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using System;
using System.Collections.Generic;

namespace libTerrain
{
    partial class Channel
    {
        /// <summary>
        /// Generates a Voronoi diagram (sort of a stained glass effect) which will fill the entire channel
        /// </summary>
        /// <remarks>3-Clause BSD Licensed</remarks>
        /// <param name="pointsPerBlock">The number of generator points in each block</param>
        /// <param name="blockSize">A multiple of the channel width and height which will have voronoi points generated in it.
        /// <para>This is to ensure a more even distribution of the points than pure random allocation.</para></param>
        /// <param name="c">The Voronoi diagram type. Usually an array with values consisting of [-1,1]. Experiment with the chain, you can have as many values as you like.</param>
        public void VoronoiDiagram(int pointsPerBlock, int blockSize, double[] c)
        {
            SetDiff();

            List<Point2D> points = new List<Point2D>();
            Random generator = new Random(seed);

            // Generate the emitter points
            int x, y, i;
            for (x = -blockSize; x < w + blockSize; x += blockSize)
            {
                for (y = -blockSize; y < h + blockSize; y += blockSize)
                {
                    for (i = 0; i < pointsPerBlock; i++)
                    {
                        double pX = x + (generator.NextDouble()*(double) blockSize);
                        double pY = y + (generator.NextDouble()*(double) blockSize);

                        points.Add(new Point2D(pX, pY));
                    }
                }
            }

            double[] distances = new double[points.Count];

            // Calculate the distance each pixel is from an emitter
            for (x = 0; x < w; x++)
            {
                for (y = 0; y < h; y++)
                {
                    for (i = 0; i < points.Count; i++)
                    {
                        double dx, dy;
                        dx = Math.Abs((double) x - points[i].x);
                        dy = Math.Abs((double) y - points[i].y);

                        distances[i] = (dx*dx + dy*dy);
                    }

                    Array.Sort(distances);

                    double f = 0.0;

                    // Multiply the distances with their 'c' counterpart
                    // ordering the distances descending
                    for (i = 0; i < c.Length; i++)
                    {
                        if (i >= points.Count)
                            break;

                        f += c[i]*distances[i];
                    }

                    map[x, y] = f;
                }
            }

            // Normalise the result
            Normalise();
        }

        public void VoronoiDiagram(List<Point2D> points, double[] c)
        {
            SetDiff();

            int x, y, i;
            double[] distances = new double[points.Count];

            // Calculate the distance each pixel is from an emitter
            for (x = 0; x < w; x++)
            {
                for (y = 0; y < h; y++)
                {
                    for (i = 0; i < points.Count; i++)
                    {
                        double dx, dy;
                        dx = Math.Abs((double) x - points[i].x);
                        dy = Math.Abs((double) y - points[i].y);

                        distances[i] = (dx*dx + dy*dy);
                    }

                    Array.Sort(distances);

                    double f = 0.0;

                    // Multiply the distances with their 'c' counterpart
                    // ordering the distances descending
                    for (i = 0; i < c.Length; i++)
                    {
                        if (i >= points.Count)
                            break;

                        f += c[i]*distances[i];
                    }

                    map[x, y] = f;
                }
            }

            // Normalise the result
            Normalise();
        }

        public void VoroflatDiagram(int pointsPerBlock, int blockSize)
        {
            SetDiff();

            List<Point2D> points = new List<Point2D>();
            Random generator = new Random(seed);

            // Generate the emitter points
            int x, y, i;
            for (x = -blockSize; x < w + blockSize; x += blockSize)
            {
                for (y = -blockSize; y < h + blockSize; y += blockSize)
                {
                    for (i = 0; i < pointsPerBlock; i++)
                    {
                        double pX = x + (generator.NextDouble()*(double) blockSize);
                        double pY = y + (generator.NextDouble()*(double) blockSize);

                        points.Add(new Point2D(pX, pY));
                    }
                }
            }

            double[] distances = new double[points.Count];

            // Calculate the distance each pixel is from an emitter
            for (x = 0; x < w; x++)
            {
                for (y = 0; y < h; y++)
                {
                    for (i = 0; i < points.Count; i++)
                    {
                        double dx, dy;
                        dx = Math.Abs((double) x - points[i].x);
                        dy = Math.Abs((double) y - points[i].y);

                        distances[i] = (dx*dx + dy*dy);
                    }

                    //Array.Sort(distances);

                    double f = 0.0;

                    double min = double.MaxValue;
                    for (int j = 0; j < distances.Length; j++)
                    {
                        if (distances[j] < min)
                        {
                            min = distances[j];
                            f = j;
                        }
                    }

                    // Multiply the distances with their 'c' counterpart
                    // ordering the distances descending

                    map[x, y] = f;
                }
            }

            // Normalise the result
            Normalise();
        }
    }
}