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/*
 * Licensed to the Apache Software Foundation (ASF) under one or more
 * contributor license agreements. See the NOTICE file distributed with
 * this work for additional information regarding copyright ownership.
 * The ASF licenses this file to You 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 org.apache.kafka.streams.query;


import org.apache.kafka.common.annotation.InterfaceStability.Evolving;
import org.apache.kafka.streams.state.KeyValueIterator;


import java.util.Optional;

/**
 * Interactive query for issuing range queries and scans over KeyValue stores.
 * 
 *  A range query retrieves a set of records, specified using an upper and/or lower bound on the keys.
 * 

 * A scan query retrieves all records contained in the store.
 * 
 */
@Evolving
public final class RangeQuery implements Query> {


    private final Optional lower;
    private final Optional upper;


    private RangeQuery(final Optional lower, final Optional upper) {
        this.lower = lower;
        this.upper = upper;
    }

    /**
     * Interactive range query using a lower and upper bound to filter the keys returned.
     * @param lower The key that specifies the lower bound of the range
     * @param upper The key that specifies the upper bound of the range
     * @param  The key type
     * @param  The value type
     */
    public static  RangeQuery withRange(final K lower, final K upper) {
        return new RangeQuery<>(Optional.ofNullable(lower), Optional.ofNullable(upper));
    }

    /**
     * Interactive range query using an upper bound to filter the keys returned.
     * If both  are null, RangQuery returns a full range scan.
     * @param upper The key that specifies the upper bound of the range
     * @param  The key type
     * @param  The value type
     */
    public static  RangeQuery withUpperBound(final K upper) {
        return new RangeQuery<>(Optional.empty(), Optional.of(upper));
    }

    /**
     * Interactive range query using a lower bound to filter the keys returned.
     * @param lower The key that specifies the lower bound of the range
     * @param  The key type
     * @param  The value type
     */
    public static  RangeQuery withLowerBound(final K lower) {
        return new RangeQuery<>(Optional.of(lower), Optional.empty());
    }

    /**
     * Interactive scan query that returns all records in the store.
     * @param  The key type
     * @param  The value type
     */
    public static  RangeQuery withNoBounds() {
        return new RangeQuery<>(Optional.empty(), Optional.empty());
    }

    /**
     * The lower bound of the query, if specified.
     */
    public Optional getLowerBound() {
        return lower;
    }

    /**
     * The upper bound of the query, if specified
     */
    public Optional getUpperBound() {
        return upper;
    }
}