package ca.concordia.ece390.VoltmeterApp;

import java.util.ArrayList;
import java.util.List;

/**
 * Stores a list of VoltageMeasurement objects. Usually, the Measurements should be added
 * in chronological order of the measurement being taken.
 */
public class MeasurementAccumulator {
    // You could define this as an interface and then a class implementing this interface...
    // but in this case we don't expect to have different kinds of implementations, so
    // just this one class will do.
    private List<VoltageMeasurement> myList = new ArrayList<VoltageMeasurement>();

    /** Add a voltage measurement to the list. */
    public void add(VoltageMeasurement v) {
        myList.add(v);
    }

    /** Clear the list of all measurements. */
    public void clear() {
        myList.clear();
    }

    /** Get the measurement at the specified index. Index = 0 is the oldest measurement, and
     * index = size() - 1 is the latest measurement. */
    public VoltageMeasurement get(int index) {
        return myList.get(index);
    }

    /** The number of measurements in this list. */
    public int size() {
        return myList.size();
    }

    /**
     * Get the waveform measurement at `index`, filtered through a FIR moving-average filter.
     *
     * The filter averages FOUR measurement at or before the given `index`. If less than four
     * measurements exist, then the average of all measurements are returned.
     *
     * @param index
     * @return The voltage at `index` after the waveform is passed through the filter
     */
    public VoltageMeasurement getFiltered(int index) {
        double tempVolt = 0.0;
        switch (index)
        {
        case 0: return myList.get(index);
        case 1: tempVolt = (myList.get(index).getVoltage() + myList.get(index-1).getVoltage()) / 2;
                return new VoltageMeasurement(myList.get(index).getTime(), tempVolt);

        case 2: tempVolt = (myList.get(index).getVoltage() + myList.get(index-1).getVoltage() + myList.get(index-2).getVoltage()) / 3;
                return new VoltageMeasurement(myList.get(index).getTime(), tempVolt);

        case 3: tempVolt = (myList.get(index).getVoltage() + myList.get(index-1).getVoltage() + myList.get(index-2).getVoltage() + myList.get(index-3).getVoltage()) / 4;
                return new VoltageMeasurement(myList.get(index).getTime(), tempVolt);

        }
        return null;
    }
}