using System;
using System.Windows;
using System.Windows.Controls;
using System.Windows.Media;
using System.Windows.Shapes;

namespace XP.ImageProcessing.RoiControl.Models
{
    /// <summary>一次点线距测量的所有视觉元素（直线两端点 + 测量点 + 垂线 + 标签）</summary>
    public class PointToLineGroup
    {
        public Ellipse DotL1 { get; set; }  // 直线端点1
        public Ellipse DotL2 { get; set; }  // 直线端点2
        public Ellipse DotP { get; set; }   // 测量点
        public Line MainLine { get; set; }  // 原始线段（实线）
        public Line ExtLine { get; set; }   // 延长线（虚线）
        public Line PerpLine { get; set; }  // 垂线（测量点→垂足）
        public Ellipse FootDot { get; set; } // 垂足
        public TextBlock Label { get; set; }
        public Point L1 { get; set; }
        public Point L2 { get; set; }
        public Point P { get; set; }

        public double Distance
        {
            get
            {
                double abx = L2.X - L1.X, aby = L2.Y - L1.Y;
                double abLen = Math.Sqrt(abx * abx + aby * aby);
                if (abLen < 0.001) return 0;
                return Math.Abs(abx * (L1.Y - P.Y) - aby * (L1.X - P.X)) / abLen;
            }
        }

        public Point FootPoint
        {
            get
            {
                double abx = L2.X - L1.X, aby = L2.Y - L1.Y;
                double abLen2 = abx * abx + aby * aby;
                if (abLen2 < 0.001) return L1;
                double t = ((P.X - L1.X) * abx + (P.Y - L1.Y) * aby) / abLen2;
                return new Point(L1.X + t * abx, L1.Y + t * aby);
            }
        }

        public void UpdateVisuals(string distanceText)
        {
            double abx = L2.X - L1.X, aby = L2.Y - L1.Y;
            double abLen2 = abx * abx + aby * aby;
            double t = abLen2 < 0.001 ? 0 : ((P.X - L1.X) * abx + (P.Y - L1.Y) * aby) / abLen2;
            var foot = FootPoint;

            // 主直线：始终画原始线段
            MainLine.X1 = L1.X; MainLine.Y1 = L1.Y;
            MainLine.X2 = L2.X; MainLine.Y2 = L2.Y;
            MainLine.Visibility = Visibility.Visible;

            // 延长线：垂足在线段外时画虚线延伸
            if (t < 0)
            {
                ExtLine.X1 = foot.X; ExtLine.Y1 = foot.Y;
                ExtLine.X2 = L1.X; ExtLine.Y2 = L1.Y;
                ExtLine.Visibility = Visibility.Visible;
            }
            else if (t > 1)
            {
                ExtLine.X1 = L2.X; ExtLine.Y1 = L2.Y;
                ExtLine.X2 = foot.X; ExtLine.Y2 = foot.Y;
                ExtLine.Visibility = Visibility.Visible;
            }
            else
            {
                ExtLine.Visibility = Visibility.Collapsed;
            }

            // 垂线
            PerpLine.X1 = P.X; PerpLine.Y1 = P.Y;
            PerpLine.X2 = foot.X; PerpLine.Y2 = foot.Y;
            PerpLine.Visibility = Visibility.Visible;

            // 垂足
            Canvas.SetLeft(FootDot, foot.X - FootDot.Width / 2);
            Canvas.SetTop(FootDot, foot.Y - FootDot.Height / 2);
            FootDot.Visibility = Visibility.Visible;

            // 标签
            Label.Text = distanceText ?? $"{Distance:F2} px";
            Canvas.SetLeft(Label, (P.X + foot.X) / 2 + 8);
            Canvas.SetTop(Label, (P.Y + foot.Y) / 2 - 18);
            Label.Visibility = Visibility.Visible;
        }

        public void UpdateVisuals() => UpdateVisuals(null);
    }
}