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/**
 * Copyright 2015 David Karnok and Netflix, Inc.
 * 
 * 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 hu.akarnokd.rxjava2.subscribers;

import org.reactivestreams.*;

import hu.akarnokd.rxjava2.functions.Consumer;
import hu.akarnokd.rxjava2.internal.functions.*;
import hu.akarnokd.rxjava2.internal.subscribers.*;
import hu.akarnokd.rxjava2.internal.subscriptions.SubscriptionHelper;
import hu.akarnokd.rxjava2.plugins.RxJavaPlugins;

/**
 * Utility class to construct various resource-holding and disposable Subscribers from lambdas.
 */
public final class Subscribers {
    /** Utility class. */
    private Subscribers() {
        throw new IllegalStateException("No instances!");
    }

    @SuppressWarnings("unchecked")
    public static  Subscriber empty() {
        return (Subscriber)EmptySubscriber.INSTANCE;
    }

    @SuppressWarnings("unchecked")
    public static  Subscriber cancelled() {
        return (Subscriber)CancelledSubscriber.INSTANCE;
    }

    public static  DisposableSubscriber emptyDisposable() {
        return new DisposableSubscriber() {
            @Override
            public void onNext(T t) {
                
            }
            
            @Override
            public void onError(Throwable t) {
                
            }
            
            @Override
            public void onComplete() {
                
            }
        };
    }

    public static  DisposableSubscriber createDisposable(
            Consumer onNext
    ) {
        return createDisposable(onNext, RxJavaPlugins.errorConsumer(), Functions.emptyRunnable(), Functions.emptyRunnable());
    }

    public static  DisposableSubscriber createDisposable(
            Consumer onNext,
            Consumer onError
    ) {
        return createDisposable(onNext, onError, Functions.emptyRunnable(), Functions.emptyRunnable());
    }

    public static  DisposableSubscriber createDisposable(
            Consumer onNext,
            Consumer onError,
            Runnable onComplete
    ) {
        return createDisposable(onNext, onError, onComplete, Functions.emptyRunnable());
    }
    
    public static  DisposableSubscriber createDisposable(
            final Consumer onNext,
            final Consumer onError,
            final Runnable onComplete,
            final Runnable onStart
    ) {
        Objects.requireNonNull(onNext, "onNext is null");
        Objects.requireNonNull(onError, "onError is null");
        Objects.requireNonNull(onComplete, "onComplete is null");
        Objects.requireNonNull(onStart, "onStart is null");
        return new DisposableSubscriber() {
            boolean done;
            @Override
            protected void onStart() {
                super.onStart();
                try {
                    onStart.run();
                } catch (Throwable e) {
                    done = true;
                    cancel();
                    try {
                        onError.accept(e);
                    } catch (Throwable ex) {
                        RxJavaPlugins.onError(ex);
                        RxJavaPlugins.onError(e);
                    }
                }
            }
            @Override
            public void onNext(T t) {
                if (done) {
                    return;
                }
                try {
                    onNext.accept(t);
                } catch (Throwable e) {
                    done = true;
                    cancel();
                    try {
                        onError.accept(e);
                    } catch (Throwable ex) {
                        RxJavaPlugins.onError(ex);
                        RxJavaPlugins.onError(e);
                    }
                }
            }
            
            @Override
            public void onError(Throwable t) {
                if (done) {
                    RxJavaPlugins.onError(t);
                    return;
                }
                done = true;
                try {
                    onError.accept(t);
                } catch (Throwable ex) {
                    RxJavaPlugins.onError(ex);
                    RxJavaPlugins.onError(t);
                }
            }
            
            @Override
            public void onComplete() {
                if (done) {
                    return;
                }
                done = true;
                try {
                    onComplete.run();
                } catch (Throwable e) {
                    RxJavaPlugins.onError(e);
                }
            }
        };
    }

    static final Consumer REQUEST_ALL = new Consumer() {
        @Override
        public void accept(Subscription t) {
            t.request(Long.MAX_VALUE);
        }
    };
    
    public static  Subscriber create(
            Consumer onNext
    ) {
        return create(onNext, RxJavaPlugins.errorConsumer(), Functions.emptyRunnable(), REQUEST_ALL);
    }

    public static  Subscriber create(
            Consumer onNext,
            Consumer onError
    ) {
        return create(onNext, onError, Functions.emptyRunnable(), REQUEST_ALL);
    }

    public static  Subscriber create(
            Consumer onNext,
            Consumer onError,
            Runnable onComplete
    ) {
        return create(onNext, onError, onComplete, REQUEST_ALL);
    }
    
    public static  Subscriber create(
            final Consumer onNext,
            final Consumer onError,
            final Runnable onComplete,
            final Consumer onStart
    ) {
        Objects.requireNonNull(onNext, "onNext is null");
        Objects.requireNonNull(onError, "onError is null");
        Objects.requireNonNull(onComplete, "onComplete is null");
        Objects.requireNonNull(onStart, "onStart is null");
        return new Subscriber() {
            boolean done;
            
            Subscription s;
            @Override
            public void onSubscribe(Subscription s) {
                if (SubscriptionHelper.validateSubscription(this.s, s)) {
                    return;
                }
                this.s = s;
                try {
                    onStart.accept(s);
                } catch (Throwable e) {
                    done = true;
                    s.cancel();
                    try {
                        onError.accept(e);
                    } catch (Throwable ex) {
                        RxJavaPlugins.onError(ex);
                        RxJavaPlugins.onError(e);
                    }
                }
            }
            @Override
            public void onNext(T t) {
                if (done) {
                    return;
                }
                try {
                    onNext.accept(t);
                } catch (Throwable e) {
                    done = true;
                    s.cancel();
                    try {
                        onError.accept(e);
                    } catch (Throwable ex) {
                        RxJavaPlugins.onError(ex);
                        RxJavaPlugins.onError(e);
                    }
                }
            }
            
            @Override
            public void onError(Throwable t) {
                if (done) {
                    RxJavaPlugins.onError(t);
                    return;
                }
                done = true;
                try {
                    onError.accept(t);
                } catch (Throwable ex) {
                    RxJavaPlugins.onError(ex);
                    RxJavaPlugins.onError(t);
                }
            }
            
            @Override
            public void onComplete() {
                if (done) {
                    return;
                }
                done = true;
                try {
                    onComplete.run();
                } catch (Throwable e) {
                    RxJavaPlugins.onError(e);
                }
            }
        };
    }
}