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 static readonly double maxLenght = 20.0*snapLenght*snapScale;

		public virtual Track.Point transformPoint(Track.Point point)

			{ return point; }

		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.count < 1)

				return double.PositiveInfinity;

			double sumWeight = 0.0;

			double sumLength = 0.0;

			double sumDeviation = 0.0;

			Point prev = track.getFirst().position;

			foreach(Track.Point tp in track.points) {

				Point p = tp.position;

				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;

					Track.Point ntp = transformPoint(tp);

					double deviation = (ntp.position - 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) {

			double bestWeight = 0.0;

			Guideline best = null;

			foreach(Guideline guideline in guidelines) {

				double weight = guideline.calcTrackWeight(track);

				if (best == null || weight < bestWeight) {

					bestWeight = weight;

					best = guideline;

				}

			}

			return best;

		}

	}

}