import "package:flutter/material.dart";
import "package:go_router/go_router.dart";
import "../models/trip.dart";
import "../services/brr_export_service.dart";

class StationSelectionPage extends StatefulWidget {
  final List<Trip> trips;
  final String fileName;
  final BRROperator operator;
  final String? routeName;

  const StationSelectionPage({
    super.key,
    required this.trips,
    required this.fileName,
    this.operator = BRROperator.arriva,
    this.routeName,
  });

  static GoRoute route = GoRoute(
    path: "/station-selection",
    builder: (context, state) {
      final extra = state.extra as Map<String, dynamic>?;
      if (extra == null) {
        WidgetsBinding.instance.addPostFrameCallback((_) {
          context.go("/");
        });
        return const SizedBox.shrink();
      }
      return StationSelectionPage(
        trips: (extra["trips"] as List).cast<Trip>(),
        fileName: extra["fileName"] as String,
        operator: extra["operator"] as BRROperator? ?? BRROperator.arriva,
        routeName: extra["routeName"] as String?,
      );
    },
  );

  @override
  State<StationSelectionPage> createState() => _StationSelectionPageState();
}

class _StationSelectionPageState extends State<StationSelectionPage> {
  String? _selectedStation;
  String? _selectedDirection;
  List<String> _availableStations = [];

  @override
  void initState() {
    super.initState();
    _extractStations();
  }

  void _extractStations() {
    final stationsSet = <String>{};
    for (final trip in widget.trips) {
      stationsSet.addAll(trip.stationOrder);
    }
    _availableStations = stationsSet.toList()..sort();
  }

  bool _isTerminus(String station) {
    for (final trip in widget.trips) {
      if (trip.stationOrder.isEmpty) continue;
      if (trip.stationOrder.first == station || trip.stationOrder.last == station) {
        return true;
      }
    }
    return false;
  }

  // For a given station, find where buses are headed in each direction
  String? _getTerminus(String station, String direction) {
    for (final trip in widget.trips) {
      if (!trip.stationOrder.contains(station)) continue;
      if (trip.stationOrder.isEmpty) continue;

      // "departing" = outbound trips, show where they end up
      if (direction == "departing" && trip.direction == "outbound") {
        return trip.stationOrder.last;
      }

      // "arriving" = inbound trips, show where they end up (opposite terminus)
      if (direction == "arriving" && trip.direction == "inbound") {
        return trip.stationOrder.last;
      }
    }
    return null;
  }

  String _getDirectionLabel(String direction) {
    if (_selectedStation == null) {
      return direction == "departing" ? "DEPARTING" : "ARRIVING";
    }

    if (_isTerminus(_selectedStation!)) {
      return direction == "departing" ? "DEPARTURES" : "ARRIVALS";
    }

    final terminus = _getTerminus(_selectedStation!, direction);
    return "towards\n${terminus ?? "..."}";
  }

  void _onContinue() {
    if (_selectedStation == null || _selectedDirection == null) {
      ScaffoldMessenger.of(context).showSnackBar(
        const SnackBar(content: Text("Select both a station and direction")),
      );
      return;
    }

    final filteredTrips = _filterAndUpdateTrips();

    if (filteredTrips.isEmpty) {
      ScaffoldMessenger.of(context).showSnackBar(
        const SnackBar(content: Text("No trips found for that selection")),
      );
      return;
    }

    context.go("/trips", extra: {
      "trips": filteredTrips,
      "fileName": widget.fileName,
      "station": _selectedStation,
      "direction": _selectedDirection,
      "operator": widget.operator,
      if (widget.routeName != null) "routeName": widget.routeName,
    });
  }

  List<Trip> _filterAndUpdateTrips() {
    final filtered = <Trip>[];
    final isTerminusStation = _isTerminus(_selectedStation!);

    for (final trip in widget.trips) {
      if (!trip.stationTimes.containsKey(_selectedStation)) continue;

      if (_selectedDirection != "both") {
        // For terminus stations, the direction logic flips:
        // "departing" from a terminus that's first on inbound = show inbound trips
        // "arriving" at a terminus thats last on outbound = show outbound trips
        final isFirstStation = trip.stationOrder.isNotEmpty && trip.stationOrder.first == _selectedStation;
        final isLastStation = trip.stationOrder.isNotEmpty && trip.stationOrder.last == _selectedStation;

        if (isTerminusStation) {
          if (_selectedDirection == "departing" && !isFirstStation) continue;
          if (_selectedDirection == "arriving" && !isLastStation) continue;
        } else {
          if (_selectedDirection == "departing" && trip.direction != "outbound") continue;
          if (_selectedDirection == "arriving" && trip.direction != "inbound") continue;
        }
      }

      final stationTime = trip.stationTimes[_selectedStation];
      if (stationTime != null) {
        filtered.add(trip.copyWith(scheduledTime: stationTime));
      }
    }

    return filtered;
  }

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(
        leading: IconButton(
          icon: const Icon(Icons.arrow_back, size: 20),
          onPressed: () => context.go("/"),
        ),
        title: const Text("SELECT STATION"),
      ),
      body: SafeArea(
        child: Padding(
          padding: const EdgeInsets.all(20),
          child: Column(
            crossAxisAlignment: CrossAxisAlignment.start,
            children: [

              // file info strip
              Container(
                padding: const EdgeInsets.symmetric(horizontal: 12, vertical: 8),
                color: const Color(0xFF1E1E1E),
                child: Row(
                  children: [
                    const Icon(Icons.description_outlined, size: 14, color: Color(0xFF777777)),
                    const SizedBox(width: 8),
                    Expanded(
                      child: Text(
                        widget.fileName,
                        style: const TextStyle(
                          fontSize: 12,
                          color: Color(0xFF777777),
                        ),
                        overflow: TextOverflow.ellipsis,
                      ),
                    ),
                    Text(
                      "${widget.trips.length} trips",
                      style: const TextStyle(
                        fontSize: 12,
                        color: Color(0xFF00A9CE),
                        fontWeight: FontWeight.w600,
                      ),
                    ),
                  ],
                ),
              ),

              const SizedBox(height: 28),

              const Text(
                "STATION",
                style: TextStyle(
                  fontSize: 11,
                  fontWeight: FontWeight.w700,
                  color: Color(0xFF777777),
                  letterSpacing: 1.5,
                ),
              ),
              const SizedBox(height: 8),

              DropdownButtonFormField<String>(
                initialValue: _selectedStation,
                dropdownColor: const Color(0xFF252525),
                style: const TextStyle(color: Color(0xFFEEEEEE), fontSize: 15),
                decoration: const InputDecoration(
                  hintText: "Choose station...",
                ),
                items: _availableStations.map((station) {
                  return DropdownMenuItem(
                    value: station,
                    child: Text(station),
                  );
                }).toList(),
                onChanged: (value) => setState(() => _selectedStation = value),
              ),

              const SizedBox(height: 24),

              const Text(
                "DIRECTION",
                style: TextStyle(
                  fontSize: 11,
                  fontWeight: FontWeight.w700,
                  color: Color(0xFF777777),
                  letterSpacing: 1.5,
                ),
              ),
              const SizedBox(height: 8),

              Row(
                children: [
                  _DirButton(
                    label: _getDirectionLabel("departing"),
                    selected: _selectedDirection == "departing",
                    onTap: () => setState(() => _selectedDirection = "departing"),
                  ),
                  const SizedBox(width: 10),
                  _DirButton(
                    label: _getDirectionLabel("arriving"),
                    selected: _selectedDirection == "arriving",
                    onTap: () => setState(() => _selectedDirection = "arriving"),
                  ),
                  if (widget.operator == BRROperator.stagecoach) ...[
                    const SizedBox(width: 10),
                    _DirButton(
                      label: "BOTH",
                      selected: _selectedDirection == "both",
                      onTap: () => setState(() => _selectedDirection = "both"),
                    ),
                  ],
                ],
              ),

              const Spacer(),

              SizedBox(
                width: double.infinity,
                height: 54,
                child: ElevatedButton(
                  onPressed: _onContinue,
                  child: const Text("VIEW TRIPS"),
                ),
              ),
            ],
          ),
        ),
      ),
    );
  }
}

class _DirButton extends StatelessWidget {
  final String label;
  final bool selected;
  final VoidCallback onTap;

  const _DirButton({
    required this.label,
    required this.selected,
    required this.onTap,
  });

  @override
  Widget build(BuildContext context) {
    return Expanded(
      child: GestureDetector(
        onTap: onTap,
        child: AnimatedContainer(
          duration: const Duration(milliseconds: 150),
          padding: const EdgeInsets.symmetric(vertical: 16, horizontal: 12),
          decoration: BoxDecoration(
            color: selected ? const Color(0xFF002A33) : const Color(0xFF1E1E1E),
            border: Border.all(
              color: selected ? const Color(0xFF00A9CE) : const Color(0xFF2E2E2E),
              width: selected ? 1.5 : 1,
            ),
            borderRadius: BorderRadius.circular(3),
          ),
          child: Text(
            label,
            style: TextStyle(
              fontSize: 12,
              fontWeight: FontWeight.w700,
              color: selected ? const Color(0xFF00A9CE) : const Color(0xFF777777),
              letterSpacing: 0.3,
            ),
          ),
        ),
      ),
    );
  }
}