namespace TriangleNet
{
    using System;
    using System.Collections.Generic;
    using TriangleNet.Geometry;

    static class Generate
    {
        private static readonly Random random = new Random(63841);

        public static List<Vertex> RandomPoints(int n, Rectangle bounds)
        {
            var points = new List<Vertex>(n);

            var xmin = bounds.Left;
            var ymin = bounds.Bottom;

            var width = bounds.Width;
            var height = bounds.Height;

            for (int i = 0; i < n; i++)
            {
                double x = random.NextDouble();
                double y = random.NextDouble();
                points.Add(new Vertex(xmin + x * width, ymin + y * height));
            }

            return points;
        }

        /// <summary>
        /// Creates a rectangle contour.
        /// </summary>
        public static Contour Rectangle(Rectangle rect, double size = 0d, int label = 0)
        {
            return Rectangle(rect.X, rect.Y, rect.Width, rect.Height, size, label);
        }

        /// <summary>
        /// Creates a rectangle contour.
        /// </summary>
        public static Contour Rectangle(double x, double y, double width, double height,
            double size = 0d, int label = 0)
        {
            // Horizontal and vertical step sizes.
            double stepH = 0d;
            double stepV = 0d;

            int nH = 1;
            int nV = 1;

            if (size > 0d)
            {
                size = Math.Min(size, Math.Min(width, height));

                nH = (int)Math.Ceiling(width / size);
                nV = (int)Math.Ceiling(height / size);

                stepH = width / nH;
                stepV = height / nV;
            }

            var points = new List<Vertex>(2 * nH + 2 * nV);

            double right = x + width;
            double top = y + height;

            // Left box boundary points
            for (int i = 0; i < nV; i++)
            {
                points.Add(new Vertex(x, y + i * stepV, label));
            }

            // Top box boundary points
            for (int i = 0; i < nH; i++)
            {
                points.Add(new Vertex(x + i * stepH, top, label));
            }

            // Right box boundary points
            for (int i = 0; i < nV; i++)
            {
                points.Add(new Vertex(right, top - i * stepV, label));
            }

            // Bottom box boundary points
            for (int i = 0; i < nH; i++)
            {
                points.Add(new Vertex(right - i * stepH, y, label));
            }

            return new Contour(points, label, true);
        }

        /// <summary>
        /// Create a circular contour.
        /// </summary>
        /// <param name="r">The radius.</param>
        /// <param name="center">The center point.</param>
        /// <param name="h">The desired segment length.</param>
        /// <param name="label">The boundary label.</param>
        /// <returns>A circular contour.</returns>
        public static Contour Circle(double r, Point center, double h, int label = 0)
        {
            int n = (int)(2 * Math.PI * r / h);

            var points = new List<Vertex>(n);

            double x, y, dphi = 2 * Math.PI / n;

            for (int i = 0; i < n; i++)
            {
                x = center.X + r * Math.Cos(i * dphi);
                y = center.Y + r * Math.Sin(i * dphi);

                points.Add(new Vertex(x, y, label));
            }

            return new Contour(points, label, true);
        }
    }
}