using System;

using System.Diagnostics;

using System.Collections.Generic;

namespace Assistance {

	public class InputModifierAssistants: InputModifierTangents {

		public readonly Workarea workarea;

		public readonly bool interpolate;

		public InputModifierAssistants(Workarea workarea, bool interpolate = false, double precision = 1.0):

			base(precision)

		{

			this.workarea = workarea;

			this.interpolate = interpolate;

		}

		public class Modifier: Track.Modifier {

			public Modifier(Track.Handler handler):

				base(handler) { }

			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 = original.calcWayPoint(originalIndex);

				return guidelines.Count > 0 ? guidelines[0].transformPoint(p) : p;

			}

		}

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

			Track subTrack;

			Modifier modifier;

			if (track.handler == null) {

				if (track.points.Count == 0)

					return;

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

				modifier = new Track.Modifier(track.handler);

				workarea.getGuidelines(modifier.guidelines, track.points[0].point.position);

				if (interpolate && modifier.guidelines.Count == 0)

					{ base.modify(track, keyPoint, outTracks); return; }

				track.handler = handler;

				subTrack = new Track(modifier);

				track.handler.tracks.Add(subTrack);

				if (modifier.guidelines.Count > 1) {

					modifier.holder = keyPoint.hold();

					outTracks.Add(subTrack);

					return;

				}

			}

			subTrack = track.handler.tracks[0];

			if (subTrack.modifier is InputModifierTangents.Modifier)

				{ base.modify(track, keyPoint, outTracks); return; }

			modifier = (Modifier)subTrack.modifier;

			outTracks.Add(subTrack);

			if (!track.isChanged)

				return;

			// remove points

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

			if (start < 0) start = 0;

			if (subTrack.points.Count < start) {

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

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

			}

			bool trackIsLong = track.points.Count > 0 && track.getLast().length > 2.0*Guideline.snapLenght;

			if (!trackIsLong && modifier.holder != null && !modifier.holder.isHolded && modifier.holder.available)

				modifier.holder.reuse();

			// select guideline

			if (modifier.holder != null && modifier.holder.isHolded) {

				Guideline guideline = Guideline.findBest(modifier.guidelines, track);

				if (guideline != modifier.guidelines[0]) {

					modifier.guidelines[ modifier.guidelines.IndexOf(guideline) ] = modifier.guidelines[0];

					modifier.guidelines[0] = guideline;

					start = 0;

					subTrack.wayPointsRemoved += subTrack.points.Count;

					subTrack.points.Clear;

				}

				if (trackIsLong)

					modifier.holder.release();

			}

			// add points

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

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

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

		}

	}

}