/*

 * Copyright (c) 2008, 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 6380723

 * @summary Decode many byte sequences in many ways

 * @run main/timeout=1800 FindDecoderBugs

 * @author Martin Buchholz

 */

import java.util.*;

import java.util.regex.*;

import java.nio.*;

import java.nio.charset.*;

public class FindDecoderBugs {

    static boolean isBroken(String csn) {

        if (csn.equals("x-COMPOUND_TEXT")) return true;

        return false;

    }

    static <T extends Comparable<? super T>> List<T> sort(Collection<T> c) {

        List<T> list = new ArrayList<T>(c);

        Collections.sort(list);

        return list;

    }

    static class TooManyFailures extends RuntimeException {

        private static final long serialVersionUID = 0L;

    }

    static String string(byte[] a) {

        final StringBuilder sb = new StringBuilder();

        for (byte b : a) {

            if (sb.length() != 0) sb.append(' ');

            sb.append(String.format("%02x", b & 0xff));

        }

        return sb.toString();

    }

    static String string(char[] a) {

        final StringBuilder sb = new StringBuilder();

        for (char c : a) {

            if (sb.length() != 0) sb.append(' ');

            sb.append(String.format("\\u%04x", (int) c));

        }

        return sb.toString();

    }

    static class Reporter {

        // Some machinery to make sure only a small number of errors

        // that are "too similar" are reported.

        static class Counts extends HashMap<String, Long> {

            private static final long serialVersionUID = -1;

            long inc(String signature) {

                Long count = get(signature);

                if (count == null) count = 0L;

                put(signature, count+1);

                return count+1;

            }

        }

        final Counts failureCounts = new Counts();

        final static long maxFailures = 2;

        final static Pattern hideBytes = Pattern.compile("\"[0-9a-f ]+\"");

        final static Pattern hideChars = Pattern.compile("\\\\u[0-9a-f]{4}");

        boolean bug(String format, Object... args) {

            String signature = String.format(format, args);

            signature = hideBytes.matcher(signature).replaceAll("\"??\"");

            signature = hideChars.matcher(signature).replaceAll("\\u????");

            failed++;

            if (failureCounts.inc(signature) <= maxFailures) {

                System.out.printf(format, args);

                System.out.println();

                return true;

            }

            return false;

        }

        void summarize() {

            for (String key : sort(failureCounts.keySet()))

                System.out.printf("-----%n%s%nfailures=%d%n",

                                  key, failureCounts.get(key));

        }

    }

    static final Reporter reporter = new Reporter();

    static class Result {

        final int limit;

        final int ipos;

        final boolean direct;

        final byte[] ia;

        final char[] oa;

        final CoderResult cr;

        Result(ByteBuffer ib, CharBuffer ob, CoderResult cr) {

            ipos = ib.position();

            ia = toArray(ib);

            oa = toArray(ob);

            direct = ib.isDirect();

            limit = ob.limit();

            this.cr = cr;

        }

        static byte[] toArray(ByteBuffer b) {

            int pos = b.position();

            byte[] a = new byte[b.limit()];

            b.position(0);

            b.get(a);

            b.position(pos);

            return a;

        }

        static char[] toArray(CharBuffer b) {

            char[] a = new char[b.position()];

            b.position(0);

            b.get(a);

            return a;

        }

        static boolean eq(Result x, Result y) {

            return x == y ||

                (x != null && y != null &&

                 (Arrays.equals(x.oa, y.oa) &&

                  x.ipos == y.ipos &&

                  x.cr == y.cr));

        }

        public String toString() {

            return String.format("\"%s\"[%d/%d] => %s \"%s\"[%d/%d]%s",

                                 string(ia), ipos, ia.length,

                                 cr, string(oa), oa.length, limit,

                                 (direct ? " (direct)" : ""));

        }

    }

    // legend: r=regular d=direct In=Input Ou=Output

    static final int maxBufSize = 20;

    static final ByteBuffer[] ribs = new ByteBuffer[maxBufSize];

    static final ByteBuffer[] dibs = new ByteBuffer[maxBufSize];

    static final CharBuffer[] robs = new CharBuffer[maxBufSize];

    static final CharBuffer[] dobs = new CharBuffer[maxBufSize];

    static {

        for (int i = 0; i < maxBufSize; i++) {

            ribs[i] = ByteBuffer.allocate(i);

            dibs[i] = ByteBuffer.allocateDirect(i);

            robs[i] = CharBuffer.allocate(i);

            dobs[i] = ByteBuffer.allocateDirect(i*2).asCharBuffer();

        }

    }

    static class CharsetTester {

        private final Charset cs;

        private static final long maxFailures = 5;

        private long failures = 0;

        // private static final long maxCharsetFailures = Long.MAX_VALUE;

        private static final long maxCharsetFailures = 10000L;

        private final long failed0 = failed;

        CharsetTester(Charset cs) {

            this.cs = cs;

        }

        static boolean bug(String format, Object... args) {

            return reporter.bug(format, args);

        }

        Result recode(ByteBuffer ib, CharBuffer ob) {

            try {

                char canary = '\u4242';

                ib.clear();     // Prepare to read

                ob.clear();     // Prepare to write

                for (int i = 0; i < ob.limit(); i++)

                    ob.put(i, canary);

                CharsetDecoder coder = cs.newDecoder();

                CoderResult cr = coder.decode(ib, ob, false);

                equal(ib.limit(), ib.capacity());

                equal(ob.limit(), ob.capacity());

                Result r = new Result(ib, ob, cr);

                if (cr.isError())

                    check(cr.length() > 0);

                if (cr.isOverflow() && ob.remaining() > 10)

                    bug("OVERFLOW, but there's lots of room: %s %s",

                        cs, r);

//              if (cr.isOverflow() && ib.remaining() == 0)

//                  bug("OVERFLOW, yet remaining() == 0: %s %s",

//                      cs, r);

                if (cr.isError() && ib.remaining() < cr.length())

                    bug("remaining() < CoderResult.length(): %s %s",

                        cs, r);

//              if (ib.position() == 0 && ob.position() > 0)

//                  reporter. bug("output only if input consumed: %s %s",

//                                cs, r);

                // Should we warn if cr.isUnmappable() ??

                CoderResult cr2 = coder.decode(ib, ob, false);

                if (ib.position() != r.ipos ||

                    ob.position() != r.oa.length ||

                    cr != cr2)

                    bug("Coding operation not idempotent: %s%n    %s%n    %s",

                        cs, r, new Result(ib, ob, cr2));

                if (ob.position() < ob.limit() &&

                    ob.get(ob.position()) != canary)

                    bug("Buffer overrun: %s %s %s",

                        cs, r, ob.get(ob.position()));

                return r;

            } catch (Throwable t) {

                if (bug("Unexpected exception: %s %s %s",

                        cs, t.getClass().getSimpleName(),

                        new Result(ib, ob, null)))

                    t.printStackTrace();

                return null;

            }

        }

        Result recode2(byte[] ia, int n) {

            int len = ia.length;

            ByteBuffer rib = ByteBuffer.wrap(ia);

            ByteBuffer dib = dibs[len];

            dib.clear(); dib.put(ia); dib.clear();

            CharBuffer rob = robs[n];

            CharBuffer dob = dobs[n];

            equal(rob.limit(), n);

            equal(dob.limit(), n);

            check(dib.isDirect());

            check(dob.isDirect());

            Result r1 = recode(rib, rob);

            Result r2 = recode(dib, dob);

            if (r1 != null && r2 != null && ! Result.eq(r1, r2))

                bug("Results differ for direct buffers: %s%n    %s%n    %s",

                    cs, r1, r2);

            return r1;

        }

        Result test(byte[] ia) {

            if (failed - failed0 >= maxCharsetFailures)

                throw new TooManyFailures();

            Result roomy = recode2(ia, maxBufSize - 1);

            if (roomy == null) return roomy;

            int olen = roomy.oa.length;

            if (olen > 0) {

                if (roomy.ipos == roomy.ia.length) {

                    Result perfectFit = recode2(ia, olen);

                    if (! Result.eq(roomy, perfectFit))

                        bug("Results differ: %s%n    %s%n    %s",

                            cs, roomy, perfectFit);

                }

                for (int i = 0; i < olen; i++) {

                    Result claustrophobic = recode2(ia, i);

                    if (claustrophobic == null) return roomy;

                    if (roomy.cr.isUnderflow() &&

                        ! claustrophobic.cr.isOverflow())

                        bug("Expected OVERFLOW: %s%n    %s%n    %s",

                            cs, roomy, claustrophobic);

                }

            }

            return roomy;

        }

        void testExhaustively(byte[] prefix, int n) {

            int len = prefix.length;

            byte[] ia = Arrays.copyOf(prefix, len + 1);

            for (int i = 0; i < 0x100; i++) {

                ia[len] = (byte) i;

                if (n == 1)

                    test(ia);

                else

                    testExhaustively(ia, n - 1);

            }

        }

        void testRandomly(byte[] prefix, int n) {

            int len = prefix.length;

            byte[] ia = Arrays.copyOf(prefix, len + n);

            for (int i = 0; i < 10000; i++) {

                for (int j = 0; j < n; j++)

                    ia[len + j] = randomByte();

                test(ia);

            }

        }

        void testPrefix(byte[] prefix) {

            if (prefix.length > 0)

                System.out.printf("Testing prefix %s%n", string(prefix));

            test(prefix);

            testExhaustively(prefix, 1);

            testExhaustively(prefix, 2);

            // Can you spare a week of CPU time?

            // testExhaustively(cs, tester, prefix, 3);

            testRandomly(prefix, 3);

            testRandomly(prefix, 4);

        }

    }

    private final static Random rnd = new Random();

    private static byte randomByte() {

        return (byte) rnd.nextInt(0x100);

    }

    private static byte[] randomBytes(int len) {

        byte[] a = new byte[len];

        for (int i = 0; i < len; i++)

            a[i] = randomByte();

        return a;

    }

    private static final byte SS2 = (byte) 0x8e;

    private static final byte SS3 = (byte) 0x8f;

    private static final byte ESC = (byte) 0x1b;

    private static final byte SO  = (byte) 0x0e;

    private static final byte SI  = (byte) 0x0f;

    private final static byte[][] stateChangers = {

        {SS2}, {SS3}, {SO}, {SI}

    };

    private final static byte[][]escapeSequences = {

        {ESC, '(', 'B'},

        {ESC, '(', 'I'},

        {ESC, '(', 'J'},

        {ESC, '$', '@'},

        {ESC, '$', 'A'},

        {ESC, '$', ')', 'A'},

        {ESC, '$', ')', 'C'},

        {ESC, '$', ')', 'G'},

        {ESC, '$', '*', 'H'},

        {ESC, '$', '+', 'I'},

        {ESC, '$', 'B'},

        {ESC, 'N'},

        {ESC, 'O'},

        {ESC, '$', '(', 'D'},

    };

    private static boolean isStateChanger(Charset cs, byte[] ia) {

        Result r = new CharsetTester(cs).recode2(ia, 9);

        return r == null ? false :

            (r.cr.isUnderflow() &&

             r.ipos == ia.length &&

             r.oa.length == 0);

    }

    private final static byte[][] incompletePrefixes = {

        {ESC},

        {ESC, '('},

        {ESC, '$'},

        {ESC, '$', '(',},

    };

    private static boolean isIncompletePrefix(Charset cs, byte[] ia) {

        Result r = new CharsetTester(cs).recode2(ia, 9);

        return r == null ? false :

            (r.cr.isUnderflow() &&

             r.ipos == 0 &&

             r.oa.length == 0);

    }

    private static void testCharset(Charset cs) throws Throwable {

        final String csn = cs.name();

        if (isBroken(csn)) {

            System.out.printf("Skipping possibly broken charset %s%n", csn);

            return;

        }

        System.out.println(csn);

        CharsetTester tester = new CharsetTester(cs);

        tester.testPrefix(new byte[0]);

        if (! csn.matches("(?:x-)?(?:UTF|JIS(?:_X)?0).*")) {

            for (byte[] prefix : stateChangers)

                if (isStateChanger(cs, prefix))

                    tester.testPrefix(prefix);

            for (byte[] prefix : incompletePrefixes)

                if (isIncompletePrefix(cs, prefix))

                    tester.testPrefix(prefix);

            if (isIncompletePrefix(cs, new byte[] {ESC}))

                for (byte[] prefix : escapeSequences)

                    if (isStateChanger(cs, prefix))

                        tester.testPrefix(prefix);

        }

    }

    private static void realMain(String[] args) {

        for (Charset cs : sort(Charset.availableCharsets().values())) {

            try {

                testCharset(cs);

            } catch (TooManyFailures e) {

                System.out.printf("Too many failures for %s%n", cs);

            } catch (Throwable t) {

                unexpected(t);

            }

        }

        reporter.summarize();

    }

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

    static volatile long passed = 0, failed = 0;

    static void pass() {passed++;}

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

    static void fail(String format, Object... args) {

        System.out.println(String.format(format, args)); failed++;}

    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 fail(x + " not equal to " + y);}

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

        try {realMain(args);} catch (Throwable t) {unexpected(t);}

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

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

}