/*

 * Copyright (c) 2013, 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

 * @summary Basic functional test of Optional

 * @author Mike Duigou

 * @run testng Basic

 */

import java.util.NoSuchElementException;

import java.util.Optional;

import static org.testng.Assert.*;

import org.testng.annotations.Test;

public class Basic {

    @Test(groups = "unit")

    public void testEmpty() {

        Optional<Boolean> empty = Optional.empty();

        Optional<String> presentEmptyString = Optional.of("");

        Optional<Boolean> present = Optional.of(Boolean.TRUE);

        // empty

        assertTrue(empty.equals(empty));

        assertTrue(empty.equals(Optional.empty()));

        assertTrue(!empty.equals(present));

        assertTrue(0 == empty.hashCode());

        assertTrue(!empty.toString().isEmpty());

        assertTrue(!empty.toString().equals(presentEmptyString.toString()));

        assertTrue(!empty.isPresent());

        empty.ifPresent(v -> { fail(); });

        assertSame(null, empty.orElse(null));

        RuntimeException orElse = new RuntimeException() { };

        assertSame(Boolean.FALSE, empty.orElse(Boolean.FALSE));

    }

    @Test(expectedExceptions=NoSuchElementException.class)

    public void testEmptyGet() {

        Optional<Boolean> empty = Optional.empty();

        Boolean got = empty.get();

    }

    @Test(expectedExceptions=NullPointerException.class)

    public void testEmptyOrElseGetNull() {

        Optional<Boolean> empty = Optional.empty();

        Boolean got = empty.orElseGet(null);

    }

    @Test(expectedExceptions=NullPointerException.class)

    public void testEmptyOrElseThrowNull() throws Throwable {

        Optional<Boolean> empty = Optional.empty();

        Boolean got = empty.orElseThrow(null);

    }

    @Test(expectedExceptions=ObscureException.class)

    public void testEmptyOrElseThrow() throws Exception {

        Optional<Boolean> empty = Optional.empty();

        Boolean got = empty.orElseThrow(ObscureException::new);

    }

    @Test(groups = "unit")

    public void testPresent() {

        Optional<Boolean> empty = Optional.empty();

        Optional<String> presentEmptyString = Optional.of("");

        Optional<Boolean> present = Optional.of(Boolean.TRUE);

        // present

        assertTrue(present.equals(present));

        assertTrue(present.equals(Optional.of(Boolean.TRUE)));

        assertTrue(!present.equals(empty));

        assertTrue(Boolean.TRUE.hashCode() == present.hashCode());

        assertTrue(!present.toString().isEmpty());

        assertTrue(!present.toString().equals(presentEmptyString.toString()));

        assertTrue(-1 != present.toString().indexOf(Boolean.TRUE.toString()));

        assertSame(Boolean.TRUE, present.get());

        try {

            present.ifPresent(v -> { throw new ObscureException(); });

            fail();

        }

        assertSame(Boolean.TRUE, present.orElse(null));

        assertSame(Boolean.TRUE, present.orElse(Boolean.FALSE));

        assertSame(Boolean.TRUE, present.orElseGet(null));

        assertSame(Boolean.TRUE, present.<RuntimeException>orElseThrow(ObscureException::new));

    }

    @Test(groups = "unit")

    public void testOfNullable() {

        Optional<String> instance = Optional.ofNullable(null);

        assertFalse(instance.isPresent());

        instance = Optional.ofNullable("Duke");

        assertTrue(instance.isPresent());

        assertEquals(instance.get(), "Duke");

    }

    @Test(groups = "unit")

    public void testFilter() {

        // Null mapper function

        Optional<String> empty = Optional.empty();

        Optional<String> duke = Optional.of("Duke");

        try {

            Optional<String> result = empty.filter(null);

            fail("Should throw NPE on null mapping function");

        } catch (NullPointerException npe) {

            // expected

        }

        Optional<String> result = empty.filter(String::isEmpty);

        assertFalse(result.isPresent());

        result = duke.filter(String::isEmpty);

        assertFalse(result.isPresent());

        result = duke.filter(s -> s.startsWith("D"));

        assertTrue(result.isPresent());

        assertEquals(result.get(), "Duke");

        Optional<String> emptyString = Optional.of("");

        result = emptyString.filter(String::isEmpty);

        assertTrue(result.isPresent());

        assertEquals(result.get(), "");

    }

    @Test(groups = "unit")

    public void testMap() {

        Optional<String> empty = Optional.empty();

        Optional<String> duke = Optional.of("Duke");

        // Null mapper function

        try {

            Optional<Boolean> b = empty.map(null);

            fail("Should throw NPE on null mapping function");

        } catch (NullPointerException npe) {

            // expected

        }

        // Map an empty value

        Optional<Boolean> b = empty.map(String::isEmpty);

        assertFalse(b.isPresent());

        // Map into null

        b = empty.map(n -> null);

        assertFalse(b.isPresent());

        b = duke.map(s -> null);

        assertFalse(b.isPresent());

        // Map to value

        Optional<Integer> l = duke.map(String::length);

        assertEquals(l.get().intValue(), 4);

    }

    @Test(groups = "unit")

    public void testFlatMap() {

        Optional<String> empty = Optional.empty();

        Optional<String> duke = Optional.of("Duke");

        // Null mapper function

        try {

            Optional<Boolean> b = empty.flatMap(null);

            fail("Should throw NPE on null mapping function");

        } catch (NullPointerException npe) {

            // expected

        }

        // Map into null

        try {

            Optional<Boolean> b = duke.flatMap(s -> null);

            fail("Should throw NPE when mapper return null");

        } catch (NullPointerException npe) {

            // expected

        }

        // Empty won't invoke mapper function

        try {

            Optional<Boolean> b = empty.flatMap(s -> null);

            assertFalse(b.isPresent());

        } catch (NullPointerException npe) {

            fail("Mapper function should not be invoked");

        }

        // Map an empty value

        Optional<Integer> l = empty.flatMap(s -> Optional.of(s.length()));

        assertFalse(l.isPresent());

        // Map to value

        Optional<Integer> fixture = Optional.of(Integer.MAX_VALUE);

        l = duke.flatMap(s -> Optional.of(s.length()));

        assertTrue(l.isPresent());

        assertEquals(l.get().intValue(), 4);

        // Verify same instance

        l = duke.flatMap(s -> fixture);

        assertSame(l, fixture);

    }

    private static class ObscureException extends RuntimeException {

    }

}