// Copyright (c) Six Labors.
// Licensed under the Six Labors Split License.

using System;
using System.Collections.Generic;
using System.Linq;

namespace SixLabors.ImageSharp.Drawing {
  /// <content>
  /// Convenience methods that can be applied to shapes and paths.
  /// </content>
  public static partial class PathExtensions
  {
      /// <summary>
      /// Create a path with the segment order reversed.
      /// </summary>
      /// <param name="path">The path to reverse.</param>
      /// <returns>The reversed <see cref="IPath"/>.</returns>
      internal static IPath Reverse(this IPath path)
      {
          // TODO. Make this a void. We can reverse the segments in place and then reverse the points in place as well.
          IEnumerable<LinearLineSegment> segments = path.Flatten().Select(static p => new LinearLineSegment(ReversePoints(p.Points.Span)));
          bool closed = false;
          if (path is ISimplePath sp)
          {
              closed = sp.IsClosed;
          }

          return closed ? new Polygon(segments) : new Path(segments);
      }

      private static PointF[] ReversePoints(ReadOnlySpan<PointF> points)
      {
          PointF[] reversed = new PointF[points.Length];
          for (int i = 0; i < reversed.Length; i++)
          {
              reversed[i] = points[points.Length - 1 - i];
          }

          return reversed;
      }
  }
}