using System;
using System.Collections.Generic;
using System.Linq;
using System.Windows;
using System.Windows.Media;

namespace HandyControl.Expression.Drawing
{
    internal static class PathFigureHelper
    {
        public static IEnumerable<PathSegmentData> AllSegments(this PathFigure figure)
        {
            if (figure != null && figure.Segments.Count > 0)
            {
                var startPoint = figure.StartPoint;
                // ReSharper disable once GenericEnumeratorNotDisposed
                var enumerator = figure.Segments.GetEnumerator();
                while (enumerator.MoveNext())
                {
                    var current = enumerator.Current;
                    var lastPoint = current.GetLastPoint();
                    yield return new PathSegmentData(startPoint, current);
                    startPoint = lastPoint;
                }
            }
        }

        internal static void ApplyTransform(this PathFigure figure, GeneralTransform transform)
        {
            figure.StartPoint = transform.Transform(figure.StartPoint);
            for (var i = 0; i < figure.Segments.Count; i++)
            {
                var segment =
                    PathSegmentHelper.ApplyTransform(figure.Segments[i], figure.StartPoint, transform);
                if (!Equals(figure.Segments[i], segment)) figure.Segments[i] = segment;
            }
        }

        internal static void FlattenFigure(PathFigure figure, IList<Point> points, double tolerance,
            bool removeRepeat)
        {
            if (figure == null) throw new ArgumentNullException(nameof(figure));
            if (points == null) throw new ArgumentNullException(nameof(points));
            if (tolerance < 0.0) throw new ArgumentOutOfRangeException(nameof(tolerance));
            var list = removeRepeat ? new List<Point>() : points;
            list.Add(figure.StartPoint);
            foreach (var data in figure.AllSegments())
                data.PathSegment.FlattenSegment(list, data.StartPoint, tolerance);
            if (figure.IsClosed) list.Add(figure.StartPoint);
            if (removeRepeat && list.Count > 0)
            {
                points.Add(list[0]);
                for (var i = 1; i < list.Count; i++)
                    if (!MathHelper.IsVerySmall(GeometryHelper.SquaredDistance(points.Last(), list[i])))
                        points.Add(list[i]);
            }
        }

        internal static bool SyncEllipseFigure(PathFigure figure, Rect bounds, SweepDirection sweepDirection,
            bool isFilled = true)
        {
            var flag = false;
            var pointArray = new Point[2];
            var size = new Size(bounds.Width / 2.0, bounds.Height / 2.0);
            var point = bounds.Center();
            if (size.Width > size.Height)
            {
                pointArray[0] = new Point(bounds.Left, point.Y);
                pointArray[1] = new Point(bounds.Right, point.Y);
            }
            else
            {
                pointArray[0] = new Point(point.X, bounds.Top);
                pointArray[1] = new Point(point.X, bounds.Bottom);
            }

            flag |= figure.SetIfDifferent(PathFigure.IsClosedProperty, true);
            flag |= figure.SetIfDifferent(PathFigure.IsFilledProperty, isFilled);
            flag |= figure.SetIfDifferent(PathFigure.StartPointProperty, pointArray[0]);
            flag |= figure.Segments.EnsureListCount(2, () => new ArcSegment());
            flag |= GeometryHelper.EnsureSegmentType(out var segment, figure.Segments, 0, () => new ArcSegment());
            flag |= segment.SetIfDifferent(ArcSegment.PointProperty, pointArray[1]);
            flag |= segment.SetIfDifferent(ArcSegment.SizeProperty, size);
            flag |= segment.SetIfDifferent(ArcSegment.IsLargeArcProperty, false);
            flag |= segment.SetIfDifferent(ArcSegment.SweepDirectionProperty, sweepDirection);
            flag |= GeometryHelper.EnsureSegmentType(out segment, figure.Segments, 1, () => new ArcSegment());
            flag |= segment.SetIfDifferent(ArcSegment.PointProperty, pointArray[0]);
            flag |= segment.SetIfDifferent(ArcSegment.SizeProperty, size);
            flag |= segment.SetIfDifferent(ArcSegment.IsLargeArcProperty, false);
            return flag | segment.SetIfDifferent(ArcSegment.SweepDirectionProperty, sweepDirection);
        }

        internal static bool SyncPolylineFigure(PathFigure figure, IList<Point> points, bool isClosed,
            bool isFilled = true)
        {
            if (figure == null) throw new ArgumentNullException(nameof(figure));
            var flag = false;
            if (points == null || points.Count == 0)
            {
                flag |= figure.ClearIfSet(PathFigure.StartPointProperty);
                flag |= figure.Segments.EnsureListCount(0);
            }
            else
            {
                flag |= figure.SetIfDifferent(PathFigure.StartPointProperty, points[0]);
                flag |= figure.Segments.EnsureListCount(1, () => new PolyLineSegment());
                flag |= PathSegmentHelper.SyncPolylineSegment(figure.Segments, 0, points, 1,
                    points.Count - 1);
            }

            flag |= figure.SetIfDifferent(PathFigure.IsClosedProperty, isClosed);
            return flag | figure.SetIfDifferent(PathFigure.IsFilledProperty, isFilled);
        }
    }
}