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

using System.Collections.Concurrent;
using System.Diagnostics;
using System.Globalization;

namespace StellaOps.ElkSharp;

internal static partial class ElkEdgeRouterIterative
{
    private static List<ElkPoint>? TryRouteShortestRepair(
        ElkPoint start,
        ElkPoint end,
        IReadOnlyCollection<ElkPositionedNode> nodes,
        (double Left, double Top, double Right, double Bottom, string Id)[] obstacles,
        string sourceId,
        string targetId,
        ElkPositionedNode? sourceNode,
        ElkPositionedNode? targetNode,
        AStarRoutingParams routingParams,
        IReadOnlyList<OrthogonalSoftObstacle> softObstacles,
        CancellationToken cancellationToken)
    {
        if (sourceNode is not null && targetNode is not null)
        {
            if (ElkEdgePostProcessor.TryBuildPreferredBoundaryShortcutPath(
                    sourceNode,
                    targetNode,
                    nodes,
                    sourceId,
                    targetId,
                    out var preferredShortcut)
                && (targetNode is null || !HasTargetApproachBacktracking(preferredShortcut, targetNode)))
            {
                return preferredShortcut;
            }
        }

        var candidateEndpoints = EnumerateShortestRepairEndpoints(start, end, targetNode).ToArray();
        var minLineClearance = ResolveMinLineClearance(nodes);
        var shortcutObstaclePadding = Math.Max(12d, Math.Min(routingParams.Margin, Math.Max(18d, minLineClearance - 4d)));
        List<ElkPoint>? bestPath = null;
        var bestLength = double.MaxValue;

        foreach (var candidateEnd in candidateEndpoints)
        {
            var orthogonalShortcut = TryBuildShortestOrthogonalPath(
                start,
                candidateEnd,
                nodes,
                sourceId,
                targetId,
                targetNode,
                shortcutObstaclePadding);
            if (orthogonalShortcut is null
                || (targetNode is not null && HasTargetApproachBacktracking(orthogonalShortcut, targetNode)))
            {
                continue;
            }

            var shortcutLength = ComputePolylineLength(orthogonalShortcut);
            if (shortcutLength < bestLength - 0.5d)
            {
                bestPath = orthogonalShortcut;
                bestLength = shortcutLength;
            }
        }

        foreach (var candidateEnd in candidateEndpoints)
        {
            var localSkirtShortcut = TryBuildLocalObstacleSkirtPath(
                start,
                candidateEnd,
                nodes,
                sourceId,
                targetId,
                targetNode,
                shortcutObstaclePadding);
            if (localSkirtShortcut is null
                || (targetNode is not null && HasTargetApproachBacktracking(localSkirtShortcut, targetNode)))
            {
                continue;
            }

            var shortcutLength = ComputePolylineLength(localSkirtShortcut);
            if (shortcutLength < bestLength - 0.5d)
            {
                bestPath = localSkirtShortcut;
                bestLength = shortcutLength;
            }
        }

        if (bestPath is not null)
        {
            return bestPath;
        }

        var shortestParams = routingParams with
        {
            Margin = Math.Max(shortcutObstaclePadding, Math.Min(routingParams.Margin, minLineClearance)),
            BendPenalty = Math.Min(routingParams.BendPenalty, 80d),
            DiagonalPenalty = Math.Min(routingParams.DiagonalPenalty, 40d),
            SoftObstacleWeight = Math.Max(0.25d, routingParams.SoftObstacleWeight * 0.35d),
            SoftObstacleClearance = Math.Max(Math.Max(18d, minLineClearance * 0.6d), routingParams.SoftObstacleClearance * 0.5d),
            IntermediateGridSpacing = Math.Max(12d, routingParams.IntermediateGridSpacing - 8d),
        };
        var shortestObstacles = nodes
            .Select(node => (
                Left: node.X - shortestParams.Margin,
                Top: node.Y - shortestParams.Margin,
                Right: node.X + node.Width + shortestParams.Margin,
                Bottom: node.Y + node.Height + shortestParams.Margin,
                Id: node.Id))
            .ToArray();

        foreach (var candidateEnd in candidateEndpoints)
        {
            var diagonalPath = ElkEdgeRouterAStar8Dir.Route(
                start,
                candidateEnd,
                shortestObstacles,
                sourceId,
                targetId,
                shortestParams,
                [],
                cancellationToken);
            if (diagonalPath is null
                || (targetNode is not null && HasTargetApproachBacktracking(diagonalPath, targetNode)))
            {
                continue;
            }

            var pathLength = ComputePolylineLength(diagonalPath);
            if (pathLength < bestLength - 0.5d)
            {
                bestPath = diagonalPath;
                bestLength = pathLength;
            }
        }

        return bestPath;
    }

    private static List<ElkPoint>? TryRouteAggressiveRepair(
        ElkPoint start,
        ElkPoint end,
        IReadOnlyCollection<ElkPositionedNode> nodes,
        (double Left, double Top, double Right, double Bottom, string Id)[] obstacles,
        string sourceId,
        string targetId,
        ElkPositionedNode? sourceNode,
        ElkPositionedNode? targetNode,
        AStarRoutingParams routingParams,
        CancellationToken cancellationToken)
    {
        var candidateEndpoints = EnumerateShortestRepairEndpoints(start, end, targetNode).ToArray();
        if (candidateEndpoints.Length == 0)
        {
            return null;
        }

        var minLineClearance = ResolveMinLineClearance(nodes);
        var aggressiveParams = routingParams with
        {
            Margin = Math.Max(10d, Math.Min(routingParams.Margin, Math.Max(14d, minLineClearance * 0.45d))),
            BendPenalty = Math.Min(routingParams.BendPenalty, 60d),
            DiagonalPenalty = Math.Min(routingParams.DiagonalPenalty, 35d),
            SoftObstacleWeight = 0d,
            SoftObstacleClearance = 0d,
            IntermediateGridSpacing = Math.Max(12d, Math.Min(routingParams.IntermediateGridSpacing, Math.Max(12d, minLineClearance * 0.45d))),
        };

        var aggressiveObstacles = obstacles
            .Select(obstacle => (
                Left: obstacle.Left + Math.Min(0d, aggressiveParams.Margin - routingParams.Margin),
                Top: obstacle.Top + Math.Min(0d, aggressiveParams.Margin - routingParams.Margin),
                Right: obstacle.Right - Math.Min(0d, aggressiveParams.Margin - routingParams.Margin),
                Bottom: obstacle.Bottom - Math.Min(0d, aggressiveParams.Margin - routingParams.Margin),
                obstacle.Id))
            .ToArray();

        List<ElkPoint>? bestPath = null;
        ElkRoutedEdge? bestEdge = null;

        foreach (var candidateEnd in candidateEndpoints)
        {
            var candidate = ElkEdgeRouterAStar8Dir.Route(
                start,
                candidateEnd,
                aggressiveObstacles,
                sourceId,
                targetId,
                aggressiveParams,
                [],
                cancellationToken);
            if (candidate is null)
            {
                continue;
            }

            if (targetNode is not null && HasTargetApproachBacktracking(candidate, targetNode))
            {
                continue;
            }

            var candidateEdge = BuildCandidateRepairEdge(
                sourceId,
                targetId,
                sourceNode,
                targetNode,
                candidate);
            if (bestPath is null || CompareSingleEdgeRepairQuality(candidateEdge, bestEdge!, nodes) < 0)
            {
                bestPath = candidate;
                bestEdge = candidateEdge;
            }
        }

        return bestPath;
    }

}