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/**
 * 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.observable;


import io.reactivex.common.Disposable;
import io.reactivex.common.annotations.NonNull;
import io.reactivex.common.functions.Consumer;
import io.reactivex.common.internal.functions.Functions;
import io.reactivex.common.internal.utils.ConnectConsumer;
import io.reactivex.observable.internal.operators.*;

/**
 * A {@code ConnectableObservable} resembles an ordinary {@link Observable}, except that it does not begin
 * emitting items when it is subscribed to, but only when its {@link #connect} method is called. In this way you
 * can wait for all intended {@link Observer}s to {@link Observable#subscribe} to the {@code Observable}
 * before the {@code Observable} begins emitting items.
 * 
 * 
 *
 * @see RxJava Wiki:
 *      Connectable Observable Operators
 * @param 
 *          the type of items emitted by the {@code ConnectableObservable}
 */
public abstract class ConnectableObservable extends Observable {

    /**
     * Instructs the {@code ConnectableObservable} to begin emitting the items from its underlying
     * {@link Observable} to its {@link Observer}s.
     *
     * @param connection
     *          the action that receives the connection subscription before the subscription to source happens
     *          allowing the caller to synchronously disconnect a synchronous source
     * @see ReactiveX documentation: Connect
     */
    public abstract void connect(@NonNull Consumer connection);

    /**
     * Instructs the {@code ConnectableObservable} to begin emitting the items from its underlying
     * {@link Observable} to its {@link Observer}s.
     * 
     * To disconnect from a synchronous source, use the {@link #connect(Consumer)} method.
     *
     * @return the subscription representing the connection
     * @see ReactiveX documentation: Connect
     */
    public final Disposable connect() {
        ConnectConsumer cc = new ConnectConsumer();
        connect(cc);
        return cc.disposable;
    }

    /**
     * Returns an {@code Observable} that stays connected to this {@code ConnectableObservable} as long as there
     * is at least one subscription to this {@code ConnectableObservable}.
     *
     * @return an {@link Observable}
     * @see ReactiveX documentation: RefCount
     */
    @NonNull
    public Observable refCount() {
        return RxJavaObservablePlugins.onAssembly(new ObservableRefCount(this));
    }

    /**
     * Returns an Observable that automatically connects to this ConnectableObservable
     * when the first Subscriber subscribes.
     *
     * @return an Observable that automatically connects to this ConnectableObservable
     *         when the first Subscriber subscribes
     */
    @NonNull
    public Observable autoConnect() {
        return autoConnect(1);
    }
    /**
     * Returns an Observable that automatically connects to this ConnectableObservable
     * when the specified number of Subscribers subscribe to it.
     *
     * @param numberOfSubscribers the number of subscribers to await before calling connect
     *                            on the ConnectableObservable. A non-positive value indicates
     *                            an immediate connection.
     * @return an Observable that automatically connects to this ConnectableObservable
     *         when the specified number of Subscribers subscribe to it
     */
    @NonNull
    public Observable autoConnect(int numberOfSubscribers) {
        return autoConnect(numberOfSubscribers, Functions.emptyConsumer());
    }

    /**
     * Returns an Observable that automatically connects to this ConnectableObservable
     * when the specified number of Subscribers subscribe to it and calls the
     * specified callback with the Subscription associated with the established connection.
     *
     * @param numberOfSubscribers the number of subscribers to await before calling connect
     *                            on the ConnectableObservable. A non-positive value indicates
     *                            an immediate connection.
     * @param connection the callback Consumer that will receive the Subscription representing the
     *                   established connection
     * @return an Observable that automatically connects to this ConnectableObservable
     *         when the specified number of Subscribers subscribe to it and calls the
     *         specified callback with the Subscription associated with the established connection
     */
    @NonNull
    public Observable autoConnect(int numberOfSubscribers, @NonNull Consumer connection) {
        if (numberOfSubscribers <= 0) {
            this.connect(connection);
            return RxJavaObservablePlugins.onAssembly(this);
        }
        return RxJavaObservablePlugins.onAssembly(new ObservableAutoConnect(this, numberOfSubscribers, connection));
    }
}