/**
 * 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.storm.topology;

import org.apache.storm.tuple.Tuple;
import org.apache.storm.windowing.TimestampExtractor;

/**
 * A {@link TimestampExtractor} that extracts timestamp from a specific field in the tuple.
 */
public final class TupleFieldTimestampExtractor implements TimestampExtractor {
    private final String fieldName;

    private TupleFieldTimestampExtractor(String fieldName) {
        this.fieldName = fieldName;
    }

    public static TupleFieldTimestampExtractor of(String fieldName) {
        return new TupleFieldTimestampExtractor(fieldName);
    }

    @Override
    public long extractTimestamp(Tuple tuple) {
        return tuple.getLongByField(fieldName);
    }

    @Override
    public String toString() {
        return "TupleFieldTimestampExtractor{"
                + "fieldName='" + fieldName + '\''
                + '}';
    }
}