import 'package:flutter/material.dart';
import 'package:latlong2/latlong.dart';

import '../connector/meshcore_connector.dart';
import '../connector/meshcore_protocol.dart';
import '../l10n/l10n.dart';
import '../models/contact.dart';
import 'signal_ui.dart';

Contact? _getRepeaterPrefixMatchNearLocation(
  List<Contact> contacts,
  int pubkeyFirstByte, {
  LatLng? searchPoint,
  bool preferFavorites = false,
}) {
  final candidates = contacts
      .where(
        (c) =>
            c.publicKey.isNotEmpty &&
            c.publicKey.first == pubkeyFirstByte &&
            (c.type == advTypeRepeater || c.type == advTypeRoom),
      )
      .toList();

  if (candidates.isEmpty) return null;

  candidates.sort((a, b) {
    if (preferFavorites) {
      final favA = a.isFavorite ? 1 : 0;
      final favB = b.isFavorite ? 1 : 0;
      final favCompare = favB.compareTo(favA);
      if (favCompare != 0) return favCompare;
    }

    final seenCompare = b.lastSeen.compareTo(a.lastSeen);
    if (seenCompare != 0) return seenCompare;

    return a.publicKeyHex.compareTo(b.publicKeyHex);
  });

  if (searchPoint == null) {
    return candidates.first;
  }

  final distance = Distance();
  Contact best = candidates.first;
  var bestDistance = double.infinity;

  for (final c in candidates) {
    if (c.hasLocation && c.latitude != null && c.longitude != null) {
      final d = distance(searchPoint, LatLng(c.latitude!, c.longitude!));
      if (d < bestDistance) {
        bestDistance = d;
        best = c;
      }
    }
  }

  return best;
}

class SNRUi {
  final IconData icon;
  final Color color;
  final String text;
  const SNRUi(this.icon, this.color, this.text);
}

List<double> getSNRfromSF(int spreadingFactor) {
  switch (spreadingFactor) {
    case 7:
      return [4.0, -2.0, -4.0, -6.0];
    case 8:
      return [4.0, -4.0, -6.0, -8.0];
    case 9:
      return [4.0, -6.0, -8.0, -10.0];
    case 10:
      return [4.0, -8.0, -10.0, -13.0];
    case 11:
      return [4.0, -10.0, -12.5, -15.0];
    case 12:
      return [4.0, -12.5, -15.0, -18.0];
    default:
      return []; // Or throw Exception('Invalid SF: $spreadingFactor');
  }
}

SNRUi snrUiFromSNR(double? snr, int? spreadingFactor) {
  if (snr == null ||
      spreadingFactor == null ||
      spreadingFactor < 7 ||
      spreadingFactor > 12) {
    return const SNRUi(Icons.signal_cellular_off, Colors.grey, '—');
  }

  final snrLevels = getSNRfromSF(spreadingFactor);

  String text = '${snr.toStringAsFixed(1)} dB';
  final tier = snr >= snrLevels[0]
      ? 0
      : snr >= snrLevels[1]
      ? 1
      : snr >= snrLevels[2]
      ? 2
      : snr >= snrLevels[3]
      ? 3
      : 4;
  final signalUi = signalUiForStrengthTier(tier);

  return SNRUi(signalUi.icon, signalUi.color, text);
}

class SNRIndicator extends StatefulWidget {
  final MeshCoreConnector connector;

  const SNRIndicator({super.key, required this.connector});

  @override
  State<SNRIndicator> createState() => _SNRIndicatorState();
}

class _SNRIndicatorState extends State<SNRIndicator> {
  bool _isValidSelfLocation(double lat, double lon) {
    const double epsilon = 1e-6;
    return (lat.abs() > epsilon || lon.abs() > epsilon) &&
        lat >= -90.0 &&
        lat <= 90.0 &&
        lon >= -180.0 &&
        lon <= 180.0;
  }

  @override
  Widget build(BuildContext context) {
    final directRepeaters = widget.connector.directRepeaters;
    final directBestRepeaters = List.of(directRepeaters)
      ..sort((a, b) => (b.ranking).compareTo(a.ranking));
    final directRepeater = directBestRepeaters.isEmpty
        ? null
        : directBestRepeaters.first;

    final snrUi = snrUiFromSNR(
      directBestRepeaters.isNotEmpty ? directRepeater!.snr : null,
      widget.connector.currentSf,
    );

    return ConstrainedBox(
      constraints: const BoxConstraints(minWidth: 40, minHeight: 40),
      child: InkWell(
        onTap: directRepeater != null
            ? () => _showFullPathDialog(context, directBestRepeaters)
            : null,
        borderRadius: BorderRadius.circular(8),
        child: Padding(
          padding: const EdgeInsets.symmetric(horizontal: 4, vertical: 8),
          child: Column(
            mainAxisSize: MainAxisSize.min,
            children: [
              Icon(snrUi.icon, size: 18, color: snrUi.color),
              Text(
                snrUi.text,
                style: TextStyle(fontSize: 12, color: snrUi.color),
              ),
              if (directRepeater != null)
                Text(
                  '${directRepeaters.length}: ${directRepeater.pubkeyFirstByte.toRadixString(16).padLeft(2, '0')}: ${_formatLastUpdated(directRepeater.lastUpdated)}',
                  style: TextStyle(
                    fontSize: 12,
                    fontWeight: FontWeight.w500,
                    color: Colors.grey,
                  ),
                  maxLines: 1,
                  overflow: TextOverflow.ellipsis,
                ),
            ],
          ),
        ),
      ),
    );
  }

  String _formatLastUpdated(DateTime lastSeen) {
    final now = DateTime.now();
    final diff = now.difference(lastSeen);
    if (diff.isNegative) {
      return "0s";
    }
    if (diff.inMinutes < 1) {
      return "${diff.inSeconds}s";
    }
    if (diff.inMinutes < 60) {
      return "${diff.inMinutes}m";
    }
    if (diff.inHours < 24) {
      final hours = diff.inHours;
      return "${hours}h";
    }
    final days = diff.inDays;
    return "${days}d";
  }

  void _showFullPathDialog(
    BuildContext context,
    List<DirectRepeater> directBestRepeaters,
  ) {
    final l10n = context.l10n;

    showDialog(
      context: context,
      builder: (context) => AlertDialog(
        title: Text(l10n.snrIndicator_nearByRepeaters),
        content: SizedBox(
          width: double.maxFinite,
          child: Scrollbar(
            child: ListView.separated(
              shrinkWrap: true,
              padding: const EdgeInsets.symmetric(vertical: 4),
              itemCount: directBestRepeaters.length,
              separatorBuilder: (_, _) => const Divider(height: 1),
              itemBuilder: (context, index) {
                final repeater = directBestRepeaters[index];
                final snrUi = snrUiFromSNR(
                  repeater.snr,
                  widget.connector.currentSf,
                );
                final allContacts = widget.connector.allContacts;

                final selfLat = widget.connector.selfLatitude;
                final selfLon = widget.connector.selfLongitude;

                LatLng? selfPoint;
                if (selfLat != null &&
                    selfLon != null &&
                    _isValidSelfLocation(selfLat, selfLon)) {
                  selfPoint = LatLng(selfLat, selfLon);
                }

                final contact = _getRepeaterPrefixMatchNearLocation(
                  allContacts,
                  repeater.pubkeyFirstByte,
                  searchPoint: selfPoint,
                  preferFavorites: true,
                );

                final name = contact?.name;

                return Column(
                  children: [
                    ListTile(
                      leading: Icon(snrUi.icon, color: snrUi.color),
                      title: Text(
                        name ??
                            repeater.pubkeyFirstByte
                                .toRadixString(16)
                                .padLeft(2, '0'),
                      ),
                      subtitle: Text(
                        'SNR: ${repeater.snr.toStringAsFixed(1)} dB\n${l10n.snrIndicator_lastSeen}: ${_formatLastUpdated(repeater.lastUpdated)}',
                      ),
                    ),
                  ],
                );
              },
            ),
          ),
        ),
        actions: [
          TextButton(
            onPressed: () => Navigator.pop(context),
            child: Text(l10n.common_close),
          ),
        ],
      ),
    );
  }
}