import 'package:flutter/material.dart';
import 'package:mileograph_flutter/objects/objects.dart';
import 'package:mileograph_flutter/services/data_service.dart';
import 'package:mileograph_flutter/services/distance_unit_service.dart';
import 'package:provider/provider.dart';

class TripsPage extends StatefulWidget {
  const TripsPage({super.key});

  @override
  State<TripsPage> createState() => _TripsPageState();
}

class _TripsPageState extends State<TripsPage> {
  bool _initialised = false;
  final Map<int, Future<List<TripLocoStat>>> _tripLocoStatsFutures = {};

  @override
  void didChangeDependencies() {
    super.didChangeDependencies();
    if (!_initialised) {
      _initialised = true;
      _refreshTrips();
    }
  }

  Future<void> _refreshTrips() async {
    _tripLocoStatsFutures.clear();
    final data = context.read<DataService>();
    await data.fetchTripDetails();
  }

  Future<void> _renameTrip(TripDetail trip, String newName) async {
    final data = context.read<DataService>();
    final api = data.api;
    final messenger = ScaffoldMessenger.maybeOf(context);
    try {
      await api.post('/trips/rename', {
        "trip_id": trip.id,
        "trip_name": newName,
      });
      await data.fetchTripDetails();
    } catch (e) {
      messenger?.showSnackBar(
        SnackBar(content: Text('Failed to rename trip: $e')),
      );
      rethrow;
    }
  }

  List<TripLocoStat> _cachedTripStats(
    TripDetail trip,
    TripSummary? summary,
  ) {
    if (trip.locoStats.isNotEmpty) return trip.locoStats;
    if (summary?.locoStats.isNotEmpty == true) return summary!.locoStats;
    return const [];
  }

  Future<List<TripLocoStat>> _loadTripStats(
    TripDetail trip,
    TripSummary? summary,
  ) {
    final cached = _cachedTripStats(trip, summary);
    if (cached.isNotEmpty) return Future.value(cached);
    return _tripLocoStatsFutures.putIfAbsent(
      trip.id,
      () => context.read<DataService>().fetchTripLocoStats(trip.id),
    );
  }

  Future<String?> _promptTripName(BuildContext context, String initial) async {
    final controller = TextEditingController(text: initial);
    final newName = await showDialog<String>(
      context: context,
      builder: (dialogCtx) => AlertDialog(
        title: const Text('Rename trip'),
        content: TextField(
          controller: controller,
          decoration: const InputDecoration(labelText: 'Trip name'),
          autofocus: true,
        ),
        actions: [
          TextButton(
            onPressed: () => Navigator.of(dialogCtx).pop(),
            child: const Text('Cancel'),
          ),
          TextButton(
            onPressed: () =>
                Navigator.of(dialogCtx).pop(controller.text.trim()),
            child: const Text('Save'),
          ),
        ],
      ),
    );
    controller.dispose();
    return newName;
  }

  @override
  Widget build(BuildContext context) {
    final data = context.watch<DataService>();
    final distanceUnits = context.watch<DistanceUnitService>();
    final tripDetails = data.tripDetails;
    final tripSummaries = data.tripList;
    final summaryById = {
      for (final summary in tripSummaries) summary.tripId: summary,
    };
    final showLoading = data.isTripDetailsLoading && tripDetails.isEmpty;

    return RefreshIndicator(
      onRefresh: _refreshTrips,
      child: ListView.builder(
        padding: const EdgeInsets.all(16),
        physics: const AlwaysScrollableScrollPhysics(),
        itemCount: () {
          if (showLoading) return 2;
          if (tripDetails.isEmpty && tripSummaries.isEmpty) return 2;
          if (tripDetails.isEmpty) return 1 + tripSummaries.length;
          return 1 + tripDetails.length;
        }(),
        itemBuilder: (context, index) {
          if (index == 0) {
            return Column(
              crossAxisAlignment: CrossAxisAlignment.start,
              children: [
                Row(
                  mainAxisAlignment: MainAxisAlignment.spaceBetween,
                  children: [
                    Column(
                      crossAxisAlignment: CrossAxisAlignment.start,
                      children: [
                        Text(
                          'Journeys',
                          style: Theme.of(context).textTheme.labelMedium,
                        ),
                        const SizedBox(height: 2),
                        Text(
                          'Trips',
                          style: Theme.of(context).textTheme.headlineSmall,
                        ),
                      ],
                    ),
                    IconButton(
                      onPressed: _refreshTrips,
                      icon: const Icon(Icons.refresh),
                      tooltip: 'Refresh trips',
                    ),
                  ],
                ),
                const SizedBox(height: 12),
              ],
            );
          }

          if (showLoading) {
            return const Center(
              child: Padding(
                padding: EdgeInsets.symmetric(vertical: 24.0),
                child: CircularProgressIndicator(),
              ),
            );
          }

          if (tripDetails.isEmpty && tripSummaries.isEmpty) {
            return Card(
              child: Padding(
                padding: const EdgeInsets.all(16.0),
                child: Column(
                  crossAxisAlignment: CrossAxisAlignment.start,
                  children: [
                    Text(
                      'No trips yet',
                      style: Theme.of(context).textTheme.titleMedium?.copyWith(
                            fontWeight: FontWeight.w700,
                          ),
                    ),
                    const SizedBox(height: 8),
                    const Text(
                      'Use the Add entry flow to start grouping legs into trips.',
                    ),
                  ],
                ),
              ),
            );
          }

          if (tripDetails.isEmpty) {
            final trip = tripSummaries[index - 1];
            return Card(
              child: ListTile(
                title: Text(trip.tripName),
                subtitle:
                    Text(distanceUnits.format(trip.tripMileage, decimals: 1)),
              ),
            );
          }

          final trip = tripDetails[index - 1];
          final summary = summaryById[trip.id];
          return _buildTripCard(context, trip, summary);
        },
      ),
    );
  }

  Widget _buildTripCard(
    BuildContext context,
    TripDetail trip,
    TripSummary? summary,
  ) {
    final distanceUnits = context.watch<DistanceUnitService>();
    final legs = trip.legs;
    final legCount =
        trip.legCount > 0 ? trip.legCount : summary?.legCount ?? legs.length;
    final dateRange = _formatDateRange(legs);
    final endpoints = _formatEndpoints(legs);
    final stats = _cachedTripStats(trip, summary);
    final winnerCount = stats.where((e) => e.won).length;

    return Card(
      child: Padding(
        padding: const EdgeInsets.all(16.0),
        child: Column(
          crossAxisAlignment: CrossAxisAlignment.start,
          children: [
            Row(
              crossAxisAlignment: CrossAxisAlignment.start,
              children: [
                Expanded(
                  child: Column(
                    crossAxisAlignment: CrossAxisAlignment.start,
                    children: [
                      Text(
                        'Trip #${trip.id}',
                        style: Theme.of(context).textTheme.labelMedium,
                      ),
                      const SizedBox(height: 4),
                      Text(
                        trip.name,
                        style: Theme.of(context).textTheme.titleMedium?.copyWith(
                          fontWeight: FontWeight.w700,
                        ),
                      ),
                    ],
                  ),
                ),
                Column(
                  crossAxisAlignment: CrossAxisAlignment.end,
                  children: [
                    Text(
                      distanceUnits.format(trip.mileage, decimals: 1),
                      style:
                          Theme.of(context).textTheme.headlineSmall?.copyWith(
                        fontWeight: FontWeight.w800,
                      ),
                    ),
                  ],
                ),
              ],
            ),
            const SizedBox(height: 12),
            Wrap(
              spacing: 8,
              runSpacing: 8,
              children: [
                _buildMetaChip(context, Icons.timeline, '$legCount legs'),
                if (dateRange != null)
                  _buildMetaChip(context, Icons.calendar_month, dateRange),
                if (endpoints != null)
                  _buildMetaChip(context, Icons.route, endpoints),
                if (stats.isNotEmpty) ...[
                  _buildMetaChip(context, Icons.train, '${stats.length} had'),
                  _buildMetaChip(
                    context,
                    Icons.emoji_events_outlined,
                    '$winnerCount winners',
                  ),
                ] else
                  _buildMetaChip(context, Icons.train, 'No traction yet'),
              ],
            ),
            const SizedBox(height: 12),
            Align(
              alignment: Alignment.centerRight,
              child: Wrap(
                spacing: 8,
                runSpacing: 8,
                alignment: WrapAlignment.end,
                children: [
                  OutlinedButton.icon(
                    icon: const Icon(Icons.train),
                    label: const Text('Locos'),
                    onPressed: () => _showTripWinners(context, trip, summary),
                  ),
                  FilledButton.icon(
                    icon: const Icon(Icons.open_in_new),
                    label: const Text('Details'),
                    onPressed: () => _showTripDetail(context, trip),
                  ),
                ],
              ),
            ),
          ],
        ),
      ),
    );
  }

  Widget _buildMetaChip(BuildContext context, IconData icon, String label) {
    return Chip(
      avatar: Icon(icon, size: 16),
      label: Text(label),
      visualDensity: const VisualDensity(horizontal: -2, vertical: -2),
      materialTapTargetSize: MaterialTapTargetSize.shrinkWrap,
    );
  }

  String? _formatDateRange(List<TripLeg> legs) {
    final beginTimes =
        legs.map((e) => e.beginTime).whereType<DateTime>().toList();
    if (beginTimes.isEmpty) return null;
    final start = beginTimes.first;
    final end = beginTimes.last;
    final startStr = _formatFriendlyDate(start);
    final endStr = _formatFriendlyDate(end);
    if (startStr == endStr) return startStr;
    return '$startStr - $endStr';
  }

  String _formatFriendlyDate(DateTime date) {
    const months = [
      'Jan',
      'Feb',
      'Mar',
      'Apr',
      'May',
      'Jun',
      'Jul',
      'Aug',
      'Sep',
      'Oct',
      'Nov',
      'Dec',
    ];
    final day = date.day.toString().padLeft(2, '0');
    final monthIndex = (date.month - 1).clamp(0, months.length - 1).toInt();
    final month = months[monthIndex];
    return '$day $month ${date.year}';
  }

  String? _formatEndpoints(List<TripLeg> legs) {
    if (legs.isEmpty) return null;
    final start = legs.first.start;
    final end = legs.last.end;
    if (start.isEmpty && end.isEmpty) return null;
    final startLabel = start.isNotEmpty ? start : '—';
    final endLabel = end.isNotEmpty ? end : '—';
    return '$startLabel → $endLabel';
  }

  String _formatDate(DateTime? date) {
    if (date == null) return '';
    return '${date.year.toString().padLeft(4, '0')}-${date.month.toString().padLeft(2, '0')}-${date.day.toString().padLeft(2, '0')}';
  }

  void _showTripDetail(BuildContext context, TripDetail trip) {
    final distanceUnits = context.read<DistanceUnitService>();
    showModalBottomSheet(
      context: context,
      isScrollControlled: true,
      builder: (_) {
        bool renaming = false;
        bool deleting = false;
        String tripName = trip.name;
        return StatefulBuilder(
          builder: (sheetCtx, setSheetState) {
            Future<void> handleRename() async {
              final newName =
                  await _promptTripName(sheetCtx, tripName) ?? tripName;
              if (newName.isEmpty || newName == tripName) return;
              setSheetState(() => renaming = true);
              try {
                await _renameTrip(trip, newName);
                tripName = newName;
                setSheetState(() {});
              } finally {
                if (mounted) setSheetState(() => renaming = false);
              }
            }

            Future<void> handleDelete() async {
              if (deleting || trip.legs.isNotEmpty) return;
              final data = context.read<DataService>();
              final api = data.api;
              final messenger = ScaffoldMessenger.maybeOf(sheetCtx);
              final navigator = Navigator.of(sheetCtx);

              final ok = await showDialog<bool>(
                context: sheetCtx,
                builder: (ctx) {
                  return AlertDialog(
                    title: const Text('Delete trip?'),
                    content: Text(
                      'This will delete "${trip.name}". This cannot be undone.',
                    ),
                    actions: [
                      TextButton(
                        onPressed: () => Navigator.of(ctx).pop(false),
                        child: const Text('Cancel'),
                      ),
                      FilledButton(
                        onPressed: () => Navigator.of(ctx).pop(true),
                        child: const Text('Delete'),
                      ),
                    ],
                  );
                },
              );
              if (ok != true || !mounted) return;

              setSheetState(() => deleting = true);
              try {
                await api.delete('/trips/delete/${trip.id}');
                await Future.wait([
                  data.fetchTripDetails(),
                  data.fetchTrips(),
                ]);
                _tripLocoStatsFutures.remove(trip.id);
                if (!mounted) return;
                messenger?.showSnackBar(
                  SnackBar(content: Text('Deleted "${trip.name}"')),
                );
                navigator.pop();
              } catch (e) {
                if (!mounted) return;
                messenger?.showSnackBar(
                  SnackBar(content: Text('Failed to delete trip: $e')),
                );
              } finally {
                if (mounted) setSheetState(() => deleting = false);
              }
            }

            return SafeArea(
              child: Padding(
                padding: const EdgeInsets.all(16.0),
                child: Column(
                  mainAxisSize: MainAxisSize.min,
                  crossAxisAlignment: CrossAxisAlignment.start,
                  children: [
                    Row(
                      children: [
                        IconButton(
                          icon: const Icon(Icons.arrow_back),
                          onPressed: () => Navigator.of(sheetCtx).pop(),
                        ),
                        Expanded(
                          child: Text(
                            tripName,
                            style: Theme.of(context).textTheme.titleMedium
                                ?.copyWith(fontWeight: FontWeight.bold),
                          ),
                        ),
                        IconButton(
                          icon: renaming
                              ? const SizedBox(
                                  width: 18,
                                  height: 18,
                                  child:
                                      CircularProgressIndicator(strokeWidth: 2),
                                )
                              : const Icon(Icons.edit),
                          tooltip: 'Rename trip',
                          onPressed: renaming ? null : handleRename,
                        ),
                        if (trip.legs.isEmpty) ...[
                          const SizedBox(width: 4),
                          IconButton(
                            icon: deleting
                                ? const SizedBox(
                                    width: 18,
                                    height: 18,
                                    child: CircularProgressIndicator(strokeWidth: 2),
                                  )
                                : const Icon(Icons.delete_outline),
                            tooltip: 'Delete trip',
                            onPressed: deleting ? null : handleDelete,
                            color: Theme.of(context).colorScheme.error,
                          ),
                        ],
                        const SizedBox(width: 4),
                        Text(
                          distanceUnits.format(trip.mileage, decimals: 1),
                        ),
                      ],
                    ),
                    const SizedBox(height: 8),
                    SizedBox(
                      height: MediaQuery.of(context).size.height * 0.6,
                      child: ListView.builder(
                        itemCount: trip.legs.length,
                        itemBuilder: (context, index) {
                          final leg = trip.legs[index];
                          return ListTile(
                            leading: const Icon(Icons.train),
                            title: Text('${leg.start} → ${leg.end}'),
                            subtitle: Text(_formatDate(leg.beginTime)),
                            trailing: Text(
                              leg.mileage == null
                                  ? '-'
                                  : distanceUnits.format(
                                      leg.mileage!,
                                      decimals: 1,
                                    ),
                              style: Theme.of(context).textTheme.labelLarge
                                  ?.copyWith(fontWeight: FontWeight.bold),
                            ),
                          );
                        },
                      ),
                    ),
                  ],
                ),
              ),
            );
          },
        );
      },
    );
  }

  void _showTripWinners(
    BuildContext context,
    TripDetail trip,
    TripSummary? summary,
  ) {
    final distanceUnits = context.read<DistanceUnitService>();
    showModalBottomSheet(
      context: context,
      isScrollControlled: true,
      builder: (_) {
        return SafeArea(
          child: FutureBuilder<List<TripLocoStat>>(
            future: _loadTripStats(trip, summary),
            initialData: _cachedTripStats(trip, summary),
            builder: (ctx, snapshot) {
              final items = snapshot.data ?? [];
              final loading =
                  snapshot.connectionState == ConnectionState.waiting;
              return Padding(
                padding: const EdgeInsets.all(16.0),
                child: Column(
                  mainAxisSize: MainAxisSize.min,
                  crossAxisAlignment: CrossAxisAlignment.start,
                  children: [
                    Row(
                      children: [
                        IconButton(
                          icon: const Icon(Icons.arrow_back),
                          onPressed: () => Navigator.of(context).pop(),
                        ),
                        Text(
                          trip.name,
                          style: Theme.of(context)
                              .textTheme
                              .titleMedium
                              ?.copyWith(fontWeight: FontWeight.bold),
                        ),
                        const Spacer(),
                        Text(
                          distanceUnits.format(trip.mileage, decimals: 1),
                        ),
                      ],
                    ),
                    const SizedBox(height: 8),
                    if (!loading && items.isNotEmpty) ...[
                      Wrap(
                        spacing: 8,
                        runSpacing: 8,
                        children: [
                          Chip(
                            avatar: const Icon(Icons.train, size: 16),
                            label: Text('Total had: ${items.length}'),
                          ),
                          Chip(
                            avatar: const Icon(Icons.star, size: 16),
                            label: Text(
                              'Winners: ${items.where((e) => e.won == true).length}',
                            ),
                          ),
                        ],
                      ),
                      const SizedBox(height: 8),
                    ],
                    if (loading)
                      const Center(
                        child: Padding(
                          padding: EdgeInsets.symmetric(vertical: 24.0),
                          child: CircularProgressIndicator(),
                        ),
                      )
                    else if (items.isEmpty)
                      const Padding(
                        padding: EdgeInsets.symmetric(vertical: 16.0),
                        child: Text('No traction recorded for this trip yet.'),
                      )
                    else
                      SizedBox(
                        height: MediaQuery.of(context).size.height * 0.6,
                        child: ListView.builder(
                          itemCount: items.length,
                          itemBuilder: (context, index) {
                            final loco = items[index];
                            final won = loco.won;
                            final isWon = won == true;
                            return ListTile(
                              leading: const Icon(Icons.train),
                              title: Text('${loco.locoClass} ${loco.number}'),
                              subtitle:
                                  loco.name == null || loco.name!.isEmpty
                                      ? null
                                      : Text(loco.name!),
                              trailing: Chip(
                                label: Text(isWon ? 'Won' : 'Dud'),
                                backgroundColor: isWon
                                    ? Colors.green.shade100
                                    : Colors.grey.shade300,
                                labelStyle: TextStyle(
                                  color: isWon
                                      ? Colors.green.shade900
                                      : Colors.grey.shade800,
                                ),
                              ),
                            );
                          },
                        ),
                      ),
                  ],
                ),
              );
            },
          ),
        );
      },
    );
  }
}