namespace StellaOps.ElkSharp;

internal static partial class ElkEdgePostProcessor
{
    private static bool TryResolveSharedLaneByPairedNodeHandoffSlotRepair(
        ElkRoutedEdge[] currentEdges,
        int leftIndex,
        ElkRoutedEdge leftEdge,
        int rightIndex,
        ElkRoutedEdge rightEdge,
        ElkPositionedNode[] nodes,
        double minLineClearance,
        double graphMinY,
        double graphMaxY,
        out ElkRoutedEdge repairedLeftEdge,
        out ElkRoutedEdge repairedRightEdge)
    {
        repairedLeftEdge = leftEdge;
        repairedRightEdge = rightEdge;
        var nodesById = nodes.ToDictionary(node => node.Id, StringComparer.Ordinal);
        if (!TryResolveSharedLaneNodeHandoffContext(leftEdge, rightEdge, nodesById, graphMinY, graphMaxY, out var leftContext)
            || !TryResolveSharedLaneNodeHandoffContext(rightEdge, leftEdge, nodesById, graphMinY, graphMaxY, out var rightContext)
            || !string.Equals(leftContext.SharedNode.Id, rightContext.SharedNode.Id, StringComparison.Ordinal)
            || !string.Equals(leftContext.Side, rightContext.Side, StringComparison.Ordinal)
            || leftContext.IsOutgoing == rightContext.IsOutgoing)
        {
            return false;
        }

        var baselineConflicts = ElkEdgeRoutingScoring.DetectSharedLaneConflicts(currentEdges, nodes);
        var baselineConflictCount = baselineConflicts.Count;
        var baselineLeftConflictCount = baselineConflicts.Count(conflict =>
            string.Equals(conflict.LeftEdgeId, leftEdge.Id, StringComparison.Ordinal)
            || string.Equals(conflict.RightEdgeId, leftEdge.Id, StringComparison.Ordinal));
        var baselineRightConflictCount = baselineConflicts.Count(conflict =>
            string.Equals(conflict.LeftEdgeId, rightEdge.Id, StringComparison.Ordinal)
            || string.Equals(conflict.RightEdgeId, rightEdge.Id, StringComparison.Ordinal));
        var baselineCombinedPathLength = ComputePathLength(leftContext.Path) + ComputePathLength(rightContext.Path);

        var peerCoordinates = CollectSharedLaneNodeFaceBoundaryCoordinates(
            currentEdges,
            leftContext.SharedNode,
            leftContext.Side,
            graphMinY,
            graphMaxY,
            leftEdge.Id);
        var leftRepairCoordinates = EnumerateSharedLaneBoundaryRepairCoordinates(
                leftContext.SharedNode,
                leftContext.Side,
                leftContext.CurrentBoundaryCoordinate,
                peerCoordinates)
            .ToArray();
        var rightRepairCoordinates = EnumerateSharedLaneBoundaryRepairCoordinates(
                rightContext.SharedNode,
                rightContext.Side,
                rightContext.CurrentBoundaryCoordinate,
                peerCoordinates)
            .ToArray();

        ElkRoutedEdge? bestLeft = null;
        ElkRoutedEdge? bestRight = null;
        var bestConflictCount = baselineConflictCount;
        var bestLeftConflictCount = baselineLeftConflictCount;
        var bestRightConflictCount = baselineRightConflictCount;
        var bestCombinedPathLength = baselineCombinedPathLength;

        foreach (var leftCoordinate in leftRepairCoordinates)
        {
            var leftCandidatePath = leftContext.IsOutgoing
                ? BuildMixedSourceFaceCandidate(leftContext.Path, leftContext.SharedNode, leftContext.Side, leftCoordinate, leftContext.AxisValue)
                : BuildMixedTargetFaceCandidate(leftContext.Path, leftContext.SharedNode, leftContext.Side, leftCoordinate, leftContext.AxisValue);
            if (!IsValidSharedLaneBoundaryRepairCandidate(
                    leftEdge,
                    leftContext.Path,
                    leftCandidatePath,
                    leftContext.SharedNode,
                    leftContext.IsOutgoing,
                    nodes,
                    graphMinY,
                    graphMaxY))
            {
                continue;
            }

            foreach (var rightCoordinate in rightRepairCoordinates)
            {
                var rightCandidatePath = rightContext.IsOutgoing
                    ? BuildMixedSourceFaceCandidate(rightContext.Path, rightContext.SharedNode, rightContext.Side, rightCoordinate, rightContext.AxisValue)
                    : BuildMixedTargetFaceCandidate(rightContext.Path, rightContext.SharedNode, rightContext.Side, rightCoordinate, rightContext.AxisValue);
                if (!IsValidSharedLaneBoundaryRepairCandidate(
                        rightEdge,
                        rightContext.Path,
                        rightCandidatePath,
                        rightContext.SharedNode,
                        rightContext.IsOutgoing,
                        nodes,
                        graphMinY,
                        graphMaxY))
                {
                    continue;
                }

                var candidateLeft = BuildSingleSectionEdge(leftEdge, leftCandidatePath);
                var candidateRight = BuildSingleSectionEdge(rightEdge, rightCandidatePath);
                if (ElkEdgeRoutingScoring.DetectSharedLaneConflicts([candidateLeft, candidateRight], nodes).Count > 0
                    || ComputeUnderNodeRepairLocalHardPressure(candidateLeft, nodes) > ComputeUnderNodeRepairLocalHardPressure(leftEdge, nodes)
                    || ComputeUnderNodeRepairLocalHardPressure(candidateRight, nodes) > ComputeUnderNodeRepairLocalHardPressure(rightEdge, nodes))
                {
                    continue;
                }

                var candidateEdges = currentEdges.ToArray();
                candidateEdges[leftIndex] = candidateLeft;
                candidateEdges[rightIndex] = candidateRight;
                var candidateConflicts = ElkEdgeRoutingScoring.DetectSharedLaneConflicts(candidateEdges, nodes);
                var candidateConflictCount = candidateConflicts.Count;
                var candidateLeftConflictCount = candidateConflicts.Count(conflict =>
                    string.Equals(conflict.LeftEdgeId, leftEdge.Id, StringComparison.Ordinal)
                    || string.Equals(conflict.RightEdgeId, leftEdge.Id, StringComparison.Ordinal));
                var candidateRightConflictCount = candidateConflicts.Count(conflict =>
                    string.Equals(conflict.LeftEdgeId, rightEdge.Id, StringComparison.Ordinal)
                    || string.Equals(conflict.RightEdgeId, rightEdge.Id, StringComparison.Ordinal));
                if (candidateConflictCount > bestConflictCount
                    || candidateLeftConflictCount > bestLeftConflictCount
                    || candidateRightConflictCount > bestRightConflictCount)
                {
                    continue;
                }

                var candidateCombinedPathLength = ComputePathLength(leftCandidatePath) + ComputePathLength(rightCandidatePath);
                var isBetter =
                    candidateConflictCount < bestConflictCount
                    || candidateLeftConflictCount < bestLeftConflictCount
                    || candidateRightConflictCount < bestRightConflictCount
                    || candidateCombinedPathLength + 0.5d < bestCombinedPathLength;
                if (!isBetter)
                {
                    continue;
                }

                bestLeft = candidateLeft;
                bestRight = candidateRight;
                bestConflictCount = candidateConflictCount;
                bestLeftConflictCount = candidateLeftConflictCount;
                bestRightConflictCount = candidateRightConflictCount;
                bestCombinedPathLength = candidateCombinedPathLength;
            }
        }

        if (bestLeft is null || bestRight is null || bestConflictCount >= baselineConflictCount)
        {
            return false;
        }

        repairedLeftEdge = bestLeft;
        repairedRightEdge = bestRight;
        return true;
    }

    private static bool TryResolveSharedLaneByDirectSourceSlotRepair(
        ElkRoutedEdge[] currentEdges,
        int repairIndex,
        ElkRoutedEdge edge,
        ElkRoutedEdge otherEdge,
        ElkPositionedNode[] nodes,
        double minLineClearance,
        double graphMinY,
        double graphMaxY,
        out ElkRoutedEdge repairedEdge)
    {
        repairedEdge = edge;
        if (string.IsNullOrWhiteSpace(edge.SourceNodeId)
            || !string.Equals(edge.SourceNodeId, otherEdge.SourceNodeId, StringComparison.Ordinal))
        {
            return false;
        }

        var nodesById = nodes.ToDictionary(node => node.Id, StringComparer.Ordinal);
        if (!nodesById.TryGetValue(edge.SourceNodeId ?? string.Empty, out var sourceNode))
        {
            return false;
        }

        var path = ExtractFullPath(edge);
        var otherPath = ExtractFullPath(otherEdge);
        if (path.Count < 2
            || otherPath.Count < 2
            || !ShouldSpreadSourceDeparture(edge, graphMinY, graphMaxY)
            || !ShouldSpreadSourceDeparture(otherEdge, graphMinY, graphMaxY))
        {
            return false;
        }

        var side = ResolveSourceDepartureSide(path, sourceNode);
        var otherSide = ResolveSourceDepartureSide(otherPath, sourceNode);
        if (!string.Equals(side, otherSide, StringComparison.Ordinal))
        {
            return false;
        }

        var axisValue = TryExtractSourceDepartureRun(path, side, out _, out var runEndIndex)
            ? side is "left" or "right"
                ? path[runEndIndex].X
                : path[runEndIndex].Y
            : ResolveDefaultSourceDepartureAxis(sourceNode, side);
        var currentBoundaryCoordinate = side is "left" or "right" ? path[0].Y : path[0].X;
        var peerCoordinates = CollectSharedLaneSourceBoundaryCoordinates(
            currentEdges,
            sourceNode,
            side,
            graphMinY,
            graphMaxY,
            edge.Id);

        foreach (var desiredCoordinate in EnumerateSharedLaneBoundaryRepairCoordinates(
                     sourceNode,
                     side,
                     currentBoundaryCoordinate,
                     peerCoordinates))
        {
            var candidatePath = BuildMixedSourceFaceCandidate(path, sourceNode, side, desiredCoordinate, axisValue);
            if (!IsValidSharedLaneBoundaryRepairCandidate(
                    edge,
                    path,
                    candidatePath,
                    sourceNode,
                    isOutgoing: true,
                    nodes,
                    graphMinY,
                    graphMaxY))
            {
                continue;
            }

            var candidateEdges = currentEdges.ToArray();
            candidateEdges[repairIndex] = BuildSingleSectionEdge(edge, candidatePath);
            if (TryAcceptFocusedSharedLanePairRepair(
                    currentEdges,
                    candidateEdges,
                    repairIndex,
                    edge,
                    otherEdge,
                    nodes,
                    graphMinY,
                    graphMaxY,
                    out repairedEdge))
            {
                return true;
            }
        }

        return false;
    }

    private static bool TryResolveSharedLaneByDirectNodeHandoffSlotRepair(
        ElkRoutedEdge[] currentEdges,
        int repairIndex,
        ElkRoutedEdge edge,
        ElkRoutedEdge otherEdge,
        ElkPositionedNode[] nodes,
        double minLineClearance,
        double graphMinY,
        double graphMaxY,
        out ElkRoutedEdge repairedEdge)
    {
        repairedEdge = edge;
        var nodesById = nodes.ToDictionary(node => node.Id, StringComparer.Ordinal);
        if (!TryResolveSharedLaneNodeHandoffContext(edge, otherEdge, nodesById, graphMinY, graphMaxY, out var context))
        {
            return false;
        }

        var peerCoordinates = CollectSharedLaneNodeFaceBoundaryCoordinates(
            currentEdges,
            context.SharedNode,
            context.Side,
            graphMinY,
            graphMaxY,
            edge.Id);

        foreach (var desiredCoordinate in EnumerateSharedLaneBoundaryRepairCoordinates(
                     context.SharedNode,
                     context.Side,
                     context.CurrentBoundaryCoordinate,
                     peerCoordinates))
        {
            var candidatePath = context.IsOutgoing
                ? BuildMixedSourceFaceCandidate(context.Path, context.SharedNode, context.Side, desiredCoordinate, context.AxisValue)
                : BuildMixedTargetFaceCandidate(context.Path, context.SharedNode, context.Side, desiredCoordinate, context.AxisValue);
            if (!IsValidSharedLaneBoundaryRepairCandidate(
                    edge,
                    context.Path,
                    candidatePath,
                    context.SharedNode,
                    context.IsOutgoing,
                    nodes,
                    graphMinY,
                    graphMaxY))
            {
                continue;
            }

            var candidateEdges = currentEdges.ToArray();
            candidateEdges[repairIndex] = BuildSingleSectionEdge(edge, candidatePath);
            if (TryAcceptFocusedSharedLanePairRepair(
                    currentEdges,
                    candidateEdges,
                    repairIndex,
                    edge,
                    otherEdge,
                    nodes,
                    graphMinY,
                    graphMaxY,
                    out repairedEdge))
            {
                return true;
            }
        }

        return false;
    }
}