import 'dart:async';
import 'dart:math';

import 'package:flutter/foundation.dart';
import 'package:flutter/material.dart';
import 'package:flutter_map/flutter_map.dart';
import 'package:latlong2/latlong.dart';
import 'package:meshcore_open/connector/meshcore_connector.dart';
import 'package:meshcore_open/connector/meshcore_protocol.dart';
import 'package:meshcore_open/helpers/path_helper.dart';
import 'package:meshcore_open/l10n/l10n.dart';
import 'package:meshcore_open/models/app_settings.dart';
import 'package:meshcore_open/models/contact.dart';
import 'package:meshcore_open/services/app_settings_service.dart';
import 'package:meshcore_open/services/map_tile_cache_service.dart';
import 'package:meshcore_open/utils/app_logger.dart';
import 'package:meshcore_open/widgets/snr_indicator.dart';
import 'package:provider/provider.dart';

double getPathDistanceMeters(List<LatLng> points) {
  if (points.length <= 1) return 0.0;

  double distanceMeters = 0.0;
  final distanceCalculator = Distance();

  for (int i = 0; i < points.length - 1; i++) {
    distanceMeters += distanceCalculator(points[i], points[i + 1]);
  }

  return distanceMeters;
}

String formatDistance(double distanceMeters, {required bool isImperial}) {
  if (isImperial) {
    return '(${(distanceMeters / 1609.34).toStringAsFixed(2)} mi)';
  }
  return '(${(distanceMeters / 1000).toStringAsFixed(2)} km)';
}

class PathTraceData {
  final List<Uint8List> pathData;
  final List<double> snrData;
  final Map<String, Contact> pathContacts;

  PathTraceData({
    required this.pathData,
    required this.snrData,
    required this.pathContacts,
  });
}

String _hopKey(Uint8List hopBytes) => PathHelper.formatHopHex(hopBytes);

Uint8List _lastHopChunk(Uint8List path, int hopWidth) {
  if (path.isEmpty) return Uint8List(0);
  final width = hopWidth.clamp(1, path.length);
  return Uint8List.fromList(path.sublist(path.length - width));
}

bool _matchesHopPrefix(Uint8List a, Uint8List b) {
  if (a.isEmpty || b.isEmpty) return false;
  final width = min(a.length, b.length);
  return listEquals(a.sublist(0, width), b.sublist(0, width));
}

class PathTraceMapScreen extends StatefulWidget {
  final String title;
  final Uint8List path;
  final int? repeaterId;
  final bool flipPathAround;
  final bool reversePathAround;
  final Contact? targetContact;
  final int pathHashByteWidth;
  final List<Contact>? pathContacts;

  const PathTraceMapScreen({
    super.key,
    required this.title,
    required this.path,
    this.repeaterId,
    this.flipPathAround = false,
    this.reversePathAround = false,
    this.targetContact,
    this.pathHashByteWidth = pathHashSize,
    this.pathContacts,
  });

  @override
  State<PathTraceMapScreen> createState() => _PathTraceMapScreenState();
}

class _PathTraceMapScreenState extends State<PathTraceMapScreen> {
  static const double _labelZoomThreshold = 8.5;
  static const double _mapMinZoom = 2.0;
  static const double _mapMaxZoom = 18.0;
  //miles to meters conversion for filtering out repeaters that are too far from the last known GPS hop to be a likely match, to avoid false matches that throw off the inferred positions of other hops in the path
  static const double _maxRepeaterMatchDistanceMeters = 40 * 1609.344;

  final MapController _mapController = MapController();
  StreamSubscription<Uint8List>? _frameSubscription;
  Timer? _timeoutTimer;

  bool _isLoading = false;
  bool _failed2Loaded = false;
  bool _hasData = false;
  PathTraceData? _traceData;
  // Inferred positions for hops that have no GPS location, keyed by hop prefix.
  Map<String, LatLng> _inferredHopPositions = {};
  // Endpoint position for the target contact (GPS or guessed).
  LatLng? _targetContactPosition;
  bool _targetContactIsGuessed = false;
  List<LatLng> _points = <LatLng>[];
  List<Polyline> _polylines = [];
  LatLng? _initialCenter = LatLng(0, 0);
  double _initialZoom = 2.0;
  LatLngBounds? _bounds;
  ValueKey<String> _mapKey = const ValueKey('initial');
  double _pathDistanceMeters = 0.0;
  bool _showNodeLabels = true;
  Contact? _targetContact;
  Uint8List? _sentTagBytes;

  String _formatPathPrefixes(Uint8List pathBytes, [int? hashByteWidth]) {
    return PathHelper.splitPathBytes(
      pathBytes,
      hashByteWidth ?? widget.pathHashByteWidth,
    ).map(PathHelper.formatHopHex).join(',');
  }

  int _traceHashByteWidth(int pathHashByteWidth) {
    final width = pathHashByteWidth.clamp(1, pubKeySize).toInt();
    if (width <= 1) return 1;
    if (width == 2) return 2;
    // Trace packets encode hash width as 1 << flags, so 3-byte path hashes
    // must be traced with a 4-byte public-key prefix.
    return 4;
  }

  int _traceFlagsForHashWidth(int traceHashByteWidth) {
    if (traceHashByteWidth <= 1) return 0;
    if (traceHashByteWidth == 2) return 1;
    return 2;
  }

  Uint8List _reversePathByHop(Uint8List pathBytes, int hopWidth) {
    final reversedHops = PathHelper.splitPathBytes(
      pathBytes,
      hopWidth,
    ).reversed;
    final bytes = <int>[];
    for (final hop in reversedHops) {
      bytes.addAll(hop);
    }
    return Uint8List.fromList(bytes);
  }

  Uint8List? _expandHopForTrace(
    Uint8List hop,
    int traceHashByteWidth,
    MeshCoreConnector connector,
  ) {
    if (hop.length == traceHashByteWidth) return hop;

    final candidates = <Contact>[
      ...?widget.pathContacts,
      if (widget.targetContact != null) widget.targetContact!,
      ...connector.allContactsUnfiltered,
    ];
    for (final contact in candidates) {
      if (contact.publicKey.length < traceHashByteWidth) continue;
      if (!listEquals(contact.publicKey.sublist(0, hop.length), hop)) continue;
      return Uint8List.fromList(
        contact.publicKey.sublist(0, traceHashByteWidth),
      );
    }
    return null;
  }

  Uint8List? _tracePathFromBytes(
    Uint8List pathBytes,
    int traceHashByteWidth,
    MeshCoreConnector connector,
  ) {
    final hops = PathHelper.splitPathBytes(pathBytes, widget.pathHashByteWidth);
    final traceBytes = <int>[];
    for (final hop in hops) {
      final traceHop = _expandHopForTrace(hop, traceHashByteWidth, connector);
      if (traceHop == null) return null;
      traceBytes.addAll(traceHop);
    }
    return Uint8List.fromList(traceBytes);
  }

  @override
  void initState() {
    super.initState();
    _setupFrameListener();
    _doPathTrace();
  }

  @override
  void dispose() {
    _mapController.dispose();
    _frameSubscription?.cancel();
    _timeoutTimer?.cancel();
    super.dispose();
  }

  bool _isDesktopPlatform(TargetPlatform platform) {
    return platform == TargetPlatform.linux ||
        platform == TargetPlatform.windows ||
        platform == TargetPlatform.macOS;
  }

  void _zoomMapBy(double delta) {
    final camera = _mapController.camera;
    final nextZoom = (camera.zoom + delta)
        .clamp(_mapMinZoom, _mapMaxZoom)
        .toDouble();
    _mapController.move(camera.center, nextZoom);
  }

  void _resetMapView() {
    final bounds = _bounds;
    if (bounds != null) {
      _mapController.fitCamera(
        CameraFit.bounds(
          bounds: bounds,
          padding: const EdgeInsets.all(64),
          maxZoom: 16,
        ),
      );
      return;
    }
    final center = _initialCenter;
    if (center != null) {
      _mapController.move(center, _initialZoom);
    }
  }

  Widget _buildDesktopMapControls() {
    return Positioned(
      top: 16,
      left: 16,
      child: Card(
        elevation: 4,
        child: Column(
          mainAxisSize: MainAxisSize.min,
          children: [
            IconButton(
              icon: const Icon(Icons.add),
              tooltip: 'Zoom in',
              onPressed: () => _zoomMapBy(1),
            ),
            IconButton(
              icon: const Icon(Icons.remove),
              tooltip: 'Zoom out',
              onPressed: () => _zoomMapBy(-1),
            ),
            IconButton(
              icon: const Icon(Icons.my_location),
              tooltip: 'Center map',
              onPressed: _resetMapView,
            ),
          ],
        ),
      ),
    );
  }

  Uint8List? buildPath(
    Uint8List pathBytes,
    int traceHashByteWidth,
    MeshCoreConnector connector,
  ) {
    final pathHops = PathHelper.splitPathBytes(
      pathBytes,
      widget.pathHashByteWidth,
    );
    final hopWidth = traceHashByteWidth.clamp(1, pubKeySize).toInt();

    // Compute targetPrefix if targetContact is provided
    Uint8List? targetPrefix;
    if (widget.targetContact != null) {
      final pk = widget.targetContact!.publicKey;
      if (pk.isNotEmpty) {
        final len = pk.length >= hopWidth ? hopWidth : pk.length;
        targetPrefix = Uint8List.fromList(pk.sublist(0, len));
      }
    }

    final outboundHops = <Uint8List>[];
    for (final hop in pathHops) {
      final traceHop = _expandHopForTrace(hop, traceHashByteWidth, connector);
      if (traceHop == null) return null;
      outboundHops.add(traceHop);
    }
    if (targetPrefix != null) {
      // Check if targetPrefix is already the last hop in pathHops to avoid duplication
      bool alreadyEndedWithTarget = false;
      if (outboundHops.isNotEmpty) {
        if (listEquals(outboundHops.last, targetPrefix)) {
          alreadyEndedWithTarget = true;
        }
      }
      if (!alreadyEndedWithTarget) {
        outboundHops.add(targetPrefix);
      }
    }

    if (outboundHops.isEmpty) {
      return Uint8List(0);
    }

    final mirroredHops = <Uint8List>[...outboundHops];
    if (outboundHops.length > 1) {
      mirroredHops.addAll(
        outboundHops.sublist(0, outboundHops.length - 1).reversed,
      );
    }

    final traceBytes = <int>[];
    for (final hop in mirroredHops) {
      traceBytes.addAll(hop);
    }
    return Uint8List.fromList(traceBytes);
  }

  Future<void> _doPathTrace() async {
    if (mounted) {
      setState(() {
        _isLoading = true;
        _failed2Loaded = false;
      });
    }

    final connector = Provider.of<MeshCoreConnector>(context, listen: false);
    final traceHashByteWidth = _traceHashByteWidth(widget.pathHashByteWidth);
    final pathTmp = widget.reversePathAround
        ? _reversePathByHop(widget.path, widget.pathHashByteWidth)
        : widget.path;

    final path = widget.flipPathAround
        ? buildPath(pathTmp, traceHashByteWidth, connector)
        : _tracePathFromBytes(pathTmp, traceHashByteWidth, connector);

    if (path == null) {
      if (!mounted) return;
      setState(() {
        _isLoading = false;
        _failed2Loaded = true;
      });
      return;
    }

    appLogger.info(
      'Initiating path trace with path: '
      '${_formatPathPrefixes(path, traceHashByteWidth)}',
      tag: 'PathTraceMapScreen',
      noNotify: !mounted,
    );

    final sentTag = DateTime.now().millisecondsSinceEpoch ~/ 1000;
    _sentTagBytes = Uint8List(4)
      ..[0] = sentTag & 0xFF
      ..[1] = (sentTag >> 8) & 0xFF
      ..[2] = (sentTag >> 16) & 0xFF
      ..[3] = (sentTag >> 24) & 0xFF;

    final flags = _traceFlagsForHashWidth(traceHashByteWidth);
    final tracePayload = path.isEmpty ? Uint8List.fromList([0x00]) : path;

    final frame = buildTraceReq(
      sentTag,
      0, // auth
      flags, // flag
      payload: tracePayload,
    );
    connector.sendFrame(frame);
  }

  void _setupFrameListener() {
    final connector = Provider.of<MeshCoreConnector>(context, listen: false);
    Uint8List tagData = Uint8List(4);
    // Listen for incoming text messages from the repeater
    _frameSubscription = connector.receivedFrames.listen((frame) {
      if (frame.isEmpty) return;
      final frameBuffer = BufferReader(frame);
      try {
        final code = frameBuffer.readUInt8();

        if (code == respCodeSent) {
          frameBuffer.skipBytes(1); //reserved
          tagData = frameBuffer.readBytes(4);
          final timeoutMilliseconds = frameBuffer.readUInt32LE();

          // Start timeout timer for trace response
          _timeoutTimer?.cancel();
          _timeoutTimer = Timer(
            Duration(milliseconds: timeoutMilliseconds),
            () {
              if (!mounted) return;
              setState(() {
                _isLoading = false;
                _failed2Loaded = true;
              });
            },
          );
        }

        if (code == respCodeErr) {
          _timeoutTimer?.cancel();
          if (!mounted) return;
          setState(() {
            _isLoading = false;
            _failed2Loaded = true;
          });
        }

        // Check if it's a binary response
        if (frame.length >= 12 &&
            code == pushCodeTraceData &&
            (listEquals(frame.sublist(4, 8), _sentTagBytes) ||
                listEquals(frame.sublist(4, 8), tagData))) {
          _timeoutTimer?.cancel();
          if (!mounted) return;
          _handleTraceResponse(frame);
        }
      } catch (e) {
        _timeoutTimer?.cancel();
        if (!mounted) return;
        setState(() {
          _isLoading = false;
          _failed2Loaded = true;
        });
        // Handle any parsing errors gracefully
        appLogger.error('Error parsing frame: $e', tag: 'PathTraceMapScreen');
      }
    });
  }

  Future<void> _handleTraceResponse(Uint8List frame) async {
    final connector = Provider.of<MeshCoreConnector>(context, listen: false);

    final buffer = BufferReader(frame);
    try {
      buffer.skipBytes(2); // Skip push code and reserved byte
      final pathLenByte = buffer.readUInt8();
      final flags = buffer.readUInt8();
      buffer.skipBytes(4); // Skip tag data
      buffer.skipBytes(4); // Skip auth code
      var width = _traceHashByteWidth(1 << (flags & 0x03));
      var pathLength = pathLenByte == 0xFF ? 0 : pathLenByte;
      if (pathLength > buffer.remaining && (pathLenByte & 0xC0) != 0) {
        final packedWidth = ((pathLenByte & 0xC0) >> 6) + 1;
        final packedLength = (pathLenByte & 0x3F) * packedWidth;
        if (packedLength <= buffer.remaining) {
          width = packedWidth;
          pathLength = packedLength;
        }
      }
      final pathBytes = buffer.readBytes(pathLength);
      final pathData = PathHelper.splitPathBytes(pathBytes, width);
      List<double> snrData = buffer
          .readRemainingBytes()
          .map((snr) => snr.toSigned(8).toDouble() / 4)
          .toList();

      Map<String, Contact> pathContacts = {};
      Contact lastContact = Contact(
        path: Uint8List(0),
        pathLength: 0,
        publicKey: connector.selfPublicKey ?? Uint8List(0),
        name: context.l10n.pathTrace_you,
        type: advTypeChat,
        latitude: connector.selfLatitude,
        longitude: connector.selfLongitude,
        lastSeen: DateTime.now(),
      );
      if (widget.pathContacts != null) {
        final hopWidth = width.clamp(1, pubKeySize).toInt();
        pathContacts = {
          for (var c in widget.pathContacts!)
            if (c.publicKey.length >= hopWidth)
              _hopKey(Uint8List.fromList(c.publicKey.sublist(0, hopWidth))): c,
        };
      } else {
        final contacts = connector.allContactsUnfiltered;
        contacts.where((c) => c.type != advTypeChat).forEach((repeater) {
          if (lastContact.latitude != null &&
              lastContact.longitude != null &&
              repeater.hasLocation &&
              lastContact.hasLocation &&
              Distance().distance(
                    LatLng(lastContact.latitude!, lastContact.longitude!),
                    LatLng(repeater.latitude!, repeater.longitude!),
                  ) >
                  _maxRepeaterMatchDistanceMeters) {
            return; //skip reapeaters that are far away from the last one with known GPS, to avoid false matches
          }
          for (final repeaterData in pathData) {
            final hopWidth = repeaterData.length;
            if (repeater.publicKey.length < hopWidth) continue;
            if (listEquals(
              repeater.publicKey.sublist(0, hopWidth),
              repeaterData,
            )) {
              pathContacts[_hopKey(repeaterData)] = repeater;
              lastContact = repeater;
            }
          }
        });
      }

      // For hops with no GPS contact, infer position from other contacts
      // with known GPS that share the same last-hop byte.
      final Map<String, LatLng> inferredPositions = {};
      for (final hop in pathData) {
        final hopKey = _hopKey(hop);
        final contact = pathContacts[hopKey];
        if (contact != null && contact.hasLocation) continue;
        final peers = connector.contacts
            .where(
              (c) =>
                  c.hasLocation &&
                  c.path.isNotEmpty &&
                  _matchesHopPrefix(
                    _lastHopChunk(c.path, widget.pathHashByteWidth),
                    hop,
                  ),
            )
            .toList();
        if (peers.isNotEmpty) {
          final lat =
              peers.map((c) => c.latitude!).reduce((a, b) => a + b) /
              peers.length;
          final lon =
              peers.map((c) => c.longitude!).reduce((a, b) => a + b) /
              peers.length;
          inferredPositions[hopKey] = LatLng(lat, lon);
        }
      }

      setState(() {
        _isLoading = false;
        _hasData = true;
        _inferredHopPositions = inferredPositions;
        _traceData = PathTraceData(
          pathData: pathData,
          snrData: snrData,
          pathContacts: pathContacts,
        );
        // Compute endpoint position for the target contact.
        LatLng? targetPos;
        bool targetGuessed = false;
        _targetContact = widget.targetContact;

        if (_targetContact != null) {
          final tc = _targetContact!;
          if (tc.hasLocation) {
            targetPos = LatLng(tc.latitude!, tc.longitude!);
          } else if (pathData.length > 1) {
            // Infer from the last hop: average GPS contacts sharing that hop.
            // For a round-trip path (flipPathAround/reversePathAround), the target-side hop
            // sits in the middle of the symmetric sequence; .last is the local side.
            final lastHop = widget.reversePathAround
                ? pathData.first
                : pathData.last;
            final lastHopKey = _hopKey(lastHop);

            final peers = connector.allContacts
                .where(
                  (c) =>
                      c.hasLocation &&
                      c.path.isNotEmpty &&
                      _matchesHopPrefix(
                        _lastHopChunk(c.path, widget.pathHashByteWidth),
                        lastHop,
                      ),
                )
                .toList();
            if (peers.isNotEmpty) {
              final lat =
                  peers.map((c) => c.latitude!).reduce((a, b) => a + b) /
                  peers.length;
              final lon =
                  peers.map((c) => c.longitude!).reduce((a, b) => a + b) /
                  peers.length;
              const offsetDeg = 0.003;
              final angle = (tc.publicKey[1] / 255.0) * 2 * pi;
              targetPos = LatLng(
                lat + offsetDeg * cos(angle),
                lon + offsetDeg * sin(angle),
              );
              targetGuessed = true;
            } else if (inferredPositions.containsKey(lastHopKey)) {
              final lat = inferredPositions[lastHopKey]!.latitude;
              final lon = inferredPositions[lastHopKey]!.longitude;
              const offsetDeg = 0.003;
              final angle = (tc.publicKey[1] / 255.0) * 2 * pi;
              targetPos = LatLng(
                lat + offsetDeg * cos(angle),
                lon + offsetDeg * sin(angle),
              );
              targetGuessed = true;
            } else {
              // As a last resort, just place it at the same position as the last hop.
              final contact = pathContacts[lastHopKey];
              if (contact != null && contact.hasLocation) {
                const offsetDeg = 0.003;
                final angle = (tc.publicKey[1] / 255.0) * 2 * pi;
                targetPos = LatLng(
                  contact.latitude! + offsetDeg * cos(angle),
                  contact.longitude! + offsetDeg * sin(angle),
                );
                targetGuessed = true;
              }
            }
          }
        }
        _targetContactPosition = targetPos;
        _targetContactIsGuessed = targetGuessed;

        _points = <LatLng>[];
        _points.add(LatLng(connector.selfLatitude!, connector.selfLongitude!));
        String hopLast = '';
        String hopLastLast = '';
        for (final hop in _traceData!.pathData) {
          final hopKey = _hopKey(hop);
          if (hopKey == hopLastLast && widget.flipPathAround) {
            break; //skip duplicate hops in round-trip paths
          }
          final contact = _traceData!.pathContacts[hopKey];
          if (contact != null && contact.hasLocation) {
            _points.add(LatLng(contact.latitude!, contact.longitude!));
          } else {
            final inferred = inferredPositions[hopKey];
            if (inferred != null) _points.add(inferred);
          }
          hopLastLast = hopLast;
          hopLast = hopKey;
        }
        if (targetPos != null) {
          if (_targetContact != null && _targetContact!.type == advTypeChat) {
            _points.add(targetPos);
          }
        }
        _polylines = _points.length > 1
            ? [
                Polyline(
                  points: _points,
                  strokeWidth: 4,
                  color: Colors.blueAccent,
                ),
              ]
            : <Polyline>[];

        _initialCenter = _points.isNotEmpty
            ? _points.first
            : const LatLng(0, 0);
        _initialZoom = _points.isNotEmpty ? 13.0 : 2.0;
        _bounds = _points.length > 1 ? LatLngBounds.fromPoints(_points) : null;
        _mapKey = ValueKey(
          '${context.l10n.pathTrace_you},${_traceData!.pathData.map(PathHelper.formatHopHex).join(',')}',
        );
        _pathDistanceMeters = getPathDistanceMeters(_points);
      });
    } catch (e) {
      appLogger.error(
        'Error handling trace response: $e',
        tag: 'PathTraceMapScreen',
      );
      if (mounted) {
        setState(() {
          _isLoading = false;
          _failed2Loaded = true;
        });
      }
    }
  }

  @override
  Widget build(BuildContext context) {
    return Consumer<MeshCoreConnector>(
      builder: (context, connector, _) {
        final settings = context.watch<AppSettingsService>().settings;
        final isImperial = settings.unitSystem == UnitSystem.imperial;
        final tileCache = context.read<MapTileCacheService>();

        return Scaffold(
          appBar: AppBar(
            title: Column(
              crossAxisAlignment: CrossAxisAlignment.start,
              mainAxisSize: MainAxisSize.min,
              children: [
                FittedBox(
                  fit: BoxFit.scaleDown,
                  child: Text(
                    widget.title,
                    style: const TextStyle(fontSize: 24),
                  ),
                ),
              ],
            ),
            centerTitle: false,
            actions: [
              IconButton(
                icon: _isLoading
                    ? const SizedBox(
                        width: 20,
                        height: 20,
                        child: CircularProgressIndicator(strokeWidth: 2),
                      )
                    : const Icon(Icons.refresh),
                onPressed: _isLoading ? null : _doPathTrace,
                tooltip: context.l10n.pathTrace_refreshTooltip,
              ),
            ],
          ),
          body: SafeArea(
            top: false,
            child: Stack(
              children: [
                if (!_hasData)
                  Center(
                    child: Column(
                      mainAxisSize: MainAxisSize.min,
                      children: [
                        if (_isLoading) const CircularProgressIndicator(),
                        const SizedBox(height: 16),
                        if (!_isLoading && _failed2Loaded)
                          Text(context.l10n.pathTrace_notAvailable),
                      ],
                    ),
                  ),
                if (_hasData)
                  _buildMapPathTrace(context, tileCache, _targetContact),
                if (_hasData && _isDesktopPlatform(defaultTargetPlatform))
                  _buildDesktopMapControls(),
                if (_points.isEmpty &&
                    !_hasData &&
                    !_isLoading &&
                    !_failed2Loaded)
                  Center(
                    child: Card(
                      color: Colors.white.withValues(alpha: 0.9),
                      child: Padding(
                        padding: EdgeInsets.all(12),
                        child: Text(
                          context.l10n.channelPath_noRepeaterLocations,
                        ),
                      ),
                    ),
                  ),
                if (_hasData)
                  _buildLegendCard(context, _traceData!, isImperial),
              ],
            ),
          ),
        );
      },
    );
  }

  List<Marker> _buildHopMarkers(
    List<Uint8List> pathData, {
    required bool showLabels,
    required Contact? target,
  }) {
    final markers = <Marker>[];
    String hopLast = '';
    String hopLastLast = '';
    for (final hop in pathData) {
      final hopKey = _hopKey(hop);
      final contact = _traceData!.pathContacts[hopKey];
      final inferred = _inferredHopPositions[hopKey];
      final hasGps = contact != null && contact.hasLocation;
      if (hopKey == hopLastLast && widget.flipPathAround) {
        continue; //skip duplicate hops in round-trip paths
      }
      if (!hasGps && inferred == null) {
        hopLastLast = hopLast;
        hopLast = hopKey;
        continue; //skip hops with no GPS and no inferred position
      }
      final point = hasGps
          ? LatLng(contact.latitude!, contact.longitude!)
          : inferred!;
      final label = PathHelper.formatHopHex(hop);
      final shortLabel = label.length > 2 ? label.substring(0, 2) : label;
      final fullLabel = label.length > 2
          ? (contact?.name != null ? '$label: ${contact!.name}' : label)
          : (contact?.name ?? label);

      markers.add(
        Marker(
          point: point,
          width: 35,
          height: 35,
          child: Container(
            padding: const EdgeInsets.all(4),
            decoration: BoxDecoration(
              color: hasGps
                  ? Colors.green
                  : Colors.orange.withValues(alpha: 0.75),
              shape: BoxShape.circle,
              border: Border.all(color: Colors.white, width: 2),
              boxShadow: [
                BoxShadow(
                  color: Colors.black.withValues(alpha: 0.3),
                  blurRadius: 4,
                  offset: const Offset(0, 2),
                ),
              ],
            ),
            alignment: Alignment.center,
            child: Text(
              hasGps ? shortLabel : '~$shortLabel',
              style: const TextStyle(
                color: Colors.white,
                fontWeight: FontWeight.bold,
                fontSize: 12,
              ),
            ),
          ),
        ),
      );
      if (showLabels) {
        markers.add(_buildNodeLabelMarker(point: point, label: fullLabel));
      }
      hopLastLast = hopLast;
      hopLast = hopKey;
    }

    final selfLat = context.read<MeshCoreConnector>().selfLatitude;
    final selfLon = context.read<MeshCoreConnector>().selfLongitude;
    if (selfLat != null && selfLon != null) {
      final selfPoint = LatLng(selfLat, selfLon);
      markers.add(
        Marker(
          point: selfPoint,
          width: 35,
          height: 35,
          child: Container(
            padding: const EdgeInsets.all(4),
            decoration: BoxDecoration(
              color: Colors.blue,
              shape: BoxShape.circle,
              border: Border.all(color: Colors.white, width: 2),
              boxShadow: [
                BoxShadow(
                  color: Colors.black.withValues(alpha: 0.3),
                  blurRadius: 4,
                  offset: const Offset(0, 2),
                ),
              ],
            ),
            alignment: Alignment.center,
            child: Text(
              context.l10n.pathTrace_you,
              style: const TextStyle(
                color: Colors.white,
                fontWeight: FontWeight.bold,
                fontSize: 12,
              ),
            ),
          ),
        ),
      );
      if (showLabels) {
        markers.add(
          _buildNodeLabelMarker(
            point: selfPoint,
            label: context.l10n.pathTrace_you,
          ),
        );
      }
    }

    // Add target contact endpoint marker.
    final targetPos = _targetContactPosition;
    if (targetPos != null && target != null && target.type == advTypeChat) {
      final isGuessed = _targetContactIsGuessed;
      final targetName = target.name;
      markers.add(
        Marker(
          point: targetPos,
          width: 35,
          height: 35,
          child: Container(
            padding: const EdgeInsets.all(4),
            decoration: BoxDecoration(
              color: isGuessed
                  ? Colors.purple.withValues(alpha: 0.55)
                  : Colors.red,
              shape: BoxShape.circle,
              border: Border.all(color: Colors.white, width: 2),
              boxShadow: [
                BoxShadow(
                  color: Colors.black.withValues(alpha: 0.3),
                  blurRadius: 4,
                  offset: const Offset(0, 2),
                ),
              ],
            ),
            alignment: Alignment.center,
            child: const Icon(Icons.person, color: Colors.white, size: 18),
          ),
        ),
      );
      if (showLabels) {
        markers.add(
          _buildNodeLabelMarker(
            point: targetPos,
            label: isGuessed ? '~$targetName' : targetName,
          ),
        );
      }
    }

    return markers;
  }

  Marker _buildNodeLabelMarker({required LatLng point, required String label}) {
    return Marker(
      point: point,
      width: 120,
      height: 24,
      alignment: Alignment.topCenter,
      child: IgnorePointer(
        child: Transform.translate(
          offset: const Offset(0, -20),
          child: FittedBox(
            fit: BoxFit.contain,
            child: Container(
              padding: const EdgeInsets.symmetric(horizontal: 6, vertical: 2),
              decoration: BoxDecoration(
                color: Colors.black54,
                borderRadius: BorderRadius.circular(8),
              ),
              alignment: Alignment.center,
              child: Text(
                label,
                maxLines: 1,
                overflow: TextOverflow.ellipsis,
                style: const TextStyle(
                  color: Colors.white,
                  fontSize: 11,
                  fontWeight: FontWeight.w500,
                ),
              ),
            ),
          ),
        ),
      ),
    );
  }

  String formatDirectionText(PathTraceData pathTraceData, int index) {
    if (pathTraceData.pathData.isEmpty) {
      return context.l10n.pathTrace_you;
    }
    if (index < 0 || index > pathTraceData.pathData.length) {
      return context.l10n.pathTrace_you;
    }

    if (index == 0 || index == pathTraceData.pathData.length) {
      if (index == 0) {
        return context.l10n.pathTrace_you;
      } else {
        final hop = pathTraceData.pathData.last;
        final contactName = pathTraceData.pathContacts[_hopKey(hop)]?.name;
        final hex = PathHelper.formatHopHex(hop);
        return contactName != null
            ? "$hex: $contactName"
            : "$hex: ${context.l10n.channelPath_unknownRepeater}";
      }
    } else {
      final hop = pathTraceData.pathData[index - 1];
      final contactName = pathTraceData.pathContacts[_hopKey(hop)]?.name;
      final hex = PathHelper.formatHopHex(hop);
      return contactName != null
          ? "$hex: $contactName"
          : "$hex: ${context.l10n.channelPath_unknownRepeater}";
    }
  }

  String formatDirectionSubText(PathTraceData pathTraceData, int index) {
    if (pathTraceData.pathData.isEmpty) {
      return context.l10n.pathTrace_you;
    }
    if (index < 0 || index > pathTraceData.pathData.length) {
      return context.l10n.pathTrace_you;
    }

    if (index == 0 || index == pathTraceData.pathData.length) {
      if (index == 0) {
        final hop = pathTraceData.pathData.first;
        final contactName = pathTraceData.pathContacts[_hopKey(hop)]?.name;
        final hex = PathHelper.formatHopHex(hop);
        return contactName != null
            ? "$hex: $contactName"
            : "$hex: ${context.l10n.channelPath_unknownRepeater}";
      } else {
        return context.l10n.pathTrace_you;
      }
    } else {
      final hop = pathTraceData.pathData[index];
      final contactName = pathTraceData.pathContacts[_hopKey(hop)]?.name;
      final hex = PathHelper.formatHopHex(hop);
      return contactName != null
          ? "$hex: $contactName"
          : "$hex: ${context.l10n.channelPath_unknownRepeater}";
    }
  }

  Widget _buildMapPathTrace(
    BuildContext context,
    MapTileCacheService tileCache,
    Contact? target,
  ) {
    final isDesktop = _isDesktopPlatform(defaultTargetPlatform);
    return FlutterMap(
      key: _mapKey,
      mapController: _mapController,
      options: MapOptions(
        interactionOptions: InteractionOptions(
          flags: ~InteractiveFlag.rotate,
          scrollWheelVelocity: isDesktop ? 0.012 : 0.005,
          cursorKeyboardRotationOptions:
              CursorKeyboardRotationOptions.disabled(),
          keyboardOptions: isDesktop
              ? const KeyboardOptions(
                  enableArrowKeysPanning: true,
                  enableWASDPanning: true,
                  enableRFZooming: true,
                )
              : const KeyboardOptions.disabled(),
        ),
        initialCenter: _initialCenter!,
        initialZoom: _initialZoom,
        initialCameraFit: _bounds == null
            ? null
            : CameraFit.bounds(
                bounds: _bounds!,
                padding: const EdgeInsets.all(64),
                maxZoom: 16,
              ),
        minZoom: _mapMinZoom,
        maxZoom: _mapMaxZoom,
        onPositionChanged: (camera, hasGesture) {
          final shouldShow = camera.zoom >= _labelZoomThreshold;
          if (shouldShow != _showNodeLabels && mounted) {
            setState(() {
              _showNodeLabels = shouldShow;
            });
          }
        },
      ),
      children: [
        TileLayer(
          urlTemplate: kMapTileUrlTemplate,
          tileProvider: tileCache.tileProvider,
          userAgentPackageName: MapTileCacheService.userAgentPackageName,
          maxZoom: 19,
        ),
        if (_polylines.isNotEmpty) PolylineLayer(polylines: _polylines),
        if (_traceData!.pathData.isNotEmpty)
          MarkerLayer(
            markers: _buildHopMarkers(
              _traceData!.pathData,
              showLabels: _showNodeLabels,
              target: target,
            ),
          ),
      ],
    );
  }

  Widget _buildLegendCard(
    BuildContext context,
    PathTraceData pathTraceData,
    bool isImperial,
  ) {
    final l10n = context.l10n;
    final maxHeight = MediaQuery.of(context).size.height * 0.35;
    final estimatedHeight = 72.0 + (pathTraceData.pathData.length * 56.0);
    final cardHeight = max(96.0, min(maxHeight, estimatedHeight));

    return Positioned(
      left: 16,
      right: 16,
      bottom: 16,
      child: SizedBox(
        height: cardHeight,
        child: Card(
          child: Column(
            crossAxisAlignment: CrossAxisAlignment.start,
            children: [
              Padding(
                padding: const EdgeInsets.all(12),
                child: Text(
                  '${l10n.channelPath_repeaterHops} ${formatDistance(_pathDistanceMeters, isImperial: isImperial)}',
                  style: const TextStyle(fontWeight: FontWeight.w600),
                ),
              ),
              const Divider(height: 1),
              Expanded(
                child: pathTraceData.pathData.isEmpty
                    ? Center(
                        child: Text(l10n.channelPath_noHopDetailsAvailable),
                      )
                    : Scrollbar(
                        child: ListView.separated(
                          padding: const EdgeInsets.symmetric(vertical: 4),
                          itemCount: pathTraceData.pathData.length + 1,
                          separatorBuilder: (_, _) => const Divider(height: 1),
                          itemBuilder: (context, index) {
                            final snrUi = snrUiFromSNR(
                              index < pathTraceData.snrData.length
                                  ? pathTraceData.snrData[index]
                                  : null,
                              context.read<MeshCoreConnector>().currentSf,
                            );
                            return Column(
                              children: [
                                ListTile(
                                  leading:
                                      index >= pathTraceData.snrData.length / 2
                                      ? Icon(Icons.call_received)
                                      : Icon(Icons.call_made),
                                  title: Text(
                                    formatDirectionText(pathTraceData, index),
                                    style: const TextStyle(fontSize: 14),
                                  ),
                                  subtitle: Text(
                                    formatDirectionSubText(
                                      pathTraceData,
                                      index,
                                    ),
                                    style: const TextStyle(fontSize: 14),
                                  ),
                                  trailing: Column(
                                    mainAxisAlignment: MainAxisAlignment.center,
                                    children: [
                                      Icon(
                                        snrUi.icon,
                                        color: snrUi.color,
                                        size: 18.0,
                                      ),
                                      Text(
                                        snrUi.text,
                                        style: TextStyle(
                                          fontSize: 10,
                                          color: snrUi.color,
                                        ),
                                      ),
                                    ],
                                  ),
                                  onTap: () {
                                    // Handle item tap
                                  },
                                ),
                              ],
                            );
                          },
                        ),
                      ),
              ),
            ],
          ),
        ),
      ),
    );
  }
}