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.
/**
 * 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.internal.operators.observable;

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

import io.reactivex.*;
import io.reactivex.functions.*;
import io.reactivex.internal.functions.*;
import io.reactivex.observables.ConnectableObservable;

Helper utility class to support Observable with inner classes.
/**
 * Helper utility class to support Observable with inner classes.
 */
public final class ObservableInternalHelper {

    private ObservableInternalHelper() {
        throw new IllegalStateException("No instances!");
    }

    static final class SimpleGenerator<T, S> implements BiFunction<S, Emitter<T>, S> {
        final Consumer<Emitter<T>> consumer;

        SimpleGenerator(Consumer<Emitter<T>> consumer) {
            this.consumer = consumer;
        }

        @Override
        public S apply(S t1, Emitter<T> t2) throws Exception {
            consumer.accept(t2);
            return t1;
        }
    }

    public static <T, S> BiFunction<S, Emitter<T>, S> simpleGenerator(Consumer<Emitter<T>> consumer) {
        return new SimpleGenerator<T, S>(consumer);
    }

    static final class SimpleBiGenerator<T, S> implements BiFunction<S, Emitter<T>, S> {
        final BiConsumer<S, Emitter<T>> consumer;

        SimpleBiGenerator(BiConsumer<S, Emitter<T>> consumer) {
            this.consumer = consumer;
        }

        @Override
        public S apply(S t1, Emitter<T> t2) throws Exception {
            consumer.accept(t1, t2);
            return t1;
        }
    }

    public static <T, S> BiFunction<S, Emitter<T>, S> simpleBiGenerator(BiConsumer<S, Emitter<T>> consumer) {
        return new SimpleBiGenerator<T, S>(consumer);
    }

    static final class ItemDelayFunction<T, U> implements Function<T, ObservableSource<T>> {
        final Function<? super T, ? extends ObservableSource<U>> itemDelay;

        ItemDelayFunction(Function<? super T, ? extends ObservableSource<U>> itemDelay) {
            this.itemDelay = itemDelay;
        }

        @Override
        public ObservableSource<T> apply(final T v) throws Exception {
            ObservableSource<U> o = ObjectHelper.requireNonNull(itemDelay.apply(v), "The itemDelay returned a null ObservableSource");
            return new ObservableTake<U>(o, 1).map(Functions.justFunction(v)).defaultIfEmpty(v);
        }
    }

    public static <T, U> Function<T, ObservableSource<T>> itemDelay(final Function<? super T, ? extends ObservableSource<U>> itemDelay) {
        return new ItemDelayFunction<T, U>(itemDelay);
    }

    static final class ObserverOnNext<T> implements Consumer<T> {
        final Observer<T> observer;

        ObserverOnNext(Observer<T> observer) {
            this.observer = observer;
        }

        @Override
        public void accept(T v) throws Exception {
            observer.onNext(v);
        }
    }

    static final class ObserverOnError<T> implements Consumer<Throwable> {
        final Observer<T> observer;

        ObserverOnError(Observer<T> observer) {
            this.observer = observer;
        }

        @Override
        public void accept(Throwable v) throws Exception {
            observer.onError(v);
        }
    }

    static final class ObserverOnComplete<T> implements Action {
        final Observer<T> observer;

        ObserverOnComplete(Observer<T> observer) {
            this.observer = observer;
        }

        @Override
        public void run() throws Exception {
            observer.onComplete();
        }
    }

    public static <T> Consumer<T> observerOnNext(Observer<T> observer) {
        return new ObserverOnNext<T>(observer);
    }

    public static <T> Consumer<Throwable> observerOnError(Observer<T> observer) {
        return new ObserverOnError<T>(observer);
    }

    public static <T> Action observerOnComplete(Observer<T> observer) {
        return new ObserverOnComplete<T>(observer);
    }

    static final class FlatMapWithCombinerInner<U, R, T> implements Function<U, R> {
        private final BiFunction<? super T, ? super U, ? extends R> combiner;
        private final T t;

        FlatMapWithCombinerInner(BiFunction<? super T, ? super U, ? extends R> combiner, T t) {
            this.combiner = combiner;
            this.t = t;
        }

        @Override
        public R apply(U w) throws Exception {
            return combiner.apply(t, w);
        }
    }

    static final class FlatMapWithCombinerOuter<T, R, U> implements Function<T, ObservableSource<R>> {
        private final BiFunction<? super T, ? super U, ? extends R> combiner;
        private final Function<? super T, ? extends ObservableSource<? extends U>> mapper;

        FlatMapWithCombinerOuter(BiFunction<? super T, ? super U, ? extends R> combiner,
                Function<? super T, ? extends ObservableSource<? extends U>> mapper) {
            this.combiner = combiner;
            this.mapper = mapper;
        }

        @Override
        public ObservableSource<R> apply(final T t) throws Exception {
            @SuppressWarnings("unchecked")
            ObservableSource<U> u = (ObservableSource<U>)ObjectHelper.requireNonNull(mapper.apply(t), "The mapper returned a null ObservableSource");
            return new ObservableMap<U, R>(u, new FlatMapWithCombinerInner<U, R, T>(combiner, t));
        }
    }

    public static <T, U, R> Function<T, ObservableSource<R>> flatMapWithCombiner(
            final Function<? super T, ? extends ObservableSource<? extends U>> mapper,
                    final BiFunction<? super T, ? super U, ? extends R> combiner) {
        return new FlatMapWithCombinerOuter<T, R, U>(combiner, mapper);
    }

    static final class FlatMapIntoIterable<T, U> implements Function<T, ObservableSource<U>> {
        private final Function<? super T, ? extends Iterable<? extends U>> mapper;

        FlatMapIntoIterable(Function<? super T, ? extends Iterable<? extends U>> mapper) {
            this.mapper = mapper;
        }

        @Override
        public ObservableSource<U> apply(T t) throws Exception {
            return new ObservableFromIterable<U>(ObjectHelper.requireNonNull(mapper.apply(t), "The mapper returned a null Iterable"));
        }
    }

    public static <T, U> Function<T, ObservableSource<U>> flatMapIntoIterable(final Function<? super T, ? extends Iterable<? extends U>> mapper) {
        return new FlatMapIntoIterable<T, U>(mapper);
    }

    enum MapToInt implements Function<Object, Object> {
        INSTANCE;
        @Override
        public Object apply(Object t) throws Exception {
            return 0;
        }
    }

    public static <T> Callable<ConnectableObservable<T>> replayCallable(final Observable<T> parent) {
        return new ReplayCallable<T>(parent);
    }

    public static <T> Callable<ConnectableObservable<T>> replayCallable(final Observable<T> parent, final int bufferSize) {
        return new BufferedReplayCallable<T>(parent, bufferSize);
    }

    public static <T> Callable<ConnectableObservable<T>> replayCallable(final Observable<T> parent, final int bufferSize, final long time, final TimeUnit unit, final Scheduler scheduler) {
        return new BufferedTimedReplayCallable<T>(parent, bufferSize, time, unit, scheduler);
    }

    public static <T> Callable<ConnectableObservable<T>> replayCallable(final Observable<T> parent, final long time, final TimeUnit unit, final Scheduler scheduler) {
        return new TimedReplayCallable<T>(parent, time, unit, scheduler);
    }

    public static <T, R> Function<Observable<T>, ObservableSource<R>> replayFunction(final Function<? super Observable<T>, ? extends ObservableSource<R>> selector, final Scheduler scheduler) {
        return new ReplayFunction<T, R>(selector, scheduler);
    }

    static final class ZipIterableFunction<T, R>
    implements Function<List<ObservableSource<? extends T>>, ObservableSource<? extends R>> {
        private final Function<? super Object[], ? extends R> zipper;

        ZipIterableFunction(Function<? super Object[], ? extends R> zipper) {
            this.zipper = zipper;
        }

        @Override
        public ObservableSource<? extends R> apply(List<ObservableSource<? extends T>> list) {
            return Observable.zipIterable(list, zipper, false, Observable.bufferSize());
        }
    }

    public static <T, R> Function<List<ObservableSource<? extends T>>, ObservableSource<? extends R>> zipIterable(final Function<? super Object[], ? extends R> zipper) {
        return new ZipIterableFunction<T, R>(zipper);
    }

    static final class ReplayCallable<T> implements Callable<ConnectableObservable<T>> {
        private final Observable<T> parent;

        ReplayCallable(Observable<T> parent) {
            this.parent = parent;
        }

        @Override
        public ConnectableObservable<T> call() {
            return parent.replay();
        }
    }

    static final class BufferedReplayCallable<T> implements Callable<ConnectableObservable<T>> {
        private final Observable<T> parent;
        private final int bufferSize;

        BufferedReplayCallable(Observable<T> parent, int bufferSize) {
            this.parent = parent;
            this.bufferSize = bufferSize;
        }

        @Override
        public ConnectableObservable<T> call() {
            return parent.replay(bufferSize);
        }
    }

    static final class BufferedTimedReplayCallable<T> implements Callable<ConnectableObservable<T>> {
        private final Observable<T> parent;
        private final int bufferSize;
        private final long time;
        private final TimeUnit unit;
        private final Scheduler scheduler;

        BufferedTimedReplayCallable(Observable<T> parent, int bufferSize, long time, TimeUnit unit, Scheduler scheduler) {
            this.parent = parent;
            this.bufferSize = bufferSize;
            this.time = time;
            this.unit = unit;
            this.scheduler = scheduler;
        }

        @Override
        public ConnectableObservable<T> call() {
            return parent.replay(bufferSize, time, unit, scheduler);
        }
    }

    static final class TimedReplayCallable<T> implements Callable<ConnectableObservable<T>> {
        private final Observable<T> parent;
        private final long time;
        private final TimeUnit unit;
        private final Scheduler scheduler;

        TimedReplayCallable(Observable<T> parent, long time, TimeUnit unit, Scheduler scheduler) {
            this.parent = parent;
            this.time = time;
            this.unit = unit;
            this.scheduler = scheduler;
        }

        @Override
        public ConnectableObservable<T> call() {
            return parent.replay(time, unit, scheduler);
        }
    }

    static final class ReplayFunction<T, R> implements Function<Observable<T>, ObservableSource<R>> {
        private final Function<? super Observable<T>, ? extends ObservableSource<R>> selector;
        private final Scheduler scheduler;

        ReplayFunction(Function<? super Observable<T>, ? extends ObservableSource<R>> selector, Scheduler scheduler) {
            this.selector = selector;
            this.scheduler = scheduler;
        }

        @Override
        public ObservableSource<R> apply(Observable<T> t) throws Exception {
            ObservableSource<R> apply = ObjectHelper.requireNonNull(selector.apply(t), "The selector returned a null ObservableSource");
            return Observable.wrap(apply).observeOn(scheduler);
        }
    }
}