namespace StellaOps.ElkSharp;

internal static class ElkEdgeChannelGutters
{
    internal static bool ExpandVerticalCorridorGutters(
        Dictionary<string, ElkPositionedNode> positionedNodes,
        IReadOnlyCollection<ElkRoutedEdge> routedEdges,
        IReadOnlyDictionary<string, int> layersByNodeId,
        IReadOnlyDictionary<string, ElkNode> nodesById,
        double baseLayerSpacing,
        ElkLayoutDirection direction)
    {
        if (direction != ElkLayoutDirection.LeftToRight)
        {
            return false;
        }

        var boundariesByLayer = layersByNodeId
            .Where(entry => positionedNodes.ContainsKey(entry.Key))
            .GroupBy(entry => entry.Value)
            .OrderBy(group => group.Key)
            .Select(group =>
            {
                var nodes = group.Select(entry => positionedNodes[entry.Key]).ToArray();
                return new
                {
                    Layer = group.Key,
                    Boundary = new LayerBoundary(
                        nodes.Min(node => node.X),
                        nodes.Max(node => node.X + node.Width),
                        nodes.Min(node => node.Y),
                        nodes.Max(node => node.Y + node.Height)),
                };
            })
            .ToArray();
        if (boundariesByLayer.Length < 2)
        {
            return false;
        }

        var requiredBoundaryDeltas = new Dictionary<int, double>();
        for (var boundaryIndex = 0; boundaryIndex < boundariesByLayer.Length - 1; boundaryIndex++)
        {
            var current = boundariesByLayer[boundaryIndex];
            var next = boundariesByLayer[boundaryIndex + 1];
            var gap = next.Boundary.MinX - current.Boundary.MaxX;
            if (gap <= 0d)
            {
                continue;
            }

            var verticalSegments = routedEdges
                .SelectMany(edge => edge.Sections.SelectMany(section =>
                {
                    var points = new List<ElkPoint> { section.StartPoint };
                    points.AddRange(section.BendPoints);
                    points.Add(section.EndPoint);
                    return points.Zip(points.Skip(1), (start, end) => new
                    {
                        Edge = edge,
                        Start = start,
                        End = end,
                    });
                }))
                .Where(segment =>
                    Math.Abs(segment.Start.X - segment.End.X) <= 0.01d
                    && Math.Abs(segment.End.Y - segment.Start.Y) >= 36d
                    && segment.Start.X > current.Boundary.MaxX + 8d
                    && segment.Start.X < next.Boundary.MinX - 8d)
                .ToArray();
            var laneCount = verticalSegments
                .Select(segment => Math.Round(segment.Start.X / 12d) * 12d)
                .Distinct()
                .Count();
            if (laneCount == 0)
            {
                continue;
            }

            var familyCount = verticalSegments
                .Select(segment => ElkEdgeChannelBands.ResolveLaneFamilyKey(segment.Edge.Label))
                .Distinct(StringComparer.Ordinal)
                .Count();
            var desiredGap = Math.Max(
                baseLayerSpacing + 88d,
                136d + (laneCount * 28d) + (Math.Max(0, familyCount - 1) * 24d));
            if (gap >= desiredGap)
            {
                continue;
            }

            requiredBoundaryDeltas[current.Layer] = desiredGap - gap;
        }

        if (requiredBoundaryDeltas.Count == 0)
        {
            return false;
        }

        foreach (var nodeId in positionedNodes.Keys.ToArray())
        {
            if (!layersByNodeId.TryGetValue(nodeId, out var nodeLayer))
            {
                continue;
            }

            var shiftX = requiredBoundaryDeltas
                .Where(entry => nodeLayer > entry.Key)
                .Sum(entry => entry.Value);
            if (shiftX <= 0.01d)
            {
                continue;
            }

            var current = positionedNodes[nodeId];
            positionedNodes[nodeId] = ElkLayoutHelpers.CreatePositionedNode(nodesById[nodeId], current.X + shiftX, current.Y, direction);
        }

        return true;
    }

    internal static bool CompactSparseVerticalCorridorGutters(
        Dictionary<string, ElkPositionedNode> positionedNodes,
        IReadOnlyCollection<ElkRoutedEdge> routedEdges,
        IReadOnlyDictionary<string, int> layersByNodeId,
        IReadOnlyDictionary<string, ElkNode> nodesById,
        double baseLayerSpacing,
        ElkLayoutDirection direction)
    {
        if (direction != ElkLayoutDirection.LeftToRight)
        {
            return false;
        }

        var boundariesByLayer = layersByNodeId
            .Where(entry => positionedNodes.ContainsKey(entry.Key))
            .GroupBy(entry => entry.Value)
            .OrderBy(group => group.Key)
            .Select(group =>
            {
                var nodes = group.Select(entry => positionedNodes[entry.Key]).ToArray();
                return new
                {
                    Layer = group.Key,
                    Boundary = new LayerBoundary(
                        nodes.Min(node => node.X),
                        nodes.Max(node => node.X + node.Width),
                        nodes.Min(node => node.Y),
                        nodes.Max(node => node.Y + node.Height)),
                };
            })
            .ToArray();
        if (boundariesByLayer.Length < 2)
        {
            return false;
        }

        var boundaryShifts = new Dictionary<int, double>();
        for (var boundaryIndex = 0; boundaryIndex < boundariesByLayer.Length - 1; boundaryIndex++)
        {
            var current = boundariesByLayer[boundaryIndex];
            var next = boundariesByLayer[boundaryIndex + 1];
            var gap = next.Boundary.MinX - current.Boundary.MaxX;
            if (gap <= 0d)
            {
                continue;
            }

            var verticalSegments = routedEdges
                .SelectMany(edge => edge.Sections.SelectMany(section =>
                {
                    var points = new List<ElkPoint> { section.StartPoint };
                    points.AddRange(section.BendPoints);
                    points.Add(section.EndPoint);
                    return points.Zip(points.Skip(1), (start, end) => new
                    {
                        Edge = edge,
                        Start = start,
                        End = end,
                    });
                }))
                .Where(segment =>
                    Math.Abs(segment.Start.X - segment.End.X) <= 0.01d
                    && Math.Abs(segment.End.Y - segment.Start.Y) >= 36d
                    && segment.Start.X > current.Boundary.MaxX + 8d
                    && segment.Start.X < next.Boundary.MinX - 8d)
                .ToArray();
            var laneCount = verticalSegments
                .Select(segment => Math.Round(segment.Start.X / 12d) * 12d)
                .Distinct()
                .Count();
            var familyCount = verticalSegments
                .Select(segment => ElkEdgeChannelBands.ResolveLaneFamilyKey(segment.Edge.Label))
                .Distinct(StringComparer.Ordinal)
                .Count();

            var desiredGap = Math.Max(
                baseLayerSpacing * 0.72d,
                120d + (laneCount * 20d) + (Math.Max(0, familyCount - 1) * 16d));
            var maxGap = desiredGap + 28d;
            if (gap <= maxGap)
            {
                continue;
            }

            boundaryShifts[current.Layer] = desiredGap - gap;
        }

        if (boundaryShifts.Count == 0)
        {
            return false;
        }

        foreach (var nodeId in positionedNodes.Keys.ToArray())
        {
            if (!layersByNodeId.TryGetValue(nodeId, out var nodeLayer))
            {
                continue;
            }

            var shiftX = boundaryShifts
                .Where(entry => nodeLayer > entry.Key)
                .Sum(entry => entry.Value);
            if (Math.Abs(shiftX) <= 0.01d)
            {
                continue;
            }

            var current = positionedNodes[nodeId];
            positionedNodes[nodeId] = ElkLayoutHelpers.CreatePositionedNode(nodesById[nodeId], current.X + shiftX, current.Y, direction);
        }

        return true;
    }
}