using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;

namespace bbiwarg.Utility
{

    class LineSegment2D
    {
        public Vector2D P1 { get; private set; }
        public Vector2D P2 { get; private set; }
        public Line2D Line { get; private set; }
        public float Length { get { return P1.getDistanceTo(P2); }}

        public LineSegment2D(Vector2D p1, Vector2D p2)
        {
            setPoints(p1, p2);
        }

        private void setPoints(Vector2D p1, Vector2D p2)
        {
            //endpoints
            P1 = p1;
            P2 = p2;

            //line
            Line = new Line2D(P1, P1 - P2);
        }

        public float getParallelDistanceTo(LineSegment2D line)
        {
            if (Line.onSide(line.P1) != Line.onSide(line.P2)) return 0;

            Vector2D a1 = Line.projectToLine(line.P1);
            Vector2D a2 = Line.projectToLine(line.P2);

            float distanceA1 = a1.getDistanceTo(line.P1);
            float distanceA2 = a2.getDistanceTo(line.P2);
            return Math.Min(distanceA1, distanceA2);
        }

        public float getVerticalDistanceTo(LineSegment2D line)
        {
            Vector2D a1 = Line.projectToLine(line.P1);
            Vector2D a2 = Line.projectToLine(line.P2);

            if (P1.isInBox(a1, a2) || P2.isInBox(a1, a2)) return 0;

            float distanceP1A1 = P1.getDistanceTo(a1);
            float distanceP1A2 = P1.getDistanceTo(a2);
            float distanceP2A1 = P2.getDistanceTo(a1);
            float distanceP2A2 = P2.getDistanceTo(a2);
            return Math.Min(Math.Min(distanceP1A1, distanceP1A2), Math.Min(distanceP2A1, distanceP2A2));
        }

        public override string ToString()
        {
            return (int)P1.X + "|" + (int)P1.Y + " --- " + (int)P2.X + "|" + (int)P2.Y;
        }
    }
}