git.stella-ops.org/src/__Libraries/StellaOps.ElkSharp/ElkEdgeRouterIterative.CollectorNormalization.cs

namespace StellaOps.ElkSharp;

internal static partial class ElkEdgeRouterIterative
{
    private static double ScoreProtectedCollectorGatewaySourceExitCandidate(
        IReadOnlyList<ElkPoint> path,
        ElkPositionedNode sourceNode,
        ElkPoint exitReference)
    {
        var score = 0d;
        if (path.Count < 2)
        {
            return double.PositiveInfinity;
        }

        var boundary = path[0];
        var adjacent = path[1];
        var centerX = sourceNode.X + (sourceNode.Width / 2d);
        var centerY = sourceNode.Y + (sourceNode.Height / 2d);
        var desiredDx = exitReference.X - centerX;
        var desiredDy = exitReference.Y - centerY;
        var boundaryDx = boundary.X - centerX;
        var boundaryDy = boundary.Y - centerY;
        var firstDx = adjacent.X - boundary.X;
        var firstDy = adjacent.Y - boundary.Y;
        const double tolerance = 0.5d;

        var dominantHorizontal = Math.Abs(desiredDx) >= Math.Abs(desiredDy) * 1.15d && Math.Sign(desiredDx) != 0;
        var dominantVertical = Math.Abs(desiredDy) >= Math.Abs(desiredDx) * 1.15d && Math.Sign(desiredDy) != 0;
        if (dominantHorizontal)
        {
            if (Math.Sign(firstDx) != Math.Sign(desiredDx) || Math.Abs(firstDx) <= tolerance)
            {
                score += 100_000d;
            }

            if (Math.Abs(boundaryDy) > sourceNode.Height * 0.28d)
            {
                score += 25_000d;
            }

            score += Math.Abs(boundaryDy) * 6d;
        }
        else if (dominantVertical)
        {
            if (Math.Sign(firstDy) != Math.Sign(desiredDy) || Math.Abs(firstDy) <= tolerance)
            {
                score += 100_000d;
            }

            if (Math.Abs(boundaryDx) > sourceNode.Width * 0.28d)
            {
                score += 25_000d;
            }

            score += Math.Abs(boundaryDx) * 6d;
        }

        if (ElkShapeBoundaries.IsNearGatewayVertex(sourceNode, boundary, 8d))
        {
            score += 4_000d;
        }

        var length = 0d;
        for (var i = 1; i < path.Count; i++)
        {
            length += ElkEdgeRoutingGeometry.ComputeSegmentLength(path[i - 1], path[i]);
        }

        return score
            + length
            + (Math.Max(0, path.Count - 2) * 6d);
    }

    private static List<ElkPoint> NormalizeProtectedCollectorTail(
        IReadOnlyList<ElkPoint> path,
        double graphMinY,
        double graphMaxY)
    {
        if (path.Count < 5)
        {
            return path.Select(point => new ElkPoint { X = point.X, Y = point.Y }).ToList();
        }

        const double corridorTolerance = 8d;
        const double coordinateTolerance = 0.5d;
        var firstCorridorIndex = -1;
        var lastCorridorIndex = -1;
        for (var i = 0; i < path.Count; i++)
        {
            if (path[i].Y < graphMinY - corridorTolerance || path[i].Y > graphMaxY + corridorTolerance)
            {
                if (firstCorridorIndex < 0)
                {
                    firstCorridorIndex = i;
                }

                lastCorridorIndex = i;
            }
        }

        if (firstCorridorIndex < 0
            || lastCorridorIndex <= firstCorridorIndex
            || lastCorridorIndex >= path.Count - 1
            || path[firstCorridorIndex].Y > graphMinY - corridorTolerance)
        {
            return path.Select(point => new ElkPoint { X = point.X, Y = point.Y }).ToList();
        }

        var desiredDx = path[^1].X - path[0].X;
        if (Math.Abs(desiredDx) <= coordinateTolerance)
        {
            return path.Select(point => new ElkPoint { X = point.X, Y = point.Y }).ToList();
        }

        var preCorridorHorizontalIndex = -1;
        for (var i = 1; i < lastCorridorIndex; i++)
        {
            if (Math.Abs(path[i].Y - path[i + 1].Y) > coordinateTolerance
                || Math.Abs(path[i].X - path[i + 1].X) <= coordinateTolerance)
            {
                continue;
            }

            var horizontalDelta = path[i + 1].X - path[i].X;
            if (Math.Sign(horizontalDelta) == 0 || Math.Sign(horizontalDelta) == Math.Sign(desiredDx))
            {
                continue;
            }

            preCorridorHorizontalIndex = i;
            break;
        }

        if (preCorridorHorizontalIndex >= 0)
        {
            var rebuiltPrefix = path
                .Take(preCorridorHorizontalIndex + 1)
                .Select(point => new ElkPoint { X = point.X, Y = point.Y })
                .ToList();
            var rewrittenCorridorY = path[lastCorridorIndex].Y;
            var rewrittenReentryPoint = path[lastCorridorIndex + 1];

            if (Math.Abs(rebuiltPrefix[^1].Y - rewrittenCorridorY) > coordinateTolerance)
            {
                rebuiltPrefix.Add(new ElkPoint
                {
                    X = rebuiltPrefix[^1].X,
                    Y = rewrittenCorridorY,
                });
            }

            if (Math.Abs(rebuiltPrefix[^1].X - rewrittenReentryPoint.X) > coordinateTolerance)
            {
                rebuiltPrefix.Add(new ElkPoint
                {
                    X = rewrittenReentryPoint.X,
                    Y = rewrittenCorridorY,
                });
            }

            for (var i = lastCorridorIndex + 1; i < path.Count; i++)
            {
                rebuiltPrefix.Add(new ElkPoint { X = path[i].X, Y = path[i].Y });
            }

            return NormalizeCollectorPoints(rebuiltPrefix);
        }

        var firstHorizontalIndex = -1;
        for (var i = firstCorridorIndex; i < lastCorridorIndex; i++)
        {
            if (Math.Abs(path[i].Y - path[i + 1].Y) <= coordinateTolerance
                && Math.Abs(path[i].X - path[i + 1].X) > coordinateTolerance)
            {
                firstHorizontalIndex = i;
                break;
            }
        }

        if (firstHorizontalIndex < 0)
        {
            return path.Select(point => new ElkPoint { X = point.X, Y = point.Y }).ToList();
        }

        var firstHorizontalDelta = path[firstHorizontalIndex + 1].X - path[firstHorizontalIndex].X;
        if (Math.Sign(firstHorizontalDelta) == 0 || Math.Sign(firstHorizontalDelta) == Math.Sign(desiredDx))
        {
            return path.Select(point => new ElkPoint { X = point.X, Y = point.Y }).ToList();
        }

        var rebuilt = path
            .Take(firstCorridorIndex + 1)
            .Select(point => new ElkPoint { X = point.X, Y = point.Y })
            .ToList();
        var targetCorridorY = path[lastCorridorIndex].Y;
        var reentryPoint = path[lastCorridorIndex + 1];

        if (Math.Abs(rebuilt[^1].Y - targetCorridorY) > coordinateTolerance)
        {
            rebuilt.Add(new ElkPoint
            {
                X = rebuilt[^1].X,
                Y = targetCorridorY,
            });
        }

        if (Math.Abs(rebuilt[^1].X - reentryPoint.X) > coordinateTolerance)
        {
            rebuilt.Add(new ElkPoint
            {
                X = reentryPoint.X,
                Y = targetCorridorY,
            });
        }

        for (var i = lastCorridorIndex + 1; i < path.Count; i++)
        {
            rebuilt.Add(new ElkPoint { X = path[i].X, Y = path[i].Y });
        }

        return NormalizeCollectorPoints(rebuilt);
    }

    private static ElkPoint? BuildOrthogonalCollectorCorner(ElkPoint from, ElkPoint to)
    {
        const double tolerance = 0.5d;
        if (Math.Abs(from.X - to.X) <= tolerance || Math.Abs(from.Y - to.Y) <= tolerance)
        {
            return null;
        }

        return Math.Abs(to.Y - from.Y) >= Math.Abs(to.X - from.X)
            ? new ElkPoint { X = from.X, Y = to.Y }
            : new ElkPoint { X = to.X, Y = from.Y };
    }

    private static List<ElkPoint> NormalizeCollectorPoints(IReadOnlyList<ElkPoint> points)
    {
        const double coordinateTolerance = 0.5d;
        var deduped = new List<ElkPoint>();
        foreach (var point in points)
        {
            if (deduped.Count == 0 || !ElkEdgeRoutingGeometry.PointsEqual(deduped[^1], point))
            {
                deduped.Add(point);
            }
        }

        if (deduped.Count <= 2)
        {
            return deduped;
        }

        var simplified = new List<ElkPoint> { deduped[0] };
        for (var i = 1; i < deduped.Count - 1; i++)
        {
            var previous = simplified[^1];
            var current = deduped[i];
            var next = deduped[i + 1];
            var sameX = Math.Abs(previous.X - current.X) <= coordinateTolerance
                && Math.Abs(current.X - next.X) <= coordinateTolerance;
            var sameY = Math.Abs(previous.Y - current.Y) <= coordinateTolerance
                && Math.Abs(current.Y - next.Y) <= coordinateTolerance;
            if (!sameX && !sameY)
            {
                simplified.Add(current);
            }
        }

        simplified.Add(deduped[^1]);
        return simplified;
    }
}