/*
 * Copyright 2011-2024 the original author or authors.
 *
 * 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
 *
 *      https://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 org.springframework.data.redis.connection;

import org.springframework.lang.Nullable;

/**
 * PubSub-specific Redis commands.
 *
 * @author Costin Leau
 * @author Mark Paluch
 * @author Christoph Strobl
 */
public interface RedisPubSubCommands {

	/**
	 * Indicates whether the current connection is subscribed (to at least one channel) or not.
	 *
	 * @return true if the connection is subscribed, false otherwise
	 */
	boolean isSubscribed();

	/**
	 * Returns the current subscription for this connection or null if the connection is not subscribed.
	 *
	 * @return the current subscription, {@literal null} if none is available.
	 */
	@Nullable
	Subscription getSubscription();

	/**
	 * Publishes the given message to the given channel.
	 *
	 * @param channel the channel to publish to. Must not be {@literal null}.
	 * @param message message to publish. Must not be {@literal null}.
	 * @return the number of clients that received the message or {@literal null} when used in pipeline / transaction.
	 * @see <a href="https://redis.io/commands/publish">Redis Documentation: PUBLISH</a>
	 */
	@Nullable
	Long publish(byte[] channel, byte[] message);

	/**
	 * Subscribes the connection to the given channels. Once subscribed, a connection enters listening mode and can only
	 * subscribe to other channels or unsubscribe. No other commands are accepted until the connection is unsubscribed.
	 * <p>
	 * Note that this operation is blocking and the current thread starts waiting for new messages immediately.
	 *
	 * @param listener message listener, must not be {@literal null}.
	 * @param channels channel names, must not be {@literal null}.
	 * @see <a href="https://redis.io/commands/subscribe">Redis Documentation: SUBSCRIBE</a>
	 */
	void subscribe(MessageListener listener, byte[]... channels);

	/**
	 * Subscribes the connection to all channels matching the given patterns. Once subscribed, a connection enters
	 * listening mode and can only subscribe to other channels or unsubscribe. No other commands are accepted until the
	 * connection is unsubscribed.
	 * <p>
	 * Note that this operation is blocking and the current thread starts waiting for new messages immediately.
	 *
	 * @param listener message listener, must not be {@literal null}.
	 * @param patterns channel name patterns, must not be {@literal null}.
	 * @see <a href="https://redis.io/commands/psubscribe">Redis Documentation: PSUBSCRIBE</a>
	 */
	void pSubscribe(MessageListener listener, byte[]... patterns);
}
