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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.codelibs.elasticsearch.taste.common;

import java.io.Serializable;

/**
 * 
 * A simple class that represents a fixed value of an average and count. This is useful
 * when an API needs to return {@link RunningAverage} but is not in a position to accept
 * updates to it.
 * 
 */
public class FixedRunningAverage implements RunningAverage, Serializable {

    /**
     *
     */
    private static final long serialVersionUID = 1L;

    private final double average;

    private final int count;

    public FixedRunningAverage(final double average, final int count) {
        this.average = average;
        this.count = count;
    }

    /**
     * @throws UnsupportedOperationException
     */
    @Override
    public synchronized void addDatum(final double datum) {
        throw new UnsupportedOperationException();
    }

    /**
     * @throws UnsupportedOperationException
     */
    @Override
    public synchronized void removeDatum(final double datum) {
        throw new UnsupportedOperationException();
    }

    /**
     * @throws UnsupportedOperationException
     */
    @Override
    public synchronized void changeDatum(final double delta) {
        throw new UnsupportedOperationException();
    }

    @Override
    public synchronized int getCount() {
        return count;
    }

    @Override
    public synchronized double getAverage() {
        return average;
    }

    @Override
    public RunningAverage inverse() {
        return new InvertedRunningAverage(this);
    }

    @Override
    public synchronized String toString() {
        return String.valueOf(average);
    }

}