import 'dart:math' as math;

import 'package:flutter/material.dart';

import '../../../models/network/network_device.dart';
import '../../../models/network/topology_graph.dart';
import '../layout/sugiyama_layout.dart';
import 'device_node.dart';

/// Pan + zoom topology canvas with Sugiyama-layered layout, M3-styled edges,
/// line-crossing jumps, port labels, multi-layer Bézier routing, and animated
/// transitions between view modes.
///
/// Layout pipeline:
///   1. On graph/viewMode change, [computeSugiyamaLayout] produces node
///      positions and edge waypoints. Positions are saved as a "target."
///   2. An [AnimationController] interpolates from the previous positions to
///      the target over 600ms with [Curves.easeInOutCubicEmphasized].
///   3. Each frame during the transition, edge geometries and line-jump
///      crossing points are recomputed from the interpolated positions.
///      O(E²) per frame is acceptable for ≤500 edges.
///
/// Rendering:
///   * Edges with no waypoints (single-layer span) draw as straight lines.
///   * Edges with waypoints (multi-layer span) draw as sequential quadratic
///     Bézier curves passing through each waypoint. The virtual nodes
///     informing those waypoints are never drawn as visible widgets.
///   * Line-jump arcs at crossings apply only to straight segments.
///
/// Performance:
///   * Hover state on two [ValueNotifier]s; the painter is wrapped in a
///     [RepaintBoundary] so hover only repaints the painter, not the widget
///     tree.
///   * Pan/zoom is pure Matrix4 transform via [InteractiveViewer]; no rebuild.
class TopologyCanvas extends StatefulWidget {
  const TopologyCanvas({
    super.key,
    required this.graph,
    required this.viewMode,
    this.selectedDeviceId,
    this.onDeviceTap,
  });

  final TopologyGraph graph;
  final TopologyViewMode viewMode;
  final String? selectedDeviceId;
  final void Function(NetworkDevice device)? onDeviceTap;

  @override
  State<TopologyCanvas> createState() => _TopologyCanvasState();
}

class _TopologyCanvasState extends State<TopologyCanvas>
    with SingleTickerProviderStateMixin {
  // ─── Hover state ─────────────────────────────────────────────────────────
  final ValueNotifier<String?> _hoveredEdgeId = ValueNotifier<String?>(null);
  final ValueNotifier<String?> _hoveredDeviceId = ValueNotifier<String?>(null);

  // ─── Animation ───────────────────────────────────────────────────────────
  late AnimationController _layoutAnim;

  // ─── Layout snapshots (for interpolation) ────────────────────────────────
  Map<String, Offset> _prevPositions = const {};
  Map<String, Offset> _targetPositions = const {};
  Map<String, List<Offset>> _prevWaypoints = const {};
  Map<String, List<Offset>> _targetWaypoints = const {};
  Size _canvasSize = const Size(600, 400);
  Map<String, List<String>> _deviceToEdges = const {};

  // ─── Constants ───────────────────────────────────────────────────────────
  static const Size _nodeSize = Size(160, 110);
  static const double _hitTolerance = 8;
  static const double _jumpRadius = 6;

  @override
  void initState() {
    super.initState();
    _layoutAnim = AnimationController(
      vsync: this,
      duration: const Duration(milliseconds: 600),
    );
    _runLayout(animate: false);
  }

  @override
  void didUpdateWidget(covariant TopologyCanvas oldWidget) {
    super.didUpdateWidget(oldWidget);
    if (!identical(oldWidget.graph, widget.graph) ||
        oldWidget.viewMode != widget.viewMode) {
      _runLayout(animate: true);
    }
  }

  @override
  void dispose() {
    _hoveredEdgeId.dispose();
    _hoveredDeviceId.dispose();
    _layoutAnim.dispose();
    super.dispose();
  }

  // ─── Layout orchestration ────────────────────────────────────────────────

  void _runLayout({required bool animate}) {
    // Snapshot current interpolated positions BEFORE recomputing target.
    final newPrev = animate
        ? Map<String, Offset>.from(_currentPositions())
        : <String, Offset>{};
    final newPrevWaypoints = animate
        ? Map<String, List<Offset>>.from(_currentWaypoints())
        : <String, List<Offset>>{};

    final input = _buildSugiyamaInput();
    final result = computeSugiyamaLayout(input);

    setState(() {
      _prevPositions = newPrev.isEmpty ? result.nodePositions : newPrev;
      _targetPositions = result.nodePositions;
      _prevWaypoints =
          newPrevWaypoints.isEmpty ? result.edgeWaypoints : newPrevWaypoints;
      _targetWaypoints = result.edgeWaypoints;
      _canvasSize = result.canvasSize;
      _deviceToEdges = _computeDeviceEdgeMap();
    });

    if (animate) {
      _layoutAnim.value = 0;
      _layoutAnim.forward();
    } else {
      _layoutAnim.value = 1.0;
    }
  }

  SugiyamaInput _buildSugiyamaInput() {
    final nodeIds = widget.graph.nodes.map((n) => n.device.id).toList();
    final edges = widget.graph.edges
        .map((e) => SugiyamaEdge(
              id: e.link.id,
              from: e.fromDeviceId,
              to: e.toDeviceId,
            ))
        .toList();

    Map<String, int>? preassigned;
    if (widget.viewMode == TopologyViewMode.logical) {
      preassigned = {};
      for (final node in widget.graph.nodes) {
        final role = node.device.role;
        if (role != null) {
          preassigned[node.device.id] = _roleToLayer(role);
        }
      }
    }
    // Physical view: no preassignment; the algorithm derives layers from
    // graph structure via longest-path. We could supply location depth as a
    // hint here in a future iteration.

    return SugiyamaInput(
      nodeIds: nodeIds,
      edges: edges,
      preassignedLayers: preassigned,
      // Sizes default for now; future: pass per-device width if cards become
      // variable-width.
    );
  }

  int _roleToLayer(NetworkDeviceRole role) {
    switch (role) {
      case NetworkDeviceRole.core:
        return 0;
      case NetworkDeviceRole.distribution:
        return 1;
      case NetworkDeviceRole.access:
        return 2;
      case NetworkDeviceRole.edge:
        return 3;
      case NetworkDeviceRole.endpoint:
        return 4;
    }
  }

  // ─── Interpolation ───────────────────────────────────────────────────────

  /// Node positions at the current animation `t`. Linearly interpolates between
  /// previous and target positions. Nodes that newly appeared use target as
  /// both endpoints (they pop in place).
  Map<String, Offset> _currentPositions() {
    final t = _layoutAnim.value;
    if (t >= 1.0) return _targetPositions;
    if (t <= 0.0) return _prevPositions.isEmpty ? _targetPositions : _prevPositions;
    final out = <String, Offset>{};
    for (final entry in _targetPositions.entries) {
      final target = entry.value;
      final prev = _prevPositions[entry.key] ?? target;
      out[entry.key] = Offset.lerp(prev, target, t)!;
    }
    return out;
  }

  /// Edge waypoints at the current animation `t`. Lerps element-wise when the
  /// previous and target waypoint lists have the same length; otherwise
  /// snaps to target (the rare case of an edge going from N-layer to M-layer).
  Map<String, List<Offset>> _currentWaypoints() {
    final t = _layoutAnim.value;
    if (t >= 1.0) return _targetWaypoints;
    if (t <= 0.0) return _prevWaypoints.isEmpty ? _targetWaypoints : _prevWaypoints;
    final out = <String, List<Offset>>{};
    for (final entry in _targetWaypoints.entries) {
      final target = entry.value;
      final prev = _prevWaypoints[entry.key];
      if (prev == null || prev.length != target.length) {
        out[entry.key] = target;
        continue;
      }
      out[entry.key] = [
        for (var i = 0; i < target.length; i++)
          Offset.lerp(prev[i], target[i], t)!,
      ];
    }
    return out;
  }

  Map<String, List<String>> _computeDeviceEdgeMap() {
    final map = <String, List<String>>{};
    for (final edge in widget.graph.edges) {
      map.putIfAbsent(edge.fromDeviceId, () => []).add(edge.link.id);
      map.putIfAbsent(edge.toDeviceId, () => []).add(edge.link.id);
    }
    return map;
  }

  // ─── Edge geometry ───────────────────────────────────────────────────────

  List<_EdgeGeometry> _buildEdgeGeometries(
    Map<String, Offset> positions,
    Map<String, List<Offset>> waypoints,
  ) {
    final out = <_EdgeGeometry>[];
    for (final edge in widget.graph.edges) {
      final fromTopLeft = positions[edge.fromDeviceId];
      final toTopLeft = positions[edge.toDeviceId];
      if (fromTopLeft == null || toTopLeft == null) continue;

      final fromCenter = Offset(
        fromTopLeft.dx + _nodeSize.width / 2,
        fromTopLeft.dy + _nodeSize.height / 2,
      );
      final toCenter = Offset(
        toTopLeft.dx + _nodeSize.width / 2,
        toTopLeft.dy + _nodeSize.height / 2,
      );

      // For edges with waypoints (multi-layer), exit points face the first/last
      // waypoint rather than the other endpoint, so the curve enters/exits the
      // card cleanly.
      final wps = waypoints[edge.link.id] ?? const <Offset>[];
      final firstAimAt = wps.isNotEmpty ? wps.first : toCenter;
      final lastAimAt = wps.isNotEmpty ? wps.last : fromCenter;
      final fromSide = _sideFacing(fromCenter, firstAimAt);
      final toSide = _sideFacing(toCenter, lastAimAt);
      final fromExit = _sideMidpoint(fromTopLeft, fromSide);
      final toExit = _sideMidpoint(toTopLeft, toSide);

      out.add(_EdgeGeometry(
        edgeId: edge.link.id,
        fromDeviceId: edge.fromDeviceId,
        toDeviceId: edge.toDeviceId,
        fromPortLabel: edge.fromPortLabel,
        toPortLabel: edge.toPortLabel,
        fromExit: fromExit,
        toExit: toExit,
        fromSide: fromSide,
        toSide: toSide,
        waypoints: wps,
      ));
    }
    return out;
  }

  _CardSide _sideFacing(Offset from, Offset to) {
    final dx = to.dx - from.dx;
    final dy = to.dy - from.dy;
    final aspectRatio = _nodeSize.width / _nodeSize.height;
    if (dx.abs() * aspectRatio > dy.abs()) {
      return dx >= 0 ? _CardSide.right : _CardSide.left;
    }
    return dy >= 0 ? _CardSide.bottom : _CardSide.top;
  }

  Offset _sideMidpoint(Offset topLeft, _CardSide side) {
    switch (side) {
      case _CardSide.left:
        return Offset(topLeft.dx, topLeft.dy + _nodeSize.height / 2);
      case _CardSide.right:
        return Offset(
            topLeft.dx + _nodeSize.width, topLeft.dy + _nodeSize.height / 2);
      case _CardSide.top:
        return Offset(topLeft.dx + _nodeSize.width / 2, topLeft.dy);
      case _CardSide.bottom:
        return Offset(
            topLeft.dx + _nodeSize.width / 2, topLeft.dy + _nodeSize.height);
    }
  }

  /// Line-jump arcs at crossings between *straight* edges. Curved (waypoint-
  /// bearing) edges don't participate — they already route around obstacles
  /// by going through their virtual-node waypoints.
  void _computeLineJumps(List<_EdgeGeometry> geos) {
    for (var i = 0; i < geos.length; i++) {
      geos[i].jumpPoints.clear();
    }
    for (var i = 0; i < geos.length; i++) {
      final a = geos[i];
      if (a.waypoints.isNotEmpty) continue;
      for (var j = i + 1; j < geos.length; j++) {
        final b = geos[j];
        if (b.waypoints.isNotEmpty) continue;
        if (_sharesDevice(a, b)) continue;
        final hit = _segmentIntersection(a.fromExit, a.toExit, b.fromExit, b.toExit);
        if (hit != null) b.jumpPoints.add(hit);
      }
    }
    for (final geo in geos) {
      if (geo.jumpPoints.isEmpty) continue;
      geo.jumpPoints.sort((p1, p2) {
        final d1 = (p1 - geo.fromExit).distanceSquared;
        final d2 = (p2 - geo.fromExit).distanceSquared;
        return d1.compareTo(d2);
      });
    }
  }

  bool _sharesDevice(_EdgeGeometry a, _EdgeGeometry b) {
    return a.fromDeviceId == b.fromDeviceId ||
        a.fromDeviceId == b.toDeviceId ||
        a.toDeviceId == b.fromDeviceId ||
        a.toDeviceId == b.toDeviceId;
  }

  Offset? _segmentIntersection(Offset p1, Offset p2, Offset p3, Offset p4) {
    final s1x = p2.dx - p1.dx;
    final s1y = p2.dy - p1.dy;
    final s2x = p4.dx - p3.dx;
    final s2y = p4.dy - p3.dy;
    final denom = -s2x * s1y + s1x * s2y;
    if (denom.abs() < 1e-6) return null;
    final s = (-s1y * (p1.dx - p3.dx) + s1x * (p1.dy - p3.dy)) / denom;
    final t = (s2x * (p1.dy - p3.dy) - s2y * (p1.dx - p3.dx)) / denom;
    if (s >= 0 && s <= 1 && t >= 0 && t <= 1) {
      return Offset(p1.dx + t * s1x, p1.dy + t * s1y);
    }
    return null;
  }

  String? _hitTestEdge(Offset localPos, List<_EdgeGeometry> geos) {
    String? bestId;
    double bestDist = _hitTolerance;
    for (final geo in geos) {
      // For curved edges, sample the Bézier path and use the nearest sample.
      // For straight edges, distance to segment.
      final d = geo.waypoints.isEmpty
          ? _distanceToSegment(localPos, geo.fromExit, geo.toExit)
          : _distanceToCurve(localPos, geo);
      if (d < bestDist) {
        bestDist = d;
        bestId = geo.edgeId;
      }
    }
    return bestId;
  }

  double _distanceToSegment(Offset p, Offset a, Offset b) {
    final ax = a.dx, ay = a.dy, bx = b.dx, by = b.dy;
    final dx = bx - ax;
    final dy = by - ay;
    final lenSq = dx * dx + dy * dy;
    if (lenSq < 1e-6) return (p - a).distance;
    var t = ((p.dx - ax) * dx + (p.dy - ay) * dy) / lenSq;
    t = t.clamp(0.0, 1.0);
    return (p - Offset(ax + t * dx, ay + t * dy)).distance;
  }

  /// Approximate distance to a Bézier curve by sampling segments between the
  /// path control points (fromExit, waypoints..., toExit) and taking the min
  /// segment distance. Coarse but cheap.
  double _distanceToCurve(Offset p, _EdgeGeometry geo) {
    final pts = <Offset>[geo.fromExit, ...geo.waypoints, geo.toExit];
    var best = double.infinity;
    for (var i = 0; i < pts.length - 1; i++) {
      final d = _distanceToSegment(p, pts[i], pts[i + 1]);
      if (d < best) best = d;
    }
    return best;
  }

  // ─── Build ───────────────────────────────────────────────────────────────

  @override
  Widget build(BuildContext context) {
    final cs = Theme.of(context).colorScheme;

    if (widget.graph.isEmpty) {
      return Center(
        child: Padding(
          padding: const EdgeInsets.all(32),
          child: Column(
            mainAxisSize: MainAxisSize.min,
            children: [
              Icon(Icons.hub_outlined, size: 56, color: cs.onSurfaceVariant),
              const SizedBox(height: 12),
              Text(
                'No devices in this view yet',
                style: Theme.of(context).textTheme.titleMedium,
              ),
              const SizedBox(height: 4),
              Text(
                'Import a document or add devices manually.',
                style: Theme.of(context).textTheme.bodyMedium?.copyWith(
                      color: cs.onSurfaceVariant,
                    ),
              ),
            ],
          ),
        ),
      );
    }

    return InteractiveViewer(
      constrained: false,
      minScale: 0.2,
      maxScale: 2.5,
      boundaryMargin: const EdgeInsets.all(200),
      child: AnimatedBuilder(
        animation: _layoutAnim,
        builder: (context, _) {
          final positions = _currentPositions();
          final waypoints = _currentWaypoints();
          final edgeGeos = _buildEdgeGeometries(positions, waypoints);
          _computeLineJumps(edgeGeos);

          return SizedBox(
            width: _canvasSize.width,
            height: _canvasSize.height,
            child: MouseRegion(
              onHover: (event) {
                final hit = _hitTestEdge(event.localPosition, edgeGeos);
                if (hit != _hoveredEdgeId.value) {
                  _hoveredEdgeId.value = hit;
                }
              },
              onExit: (_) => _hoveredEdgeId.value = null,
              child: Stack(
                children: [
                  // Painter — repaints on hover via inner AnimatedBuilder.
                  Positioned.fill(
                    child: RepaintBoundary(
                      child: AnimatedBuilder(
                        animation: _hoveredEdgeId,
                        builder: (_, _) {
                          return CustomPaint(
                            painter: _CanvasPainter(
                              edgeGeos: edgeGeos,
                              jumpRadius: _jumpRadius,
                              hoveredEdgeId: _hoveredEdgeId.value,
                              theme: _CanvasTheme.from(Theme.of(context)),
                            ),
                          );
                        },
                      ),
                    ),
                  ),
                  // Devices on top, hover-aware.
                  for (final node in widget.graph.nodes)
                    if (positions[node.device.id] != null)
                      Positioned(
                        left: positions[node.device.id]!.dx,
                        top: positions[node.device.id]!.dy,
                        child: _HoverAwareDevice(
                          node: node,
                          selectedId: widget.selectedDeviceId,
                          hoveredEdgeId: _hoveredEdgeId,
                          hoveredDeviceId: _hoveredDeviceId,
                          connectedEdgeIds:
                              _deviceToEdges[node.device.id] ?? const [],
                          onTap: widget.onDeviceTap,
                        ),
                      ),
                ],
              ),
            ),
          );
        },
      ),
    );
  }
}

enum _CardSide { left, right, top, bottom }

class _EdgeGeometry {
  _EdgeGeometry({
    required this.edgeId,
    required this.fromDeviceId,
    required this.toDeviceId,
    required this.fromPortLabel,
    required this.toPortLabel,
    required this.fromExit,
    required this.toExit,
    required this.fromSide,
    required this.toSide,
    required this.waypoints,
  });

  final String edgeId;
  final String fromDeviceId;
  final String toDeviceId;
  final String fromPortLabel;
  final String toPortLabel;
  final Offset fromExit;
  final Offset toExit;
  final _CardSide fromSide;
  final _CardSide toSide;

  /// Intermediate points the edge passes through. Empty for single-layer
  /// edges (drawn as straight lines). Non-empty for multi-layer edges (drawn
  /// as sequential quadratic Béziers through these points).
  final List<Offset> waypoints;

  /// Line-jump points along the *main* segment. Only populated for straight
  /// edges (curved/waypoint edges skip line jumps).
  final List<Offset> jumpPoints = [];
}

// ─── Theme snapshot ────────────────────────────────────────────────────────

class _CanvasTheme {
  const _CanvasTheme({
    required this.defaultEdgeColor,
    required this.hoverEdgeColor,
    required this.chipBg,
    required this.chipHoverBg,
    required this.chipBorder,
    required this.chipHoverBorder,
    required this.chipText,
    required this.chipHoverText,
  });

  factory _CanvasTheme.from(ThemeData theme) {
    final cs = theme.colorScheme;
    return _CanvasTheme(
      defaultEdgeColor: cs.outline.withValues(alpha: 0.75),
      hoverEdgeColor: cs.primary,
      chipBg: cs.surfaceContainerHigh.withValues(alpha: 0.95),
      chipHoverBg: cs.primaryContainer,
      chipBorder: cs.outlineVariant.withValues(alpha: 0.7),
      chipHoverBorder: cs.primary,
      chipText: cs.onSurfaceVariant,
      chipHoverText: cs.onPrimaryContainer,
    );
  }

  final Color defaultEdgeColor;
  final Color hoverEdgeColor;
  final Color chipBg;
  final Color chipHoverBg;
  final Color chipBorder;
  final Color chipHoverBorder;
  final Color chipText;
  final Color chipHoverText;
}

// ─── Painter ───────────────────────────────────────────────────────────────

class _CanvasPainter extends CustomPainter {
  _CanvasPainter({
    required this.edgeGeos,
    required this.jumpRadius,
    required this.hoveredEdgeId,
    required this.theme,
  });

  final List<_EdgeGeometry> edgeGeos;
  final double jumpRadius;
  final String? hoveredEdgeId;
  final _CanvasTheme theme;

  @override
  void paint(Canvas canvas, Size size) {
    for (final geo in edgeGeos) {
      if (geo.edgeId == hoveredEdgeId) continue;
      _drawEdge(canvas, geo, hovered: false);
    }
    for (final geo in edgeGeos) {
      if (geo.edgeId != hoveredEdgeId) continue;
      _drawEdge(canvas, geo, hovered: true);
    }
    for (final geo in edgeGeos) {
      if (geo.edgeId == hoveredEdgeId) continue;
      _drawChips(canvas, geo, hovered: false);
    }
    for (final geo in edgeGeos) {
      if (geo.edgeId != hoveredEdgeId) continue;
      _drawChips(canvas, geo, hovered: true);
    }
  }

  void _drawEdge(Canvas canvas, _EdgeGeometry geo, {required bool hovered}) {
    final color = hovered ? theme.hoverEdgeColor : theme.defaultEdgeColor;
    final strokeWidth = hovered ? 2.5 : 1.4;
    final paint = Paint()
      ..color = color
      ..strokeWidth = strokeWidth
      ..strokeCap = StrokeCap.round
      ..style = PaintingStyle.stroke;

    if (geo.waypoints.isNotEmpty) {
      _drawCurvedEdge(canvas, geo, paint);
    } else {
      _drawStraightEdge(canvas, geo, paint);
    }

    // Endpoint plug dots.
    final dotPaint = Paint()..color = color..style = PaintingStyle.fill;
    final radius = hovered ? 4.0 : 3.0;
    canvas.drawCircle(geo.fromExit, radius, dotPaint);
    canvas.drawCircle(geo.toExit, radius, dotPaint);
  }

  void _drawStraightEdge(Canvas canvas, _EdgeGeometry geo, Paint paint) {
    final dx = geo.toExit.dx - geo.fromExit.dx;
    final dy = geo.toExit.dy - geo.fromExit.dy;
    final len = math.sqrt(dx * dx + dy * dy);
    if (len < 1) return;
    final ux = dx / len;
    final uy = dy / len;

    final path = Path()..moveTo(geo.fromExit.dx, geo.fromExit.dy);
    for (final jump in geo.jumpPoints) {
      final beforeX = jump.dx - ux * jumpRadius;
      final beforeY = jump.dy - uy * jumpRadius;
      final afterX = jump.dx + ux * jumpRadius;
      final afterY = jump.dy + uy * jumpRadius;
      path.lineTo(beforeX, beforeY);
      path.arcToPoint(
        Offset(afterX, afterY),
        radius: Radius.circular(jumpRadius),
        clockwise: false,
      );
    }
    path.lineTo(geo.toExit.dx, geo.toExit.dy);
    canvas.drawPath(path, paint);
  }

  /// Render an edge through its waypoints as sequential quadratic Bézier
  /// curves. The control point for each segment is the waypoint itself,
  /// with each segment's anchor being the midpoint between consecutive
  /// waypoints. This produces a smooth C1-continuous curve passing AT each
  /// waypoint, mimicking what the eye expects from "a cable bending through
  /// multiple connection points."
  void _drawCurvedEdge(Canvas canvas, _EdgeGeometry geo, Paint paint) {
    final pts = <Offset>[geo.fromExit, ...geo.waypoints, geo.toExit];
    final path = Path()..moveTo(pts.first.dx, pts.first.dy);

    if (pts.length == 2) {
      path.lineTo(pts.last.dx, pts.last.dy);
      canvas.drawPath(path, paint);
      return;
    }
    // For each intermediate waypoint, draw a quadratic Bézier from the
    // previous-anchor to the next-anchor, with this waypoint as the control.
    // First anchor: midpoint between pts[0] and pts[1]. Last anchor: midpoint
    // between pts[n-2] and pts[n-1]. This produces a smooth curve passing
    // through every waypoint.
    var anchor = Offset(
      (pts[0].dx + pts[1].dx) / 2,
      (pts[0].dy + pts[1].dy) / 2,
    );
    path.lineTo(anchor.dx, anchor.dy);
    for (var i = 1; i < pts.length - 1; i++) {
      final nextAnchor = Offset(
        (pts[i].dx + pts[i + 1].dx) / 2,
        (pts[i].dy + pts[i + 1].dy) / 2,
      );
      path.quadraticBezierTo(pts[i].dx, pts[i].dy, nextAnchor.dx, nextAnchor.dy);
      anchor = nextAnchor;
    }
    path.lineTo(pts.last.dx, pts.last.dy);
    canvas.drawPath(path, paint);
  }

  void _drawChips(Canvas canvas, _EdgeGeometry geo, {required bool hovered}) {
    _drawChip(
      canvas,
      anchor: geo.fromExit,
      side: geo.fromSide,
      label: geo.fromPortLabel,
      hovered: hovered,
    );
    _drawChip(
      canvas,
      anchor: geo.toExit,
      side: geo.toSide,
      label: geo.toPortLabel,
      hovered: hovered,
    );
  }

  void _drawChip(
    Canvas canvas, {
    required Offset anchor,
    required _CardSide side,
    required String label,
    required bool hovered,
  }) {
    if (label.isEmpty) return;
    final tp = TextPainter(
      text: TextSpan(
        text: label,
        style: TextStyle(
          fontSize: 10,
          fontWeight: FontWeight.w500,
          color: hovered ? theme.chipHoverText : theme.chipText,
          fontFeatures: const [FontFeature.tabularFigures()],
        ),
      ),
      textDirection: TextDirection.ltr,
      maxLines: 1,
      ellipsis: '…',
    )..layout(maxWidth: 100);

    const padH = 6.0;
    const padV = 2.0;
    final chipW = tp.width + padH * 2;
    final chipH = tp.height + padV * 2;

    const gap = 6.0;
    Offset chipTopLeft;
    switch (side) {
      case _CardSide.left:
        chipTopLeft = Offset(anchor.dx - gap - chipW, anchor.dy - chipH / 2);
        break;
      case _CardSide.right:
        chipTopLeft = Offset(anchor.dx + gap, anchor.dy - chipH / 2);
        break;
      case _CardSide.top:
        chipTopLeft = Offset(anchor.dx - chipW / 2, anchor.dy - gap - chipH);
        break;
      case _CardSide.bottom:
        chipTopLeft = Offset(anchor.dx - chipW / 2, anchor.dy + gap);
        break;
    }

    final rect = Rect.fromLTWH(chipTopLeft.dx, chipTopLeft.dy, chipW, chipH);
    final rrect = RRect.fromRectAndRadius(rect, const Radius.circular(6));

    final bgPaint = Paint()
      ..color = hovered ? theme.chipHoverBg : theme.chipBg
      ..style = PaintingStyle.fill;
    canvas.drawRRect(rrect, bgPaint);

    final borderPaint = Paint()
      ..color = hovered ? theme.chipHoverBorder : theme.chipBorder
      ..style = PaintingStyle.stroke
      ..strokeWidth = hovered ? 1.2 : 0.7;
    canvas.drawRRect(rrect, borderPaint);

    tp.paint(canvas, Offset(chipTopLeft.dx + padH, chipTopLeft.dy + padV));
  }

  @override
  bool shouldRepaint(covariant _CanvasPainter old) {
    return old.edgeGeos != edgeGeos ||
        old.hoveredEdgeId != hoveredEdgeId ||
        old.theme.defaultEdgeColor != theme.defaultEdgeColor;
  }
}

// ─── Hover-aware device ───────────────────────────────────────────────────

class _HoverAwareDevice extends StatelessWidget {
  const _HoverAwareDevice({
    required this.node,
    required this.selectedId,
    required this.hoveredEdgeId,
    required this.hoveredDeviceId,
    required this.connectedEdgeIds,
    required this.onTap,
  });

  final TopologyNode node;
  final String? selectedId;
  final ValueNotifier<String?> hoveredEdgeId;
  final ValueNotifier<String?> hoveredDeviceId;
  final List<String> connectedEdgeIds;
  final void Function(NetworkDevice device)? onTap;

  @override
  Widget build(BuildContext context) {
    return MouseRegion(
      onEnter: (_) => hoveredDeviceId.value = node.device.id,
      onExit: (_) {
        if (hoveredDeviceId.value == node.device.id) {
          hoveredDeviceId.value = null;
        }
      },
      child: AnimatedBuilder(
        animation: Listenable.merge([hoveredEdgeId, hoveredDeviceId]),
        builder: (_, _) {
          final isOwnHover = hoveredDeviceId.value == node.device.id;
          final isEdgeEndpoint = hoveredEdgeId.value != null &&
              connectedEdgeIds.contains(hoveredEdgeId.value);
          return DeviceNode(
            device: node.device,
            portCount: node.ports.length,
            isSelected: selectedId == node.device.id,
            isHighlighted: isOwnHover || isEdgeEndpoint,
            onTap: () => onTap?.call(node.device),
          );
        },
      ),
    );
  }
}