using System;
using System.Windows;
using System.Collections.Generic;
using Aga.Diagrams.Controls;
using Aga.Diagrams;

namespace FlowWorkEditDemo
{
    public class OrthogonalLink : SegmentLink
    {
        public OrthogonalLink() { }
        protected override Point[] CalculateSegments()
        {
            if (Source != null && Target != null)
            {
                var points = new List<Point>();
                var ends = GetEndPoinds();
                if (ends == null)
                    return ends;
                else
                {
                    points.Add(ends[0]);
                    points.AddRange(GetMiddlePoints(ends[0], ends[1]));
                    points.Add(ends[1]);
                    var res = points.ToArray();
                    UpdateEdges(res);
                    return res;
                }
            }
            else
                return base.CalculateSegments();
        }

        private IEnumerable<Point> GetMiddlePoints(Point start, Point end)
        {
            var view = VisualHelper.FindParent<DiagramView>(this);
            if (view == null)
                return new Point[0];

            var points = new List<Point>();

            var p0 = GetFirstSegment(Source, start, view.GridCellSize);
            var p1 = GetFirstSegment(Target, end, view.GridCellSize);

            if (p0 == p1)
                return points;


            var p2 = new Point(GetNearestCross(p0.X, p1.X), GetNearestCross(p0.Y, p1.Y));
            var p3 = new Point(GetNearestCross(p1.X, p0.X), GetNearestCross(p1.Y, p0.Y));
            if (p2 == p3)
            {
                points.Add(p0);
                points.Add(p2);
                points.Add(p1);
            }
            else
            {
                points.Add(p0);
                points.Add(p2);
                if (!GeometryHelper.AreEquals(p2.X, p3.X) && !GeometryHelper.AreEquals(p2.Y, p3.Y))
                    points.Add(new Point(p2.X, p3.Y));
                points.Add(p3);
                points.Add(p1);
            }
            DoScale(points, view.GridCellSize);
            return points;
        }

        private void DoScale(List<Point> points, Size cellSize)
        {
            for (int i = 0; i < points.Count; i++)
            {
                points[i] = new Point(points[i].X * cellSize.Width,
                    points[i].Y * cellSize.Height);
            }
        }

        private static double GetNearestCross(double a, double b)
        {
            if (GeometryHelper.AreEquals(a, b) && (int)a == a)
                return a;
            else if (a < b)
                return Math.Ceiling(a);
            else
                return Math.Floor(a);
        }

        private Point GetFirstSegment(IPort iPort, Point point, Size cellSize)
        {
            var port = iPort as PortBase;
            double x = (int)(point.X / cellSize.Width) + 0.5;
            double y = (int)(point.Y / cellSize.Height) + 0.5;
            if (port.VerticalAlignment == VerticalAlignment.Top)
                return new Point(x, y - 0.5);
            else if (port.VerticalAlignment == VerticalAlignment.Bottom)
                return new Point(x, y + 0.5);
            else if (port.HorizontalAlignment == HorizontalAlignment.Left)
                return new Point(x - 0.5, y);
            else
                return new Point(x + 0.5, y);
        }
    }
}