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

namespace StellaOps.ElkSharp;

internal static partial class ElkEdgeRouterIterative
{
    private static RouteAllEdgesResult? RouteAllEdges(
        ElkRoutedEdge[] existingEdges,
        ElkPositionedNode[] nodes,
        double baseObstacleMargin,
        RoutingStrategy strategy,
        CancellationToken cancellationToken)
    {
        var routedEdges = new ElkRoutedEdge[existingEdges.Length];
        Array.Copy(existingEdges, routedEdges, existingEdges.Length);

        var obstacleMargin = Math.Max(
            baseObstacleMargin,
            Math.Max(strategy.MinLineClearance + 4d, strategy.RoutingParams.Margin));
        var obstacles = BuildObstacles(nodes, obstacleMargin);
        var originalNodeBounds = BuildOriginalNodeBounds(nodes);
        var graphMinY = nodes.Length > 0 ? nodes.Min(n => n.Y) : 0d;
        var graphMaxY = nodes.Length > 0 ? nodes.Max(n => n.Y + n.Height) : 0d;
        var nodesById = nodes.ToDictionary(n => n.Id, StringComparer.Ordinal);
        var routedEdgeCount = 0;
        var skippedEdgeCount = 0;
        var routedSectionCount = 0;
        var fallbackSectionCount = 0;

        // Spread endpoints: distribute edges arriving at the same target side
        var spreadEndpoints = SpreadTargetEndpoints(existingEdges, nodesById, graphMinY, graphMaxY, strategy.MinLineClearance);

        var softObstacles = new List<OrthogonalSoftObstacle>();

        foreach (var edgeIndex in strategy.EdgeOrder)
        {
            if (edgeIndex < 0 || edgeIndex >= existingEdges.Length)
            {
                continue;
            }

            cancellationToken.ThrowIfCancellationRequested();

            var edge = existingEdges[edgeIndex];

            // Skip edges that need special routing (backward, ports, corridors, collectors)
            if (!CanRepairEdgeLocally(edge, nodes, graphMinY, graphMaxY))
            {
                skippedEdgeCount++;
                foreach (var segment in ElkEdgeRoutingGeometry.FlattenSegments(edge))
                {
                    softObstacles.Add(new OrthogonalSoftObstacle(segment.Start, segment.End));
                }

                continue;
            }

            var newSections = new List<ElkEdgeSection>(edge.Sections.Count);

            foreach (var section in edge.Sections)
            {
                var endPoint = spreadEndpoints.TryGetValue(edge.Id, out var spread)
                    ? spread
                    : section.EndPoint;
                var (startPoint, adjustedEndPoint) = ResolveRoutingEndpoints(
                    section.StartPoint,
                    endPoint,
                    edge.SourceNodeId,
                    edge.TargetNodeId,
                    nodesById);

                var rerouted = ElkEdgeRouterAStar8Dir.Route(
                    startPoint,
                    adjustedEndPoint,
                    obstacles,
                    originalNodeBounds,
                    edge.SourceNodeId ?? "",
                    edge.TargetNodeId ?? "",
                    strategy.RoutingParams,
                    softObstacles,
                    cancellationToken);

                if (rerouted is not null && rerouted.Count >= 2)
                {
                    routedSectionCount++;
                    newSections.Add(new ElkEdgeSection
                    {
                        StartPoint = rerouted[0],
                        EndPoint = rerouted[^1],
                        BendPoints = rerouted.Skip(1).Take(rerouted.Count - 2).ToArray(),
                    });
                }
                else
                {
                    fallbackSectionCount++;
                    newSections.Add(section);
                }
            }

            routedEdgeCount++;

            routedEdges[edgeIndex] = new ElkRoutedEdge
            {
                Id = edge.Id,
                SourceNodeId = edge.SourceNodeId,
                TargetNodeId = edge.TargetNodeId,
                SourcePortId = edge.SourcePortId,
                TargetPortId = edge.TargetPortId,
                Kind = edge.Kind,
                Label = edge.Label,
                Sections = newSections,
            };

            foreach (var segment in ElkEdgeRoutingGeometry.FlattenSegments(routedEdges[edgeIndex]))
            {
                softObstacles.Add(new OrthogonalSoftObstacle(segment.Start, segment.End));
            }
        }

        return new RouteAllEdgesResult(
            routedEdges,
            new ElkIterativeRouteDiagnostics
            {
                Mode = "full-strategy",
                TotalEdges = existingEdges.Length,
                RoutedEdges = routedEdgeCount,
                SkippedEdges = skippedEdgeCount,
                RoutedSections = routedSectionCount,
                FallbackSections = fallbackSectionCount,
                SoftObstacleSegments = softObstacles.Count,
            });
    }

}