/*

* @author Valentin Simonov / http://va.lent.in/

*/

using System.Collections.Generic;

using TouchScript.Utils;

using UnityEngine;

namespace TouchScript.Clusters

{

/// <summary>

/// Represents a pool of points separated into two clusters.

/// </summary>

public sealed class Clusters

{

#region Constants

/// <summary>The first cluster.</summary>

public const int CLUSTER1 = 0;

/// <summary>The second cluster.</summary>

public const int CLUSTER2 = 1;

#endregion

#region Public properties

/// <summary>Gets the total number of points in clusters represented by this object.</summary>

public int PointsCount

{

get { return points.Count; }

}

/// <summary>Gets or sets minimum distance in pixels between clusters to treat them as two separate clusters.</summary>

/// <value>Minimum distance in pixels which must be between cluster centers to consider them as separate clusters.</value>

/// <remarks>This value is used to set the limit of how close cluster can be. Sometimes very close points shouldn't be treated as being in separate clusters.</remarks>

public float MinPointsDistance

{

get { return minPointDistance; }

set

{

minPointDistance = value;

minPointDistanceSqr = value * value;

}

}

/// <summary>Indicates that this cluster instance has two valid clusters.</summary>

/// <value><c>true</c> if this instance has clusters; otherwise, <c>false</c>.</value>

public bool HasClusters

{

get

{

if (dirty) distributePoints();

return hasClusters;

}

}

#endregion

#region Private variables

private List<ITouch> points = new List<ITouch>();

private bool dirty;

private List<ITouch> cluster1 = new List<ITouch>();

private List<ITouch> cluster2 = new List<ITouch>();

private float minPointDistance, minPointDistanceSqr;

private bool hasClusters = false;

#endregion

/// <summary>Initializes a new instance of the <see cref="Clusters"/> class.</summary>

public Clusters()

{

MinPointsDistance = 0;

markDirty();

}

#region Public methods

/// <summary>Calculates the center position of one of the clusters.</summary>

/// <param name="id">Cluster id. Either <see cref="CLUSTER1"/> or <see cref="CLUSTER2"/>.</param>

/// <returns>Cluster's centroid position or <see cref="TouchManager.INVALID_POSITION"/> if cluster contains no points.</returns>

public Vector2 GetCenterPosition(int id)

{

if (!HasClusters) return TouchManager.INVALID_POSITION;

Vector2 result;

switch (id)

{

case CLUSTER1:

result = ClusterUtils.Get2DCenterPosition(cluster1);

break;

case CLUSTER2:

result = ClusterUtils.Get2DCenterPosition(cluster2);

break;

default:

return TouchManager.INVALID_POSITION;

}

return result;

}

/// <summary>Calculates previous center position of one of the clusters.</summary>

/// <param name="id">Cluster id. Either <see cref="CLUSTER1"/> or <see cref="CLUSTER2"/>.</param>

/// <returns>Cluster's centroid previous position or <see cref="TouchManager.INVALID_POSITION"/> if cluster contains no points.</returns>

public Vector2 GetPreviousCenterPosition(int id)

{

if (!HasClusters) return TouchManager.INVALID_POSITION;

Vector2 result;

switch (id)

{

case CLUSTER1:

result = ClusterUtils.GetPrevious2DCenterPosition(cluster1);

break;

case CLUSTER2:

result = ClusterUtils.GetPrevious2DCenterPosition(cluster2);

break;

default:

return TouchManager.INVALID_POSITION;

}

return result;

}

/// <summary>Adds a point to cluster.</summary>

/// <param name="point">A point.</param>

public void AddPoint(ITouch point)

{

if (points.Contains(point)) return;

points.Add(point);

markDirty();

}

/// <summary>Adds a list of points to cluster.</summary>

/// <param name="points">List of points.</param>

public void AddPoints(IList<ITouch> points)

{

foreach (var point in points) AddPoint(point);

}

/// <summary>Removes a point from cluster.</summary>

/// <param name="point">A point.</param>

public void RemovePoint(ITouch point)

{

if (!points.Contains(point)) return;

points.Remove(point);

markDirty();

}

/// <summary>Removes a list of points from cluster.</summary>

/// <param name="points">List of points.</param>

public void RemovePoints(IList<ITouch> points)

{

foreach (var point in points) RemovePoint(point);

}

/// <summary>Removes all points from cluster.</summary>

public void RemoveAllPoints()

{

points.Clear();

markDirty();

}

/// <summary>Invalidates cluster state. Call this method to recalculate cluster properties.</summary>

public void Invalidate()

{

markDirty();

}

#endregion

#region Private functions

private void distributePoints()

{

cluster1.Clear();

cluster2.Clear();

hasClusters = checkClusters();

if (!hasClusters) return;

cluster1.Add(points[0]);

cluster2.Add(points[1]);

var total = points.Count;

if (total == 2) return;

var oldHash1 = "";

var oldHash2 = "";

var hash1 = "#";

var hash2 = "#";

while (oldHash1 != hash1 || oldHash2 != hash2)

{

var center1 = ClusterUtils.Get2DCenterPosition(cluster1);

var center2 = ClusterUtils.Get2DCenterPosition(cluster2);

ITouch obj1 = null;

ITouch obj2 = null;

// Take most distant points from cluster1 and cluster2

var maxDist1 = -float.MaxValue;

var maxDist2 = -float.MaxValue;

for (var i = 0; i < total; i++)

{

var obj = points[i];

var dist = (center1 - obj.Position).sqrMagnitude;

if (dist > maxDist2)

{

maxDist2 = dist;

obj2 = obj;

}

dist = (center2 - obj.Position).sqrMagnitude;

if (dist > maxDist1)

{

maxDist1 = dist;

obj1 = obj;

}

}

// If it is the same point it means that this point is too far away from both clusters and has to be in a separate cluster

if (obj1 == obj2)

{

center1 = (center1 + center2) * .5f;

center2 = obj2.Position;

}

else

{

center1 = obj1.Position;

center2 = obj2.Position;

}

cluster1.Clear();

cluster2.Clear();

for (var i = 0; i < total; i++)

{

var obj = points[i];

if ((center1 - obj.Position).sqrMagnitude < (center2 - obj.Position).sqrMagnitude)

{

cluster1.Add(obj);

}

else

{

cluster2.Add(obj);

}

}

oldHash1 = hash1;

oldHash2 = hash2;

hash1 = ClusterUtils.GetPointsHash(cluster1);

hash2 = ClusterUtils.GetPointsHash(cluster2);

}

markClean();

}

private bool checkClusters()

{

var length = points.Count - 1;

if (length < 1) return false;

if (length == 1)

{

var p1 = points[0].Position;

var p2 = points[1].Position;

var dx = p1.x - p2.x;

var dy = p1.y - p2.y;

if (dx * dx + dy * dy >= minPointDistanceSqr) return true;

return false;

}

for (var i = 0; i < length; i++)

{

for (var j = i + 1; j <= length; j++)

{

var p1 = points[i].Position;

var p2 = points[j].Position;

var dx = p1.x - p2.x;

var dy = p1.y - p2.y;

if (dx * dx + dy * dy >= minPointDistanceSqr) return true;

}

}

return false;

}

private void markDirty()

{

dirty = true;

}

private void markClean()

{

dirty = false;

}

#endregion

}

}