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

namespace StellaOps.ElkSharp;

internal static partial class ElkEdgeRouterIterative
{
    private static CandidateSolution ApplyFinalBoundarySlotPolish(
        CandidateSolution solution,
        ElkPositionedNode[] nodes,
        ElkLayoutDirection direction,
        double minLineClearance,
        int maxRounds = 3)
    {
        var current = solution;
        var nodesById = nodes.ToDictionary(node => node.Id, StringComparer.Ordinal);

        for (var round = 0; round < maxRounds; round++)
        {
            var boundarySlotSeverity = new Dictionary<string, int>(StringComparer.Ordinal);
            ElkEdgeRoutingScoring.CountBoundarySlotViolations(current.Edges, nodes, boundarySlotSeverity, 10);
            if (boundarySlotSeverity.Count == 0)
            {
                break;
            }

            var batchedRootEdgeIds = boundarySlotSeverity
                .OrderByDescending(pair => pair.Value)
                .ThenBy(pair => pair.Key, StringComparer.Ordinal)
                .Take(MaxWinnerPolishBatchedRootEdges)
                .Select(pair => pair.Key)
                .ToArray();
            var batchedFocusEdgeIds = ResolveBoundarySlotRepairFocus(
                current.Edges,
                nodesById,
                batchedRootEdgeIds);
            if (batchedFocusEdgeIds.Length > 0)
            {
                var batchedCandidateEdges = BuildFinalBoundarySlotCandidate(
                    current.Edges,
                    nodes,
                    direction,
                    minLineClearance,
                    batchedFocusEdgeIds,
                    allowLateRestabilizedClosure: false);
                if (TryPromoteFinalBoundarySlotCandidate(current, batchedCandidateEdges, nodes, out var batchedPromoted))
                {
                    current = batchedPromoted;
                    continue;
                }
            }

            var improved = false;
            foreach (var edgeId in boundarySlotSeverity
                         .OrderByDescending(pair => pair.Value)
                         .ThenBy(pair => pair.Key, StringComparer.Ordinal)
                         .Select(pair => pair.Key))
            {
                var focusEdgeIds = ResolveBoundarySlotRepairFocus(
                    current.Edges,
                    nodesById,
                    [edgeId]);
                if (focusEdgeIds.Length == 0)
                {
                    continue;
                }

                var candidateEdges = BuildFinalBoundarySlotCandidate(
                    current.Edges,
                    nodes,
                    direction,
                    minLineClearance,
                    focusEdgeIds,
                    allowLateRestabilizedClosure: false);

                if (!TryPromoteFinalBoundarySlotCandidate(current, candidateEdges, nodes, out var promoted))
                {
                    continue;
                }

                current = promoted;
                improved = true;
                break;
            }

            if (!improved)
            {
                break;
            }
        }

        return current;
    }

    private static string[] ResolveBoundarySlotRepairFocus(
        IReadOnlyCollection<ElkRoutedEdge> edges,
        IReadOnlyDictionary<string, ElkPositionedNode> nodesById,
        IReadOnlyCollection<string> rootEdgeIds)
    {
        if (rootEdgeIds.Count == 0)
        {
            return [];
        }

        if (TryResolveGatewayBoundarySlotLocalFocus(edges, nodesById, rootEdgeIds, out var localFocus))
        {
            return localFocus;
        }

        return ExpandWinningSolutionFocus(edges, rootEdgeIds).ToArray();
    }

    private static bool TryResolveGatewayBoundarySlotLocalFocus(
        IReadOnlyCollection<ElkRoutedEdge> edges,
        IReadOnlyDictionary<string, ElkPositionedNode> nodesById,
        IReadOnlyCollection<string> rootEdgeIds,
        out string[] focusEdgeIds)
    {
        focusEdgeIds = [];
        if (rootEdgeIds.Count == 0)
        {
            return false;
        }

        var edgesById = edges.ToDictionary(edge => edge.Id, StringComparer.Ordinal);
        var localFocus = new HashSet<string>(StringComparer.Ordinal);

        foreach (var edgeId in rootEdgeIds)
        {
            if (!edgesById.TryGetValue(edgeId, out var edge))
            {
                return false;
            }

            var touchesGateway = false;
            if (!string.IsNullOrWhiteSpace(edge.SourceNodeId)
                && nodesById.TryGetValue(edge.SourceNodeId, out var sourceNode)
                && ElkShapeBoundaries.IsGatewayShape(sourceNode))
            {
                touchesGateway = true;
            }

            if (!touchesGateway
                && !string.IsNullOrWhiteSpace(edge.TargetNodeId)
                && nodesById.TryGetValue(edge.TargetNodeId, out var targetNode)
                && ElkShapeBoundaries.IsGatewayShape(targetNode))
            {
                touchesGateway = true;
            }

            if (!touchesGateway)
            {
                return false;
            }

            localFocus.Add(edgeId);
        }

        focusEdgeIds = localFocus
            .OrderBy(edgeId => edgeId, StringComparer.Ordinal)
            .ToArray();
        return focusEdgeIds.Length > 0;
    }

    private static CandidateSolution ApplyFinalPostSlotHardRulePolish(
        CandidateSolution solution,
        ElkPositionedNode[] nodes,
        ElkLayoutDirection direction,
        double minLineClearance,
        int maxRounds = 3)
    {
        var current = solution;

        for (var round = 0; round < maxRounds; round++)
        {
            var severityByEdgeId = new Dictionary<string, int>(StringComparer.Ordinal);
            var pressure =
                ElkEdgeRoutingScoring.CountEdgeNodeCrossings(current.Edges, nodes, severityByEdgeId, 10)
                + ElkEdgeRoutingScoring.CountBadBoundaryAngles(current.Edges, nodes, severityByEdgeId, 10)
                + ElkEdgeRoutingScoring.CountGatewaySourceExitViolations(current.Edges, nodes, severityByEdgeId, 10)
                + ElkEdgeRoutingScoring.CountTargetApproachJoinViolations(current.Edges, nodes, severityByEdgeId, 10)
                + ElkEdgeRoutingScoring.CountSharedLaneViolations(current.Edges, nodes, severityByEdgeId, 10)
                + ElkEdgeRoutingScoring.CountBoundarySlotViolations(current.Edges, nodes, severityByEdgeId, 10)
                + ElkEdgeRoutingScoring.CountTargetApproachBacktrackingViolations(current.Edges, nodes, severityByEdgeId, 10)
                + ElkEdgeRoutingScoring.CountExcessiveDetourViolations(current.Edges, nodes, severityByEdgeId, 10)
                + ElkEdgeRoutingScoring.CountBelowGraphViolations(current.Edges, nodes, severityByEdgeId, 10)
                + ElkEdgeRoutingScoring.CountUnderNodeViolations(current.Edges, nodes, severityByEdgeId, 10)
                + ElkEdgeRoutingScoring.CountLongDiagonalViolations(current.Edges, nodes, severityByEdgeId, 10);
            ElkLayoutDiagnostics.LogProgress(
                $"Winner post-slot hard-rule round {round + 1} start: pressure={pressure} retry={DescribeRetryState(current.RetryState)} focus={severityByEdgeId.Count}");
            if (pressure == 0)
            {
                break;
            }

            var preferFastTerminalOnly = ShouldPreferFastTerminalOnlyHardRuleClosure(current.RetryState);

            var batchedRootEdgeIds = severityByEdgeId
                .OrderByDescending(pair => pair.Value)
                .ThenBy(pair => pair.Key, StringComparer.Ordinal)
                .Take(MaxWinnerPolishBatchedRootEdges)
                .Select(pair => pair.Key)
                .ToArray();
            var batchedFocusEdgeIds = preferFastTerminalOnly
                ? batchedRootEdgeIds
                : ExpandWinningSolutionFocus(current.Edges, batchedRootEdgeIds).ToArray();
            if (batchedFocusEdgeIds.Length > 0)
            {
                if (preferFastTerminalOnly)
                {
                    ElkLayoutDiagnostics.LogProgress(
                        $"Winner post-slot hard-rule round {round + 1} fast-terminal focus=[{string.Join(", ", batchedFocusEdgeIds)}]");
                    var quickBatchedCandidateEdges = BuildFastTerminalOnlyHardRuleCandidate(
                        current.Edges,
                        nodes,
                        direction,
                        minLineClearance,
                        batchedFocusEdgeIds);
                    if (TryPromoteFinalHardRuleCandidate(current, quickBatchedCandidateEdges, nodes, out var quickBatchedPromoted))
                    {
                        current = quickBatchedPromoted;
                        continue;
                    }

                    var focusedTerminalClosureEdges = CloseRemainingTerminalViolations(
                        current.Edges,
                        nodes,
                        direction,
                        minLineClearance,
                        batchedFocusEdgeIds);
                    if (TryPromoteFinalHardRuleCandidate(current, focusedTerminalClosureEdges, nodes, out var focusedTerminalPromoted))
                    {
                        current = focusedTerminalPromoted;
                        continue;
                    }

                    var exactRestabilizedEdges = BuildFinalRestabilizedCandidate(
                        current.Edges,
                        nodes,
                        direction,
                        minLineClearance,
                        batchedFocusEdgeIds);
                    if (TryPromoteFinalHardRuleCandidate(current, exactRestabilizedEdges, nodes, out var exactRestabilizedPromoted))
                    {
                        current = exactRestabilizedPromoted;
                        continue;
                    }

                    var quickBatchedScore = ElkEdgeRoutingScoring.ComputeScore(quickBatchedCandidateEdges, nodes);
                    var quickBatchedRetryState = BuildRetryState(
                        quickBatchedScore,
                        HighwayProcessingEnabled
                            ? ElkEdgeRouterHighway.DetectRemainingBrokenHighways(quickBatchedCandidateEdges, nodes).Count
                            : 0);
                    var changedFocusEdgeIds = batchedFocusEdgeIds
                        .Where(edgeId => HasEdgeGeometryChanged(current.Edges, quickBatchedCandidateEdges, edgeId))
                        .ToArray();
                    ElkLayoutDiagnostics.LogProgress(
                        $"Winner post-slot hard-rule round {round + 1} fast-terminal made no promotion: candidate={DescribeRetryState(quickBatchedRetryState)} changed=[{string.Join(", ", changedFocusEdgeIds)}]");
                }
                else
                {
                    ElkLayoutDiagnostics.LogProgress(
                        $"Winner post-slot hard-rule round {round + 1} full-restabilize focus=[{string.Join(", ", batchedFocusEdgeIds)}]");
                    var batchedCandidateEdges = BuildFinalRestabilizedCandidate(
                        current.Edges,
                        nodes,
                        direction,
                        minLineClearance,
                        batchedFocusEdgeIds);
                    if (TryPromoteFinalHardRuleCandidate(current, batchedCandidateEdges, nodes, out var batchedPromoted))
                    {
                        current = batchedPromoted;
                        continue;
                    }
                }
            }

            var orderedSeverityEdgeIds = severityByEdgeId
                .OrderByDescending(pair => pair.Value)
                .ThenBy(pair => pair.Key, StringComparer.Ordinal)
                .Select(pair => pair.Key)
                .ToArray();
            var improved = false;
            if (preferFastTerminalOnly)
            {
                var candidateEdgeIds = orderedSeverityEdgeIds
                    .Take(MaxWinnerPolishFastTerminalSingleEdgeCandidates)
                    .ToArray();
                ElkLayoutDiagnostics.LogProgress(
                    $"Winner post-slot hard-rule round {round + 1} evaluating {candidateEdgeIds.Length}/{orderedSeverityEdgeIds.Length} fast-terminal single-edge candidates in parallel");
                if (TryPromoteFastTerminalCandidates(
                        current,
                        nodes,
                        direction,
                        minLineClearance,
                        candidateEdgeIds,
                        out var parallelPromoted))
                {
                    current = parallelPromoted;
                    improved = true;
                }
            }
            else
            {
                foreach (var edgeId in orderedSeverityEdgeIds)
                {
                    var focusEdgeIds = ExpandWinningSolutionFocus(current.Edges, [edgeId]).ToArray();
                    if (focusEdgeIds.Length == 0)
                    {
                        continue;
                    }

                    var candidateEdges = BuildFinalRestabilizedCandidate(
                        current.Edges,
                        nodes,
                        direction,
                        minLineClearance,
                        focusEdgeIds);
                    if (!TryPromoteFinalHardRuleCandidate(current, candidateEdges, nodes, out var promoted))
                    {
                        continue;
                    }

                    current = promoted;
                    improved = true;
                    break;
                }
            }

            if (!improved)
            {
                break;
            }
        }

        return current;
    }

}