/*
 * Copyright 2017-2024 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.core;

import reactor.core.publisher.Flux;
import reactor.core.publisher.Mono;

import java.nio.ByteBuffer;
import java.util.Collection;
import java.util.List;
import java.util.Map;

/**
 * Reactive Redis operations for Hash Commands.
 * <p>
 * Streams of methods returning {@code Mono<K>} or {@code Flux<M>} are terminated with
 * {@link org.springframework.dao.InvalidDataAccessApiUsageException} when
 * {@link org.springframework.data.redis.serializer.RedisElementReader#read(ByteBuffer)} returns {@code null} for a
 * particular element as Reactive Streams prohibit the usage of {@code null} values.
 *
 * @author Mark Paluch
 * @author Christoph Strobl
 * @since 2.0
 */
public interface ReactiveHashOperations<H, HK, HV> {

	/**
	 * Delete given hash {@code hashKeys} from the hash at {@literal key}.
	 *
	 * @param key must not be {@literal null}.
	 * @param hashKeys must not be {@literal null}.
	 * @return
	 */
	Mono<Long> remove(H key, Object... hashKeys);

	/**
	 * Determine if given hash {@code hashKey} exists.
	 *
	 * @param key must not be {@literal null}.
	 * @param hashKey must not be {@literal null}.
	 * @return
	 */
	Mono<Boolean> hasKey(H key, Object hashKey);

	/**
	 * Get value for given {@code hashKey} from hash at {@code key}.
	 *
	 * @param key must not be {@literal null}.
	 * @param hashKey must not be {@literal null}.
	 * @return
	 */
	Mono<HV> get(H key, Object hashKey);

	/**
	 * Get values for given {@code hashKeys} from hash at {@code key}. Values are in the order of the requested keys.
	 * Absent field values are represented using {@code null} in the resulting {@link List}.
	 *
	 * @param key must not be {@literal null}.
	 * @param hashKeys must not be {@literal null}.
	 * @return
	 */
	Mono<List<HV>> multiGet(H key, Collection<HK> hashKeys);

	/**
	 * Increment {@code value} of a hash {@code hashKey} by the given {@code delta}.
	 *
	 * @param key must not be {@literal null}.
	 * @param hashKey must not be {@literal null}.
	 * @param delta
	 * @return
	 */
	Mono<Long> increment(H key, HK hashKey, long delta);

	/**
	 * Increment {@code value} of a hash {@code hashKey} by the given {@code delta}.
	 *
	 * @param key must not be {@literal null}.
	 * @param hashKey must not be {@literal null}.
	 * @param delta
	 * @return
	 */
	Mono<Double> increment(H key, HK hashKey, double delta);

	/**
	 * Return a random hash key (aka field) from the hash stored at {@code key}.
	 *
	 * @param key must not be {@literal null}.
	 * @return
	 * @since 2.6
	 * @see <a href="https://redis.io/commands/hrandfield">Redis Documentation: HRANDFIELD</a>
	 */
	Mono<HK> randomKey(H key);

	/**
	 * Return a random entry from the hash stored at {@code key}.
	 *
	 * @param key must not be {@literal null}.
	 * @return
	 * @since 2.6
	 * @see <a href="https://redis.io/commands/hrandfield">Redis Documentation: HRANDFIELD</a>
	 */
	Mono<Map.Entry<HK, HV>> randomEntry(H key);

	/**
	 * Return random hash keys (aka fields) from the hash stored at {@code key}. If the provided {@code count} argument is
	 * positive, return a list of distinct hash keys, capped either at {@code count} or the hash size. If {@code count} is
	 * negative, the behavior changes and the command is allowed to return the same hash key multiple times. In this case,
	 * the number of returned fields is the absolute value of the specified count.
	 *
	 * @param key must not be {@literal null}.
	 * @param count number of fields to return.
	 * @return
	 * @since 2.6
	 * @see <a href="https://redis.io/commands/hrandfield">Redis Documentation: HRANDFIELD</a>
	 */
	Flux<HK> randomKeys(H key, long count);

	/**
	 * Return random entries from the hash stored at {@code key}. If the provided {@code count} argument is positive,
	 * return a list of distinct entries, capped either at {@code count} or the hash size. If {@code count} is negative,
	 * the behavior changes and the command is allowed to return the same entry multiple times. In this case, the number
	 * of returned fields is the absolute value of the specified count.
	 *
	 * @param key must not be {@literal null}.
	 * @param count number of fields to return.
	 * @return {@literal null} if key does not exist or when used in pipeline / transaction.
	 * @since 2.6
	 * @see <a href="https://redis.io/commands/hrandfield">Redis Documentation: HRANDFIELD</a>
	 */
	Flux<Map.Entry<HK, HV>> randomEntries(H key, long count);

	/**
	 * Get key set (fields) of hash at {@code key}.
	 *
	 * @param key must not be {@literal null}.
	 * @return
	 */
	Flux<HK> keys(H key);

	/**
	 * Get size of hash at {@code key}.
	 *
	 * @param key must not be {@literal null}.
	 * @return
	 */
	Mono<Long> size(H key);

	/**
	 * Set multiple hash fields to multiple values using data provided in {@code m}.
	 *
	 * @param key must not be {@literal null}.
	 * @param map must not be {@literal null}.
	 */
	Mono<Boolean> putAll(H key, Map<? extends HK, ? extends HV> map);

	/**
	 * Set the {@code value} of a hash {@code hashKey}.
	 *
	 * @param key must not be {@literal null}.
	 * @param hashKey must not be {@literal null}.
	 * @param value
	 */
	Mono<Boolean> put(H key, HK hashKey, HV value);

	/**
	 * Set the {@code value} of a hash {@code hashKey} only if {@code hashKey} does not exist.
	 *
	 * @param key must not be {@literal null}.
	 * @param hashKey must not be {@literal null}.
	 * @param value
	 * @return
	 */
	Mono<Boolean> putIfAbsent(H key, HK hashKey, HV value);

	/**
	 * Get entry set (values) of hash at {@code key}.
	 *
	 * @param key must not be {@literal null}.
	 * @return
	 */
	Flux<HV> values(H key);

	/**
	 * Get entire hash stored at {@code key}.
	 *
	 * @param key must not be {@literal null}.
	 * @return
	 */
	Flux<Map.Entry<HK, HV>> entries(H key);

	/**
	 * Use a {@link Flux} to iterate over entries in the hash at {@code key}. The resulting {@link Flux} acts as a cursor
	 * and issues {@code HSCAN} commands itself as long as the subscriber signals demand.
	 *
	 * @param key must not be {@literal null}.
	 * @return the {@link Flux} emitting the {@link java.util.Map.Entry entries} on by one or an {@link Flux#empty() empty
	 *         flux} if the key does not exist.
	 * @throws IllegalArgumentException when the given {@code key} is {@literal null}.
	 * @see <a href="https://redis.io/commands/hscan">Redis Documentation: HSCAN</a>
	 * @since 2.1
	 */
	default Flux<Map.Entry<HK, HV>> scan(H key) {
		return scan(key, ScanOptions.NONE);
	}

	/**
	 * Use a {@link Flux} to iterate over entries in the hash at {@code key} given {@link ScanOptions}. The resulting
	 * {@link Flux} acts as a cursor and issues {@code HSCAN} commands itself as long as the subscriber signals demand.
	 *
	 * @param key must not be {@literal null}.
	 * @param options must not be {@literal null}. Use {@link ScanOptions#NONE} instead.
	 * @return the {@link Flux} emitting the {@link java.util.Map.Entry entries} on by one or an {@link Flux#empty() empty
	 *         flux} if the key does not exist.
	 * @throws IllegalArgumentException when one of the required arguments is {@literal null}.
	 * @see <a href="https://redis.io/commands/hscan">Redis Documentation: HSCAN</a>
	 * @since 2.1
	 */
	Flux<Map.Entry<HK, HV>> scan(H key, ScanOptions options);

	/**
	 * Removes the given {@literal key}.
	 *
	 * @param key must not be {@literal null}.
	 */
	Mono<Boolean> delete(H key);
}
