using System;
using System.Collections.Generic;
using System.Text;
using AIStudio.Wpf.DiagramDesigner.Geometrys;

namespace AIStudio.Wpf.DiagramDesigner
{
    public static partial class PathGenerators
    {
        public static PathGeneratorResult Corner(IDiagramViewModel _, ConnectionViewModel link, PointBase[] route, PointBase source, PointBase target)
        {
            route = ConcatRouteAndSourceAndTarget(route, source, target);

            if (route.Length > 2)
                return CurveThroughPoints(route, link);

            if (link.IsFullConnection)
                route = GetRouteWithFullConnectionLine(_, link, route);
            else
                route = GetRouteWithPartConnectionLine(_, link, route);

            double sourceAngle = SourceMarkerAdjustement(route, link.GetSourceMarkerWidth(), link.GetSourceMarkerHeight());
            double targetAngle = TargetMarkerAdjustement(route, link.GetSinkMarkerWidth(), link.GetSinkMarkerHeight());

            DoShift(route, link);

            var paths = new string[route.Length - 1];
            for (var i = 0; i < route.Length - 1; i++)
            {
                paths[i] = FormattableString.Invariant($"M {route[i].X} {route[i].Y} L {route[i + 1].X} {route[i + 1].Y}");
            }

            return new PathGeneratorResult(paths, sourceAngle, route[0], targetAngle, route[route.Length - 1]);
        }

        private const int const_margin = 20;

        private static PointBase[] GetRouteWithFullConnectionLine(IDiagramViewModel _, ConnectionViewModel link, PointBase[] route)
        {
            var sourceInnerPoint = link.SourceConnectorInfo.IsInnerPoint;
            PointBase sourcePoint = link.SourceConnectorInfo.MiddlePosition;
            PointBase sinkPoint = link.SinkConnectorInfo.MiddlePosition;
            ConnectorOrientation sourceOrientation = link.SourceConnectorInfo.Orientation;
            ConnectorOrientation sinkOrientation = link.SinkConnectorInfoFully.Orientation;

            List<PointBase> linePoints = new List<PointBase>();
            int margin1 = sourceInnerPoint ? 0 : const_margin;
            int margin2 = const_margin;

            RectangleBase rectSource = GetRectWithMargin(sourcePoint, margin1);
            RectangleBase rectSink = GetRectWithMargin(sinkPoint, margin2);

            PointBase startPoint = GetOffsetPoint(sourcePoint, sourceOrientation, rectSource, sourceInnerPoint);
            PointBase endPoint = GetOffsetPoint(sinkPoint, sinkOrientation, rectSink);

            linePoints.Add(startPoint);
            PointBase currentPoint = startPoint;

            if (!rectSink.Contains(currentPoint) && !rectSource.Contains(endPoint))
            {
                while (true)
                {
                    #region source node

                    if (IsPointVisible(currentPoint, endPoint, new RectangleBase[] { rectSource, rectSink }))
                    {
                        linePoints.Add(endPoint);
                        currentPoint = endPoint;
                        break;
                    }

                    PointBase neighbour = GetNearestVisibleNeighborSink(currentPoint, endPoint, sinkOrientation, rectSource, rectSink);
                    if (!double.IsNaN(neighbour.X))
                    {
                        linePoints.Add(neighbour);
                        linePoints.Add(endPoint);
                        currentPoint = endPoint;
                        break;
                    }

                    if (currentPoint == startPoint)
                    {
                        bool flag;
                        PointBase n = GetNearestNeighborSource(sourceOrientation, endPoint, rectSource, rectSink, out flag, sourceInnerPoint);
                        if (linePoints.Contains(n))
                        {
                            break;
                        }
                        linePoints.Add(n);
                        currentPoint = n;

                        if (!IsRectVisible(currentPoint, rectSink, new RectangleBase[] { rectSource }))
                        {
                            PointBase n1, n2;
                            GetOppositeCorners(sourceOrientation, rectSource, out n1, out n2, sourceInnerPoint);
                            if (flag)
                            {
                                linePoints.Add(n1);
                                currentPoint = n1;
                            }
                            else
                            {
                                linePoints.Add(n2);
                                currentPoint = n2;
                            }
                            if (!IsRectVisible(currentPoint, rectSink, new RectangleBase[] { rectSource }))
                            {
                                if (flag)
                                {
                                    linePoints.Add(n2);
                                    currentPoint = n2;
                                }
                                else
                                {
                                    linePoints.Add(n1);
                                    currentPoint = n1;
                                }
                            }
                        }
                    }
                    #endregion

                    #region sink node

                    else // from here on we jump to the sink node
                    {
                        PointBase n1, n2; // neighbour corner
                        PointBase s1, s2; // opposite corner
                        GetNeighborCorners(sinkOrientation, rectSink, out s1, out s2);
                        GetOppositeCorners(sinkOrientation, rectSink, out n1, out n2);

                        bool n1Visible = IsPointVisible(currentPoint, n1, new RectangleBase[] { rectSource, rectSink });
                        bool n2Visible = IsPointVisible(currentPoint, n2, new RectangleBase[] { rectSource, rectSink });

                        if (n1Visible && n2Visible)
                        {
                            if (rectSource.Contains(n1))
                            {
                                linePoints.Add(n2);
                                if (rectSource.Contains(s2))
                                {
                                    linePoints.Add(n1);
                                    linePoints.Add(s1);
                                }
                                else
                                    linePoints.Add(s2);

                                linePoints.Add(endPoint);
                                currentPoint = endPoint;
                                break;
                            }

                            if (rectSource.Contains(n2))
                            {
                                linePoints.Add(n1);
                                if (rectSource.Contains(s1))
                                {
                                    linePoints.Add(n2);
                                    linePoints.Add(s2);
                                }
                                else
                                    linePoints.Add(s1);

                                linePoints.Add(endPoint);
                                currentPoint = endPoint;
                                break;
                            }

                            if ((Distance(n1, endPoint) <= Distance(n2, endPoint)))
                            {
                                linePoints.Add(n1);
                                if (rectSource.Contains(s1))
                                {
                                    linePoints.Add(n2);
                                    linePoints.Add(s2);
                                }
                                else
                                    linePoints.Add(s1);
                                linePoints.Add(endPoint);
                                currentPoint = endPoint;
                                break;
                            }
                            else
                            {
                                linePoints.Add(n2);
                                if (rectSource.Contains(s2))
                                {
                                    linePoints.Add(n1);
                                    linePoints.Add(s1);
                                }
                                else
                                    linePoints.Add(s2);
                                linePoints.Add(endPoint);
                                currentPoint = endPoint;
                                break;
                            }
                        }
                        else if (n1Visible)
                        {
                            linePoints.Add(n1);
                            if (rectSource.Contains(s1))
                            {
                                linePoints.Add(n2);
                                linePoints.Add(s2);
                            }
                            else
                                linePoints.Add(s1);
                            linePoints.Add(endPoint);
                            currentPoint = endPoint;
                            break;
                        }
                        else
                        {
                            linePoints.Add(n2);
                            if (rectSource.Contains(s2))
                            {
                                linePoints.Add(n1);
                                linePoints.Add(s1);
                            }
                            else
                                linePoints.Add(s2);
                            linePoints.Add(endPoint);
                            currentPoint = endPoint;
                            break;
                        }
                    }
                    #endregion
                }
            }
            else
            {
                linePoints.Add(endPoint);
            }

            linePoints = OptimizeLinePoints(linePoints, new RectangleBase[] { rectSource, rectSink }, sourceOrientation, sinkOrientation);

            linePoints.Insert(0, sourcePoint);
            linePoints.Add(sinkPoint);

            return linePoints.ToArray();
        }

        private static PointBase[] GetRouteWithPartConnectionLine(IDiagramViewModel diagramViewModel, ConnectionViewModel link, PointBase[] route)
        {
            var sourceInnerPoint = link.SourceConnectorInfo.IsInnerPoint;
            PointBase sourcePoint = link.SourceConnectorInfo.MiddlePosition;
            PointBase sinkPoint = link.SinkConnectorInfo.MiddlePosition;
            ConnectorOrientation sourceOrientation = link.SourceConnectorInfo.Orientation;
            ConnectorOrientation preferredOrientation = link.SourceConnectorInfo.Orientation;

            List<PointBase> linePoints = new List<PointBase>();
            int margin = sourceInnerPoint ? 0 : const_margin;

            RectangleBase rectSource = GetRectWithMargin(sourcePoint, margin);
            PointBase startPoint = GetOffsetPoint(sourcePoint, sourceOrientation, rectSource, sourceInnerPoint);
            PointBase endPoint = sinkPoint;

            linePoints.Add(startPoint);
            PointBase currentPoint = startPoint;

            if (!rectSource.Contains(endPoint))
            {
                while (true)
                {
                    if (IsPointVisible(currentPoint, endPoint, new RectangleBase[] { rectSource }))
                    {
                        linePoints.Add(endPoint);
                        break;
                    }

                    bool sideFlag;
                    PointBase n = GetNearestNeighborSource(sourceOrientation, endPoint, rectSource, out sideFlag, sourceInnerPoint);
                    linePoints.Add(n);
                    currentPoint = n;

                    if (IsPointVisible(currentPoint, endPoint, new RectangleBase[] { rectSource }))
                    {
                        linePoints.Add(endPoint);
                        break;
                    }
                    else
                    {
                        PointBase n1, n2;
                        GetOppositeCorners(sourceOrientation, rectSource, out n1, out n2, sourceInnerPoint);
                        if (sideFlag)
                            linePoints.Add(n1);
                        else
                            linePoints.Add(n2);

                        linePoints.Add(endPoint);
                        break;
                    }
                }
            }
            else
            {
                linePoints.Add(endPoint);
            }

            if (preferredOrientation != ConnectorOrientation.None)
                linePoints = OptimizeLinePoints(linePoints, new RectangleBase[] { rectSource }, sourceOrientation, preferredOrientation);
            else
                linePoints = OptimizeLinePoints(linePoints, new RectangleBase[] { rectSource }, sourceOrientation, GetOpositeOrientation(sourceOrientation));
         
            linePoints.Insert(0, sourcePoint);            

            return linePoints.ToArray();
        }

        private static List<PointBase> OptimizeLinePoints(List<PointBase> linePoints, RectangleBase[] rectangles, ConnectorOrientation sourceOrientation, ConnectorOrientation sinkOrientation)
        {
            List<PointBase> points = new List<PointBase>();
            int cut = 0;

            for (int i = 0; i < linePoints.Count; i++)
            {
                if (i >= cut)
                {
                    for (int k = linePoints.Count - 1; k > i; k--)
                    {
                        if (IsPointVisible(linePoints[i], linePoints[k], rectangles))
                        {
                            cut = k;
                            break;
                        }
                    }
                    points.Add(linePoints[i]);
                }
            }

            #region Line
            for (int j = 0; j < points.Count - 1; j++)
            {
                if (points[j].X != points[j + 1].X && points[j].Y != points[j + 1].Y)
                {
                    ConnectorOrientation orientationFrom;
                    ConnectorOrientation orientationTo;

                    // orientation from point
                    if (j == 0)
                        orientationFrom = sourceOrientation;
                    else
                        orientationFrom = GetOrientation(points[j], points[j - 1]);

                    // orientation to pint 
                    if (j == points.Count - 2)
                        orientationTo = sinkOrientation;
                    else
                        orientationTo = GetOrientation(points[j + 1], points[j + 2]);


                    if ((orientationFrom == ConnectorOrientation.Left || orientationFrom == ConnectorOrientation.Right) &&
                        (orientationTo == ConnectorOrientation.Left || orientationTo == ConnectorOrientation.Right))
                    {
                        double centerX = Math.Min(points[j].X, points[j + 1].X) + Math.Abs(points[j].X - points[j + 1].X) / 2;
                        points.Insert(j + 1, new PointBase(centerX, points[j].Y));
                        points.Insert(j + 2, new PointBase(centerX, points[j + 2].Y));
                        if (points.Count - 1 > j + 3)
                            points.RemoveAt(j + 3);
                        return points;
                    }

                    if ((orientationFrom == ConnectorOrientation.Top || orientationFrom == ConnectorOrientation.Bottom) &&
                        (orientationTo == ConnectorOrientation.Top || orientationTo == ConnectorOrientation.Bottom))
                    {
                        double centerY = Math.Min(points[j].Y, points[j + 1].Y) + Math.Abs(points[j].Y - points[j + 1].Y) / 2;
                        points.Insert(j + 1, new PointBase(points[j].X, centerY));
                        points.Insert(j + 2, new PointBase(points[j + 2].X, centerY));
                        if (points.Count - 1 > j + 3)
                            points.RemoveAt(j + 3);
                        return points;
                    }

                    if ((orientationFrom == ConnectorOrientation.Left || orientationFrom == ConnectorOrientation.Right) &&
                        (orientationTo == ConnectorOrientation.Top || orientationTo == ConnectorOrientation.Bottom))
                    {
                        points.Insert(j + 1, new PointBase(points[j + 1].X, points[j].Y));
                        return points;
                    }

                    if ((orientationFrom == ConnectorOrientation.Top || orientationFrom == ConnectorOrientation.Bottom) &&
                        (orientationTo == ConnectorOrientation.Left || orientationTo == ConnectorOrientation.Right))
                    {
                        points.Insert(j + 1, new PointBase(points[j].X, points[j + 1].Y));
                        return points;
                    }
                }
            }
            #endregion

            return points;
        }

        private static ConnectorOrientation GetOrientation(PointBase p1, PointBase p2)
        {
            if (p1.X == p2.X)
            {
                if (p1.Y >= p2.Y)
                    return ConnectorOrientation.Bottom;
                else
                    return ConnectorOrientation.Top;
            }
            else if (p1.Y == p2.Y)
            {
                if (p1.X >= p2.X)
                    return ConnectorOrientation.Right;
                else
                    return ConnectorOrientation.Left;
            }
            throw new Exception("Failed to retrieve orientation");
        }

        private static PointBase GetNearestNeighborSource(ConnectorOrientation orientation, PointBase endPoint, RectangleBase rectSource, RectangleBase rectSink, out bool flag, bool isInnerPoint)
        {
            PointBase n1, n2; // neighbors
            GetNeighborCorners(orientation, rectSource, out n1, out n2, isInnerPoint);

            if (rectSink.Contains(n1))
            {
                flag = false;
                return n2;
            }

            if (rectSink.Contains(n2))
            {
                flag = true;
                return n1;
            }

            if ((Distance(n1, endPoint) <= Distance(n2, endPoint)))
            {
                flag = true;
                return n1;
            }
            else
            {
                flag = false;
                return n2;
            }
        }

        private static PointBase GetNearestNeighborSource(ConnectorOrientation orientation, PointBase endPoint, RectangleBase rectSource, out bool flag, bool isInnerPoint)
        {
            PointBase n1, n2; // neighbors
            GetNeighborCorners(orientation, rectSource, out n1, out n2, isInnerPoint);

            if ((Distance(n1, endPoint) <= Distance(n2, endPoint)))
            {
                flag = true;
                return n1;
            }
            else
            {
                flag = false;
                return n2;
            }
        }

        private static PointBase GetNearestVisibleNeighborSink(PointBase currentPoint, PointBase endPoint, ConnectorOrientation orientation, RectangleBase rectSource, RectangleBase rectSink)
        {
            PointBase s1, s2; // neighbors on sink side
            GetNeighborCorners(orientation, rectSink, out s1, out s2);

            bool flag1 = IsPointVisible(currentPoint, s1, new RectangleBase[] { rectSource, rectSink });
            bool flag2 = IsPointVisible(currentPoint, s2, new RectangleBase[] { rectSource, rectSink });

            if (flag1) // s1 visible
            {
                if (flag2) // s1 and s2 visible
                {
                    if (rectSink.Contains(s1))
                        return s2;

                    if (rectSink.Contains(s2))
                        return s1;

                    if ((Distance(s1, endPoint) <= Distance(s2, endPoint)))
                        return s1;
                    else
                        return s2;

                }
                else
                {
                    return s1;
                }
            }
            else // s1 not visible
            {
                if (flag2) // only s2 visible
                {
                    return s2;
                }
                else // s1 and s2 not visible
                {
                    return new PointBase(double.NaN, double.NaN);
                }
            }
        }

        private static bool IsPointVisible(PointBase fromPoint, PointBase targetPoint, RectangleBase[] rectangles)
        {
            foreach (RectangleBase rect in rectangles)
            {
                if (RectangleIntersectsLine(rect, fromPoint, targetPoint))
                    return false;
            }
            return true;
        }

        private static bool IsRectVisible(PointBase fromPoint, RectangleBase targetRect, RectangleBase[] rectangles)
        {
            if (IsPointVisible(fromPoint, targetRect.TopLeft, rectangles))
                return true;

            if (IsPointVisible(fromPoint, targetRect.TopRight, rectangles))
                return true;

            if (IsPointVisible(fromPoint, targetRect.BottomLeft, rectangles))
                return true;

            if (IsPointVisible(fromPoint, targetRect.BottomRight, rectangles))
                return true;

            return false;
        }

        private static bool RectangleIntersectsLine(RectangleBase rect, PointBase startPoint, PointBase endPoint)
        {
            rect.Inflate(-1, -1);
            return rect.IntersectsWith(new RectangleBase(startPoint, endPoint));
        }

        private static void GetOppositeCorners(ConnectorOrientation orientation, RectangleBase rect, out PointBase n1, out PointBase n2, bool isInnerPoint = false)
        {
            if (isInnerPoint)
            {
                n1 = rect.Location; n2 = rect.Location;
                return;
            }
            switch (orientation)
            {
                case ConnectorOrientation.Left:
                    n1 = rect.TopRight; n2 = rect.BottomRight;
                    break;
                case ConnectorOrientation.Top:
                    n1 = rect.BottomLeft; n2 = rect.BottomRight;
                    break;
                case ConnectorOrientation.Right:
                    n1 = rect.TopLeft; n2 = rect.BottomLeft;
                    break;
                case ConnectorOrientation.Bottom:
                    n1 = rect.TopLeft; n2 = rect.TopRight;
                    break;
                default:
                    throw new Exception("No opposite corners found!");
            }
        }

        private static void GetNeighborCorners(ConnectorOrientation orientation, RectangleBase rect, out PointBase n1, out PointBase n2, bool isInnerPoint = false)
        {
            if (isInnerPoint)
            {
                n1 = rect.Location; n2 = rect.Location;
                return;
            }
            switch (orientation)
            {
                case ConnectorOrientation.Left:
                    n1 = rect.TopLeft; n2 = rect.BottomLeft;
                    break;
                case ConnectorOrientation.Top:
                    n1 = rect.TopLeft; n2 = rect.TopRight;
                    break;
                case ConnectorOrientation.Right:
                    n1 = rect.TopRight; n2 = rect.BottomRight;
                    break;
                case ConnectorOrientation.Bottom:
                    n1 = rect.BottomLeft; n2 = rect.BottomRight;
                    break;
                default:
                    throw new Exception("No neighour corners found!");
            }
        }

        private static double Distance(PointBase p1, PointBase p2)
        {
            return PointBase.Subtract(p1, p2).Length;
        }

        private static RectangleBase GetRectWithMargin(PointBase point, double margin)
        {
            RectangleBase rect = new RectangleBase(point.X, point.Y, 0, 0);
            rect.Inflate(margin, margin);

            return rect;
        }

        private static PointBase GetOffsetPoint(PointBase point, ConnectorOrientation orientation, RectangleBase rect, bool isInnerPoint = false)
        {
            PointBase offsetPoint = new PointBase();
            if (isInnerPoint)
            {
                offsetPoint = new PointBase(point.X, point.Y);
                return offsetPoint;
            }

            switch (orientation)
            {
                case ConnectorOrientation.Left:
                    offsetPoint = new PointBase(rect.Left, point.Y);
                    break;
                case ConnectorOrientation.Top:
                    offsetPoint = new PointBase(point.X, rect.Top);
                    break;
                case ConnectorOrientation.Right:
                    offsetPoint = new PointBase(rect.Right, point.Y);
                    break;
                case ConnectorOrientation.Bottom:
                    offsetPoint = new PointBase(point.X, rect.Bottom);
                    break;
                default:
                    break;
            }

            return offsetPoint;
        }

        private static ConnectorOrientation GetOpositeOrientation(ConnectorOrientation connectorOrientation)
        {
            switch (connectorOrientation)
            {
                case ConnectorOrientation.Left:
                    return ConnectorOrientation.Right;
                case ConnectorOrientation.Top:
                    return ConnectorOrientation.Bottom;
                case ConnectorOrientation.Right:
                    return ConnectorOrientation.Left;
                case ConnectorOrientation.Bottom:
                    return ConnectorOrientation.Top;
                default:
                    return ConnectorOrientation.Top;
            }
        }
    }
}