endDigits1, results.get(0).end(1));
        assertEquals(endLetters1, results.get(0).end(2));
        assertEquals(endDigits1, results.get(0).end(3));

        assertEquals(letters1 + digits1, results.get(0).group());
        assertEquals(letters1 + digits1, results.get(0).group(0));
        assertEquals(letters1 + digits1, results.get(0).group(1));
        assertEquals(letters1, results.get(0).group(2));
        assertEquals(digits1, results.get(0).group(3));

        int startLetters2 = endDigits1 + infixLen;
        int endLetters2 = startLetters2 + letters2.length();
        int startDigits2 = endLetters2;
        int endDigits2 = startDigits2 + digits2.length();

        assertEquals(startLetters2, results.get(1).start());
        assertEquals(startLetters2, results.get(1).start(0));
        assertEquals(startLetters2, results.get(1).start(1));
        assertEquals(startLetters2, results.get(1).start(2));
        assertEquals(startDigits2, results.get(1).start(3));

        assertEquals(endDigits2, results.get(1).end());
        assertEquals(endDigits2, results.get(1).end(0));
        assertEquals(endDigits2, results.get(1).end(1));
        assertEquals(endLetters2, results.get(1).end(2));
        assertEquals(endDigits2, results.get(1).end(3));

        assertEquals(letters2 + digits2, results.get(1).group());
        assertEquals(letters2 + digits2, results.get(1).group(0));
        assertEquals(letters2 + digits2, results.get(1).group(1));
        assertEquals(letters2, results.get(1).group(2));
        assertEquals(digits2, results.get(1).group(3));
    }

    @Test
    void testResultsStreamString() {
        testResultsStream(inResults);
    }

    @Test
    void testResultsStreamStringBuilder() {
        testResultsStream(new StringBuilder(inResults));
    }

    @Test
    void testResultsStreamStringBuffer() {
        testResultsStream(new StringBuffer(inResults));
    }

    @Test
    void testResultsStreamCharBuffer() {
        testResultsStream(CharBuffer.wrap(inResults));
    }

}
