/*
 * Copyright © 2017 Keith Packard <keithp@keithp.com>
 *
 * This program 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 2 of the License, or
 * (at your option) any later version.
 *
 * This program 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.
 */

package org.altusmetrum.altoslib_11;

import java.util.*;

public class AltosTimeSeries implements Iterable<AltosTimeValue> {
	public String		label;
	public AltosUnits	units;
	List<AltosTimeValue>	values;

	public void add(AltosTimeValue tv) {
		values.add(tv);
	}

	public void add(double time, double value) {
		add(new AltosTimeValue(time, value));
	}

	public AltosTimeValue get(int i) {
		return values.get(i);
	}

	public int size() {
		return values.size();
	}

	public Iterator<AltosTimeValue> iterator() {
		return values.iterator();
	}

	public double max() {
		double max = AltosLib.MISSING;
		for (AltosTimeValue tv : values) {
			if (max == AltosLib.MISSING || tv.value > max)
				max = tv.value;
		}
		return max;
	}

	public double min() {
		double min = AltosLib.MISSING;
		for (AltosTimeValue tv : values) {
			if (min == AltosLib.MISSING || tv.value < min)
				min = tv.value;
		}
		return min;
	}

	public AltosTimeSeries integrate(AltosTimeSeries integral) {
		double	value = 0.0;
		double	pvalue = 0.0;
		double 	time = 0.0;
		boolean start = true;

		for (AltosTimeValue v : values) {
			if (start) {
				value = 0.0;
				start = false;
			} else {
				value += (pvalue + v.value) / 2.0 * (v.time - time);
			}
			pvalue = v.value;
			time = v.time;
//			System.out.printf("%g %g %g\n", time, v.value, value);
			integral.add(time, value);

		}
		return integral;
	}

	public AltosTimeSeries differentiate(AltosTimeSeries diff) {
		double value = 0.0;
		double time = 0.0;
		boolean start = true;

		for (AltosTimeValue v: values) {
			if (start) {
				value = v.value;
				time = v.time;
				start = false;
			} else {
				double	dx = v.time - time;
				double	dy = v.value - value;

				if (dx != 0)
					diff.add(time, dy/dx);

				time = v.time;
				value = v.value;
			}
		}
		return diff;
	}

	private int find_left(int i, double dt) {
		int j;
		double t = values.get(i).time - dt;
		for (j = i; j >= 0; j--)	{
			if (values.get(j).time < t)
				break;
		}
		return j + 1;

	}

	private int find_right(int i, double dt) {
		int j;
		double t = values.get(i).time + dt;
		for (j = i; j < values.size(); j++) {
			if (values.get(j).time > t)
				break;
		}
		return j - 1;

	}

	private double filter_coeff(double dist, double width) {
		double ratio = dist / (width / 2);

		return Math.cos(ratio * Math.PI / 2);
	}

	public AltosTimeSeries filter(AltosTimeSeries f, double width) {
		double	half_width = width/2;
		for (int i = 0; i < values.size(); i++) {
			double	center_time = values.get(i).time;
			double	left_time = center_time - half_width;
			double	right_time = center_time + half_width;
			double	total_coeff = 0.0;
			double	total_value = 0.0;

			int	left = find_left(i, half_width);
			int	right = find_right(i, half_width);
			for (int j = left; j <= right; j++) {
				double	j_time = values.get(j).time;

				if (left_time <= j_time && j_time <= right_time) {
					double	coeff = filter_coeff(j_time - center_time, width);
					total_coeff += coeff;
					total_value += coeff * values.get(j).value;
				}
			}
			if (total_coeff != 0.0)
				f.add(center_time, total_value / total_coeff);
		}
		return f;
	}

	public AltosTimeSeries(String label, AltosUnits units) {
		this.label = label;
		this.units = units;
		this.values = new ArrayList<AltosTimeValue>();
	}
}