using System;

using System.Collections.Generic;

namespace Assistance {

	public class ModifierSnowflake: Modifier {

		public class Modifier: Track.Modifier {

			Point center, px, py;

			public Modifier(Track.Handler handler, Point center, double angle, bool flip):

				base(handler)

			{

				this.center = center;

				double s = Math.Sin(angle);

				double c = Math.Cos(angle);

				if (flip) { px = new Point(c, s); py = new Point(s,-c); }

				     else { px = new Point(c,-s); py = new Point(s, c); }

			}

			public InputManager.KeyPoint.Holder holder = null;

			public List<guideline> guidelines = new List<guideline>();</guideline></guideline>

			public override Track.WayPoint calcWayPoint(double originalIndex) {

				Track.WayPoint p = base.calcWayPoint(originalIndex);

				Point pp = p.point.position - center;

				p.point.position = center + new Point(Point.dot(pp, px), Point.dot(pp, py));

				p.tangent.position = new Point(Point.dot(p.tangent.position, px), Point.dot(p.tangent.position, py));

				return p;

			}

		}

		public ActivePoint center;

		public int rays;

		public ModifierSnowflake(Document document, Point center, int rays = 6): base(document) {

			this.center = new ActivePoint(this, ActivePoint.Type.CircleCross, center);

			this.rays = rays;

		}

		public override void draw(Cairo.Context context) {

			for(int i = 0; i < rays/2; ++i) {

				Point pp0 = center.position;

				Point pp1 = center.position + new Point(100.0, 0.0).rotate( i*2.0*Math.PI/(double)rays );

				Rectangle bounds = Drawing.Helper.getBounds(context);

				Geometry.truncateInfiniteLine(bounds, ref pp0, ref pp1);

				context.Save();

				pen.apply(context);

				context.MoveTo(pp0.x, pp0.y);

				context.LineTo(pp1.x, pp1.y);

				context.Stroke();

				context.Restore();

			}

		}

		public override void modify(Track track, InputManager.KeyPoint keyPoint, List<track> outTracks) {

			if (track.handler == null) {

				track.handler = new Track.Handler(this, track);

				for(int i = 0; i < rays; ++i) {

					double angle = i*2.0*Math.PI/(double)rays;

					track.handler.tracks.Add(new Track( new Modifier(track.handler, center.position, angle, false) ));

					track.handler.tracks.Add(new Track( new Modifier(track.handler, center.position, angle, true) ));

				}

			}

			outTracks.AddRange(track.handler.tracks);

			if (!track.isChanged)

				return;

			int start = track.points.Count - track.wayPointsAdded;

			if (start < 0) start = 0;

			foreach(Track subTrack in track.handler.tracks) {

				// remove points

				if (start < subTrack.points.Count) {

					subTrack.wayPointsRemoved += subTrack.points.Count - start;

					subTrack.points.RemoveRange(start, subTrack.points.Count - start);

				}

				// add points

				for(int i = start; i < track.points.Count; ++i)

					subTrack.points.Add( subTrack.modifier.calcWayPoint(i) );

				subTrack.wayPointsAdded += subTrack.points.Count - start;

			}

			track.wayPointsRemoved = 0;

			track.wayPointsAdded = 0;

		}

	}

}