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

namespace StellaOps.ElkSharp;

internal static partial class ElkEdgeRouterIterative
{
    private static RouteAllEdgesResult RepairPenalizedEdges(
        ElkRoutedEdge[] existingEdges,
        ElkPositionedNode[] nodes,
        double baseObstacleMargin,
        RoutingStrategy strategy,
        RepairPlan repairPlan,
        CancellationToken cancellationToken,
        int maxParallelRepairBuilds,
        bool trustIndependentParallelBuilds = false)
    {
        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 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;
        var repairSet = repairPlan.EdgeIndices.ToHashSet();
        var routeRepairEdgeIdSet = repairPlan.RouteRepairEdgeIds.ToHashSet(StringComparer.Ordinal);
        var collectorRepairSet = repairPlan.Reasons.Contains("collector-corridors", StringComparer.Ordinal)
            ? repairSet
                .Where(edgeIndex => edgeIndex >= 0
                    && edgeIndex < existingEdges.Length
                    && ElkEdgePostProcessor.IsRepeatCollectorLabel(existingEdges[edgeIndex].Label))
                .Where(edgeIndex => !routeRepairEdgeIdSet.Contains(existingEdges[edgeIndex].Id))
                .ToHashSet()
            : [];
        var preferredShortestEdgeIdSet = repairPlan.PreferredShortestEdgeIds.ToHashSet(StringComparer.Ordinal);
        if (collectorRepairSet.Count > 0)
        {
            var collectorEdgeIds = collectorRepairSet
                .Select(edgeIndex => existingEdges[edgeIndex].Id)
                .ToArray();
            routedEdges = ElkRepeatCollectorCorridors.SeparateSharedLanes(routedEdges, nodes, collectorEdgeIds);
            routedEdgeCount += collectorRepairSet.Count;
        }

        var aStarRepairSet = repairSet
            .Where(edgeIndex => !collectorRepairSet.Contains(edgeIndex))
            .ToHashSet();
        var spreadEndpoints = SpreadTargetEndpoints(existingEdges, nodesById, graphMinY, graphMaxY, strategy.MinLineClearance);
        var softObstacles = new List<OrthogonalSoftObstacle>();

        for (var edgeIndex = 0; edgeIndex < existingEdges.Length; edgeIndex++)
        {
            if (aStarRepairSet.Contains(edgeIndex))
            {
                continue;
            }

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

        var orderedRepairIndices = strategy.EdgeOrder
            .Where(aStarRepairSet.Contains)
            .Concat(aStarRepairSet.Where(edgeIndex => !strategy.EdgeOrder.Contains(edgeIndex)))
            .Distinct()
            .ToArray();
        var repairBuilderParallelism = (trustIndependentParallelBuilds || CanParallelizeRepairBuilds(orderedRepairIndices, existingEdges))
            ? DetermineRepairBuildParallelism(orderedRepairIndices.Length, maxParallelRepairBuilds)
            : 1;
        var builtRepairResults = new ConcurrentDictionary<int, RepairEdgeBuildResult>();
        var repairBuildLocks = new ConcurrentDictionary<string, object>(StringComparer.Ordinal);
        if (repairBuilderParallelism > 1 && orderedRepairIndices.Length > 1)
        {
            var immutableSoftObstacles = softObstacles.ToArray();
            var parallelOptions = new ParallelOptions
            {
                CancellationToken = cancellationToken,
                MaxDegreeOfParallelism = repairBuilderParallelism,
            };

            Parallel.ForEach(
                orderedRepairIndices,
                parallelOptions,
                edgeIndex =>
                {
                    if (edgeIndex < 0 || edgeIndex >= existingEdges.Length)
                    {
                        return;
                    }

                    var edge = existingEdges[edgeIndex];
                    var lockKeys = trustIndependentParallelBuilds
                        ? []
                        : GetRepairBuildLockKeys(edge);
                    ExecuteWithRepairBuildLocks(
                        repairBuildLocks,
                        lockKeys,
                        () =>
                        {
                            builtRepairResults[edgeIndex] = BuildRepairEdgeResult(
                                edgeIndex,
                                existingEdges,
                                nodes,
                                obstacles,
                                spreadEndpoints,
                                nodesById,
                                immutableSoftObstacles,
                                routeRepairEdgeIdSet,
                                preferredShortestEdgeIdSet,
                                repairPlan.Reasons,
                                graphMinY,
                                graphMaxY,
                                strategy,
                                cancellationToken);
                        });
                });
        }

        foreach (var edgeIndex in orderedRepairIndices)
        {
            cancellationToken.ThrowIfCancellationRequested();

            if (edgeIndex < 0 || edgeIndex >= existingEdges.Length)
            {
                continue;
            }

            var buildResult = builtRepairResults.TryGetValue(edgeIndex, out var parallelBuildResult)
                ? parallelBuildResult
                : BuildRepairEdgeResult(
                    edgeIndex,
                    existingEdges,
                    nodes,
                    obstacles,
                    spreadEndpoints,
                    nodesById,
                    softObstacles,
                    routeRepairEdgeIdSet,
                    preferredShortestEdgeIdSet,
                    repairPlan.Reasons,
                    graphMinY,
                    graphMaxY,
                    strategy,
                    cancellationToken);
            if (buildResult.WasSkipped)
            {
                skippedEdgeCount++;
                foreach (var segment in ElkEdgeRoutingGeometry.FlattenSegments(buildResult.Edge))
                {
                    softObstacles.Add(new OrthogonalSoftObstacle(segment.Start, segment.End));
                }

                continue;
            }

            routedSectionCount += buildResult.RoutedSections;
            fallbackSectionCount += buildResult.FallbackSections;
            routedEdgeCount++;
            routedEdges[edgeIndex] = buildResult.Edge;

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

        var repeatRouteRepairIds = repairPlan.RouteRepairEdgeIds
            .Where(edgeId => routedEdges.Any(edge =>
                string.Equals(edge.Id, edgeId, StringComparison.Ordinal)
                && ElkEdgePostProcessor.IsRepeatCollectorLabel(edge.Label)))
            .ToArray();
        if (repeatRouteRepairIds.Length > 0)
        {
            routedEdges = ElkRepeatCollectorCorridors.SeparateSharedLanes(routedEdges, nodes, repeatRouteRepairIds);
        }

        return new RouteAllEdgesResult(
            routedEdges,
            new ElkIterativeRouteDiagnostics
            {
                Mode = "local-repair",
                TotalEdges = existingEdges.Length,
                RoutedEdges = routedEdgeCount,
                SkippedEdges = skippedEdgeCount,
                RoutedSections = routedSectionCount,
                FallbackSections = fallbackSectionCount,
                SoftObstacleSegments = softObstacles.Count,
                RepairedEdgeIds = repairPlan.EdgeIds,
                RepairReasons = repairPlan.Reasons,
                BuilderMode = repairBuilderParallelism > 1 ? "parallel-locked-local-build" : "sequential-local-build",
                BuilderParallelism = repairBuilderParallelism,
            });
    }

}