/*

 * 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

 * or visit www.oracle.com if you need additional information or have any

 * questions.

 */

import java.io.BufferedReader;

import java.io.ByteArrayInputStream;

import java.io.CharArrayReader;

import java.io.File;

import java.io.FileReader;

import java.io.FileWriter;

import java.io.IOException;

import java.io.InputStreamReader;

import java.io.LineNumberReader;

import java.io.PipedReader;

import java.io.PipedWriter;

import java.io.PushbackReader;

import java.io.Reader;

import java.io.StringReader;

import java.io.UncheckedIOException;

import java.util.Arrays;

import java.util.Collections;

import java.util.Iterator;

import java.util.LinkedList;

import java.util.List;

import java.util.concurrent.ConcurrentHashMap;

import java.util.function.Function;

import static java.lang.String.format;

/*

 * @test

 * @bug 8029689

 * @summary checks the bounds part of the contract of java.io.Reader.read(char[], int, int):

 *

 *              0 <= off <= off+len <= cbuf.length

 *

 *          for publicly exported subtypes of java.io.Reader

 */

public class ReaderBulkReadContract {

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

        ReaderBulkReadContract t = new ReaderBulkReadContract();

        t.test();

    }

    private void test() throws IOException {

        Iterator<Object[]> args = args();

        while (args.hasNext()) {

            Object[] a = args.next();

            Reader r = (Reader) a[0];

            int size = (int) a[1];

            int off = (int) a[2];

            int len = (int) a[3];

            try {

                read(r, size, off, len);

            } finally {

                r.close();

            }

        }

    }

    private Iterator<Object[]> args() {

        Integer[] lens = {Integer.MIN_VALUE, -5, -4, -3, -2, -1, 0, 1, 2, 3, 4, 5, Integer.MAX_VALUE};

        Integer[] offs = {Integer.MIN_VALUE, -5, -4, -3, -2, -1, 0, 1, 2, 3, 4, 5, Integer.MAX_VALUE};

        Integer[] sizes = {0, 1, 2, 3, 4, 5};

        String[] contents = {"", "a", "ab"};

        List<Function<String, Reader>> fs = Arrays.asList(

                (String s) -> new BufferedReader(new StringReader(s)),

                (String s) -> new LineNumberReader(new StringReader(s)),

                (String s) -> new CharArrayReader(s.toCharArray()),

                (String s) -> new InputStreamReader(new ByteArrayInputStream(s.getBytes())),

                (String s) -> newFileReader(s),

                (String s) -> new PushbackReader(new StringReader(s)),

                (String s) -> newPipedReader(s),

                (String s) -> new StringReader(s)

        );

        // The easiest way to produce a cartesian product from a small fixed number of sets

        List<Object[]> tuples = Collections.synchronizedList(new LinkedList<>());

        for (Integer len : lens)

            for (Integer off : offs)

                for (String s : contents)

                    for (Integer size : sizes)

                        for (Function<String, Reader> f : fs)

                            tuples.add(new Object[]{f.apply(s), size, off, len});

        return tuples.iterator();

    }

    private void read(Reader r, int size, int off, int len) throws IOException {

        IndexOutOfBoundsException ex = null;

        try {

            r.read(new char[size], off, len);

        } catch (IndexOutOfBoundsException e) {

            ex = e;

        }

        boolean incorrectBounds = off < 0 || len < 0 || len > size - off;

        boolean exceptionThrown = ex != null;

        if (incorrectBounds != exceptionThrown) { // incorrectBounds iff exceptionThrown

            throw new AssertionError(format("r=%s, size=%s, off=%s, len=%s, incorrectBounds=%s, exceptionThrown=%s",

                    r, size, off, len, incorrectBounds, exceptionThrown));

        }

    }

    private static PipedReader newPipedReader(String contents) {

        try (PipedWriter w = new PipedWriter()) {

            PipedReader r = new PipedReader(w);

            w.write(contents);

            return r;

        } catch (IOException e) {

            throw new UncheckedIOException(e);

        }

    }

    private FileReader newFileReader(String contents) {

        try {

            // To not create an enormous amount of files

            File f = cache.computeIfAbsent(contents,

                    ReaderBulkReadContract::createTempFileWithContents);

            return new FileReader(f);

        } catch (IOException e) {

            throw new UncheckedIOException(e);

        }

    }

    private static File createTempFileWithContents(String contents) {

        try {

            File testDir = new File(System.getProperty("test.dir", "."));

            File file = File.createTempFile("ReaderContract", "", testDir);

            try (FileWriter w = new FileWriter(file)) {

                w.write(contents);

            }

            return file;

        } catch (IOException e) {

            throw new UncheckedIOException(e);

        }

    }

    //

    // To avoid myriads of tiny files a cache is used.

    // ConcurrentHashMap.computeIfAbsent promises a crucial thing:

    //

    // ...The entire method invocation is performed atomically, so the

    // function is applied at most once per key...

    //  ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

    //

    private final ConcurrentHashMap<String, File> cache = new ConcurrentHashMap<>();

}