using System.Windows;
using OneClickRun.Helpers;
using Xunit;

namespace OneClickRun.Tests;

public class WheelGeometryTests
{
    private const double InnerR = 70;
    private const double OuterR = 220;
    private const double Gap = 10;
    private static readonly Point Center = new(300, 300);

    /// <summary>
    /// 需求核心：“不论距离中心多远，扇形之间的间距都相等”。
    /// 相邻扇形在任意半径处，右边界点与左边界点间的距离应恒等于 Gap。
    /// </summary>
    [Fact]
    public void AdjacentSectorGapIsConstantAtEveryRadius()
    {
        var radii = new[] { InnerR, 80, 100, 145, 200, OuterR };
        for (var count = 2; count <= 12; count++)
        {
            for (var k = 0; k < count; k++)
            {
                var rightEdgeAngle = WheelGeometry.SectorStartAngle(k, count) + WheelGeometry.TwoPi / count;
                var leftEdgeAngle = WheelGeometry.SectorStartAngle((k + 1) % count, count);
                // 共享同一条原始径向射线（允许相差 2π 整周期）
                Assert.Equal(0.0, (rightEdgeAngle - leftEdgeAngle) % WheelGeometry.TwoPi, 12);

                foreach (var rho in radii)
                {
                    // 扇形 k 的右边界点：角度 - ε(ρ)；扇形 k+1 的左边界点：角度 + ε(ρ)
                    var right = WheelGeometry.PointOnCircle(Center, rho, rightEdgeAngle - WheelGeometry.EdgeOffset(rho, Gap));
                    var left = WheelGeometry.PointOnCircle(Center, rho, leftEdgeAngle + WheelGeometry.EdgeOffset(rho, Gap));
                    var distance = (right - left).Length;
                    Assert.True(Math.Abs(distance - Gap) < 1e-9,
                        $"count={count}, sector={k}, rho={rho}: gap={distance}, expected={Gap}");
                }
            }
        }
    }

    /// <summary>两个相邻边界点是同一条偏移直线上的点（平行边 ⇒ 处处等距）</summary>
    [Fact]
    public void AdjacentEdgePointsLieOnParallelOffsetLines()
    {
        const int count = 6;
        const int sector = 2;
        var edgeAngle = WheelGeometry.SectorStartAngle(sector, count) + WheelGeometry.TwoPi / count;
        // 同一偏移线在不同半径上的点应共线：取三点验证叉积为 0
        var p1 = WheelGeometry.PointOnCircle(Center, 80, edgeAngle + WheelGeometry.EdgeOffset(80, Gap));
        var p2 = WheelGeometry.PointOnCircle(Center, 145, edgeAngle + WheelGeometry.EdgeOffset(145, Gap));
        var p3 = WheelGeometry.PointOnCircle(Center, 200, edgeAngle + WheelGeometry.EdgeOffset(200, Gap));
        var cross = (p2.X - p1.X) * (p3.Y - p1.Y) - (p2.Y - p1.Y) * (p3.X - p1.X);
        Assert.True(Math.Abs(cross) < 1e-9, $"边界点不共线，叉积={cross}");
    }

    [Fact]
    public void SectorCornersHaveExactRadii()
    {
        for (var count = 1; count <= 12; count++)
        {
            for (var k = 0; k < count; k++)
            {
                var (p1, p2, p3, p4) = WheelGeometry.SectorCorners(Center, InnerR, OuterR, Gap, k, count);
                Assert.Equal(InnerR, (p1 - Center).Length, 9);
                Assert.Equal(OuterR, (p2 - Center).Length, 9);
                Assert.Equal(OuterR, (p3 - Center).Length, 9);
                Assert.Equal(InnerR, (p4 - Center).Length, 9);
            }
        }
    }

    [Theory]
    [InlineData(1)]
    [InlineData(4)]
    [InlineData(6)]
    [InlineData(12)]
    public void HitTestMapsSectorMidPointsToExpectedSector(int count)
    {
        for (var k = 0; k < count; k++)
        {
            var mid = WheelGeometry.SectorMidPoint(Center, InnerR, OuterR, k, count);
            var hit = WheelGeometry.HitTest(mid, Center, InnerR, OuterR, Gap, count);
            Assert.Equal(k, hit);
        }
    }

    [Fact]
    public void HitTestReturnsNullForCenterOutsideAndGap()
    {
        // 中心区域
        Assert.Null(WheelGeometry.HitTest(Center, Center, InnerR, OuterR, Gap, 4));
        // 圆环外
        Assert.Null(WheelGeometry.HitTest(new Point(Center.X + OuterR + 5, Center.Y), Center, InnerR, OuterR, Gap, 4));
        // 间隙正中间：原始径向边界角度处
        var midRadius = (InnerR + OuterR) / 2;
        var edge = WheelGeometry.SectorStartAngle(1, 4);
        var inGap = WheelGeometry.PointOnCircle(Center, midRadius, edge);
        Assert.Null(WheelGeometry.HitTest(inGap, Center, InnerR, OuterR, Gap, 4));
    }

    [Fact]
    public void SingleSectorIsFullRing()
    {
        var angles = new[] { -Math.PI / 2, 0.0, Math.PI / 2, Math.PI, Math.PI * 1.5 };
        foreach (var angle in angles)
        {
            var point = WheelGeometry.PointOnCircle(Center, (InnerR + OuterR) / 2, angle);
            Assert.Equal(0, WheelGeometry.HitTest(point, Center, InnerR, OuterR, Gap, 1));
        }
        Assert.NotNull(WheelGeometry.CreateSectorGeometry(Center, InnerR, OuterR, Gap, 0, 1));
    }

    [Fact]
    public void SectorGeometryIsFrozen()
    {
        var geometry = WheelGeometry.CreateSectorGeometry(Center, InnerR, OuterR, Gap, 0, 4);
        Assert.True(geometry.IsFrozen);
        Assert.False(geometry.IsEmpty());
    }
}