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

namespace HandyControl.Expression.Drawing
{
    internal static class PolylineHelper
    {
        public static IEnumerable<PolylineData> GetWrappedPolylines(IList<PolylineData> lines,
            ref double startArcLength)
        {
            var count = 0;
            for (var i = 0; i < lines.Count; i++)
            {
                count = i;
                startArcLength -= lines[i].TotalLength;
                if (MathHelper.LessThanOrClose(startArcLength, 0.0)) break;
            }

            if (!MathHelper.LessThanOrClose(startArcLength, 0.0))
                throw new ArgumentOutOfRangeException(nameof(startArcLength));
            startArcLength += lines[count].TotalLength;
            return lines.Skip(count).Concat(lines.Take(count + 1));
        }

        public static void PathMarch(PolylineData polyline, double startArcLength, double cornerThreshold,
            Func<MarchLocation, double> stopCallback)
        {
            if (polyline == null) throw new ArgumentNullException(nameof(polyline));
            var count = polyline.Count;
            if (count <= 1) throw new ArgumentOutOfRangeException(nameof(polyline));
            var flag = false;
            var x = startArcLength;
            var before = 0.0;
            var index = 0;
            var num5 = Math.Cos(cornerThreshold * 3.1415926535897931 / 180.0);
            while (true)
            {
                var num6 = polyline.Lengths[index];
                if (!MathHelper.IsFiniteDouble(x)) return;
                if (MathHelper.IsVerySmall(x))
                {
                    x = stopCallback(MarchLocation.Create(MarchStopReason.CompleteStep, index, before,
                        num6 - before, x));
                    flag = true;
                }
                else if (MathHelper.GreaterThan(x, 0.0))
                {
                    if (MathHelper.LessThanOrClose(x + before, num6))
                    {
                        before += x;
                        x = stopCallback(MarchLocation.Create(MarchStopReason.CompleteStep, index, before,
                            num6 - before, 0.0));
                        flag = true;
                    }
                    else if (index < count - 2)
                    {
                        index++;
                        var num7 = num6 - before;
                        x -= num7;
                        before = 0.0;
                        // ReSharper disable once CompareOfFloatsByEqualityOperator
                        if (flag && num5 != 1.0 && polyline.Angles[index] > num5)
                        {
                            num6 = polyline.Lengths[index];
                            x = stopCallback(MarchLocation.Create(MarchStopReason.CornerPoint, index, before,
                                num6 - before, x));
                        }
                    }
                    else
                    {
                        var num8 = num6 - before;
                        x -= num8;
                        num6 = polyline.Lengths[index];
                        before = polyline.Lengths[index];
                        x = stopCallback(MarchLocation.Create(MarchStopReason.CompletePolyline, index, before,
                            num6 - before, x));
                        flag = true;
                    }
                }
                else if (MathHelper.LessThan(x, 0.0))
                {
                    if (MathHelper.GreaterThanOrClose(x + before, 0.0))
                    {
                        before += x;
                        x = stopCallback(MarchLocation.Create(MarchStopReason.CompleteStep, index, before,
                            num6 - before, 0.0));
                        flag = true;
                    }
                    else if (index > 0)
                    {
                        index--;
                        x += before;
                        before = polyline.Lengths[index];
                        // ReSharper disable once CompareOfFloatsByEqualityOperator
                        if (flag && num5 != 1.0 && polyline.Angles[index + 1] > num5)
                        {
                            num6 = polyline.Lengths[index];
                            x = stopCallback(MarchLocation.Create(MarchStopReason.CornerPoint, index, before,
                                num6 - before, x));
                        }
                    }
                    else
                    {
                        x += before;
                        num6 = polyline.Lengths[index];
                        before = 0.0;
                        x = stopCallback(MarchLocation.Create(MarchStopReason.CompletePolyline, index, before,
                            num6 - before, x));
                        flag = true;
                    }
                }
            }
        }
    }
}
