using System;

using System.Diagnostics;

using System.Collections.Generic;

namespace Assistance {

	public class InputModifierAssistants: InputManager.Modifier {

		public readonly Workarea workarea;

		public readonly List<guideline> shownGuidelines = new List<guideline>();</guideline></guideline>

		public InputModifierAssistants(Workarea workarea)

			{ this.workarea = workarea; }

		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.Point calcPoint(double originalIndex) {

				Track.Point p = base.calcPoint(originalIndex);

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

			}

		}

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

			Track subTrack;

			Modifier modifier;

			if (track.handler == null) {

				if (track.isEmpty)

					return;

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

				modifier = new Modifier(track.handler);

				workarea.getGuidelines(modifier.guidelines, track.getFirst().position);

				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];

			modifier = (Modifier)subTrack.modifier;

			outTracks.Add(subTrack);

			if (!track.wasChanged)

				return;

			// remove points

			int start = track.count - track.pointsAdded;

			if (start < 0) start = 0;

			subTrack.truncate(start);

			bool trackIsLong = !track.isEmpty && (track.getLast().length >= Guideline.maxLenght || track.isFinished());

			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 != null && guideline != modifier.guidelines[0]) {

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

					modifier.guidelines[0] = guideline;

					start = 0;

					subTrack.truncate(0);

				}

				if (trackIsLong)

					modifier.holder.release();

			}

			// add points

			for(int i = start; i < track.count; ++i) {

				double di = (double)i;

				Track.Point p = modifier.calcPoint(di);

				subTrack.add(p);

			}

			track.resetCounters();

		}

		public override void drawHover(Cairo.Context context, Point hover) {

			workarea.getGuidelines(shownGuidelines, hover);

			foreach(Guideline guideline in shownGuidelines)

				guideline.draw(context);

			shownGuidelines.Clear();

		}

		public override void drawTrack(Cairo.Context context, Track track) {

			if (track.handler == null) return;

			Track subTrack = track.handler.tracks[0];

			if (!subTrack.isEmpty)

				drawHover(context, subTrack.getLast().position);

		}

	}

}