/*

 * 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.

 */

/*

 * @test

 * @bug 8020968

 * @summary Sanity test for Function wildcard signature

 * @run main WalkFunction

 */

import java.lang.StackWalker.StackFrame;

import java.util.Optional;

import java.util.function.Function;

import java.util.stream.Stream;

public class WalkFunction {

    private static final StackWalker walker = StackWalker.getInstance();

    public static void main(String... args) throws Exception {

        testFunctions();

        testWildcards();

        walker.walk(counter());

        walker.walk(wildCounter());

    }

    private static void testFunctions() {

        walker.walk(Stream::count);

        try {

            walker.walk(null);

            throw new RuntimeException("NPE expected");

        } catch (NullPointerException e) {}

        Optional<StackFrame> result = walker.walk(WalkFunction::reduce);

        if (!result.get().getClassName().equals(WalkFunction.class.getName())) {

            throw new RuntimeException(result.get() + " expected: " + WalkFunction.class.getName());

        }

    }

    static Optional<StackFrame> reduce(Stream<StackFrame> stream) {

        return stream.reduce((r,f) -> r.getClassName().compareTo(f.getClassName()) > 0 ? f : r);

    }

    private static void testWildcards() {

        Function<? super Stream<? extends  StackFrame>, Void> f1 = WalkFunction::function;

        Function<? super Stream<? super StackFrame>, Void> f2 = WalkFunction::function;

        Function<? super Stream<StackFrame>, Void> f3 = WalkFunction::function;

        Function<Stream<? extends StackFrame>, Void> f4 = WalkFunction::function;

        Function<Stream<? super StackFrame>, Void> f5 = WalkFunction::function;

        Function<Stream<StackFrame>, Void> f6 = WalkFunction::function;

        walker.walk(f1);

        walker.walk(f2);

        walker.walk(f3);

        walker.walk(f4);

        walker.walk(f5);

        walker.walk(f6);

    }

    private static Void function(Stream<?> s) {

        return null;

    }

    private static Function<Stream<?>, Long> wildCounter() {

        return Stream::count;

    }

    private static <T> Function<Stream<T>, Long> counter() {

        return Stream::count;

    }

}