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/*
 * Copyright (C) 2008-2012 AgroSense Foundation.
 *
 * AgroSense is free software: you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation, either version 3 of the License, or
 * (at your option) any later version.
 *
 * There are special exceptions to the terms and conditions of the GPLv3 as it is applied to
 * this software, see the FLOSS License Exception
 * .
 *
 * AgroSense is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with AgroSense.  If not, see .
 * 
 * Contributors:
 *    johan - initial API and implementation and/or initial documentation
 */
package eu.agrosense.client.grid.util;

import eu.agrosense.client.grid.util.AggregationStrategy.Factory;

/**
 * Basic aggregation strategy implementations.
 * 
 * @author johan
 */
public class AggregationStrategies {
    
    // absolute amounts:
    protected static final class Sum implements AggregationStrategy {
        private double sum;

        private Sum(double initialValue) {
            sum = initialValue;
        }

        @Override
        public void add(double value) {
            sum += value;
        }

        @Override
        public double getAggregate() {
            return sum;
        }
    }
    
    public static Factory sum() {
        return new Factory() {
            @Override
            public AggregationStrategy create(double value) { return new Sum(value); }
        };
    }

    // e.g. setpoint rates:
    protected static final class Average implements AggregationStrategy {
        private double sum;
        private int count;

        private Average(double initialValue) {
            sum = initialValue;
            count = 1;
        }

        @Override
        public void add(double value) {
            sum += value;
            count++;
        }

        @Override
        public double getAggregate() {
            return sum / count;
        }
    }
    
    public static Factory average() {
        return new Factory() {
            @Override
            public AggregationStrategy create(double value) { return new Average(value); }
        };
    }
    
    protected static final class Max implements AggregationStrategy {
        private double max;

        private Max(double value) {
            this.max = value;
        }

        @Override
        public void add(double value) {
            if (value > max) { max = value; }
        }

        @Override
        public double getAggregate() {
            return max;
        }
    }
    
    public static Factory max() {
        return new Factory() {
            @Override
            public AggregationStrategy create(double value) { return new Max(value); }
        };
    }
      
}