namespace StellaOps.ElkSharp;

internal static partial class ElkEdgePostProcessor
{
    internal static ElkRoutedEdge[] SpreadSourceDepartureJoins(
        ElkRoutedEdge[] edges,
        ElkPositionedNode[] nodes,
        double minLineClearance,
        IReadOnlyCollection<string>? restrictedEdgeIds = null)
    {
        if (edges.Length == 0 || nodes.Length == 0)
        {
            return edges;
        }

        var nodesById = nodes.ToDictionary(node => node.Id, StringComparer.Ordinal);
        var graphMinY = nodes.Min(node => node.Y);
        var graphMaxY = nodes.Max(node => node.Y + node.Height);
        var restrictedSet = restrictedEdgeIds is null
            ? null
            : restrictedEdgeIds.ToHashSet(StringComparer.Ordinal);
        var result = edges.ToArray();
        var groups = result
            .Select((edge, index) => new
            {
                Edge = edge,
                Index = index,
                Path = ExtractFullPath(edge),
            })
            .Where(item => item.Path.Count >= 2
                && nodesById.TryGetValue(item.Edge.SourceNodeId ?? string.Empty, out _)
                && ShouldSpreadSourceDeparture(item.Edge, graphMinY, graphMaxY))
            .GroupBy(
                item =>
                {
                    var sourceNode = nodesById[item.Edge.SourceNodeId ?? string.Empty];
                    var side = ResolveSourceDepartureSide(item.Path, sourceNode);
                    return $"{sourceNode.Id}|{side}";
                },
                StringComparer.Ordinal);

        foreach (var group in groups)
        {
            var entries = group
                .Select(item =>
                {
                    var sourceNode = nodesById[item.Edge.SourceNodeId ?? string.Empty];
                    var side = ResolveSourceDepartureSide(item.Path, sourceNode);
                    return new
                    {
                        item.Edge,
                        item.Index,
                        item.Path,
                        SourceNode = sourceNode,
                        Side = side,
                        Boundary = item.Path[0],
                        TargetReference = side is "left" or "right"
                            ? item.Path[^1].Y
                            : item.Path[^1].X,
                        PathLength = ComputePathLength(item.Path),
                    };
                })
                .ToArray();
            if (entries.Length < 2)
            {
                continue;
            }

            if (restrictedSet is not null && !entries.Any(entry => restrictedSet.Contains(entry.Edge.Id)))
            {
                continue;
            }

            var sourceNode = entries[0].SourceNode;
            var side = entries[0].Side;
            var sourceBoundaryEntries = entries
                .Select(entry => (
                    entry.Edge.Id,
                    Coordinate: side is "left" or "right" ? entry.Boundary.Y : entry.Boundary.X,
                    IsOutgoing: true))
                .ToArray();
            var joinEntries = entries
                .Select(entry => (Path: (IReadOnlyList<ElkPoint>)entry.Path, Side: entry.Side))
                .ToArray();
            var hasDepartureJoin = GroupHasSourceDepartureJoin(joinEntries, minLineClearance);
            var hasBoundarySlotIssue = HasBoundarySlotAlignmentIssue(
                sourceBoundaryEntries,
                sourceNode,
                side,
                minLineClearance);
            if (!hasDepartureJoin && !hasBoundarySlotIssue)
            {
                continue;
            }

            var isGatewaySource = ElkShapeBoundaries.IsGatewayShape(sourceNode);
            var slotOnlyRepair = !hasDepartureJoin && hasBoundarySlotIssue;
            var boundaryCoordinate = side is "left" or "right"
                ? entries[0].Boundary.Y
                : entries[0].Boundary.X;
            var anchor = entries
                .OrderBy(entry => Math.Abs(entry.TargetReference - boundaryCoordinate))
                .ThenBy(entry => entry.PathLength)
                .ThenBy(entry => entry.Edge.Id, StringComparer.Ordinal)
                .First();
            var sorted = entries
                .OrderBy(entry => entry.TargetReference)
                .ThenBy(entry => entry.PathLength)
                .ThenBy(entry => entry.Edge.Id, StringComparer.Ordinal)
                .ToArray();
            var assignedSlotCoordinates = ElkBoundarySlots.BuildAssignedBoundarySlotCoordinates(
                sourceNode,
                side,
                sorted.Select(entry => entry.TargetReference).ToArray());
            var desiredCoordinateByEdgeId = new Dictionary<string, double>(StringComparer.Ordinal);
            var anchorDepartureAxis = TryExtractSourceDepartureRun(anchor.Path, side, out _, out var anchorRunEndIndex)
                ? side is "left" or "right"
                    ? anchor.Path[anchorRunEndIndex].X
                    : anchor.Path[anchorRunEndIndex].Y
                : side switch
                {
                    "left" => sourceNode.X - 24d,
                    "right" => sourceNode.X + sourceNode.Width + 24d,
                    "top" => sourceNode.Y - 24d,
                    "bottom" => sourceNode.Y + sourceNode.Height + 24d,
                    _ => 0d,
                };
            var desiredAxisByEdgeId = new Dictionary<string, double>(StringComparer.Ordinal);
            for (var i = 0; i < sorted.Length; i++)
            {
                desiredCoordinateByEdgeId[sorted[i].Edge.Id] = assignedSlotCoordinates[i];
                desiredAxisByEdgeId[sorted[i].Edge.Id] = slotOnlyRepair
                    ? TryExtractSourceDepartureRun(sorted[i].Path, side, out _, out var sortedRunEndIndex)
                        ? side is "left" or "right"
                            ? sorted[i].Path[sortedRunEndIndex].X
                            : sorted[i].Path[sortedRunEndIndex].Y
                        : anchorDepartureAxis
                    : anchorDepartureAxis;
            }

            foreach (var entry in entries)
            {
                if (!desiredCoordinateByEdgeId.TryGetValue(entry.Edge.Id, out var slotCoordinate))
                {
                    continue;
                }
                if (!desiredAxisByEdgeId.TryGetValue(entry.Edge.Id, out var desiredAxis))
                {
                    continue;
                }

                var originalCoordinate = side is "left" or "right"
                    ? entry.Boundary.Y
                    : entry.Boundary.X;
                var originalAxis = TryExtractSourceDepartureRun(entry.Path, side, out _, out var runEndIndex)
                    ? side is "left" or "right"
                        ? entry.Path[runEndIndex].X
                        : entry.Path[runEndIndex].Y
                    : desiredAxis;
                if (Math.Abs(originalCoordinate - slotCoordinate) <= 0.5d
                    && Math.Abs(originalAxis - desiredAxis) <= 0.5d)
                {
                    continue;
                }

                var boundaryPoint = ElkBoundarySlots.BuildBoundarySlotPoint(sourceNode, side, slotCoordinate);
                if (isGatewaySource)
                {
                    var continuation = entry.Path.Count > 1 ? entry.Path[1] : entry.Path[0];
                    boundaryPoint = ElkShapeBoundaries.PreferGatewayEdgeInteriorBoundary(sourceNode, boundaryPoint, continuation);
                }

                var candidate = BuildSourceDepartureCandidatePath(
                    entry.Path,
                    sourceNode,
                    side,
                    boundaryPoint,
                    desiredAxis,
                    nodes,
                    entry.Edge.SourceNodeId,
                    entry.Edge.TargetNodeId);
                if (!PathChanged(entry.Path, candidate))
                {
                    continue;
                }

                if (isGatewaySource)
                {
                    if (!HasAcceptableGatewayBoundaryPath(candidate, nodes, entry.Edge.SourceNodeId, entry.Edge.TargetNodeId, sourceNode, fromStart: true))
                    {
                        continue;
                    }
                }
                else
                {
                    if (!HasClearBoundarySegments(candidate, nodes, entry.Edge.SourceNodeId, entry.Edge.TargetNodeId, true, 2)
                        || !HasValidBoundaryAngle(candidate[0], candidate[1], sourceNode)
                        || HasNodeObstacleCrossing(candidate, nodes, entry.Edge.SourceNodeId, entry.Edge.TargetNodeId))
                    {
                        continue;
                    }
                }

                result[entry.Index] = BuildSingleSectionEdge(entry.Edge, candidate);
            }
        }

        return result;
    }

    internal static ElkRoutedEdge[] SpreadRectTargetApproachFeederBands(
        ElkRoutedEdge[] edges,
        ElkPositionedNode[] nodes,
        double minLineClearance,
        IReadOnlyCollection<string>? restrictedEdgeIds = null)
    {
        if (edges.Length < 2 || nodes.Length == 0)
        {
            return edges;
        }

        var nodesById = nodes.ToDictionary(node => node.Id, StringComparer.Ordinal);
        var restrictedSet = restrictedEdgeIds is null
            ? null
            : restrictedEdgeIds.ToHashSet(StringComparer.Ordinal);
        var result = edges.ToArray();
        var groups = result
            .Select((edge, index) => new
            {
                Edge = edge,
                Index = index,
                Path = ExtractFullPath(edge),
            })
            .Where(item => item.Path.Count >= 3
                && nodesById.TryGetValue(item.Edge.TargetNodeId ?? string.Empty, out var targetNode)
                && !ElkShapeBoundaries.IsGatewayShape(targetNode))
            .GroupBy(
                item =>
                {
                    var targetNode = nodesById[item.Edge.TargetNodeId ?? string.Empty];
                    var side = ResolveTargetApproachSide(item.Path, targetNode);
                    return $"{targetNode.Id}|{side}";
                },
                StringComparer.Ordinal);

        foreach (var group in groups)
        {
            var entries = group
                .Select(item =>
                {
                    var targetNode = nodesById[item.Edge.TargetNodeId ?? string.Empty];
                    var side = ResolveTargetApproachSide(item.Path, targetNode);
                    return TryExtractTargetApproachFeeder(item.Path, side, out var feeder)
                        ? new
                        {
                            item.Edge,
                            item.Index,
                            item.Path,
                            TargetNode = targetNode,
                            Side = side,
                            Feeder = feeder,
                        }
                        : null;
                })
                .Where(entry => entry is not null)
                .Select(entry => entry!)
                .ToArray();
            if (entries.Length < 2)
            {
                continue;
            }

            if (restrictedSet is not null && !entries.Any(entry => restrictedSet.Contains(entry.Edge.Id)))
            {
                continue;
            }

            var conflictNeighbors = new List<int>[entries.Length];
            for (var i = 0; i < entries.Length; i++)
            {
                conflictNeighbors[i] = [];
            }

            var hasConflict = false;
            for (var i = 0; i < entries.Length; i++)
            {
                for (var j = i + 1; j < entries.Length; j++)
                {
                    if (ElkEdgeRoutingGeometry.AreParallelAndClose(
                            entries[i].Feeder.Start,
                            entries[i].Feeder.End,
                            entries[j].Feeder.Start,
                            entries[j].Feeder.End,
                            minLineClearance))
                    {
                        hasConflict = true;
                        conflictNeighbors[i].Add(j);
                        conflictNeighbors[j].Add(i);
                    }
                }
            }

            if (!hasConflict)
            {
                continue;
            }

            var visited = new bool[entries.Length];
            for (var componentStart = 0; componentStart < entries.Length; componentStart++)
            {
                if (visited[componentStart] || conflictNeighbors[componentStart].Count == 0)
                {
                    continue;
                }

                var queue = new Queue<int>();
                var componentIndices = new List<int>();
                queue.Enqueue(componentStart);
                visited[componentStart] = true;
                while (queue.Count > 0)
                {
                    var current = queue.Dequeue();
                    componentIndices.Add(current);
                    foreach (var neighbor in conflictNeighbors[current])
                    {
                        if (visited[neighbor])
                        {
                            continue;
                        }

                        visited[neighbor] = true;
                        queue.Enqueue(neighbor);
                    }
                }

                if (componentIndices.Count < 2)
                {
                    continue;
                }

                var componentEntries = componentIndices
                    .Select(index => entries[index])
                    .ToArray();
                if (restrictedSet is not null && !componentEntries.Any(entry => restrictedSet.Contains(entry.Edge.Id)))
                {
                    continue;
                }

                var spacing = Math.Max(12d, minLineClearance + 4d);
                var sorted = componentEntries
                    .OrderBy(entry => entry.Feeder.BandCoordinate)
                    .ThenBy(entry => entry.Edge.Id, StringComparer.Ordinal)
                    .ToArray();
                var baseBand = sorted[0].Side is "left" or "top"
                    ? sorted.Max(entry => entry.Feeder.BandCoordinate)
                    : sorted.Min(entry => entry.Feeder.BandCoordinate);

                for (var i = 0; i < sorted.Length; i++)
                {
                    var desiredBand = ResolveDesiredTargetApproachAxis(
                        sorted[i].TargetNode,
                        sorted[i].Side,
                        baseBand,
                        spacing,
                        i,
                        forceOutwardFromBoundary: true);

                    if (Math.Abs(sorted[i].Feeder.BandCoordinate - desiredBand) <= 0.5d)
                    {
                        continue;
                    }

                    var candidate = RewriteTargetApproachFeederBand(sorted[i].Path, sorted[i].Side, desiredBand);
                    if (!PathChanged(sorted[i].Path, candidate)
                        || !HasClearBoundarySegments(candidate, nodes, sorted[i].Edge.SourceNodeId, sorted[i].Edge.TargetNodeId, false, 4)
                        || HasNodeObstacleCrossing(candidate, nodes, sorted[i].Edge.SourceNodeId, sorted[i].Edge.TargetNodeId))
                    {
                        continue;
                    }

                    result[sorted[i].Index] = BuildSingleSectionEdge(sorted[i].Edge, candidate);
                }
            }
        }

        return result;
    }
}