using System;

using System.Collections.Generic;

using Assistance.Drawing;

namespace Assistance {

	public class Guideline {

		public static readonly Pen pen = new Pen("Light Gray");

		public static readonly Pen penActive = new Pen("Deep Sky Blue");

		public static readonly double snapLenght = 20.0;

		public static readonly double snapScale = 1.0;

		public virtual Point transformPoint(Point p) {

			return p;

		}

		public virtual void draw(Cairo.Context context, bool active) { }

		public void draw(Cairo.Context context) {

			draw(context, false);

		}

		public double calcTrackWeight(Track track) {

			if (track.points.Count < 1)

				return double.PositiveInfinity;

			double sumWeight = 0.0;

			double sumLength = 0.0;

			double sumDeviation = 0.0;

			Point prev = track.points[0].point;

			foreach(TrackPoint tp in track.points) {

				Point p = tp.point;

				double length = (p - prev).len();

				sumLength += length;

				double midStepLength = sumLength - 0.5*length;

				if (midStepLength > Geometry.precision) {

					double weight = length*Geometry.logNormalDistribuitionUnscaled(midStepLength, snapLenght, snapScale);

					sumWeight += weight;

					double deviation = (transformPoint(p) - p).len();

					sumDeviation += weight*deviation;

				}

				prev = p;

			}

			if (sumWeight < Geometry.precision)

				return double.PositiveInfinity;

			return sumDeviation/sumWeight;

		}

		public static Guideline findBest(List<guideline> guidelines, Track track) {</guideline>

			double bestWeight = double.PositiveInfinity;

			Guideline best = null;

			foreach(Guideline guideline in guidelines) {

				double weight = guideline.calcTrackWeight(track);

				if (weight < bestWeight) {

					bestWeight = weight;

					best = guideline;

				}

			}

			return best;

		}

	}

}