/*
 * Copyright (c) 2016-present, RxJava Contributors.
 *
 * Licensed under the Apache License, Version 2.0 (the "License"); you may not use this file except in
 * compliance with the License. You may obtain a copy of the License at
 *
 * http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software distributed under the License is
 * distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See
 * the License for the specific language governing permissions and limitations under the License.
 */

package io.reactivex.rxjava4.internal.operators.observable;

import static org.junit.Assert.*;

import java.util.List;
import java.util.concurrent.*;

import org.junit.Test;

import io.reactivex.rxjava4.core.*;
import io.reactivex.rxjava4.disposables.Disposable;
import io.reactivex.rxjava4.exceptions.*;
import io.reactivex.rxjava4.functions.Function;
import io.reactivex.rxjava4.internal.functions.Functions;
import io.reactivex.rxjava4.observers.TestObserver;
import io.reactivex.rxjava4.plugins.RxJavaPlugins;
import io.reactivex.rxjava4.schedulers.Schedulers;
import io.reactivex.rxjava4.subjects.*;
import io.reactivex.rxjava4.testsupport.*;

public class ObservableFlatMapSingleTest extends RxJavaTest {

    @Test
    public void normal() {
        Observable.range(1, 10)
        .flatMapSingle(new Function<Integer, SingleSource<Integer>>() {
            @Override
            public SingleSource<Integer> apply(Integer v) throws Exception {
                return Single.just(v);
            }
        })
        .test()
        .assertResult(1, 2, 3, 4, 5, 6, 7, 8, 9, 10);
    }

    @Test
    public void normalDelayError() {
        Observable.range(1, 10)
        .flatMapSingle(new Function<Integer, SingleSource<Integer>>() {
            @Override
            public SingleSource<Integer> apply(Integer v) throws Exception {
                return Single.just(v);
            }
        }, true)
        .test()
        .assertResult(1, 2, 3, 4, 5, 6, 7, 8, 9, 10);
    }

    @Test
    public void normalAsync() {
        TestObserverEx<Integer> to = Observable.range(1, 10)
        .flatMapSingle(new Function<Integer, SingleSource<Integer>>() {
            @Override
            public SingleSource<Integer> apply(Integer v) throws Exception {
                return Single.just(v).subscribeOn(Schedulers.computation());
            }
        })
        .to(TestHelper.<Integer>testConsumer())
        .awaitDone(5, TimeUnit.SECONDS)
        .assertSubscribed()
        .assertNoErrors()
        .assertComplete();

        TestHelper.assertValueSet(to, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10);
    }

    @Test
    public void mapperThrowsObservable() {
        PublishSubject<Integer> ps = PublishSubject.create();

        TestObserver<Integer> to = ps
        .flatMapSingle(new Function<Integer, SingleSource<Integer>>() {
            @Override
            public SingleSource<Integer> apply(Integer v) throws Exception {
                throw new TestException();
            }
        })
        .test();

        assertTrue(ps.hasObservers());

        ps.onNext(1);

        to.assertFailure(TestException.class);

        assertFalse(ps.hasObservers());
    }

    @Test
    public void mapperReturnsNullObservable() {
        PublishSubject<Integer> ps = PublishSubject.create();

        TestObserver<Integer> to = ps
        .flatMapSingle(new Function<Integer, SingleSource<Integer>>() {
            @Override
            public SingleSource<Integer> apply(Integer v) throws Exception {
                return null;
            }
        })
        .test();

        assertTrue(ps.hasObservers());

        ps.onNext(1);

        to.assertFailure(NullPointerException.class);

        assertFalse(ps.hasObservers());
    }

    @Test
    public void normalDelayErrorAll() {
        TestObserverEx<Integer> to = Observable.range(1, 10).concatWith(Observable.<Integer>error(new TestException()))
        .flatMapSingle(new Function<Integer, SingleSource<Integer>>() {
            @Override
            public SingleSource<Integer> apply(Integer v) throws Exception {
                return Single.error(new TestException());
            }
        }, true)
        .to(TestHelper.<Integer>testConsumer())
        .assertFailure(CompositeException.class);

        List<Throwable> errors = TestHelper.compositeList(to.errors().get(0));

        for (int i = 0; i < 11; i++) {
            TestHelper.assertError(errors, i, TestException.class);
        }
    }

    @Test
    public void takeAsync() {
        TestObserverEx<Integer> to = Observable.range(1, 10)
        .flatMapSingle(new Function<Integer, SingleSource<Integer>>() {
            @Override
            public SingleSource<Integer> apply(Integer v) throws Exception {
                return Single.just(v).subscribeOn(Schedulers.computation());
            }
        })
        .take(2)
        .to(TestHelper.<Integer>testConsumer())
        .awaitDone(5, TimeUnit.SECONDS)
        .assertSubscribed()
        .assertValueCount(2)
        .assertNoErrors()
        .assertComplete();

        TestHelper.assertValueSet(to, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10);
    }

    @Test
    public void take() {
        Observable.range(1, 10)
        .flatMapSingle(new Function<Integer, SingleSource<Integer>>() {
            @Override
            public SingleSource<Integer> apply(Integer v) throws Exception {
                return Single.just(v);
            }
        })
        .take(2)
        .test()
        .assertResult(1, 2);
    }

    @Test
    public void middleError() {
        Observable.fromArray(new String[]{"1", "a", "2"}).flatMapSingle(new Function<String, SingleSource<Integer>>() {
            @Override
            public SingleSource<Integer> apply(final String s) throws NumberFormatException {
                //return Single.just(Integer.valueOf(s)); //This works
                return Single.fromCallable(new Callable<Integer>() {
                    @Override
                    public Integer call() throws NumberFormatException {
                        return Integer.valueOf(s);
                    }
                });
            }
        })
        .test()
        .assertFailure(NumberFormatException.class, 1);
    }

    @Test
    public void asyncFlatten() {
        Observable.range(1, 1000)
        .flatMapSingle(new Function<Integer, SingleSource<Integer>>() {
            @Override
            public SingleSource<Integer> apply(Integer v) throws Exception {
                return Single.just(1).subscribeOn(Schedulers.computation());
            }
        })
        .take(500)
        .to(TestHelper.<Integer>testConsumer())
        .awaitDone(5, TimeUnit.SECONDS)
        .assertSubscribed()
        .assertValueCount(500)
        .assertNoErrors()
        .assertComplete();
    }

    @Test
    public void successError() {
        final PublishSubject<Integer> ps = PublishSubject.create();

        TestObserver<Integer> to = Observable.range(1, 2)
        .flatMapSingle(new Function<Integer, SingleSource<Integer>>() {
            @Override
            public SingleSource<Integer> apply(Integer v) throws Exception {
                if (v == 2) {
                    return ps.singleOrError();
                }
                return Single.error(new TestException());
            }
        }, true)
        .test();

        ps.onNext(1);
        ps.onComplete();

        to
        .assertFailure(TestException.class, 1);
    }

    @Test
    public void disposed() {
        TestHelper.checkDisposed(PublishSubject.<Integer>create().flatMapSingle(new Function<Integer, SingleSource<Integer>>() {
            @Override
            public SingleSource<Integer> apply(Integer v) throws Exception {
                return Single.<Integer>just(1);
            }
        }));
    }

    @Test
    public void innerSuccessCompletesAfterMain() {
        PublishSubject<Integer> ps = PublishSubject.create();

        TestObserver<Integer> to = Observable.just(1).flatMapSingle(Functions.justFunction(ps.singleOrError()))
        .test();

        ps.onNext(2);
        ps.onComplete();

        to
        .assertResult(2);
    }

    @Test
    public void doubleOnSubscribe() {
        TestHelper.checkDoubleOnSubscribeObservable(new Function<Observable<Object>, ObservableSource<Integer>>() {
            @Override
            public ObservableSource<Integer> apply(Observable<Object> f) throws Exception {
                return f.flatMapSingle(Functions.justFunction(Single.just(2)));
            }
        });
    }

    @Test
    public void badSource() {
        List<Throwable> errors = TestHelper.trackPluginErrors();
        try {
            new Observable<Integer>() {
                @Override
                protected void subscribeActual(Observer<? super Integer> observer) {
                    observer.onSubscribe(Disposable.empty());
                    observer.onError(new TestException("First"));
                    observer.onError(new TestException("Second"));
                }
            }
            .flatMapSingle(Functions.justFunction(Single.just(2)))
            .to(TestHelper.<Integer>testConsumer())
            .assertFailureAndMessage(TestException.class, "First");

            TestHelper.assertUndeliverable(errors, 0, TestException.class, "Second");
        } finally {
            RxJavaPlugins.reset();
        }
    }

    @Test
    public void badInnerSource() {
        List<Throwable> errors = TestHelper.trackPluginErrors();
        try {
            Observable.just(1)
            .flatMapSingle(Functions.justFunction(new Single<Integer>() {
                @Override
                protected void subscribeActual(SingleObserver<? super Integer> observer) {
                    observer.onSubscribe(Disposable.empty());
                    observer.onError(new TestException("First"));
                    observer.onError(new TestException("Second"));
                }
            }))
            .to(TestHelper.<Integer>testConsumer())
            .assertFailureAndMessage(TestException.class, "First");

            TestHelper.assertUndeliverable(errors, 0, TestException.class, "Second");
        } finally {
            RxJavaPlugins.reset();
        }
    }

    @Test
    public void emissionQueueTrigger() {
        final PublishSubject<Integer> ps1 = PublishSubject.create();
        final PublishSubject<Integer> ps2 = PublishSubject.create();

        TestObserver<Integer> to = new TestObserver<Integer>() {
            @Override
            public void onNext(Integer t) {
                super.onNext(t);
                if (t == 1) {
                    ps2.onNext(2);
                    ps2.onComplete();
                }
            }
        };

        Observable.just(ps1, ps2)
                .flatMapSingle(new Function<PublishSubject<Integer>, SingleSource<Integer>>() {
                    @Override
                    public SingleSource<Integer> apply(PublishSubject<Integer> v) throws Exception {
                        return v.singleOrError();
                    }
                })
        .subscribe(to);

        ps1.onNext(1);
        ps1.onComplete();

        to.assertResult(1, 2);
    }

    @Test
    public void disposeInner() {
        final TestObserver<Object> to = new TestObserver<>();

        Observable.just(1).flatMapSingle(new Function<Integer, SingleSource<Object>>() {
            @Override
            public SingleSource<Object> apply(Integer v) throws Exception {
                return new Single<Object>() {
                    @Override
                    protected void subscribeActual(SingleObserver<? super Object> observer) {
                        observer.onSubscribe(Disposable.empty());

                        assertFalse(((Disposable)observer).isDisposed());

                        to.dispose();

                        assertTrue(((Disposable)observer).isDisposed());
                    }
                };
            }
        })
        .subscribe(to);

        to
        .assertEmpty();
    }

    @Test
    public void undeliverableUponCancel() {
        TestHelper.checkUndeliverableUponCancel(new ObservableConverter<Integer, Observable<Integer>>() {
            @Override
            public Observable<Integer> apply(Observable<Integer> upstream) {
                return upstream.flatMapSingle(new Function<Integer, Single<Integer>>() {
                    @Override
                    public Single<Integer> apply(Integer v) throws Throwable {
                        return Single.just(v).hide();
                    }
                });
            }
        });
    }

    @Test
    public void undeliverableUponCancelDelayError() {
        TestHelper.checkUndeliverableUponCancel(new ObservableConverter<Integer, Observable<Integer>>() {
            @Override
            public Observable<Integer> apply(Observable<Integer> upstream) {
                return upstream.flatMapSingle(new Function<Integer, Single<Integer>>() {
                    @Override
                    public Single<Integer> apply(Integer v) throws Throwable {
                        return Single.just(v).hide();
                    }
                }, true);
            }
        });
    }

    @Test
    public void innerErrorOuterCompleteRace() {
        TestException ex = new TestException();
        for (int i = 0; i < TestHelper.RACE_DEFAULT_LOOPS; i++) {
            PublishSubject<Integer> ps1 = PublishSubject.create();
            SingleSubject<Integer> ps2 = SingleSubject.create();

            TestObserver<Integer> to = ps1.flatMapSingle(_ -> ps2)
            .test();

            ps1.onNext(1);

            TestHelper.race(
                    () -> ps1.onComplete(),
                    () -> ps2.onError(ex)
            );

            to.assertFailure(TestException.class);
        }
    }

    @Test
    public void cancelWhileMapping() throws Throwable {
        for (int i = 0; i < TestHelper.RACE_DEFAULT_LOOPS; i++) {
            PublishSubject<Integer> ps1 = PublishSubject.create();

            TestObserver<Integer> to = new TestObserver<>();
            CountDownLatch cdl = new CountDownLatch(1);

            ps1.flatMapSingle(_ -> {
                TestHelper.raceOther(() -> {
                    to.dispose();
                }, cdl);
                return Single.just(1);
            })
            .subscribe(to);

            ps1.onNext(1);

            cdl.await();
        }
    }

    @Test
    public void onNextDrainCancel() {
        SingleSubject<Integer> ss1 = SingleSubject.create();
        SingleSubject<Integer> ss2 = SingleSubject.create();

        TestObserver<Integer> to = new TestObserver<>();

        Observable.just(1, 2)
        .flatMapSingle(v -> v == 1 ? ss1 : ss2)
        .doOnNext(v -> {
            if (v == 1) {
                ss2.onSuccess(2);
                to.dispose();
            }
        })
        .subscribe(to);

        ss1.onSuccess(1);

        to.assertValuesOnly(1);
    }
}
