import 'package:flutter/material.dart';
import 'package:flutter_bloc/flutter_bloc.dart';

import '../../../../api/connect/rmv/rmv_models.dart';
import '../../../../api/errors/error_mapper.dart';
import '../../../../state/app/modules/rmv/repository/rmv_repository.dart';
import '../../../../state/app/modules/settings/bloc/settings_cubit.dart';
import '../../../../utils/debouncer.dart';
import '../../../../widget/app_progress_indicator.dart';
import '../../../../widget/centered_leading.dart';
import '../favorites_controller.dart';

/// Modal search sheet for picking a [StopLocation]. Shows favorites + recents
/// when the search field is empty, switches to live search results as soon as
/// the user types. Returns the chosen stop via [Navigator.pop], or `null` if
/// the user dismisses the sheet.
Future<StopLocation?> showStationPickerSheet(
  BuildContext context, {
  String title = 'Station auswählen',
}) => showModalBottomSheet<StopLocation>(
  context: context,
  isScrollControlled: true,
  showDragHandle: true,
  useSafeArea: true,
  builder: (sheetCtx) => _StationPickerSheet(title: title),
);

class _StationPickerSheet extends StatefulWidget {
  final String title;
  const _StationPickerSheet({required this.title});

  @override
  State<_StationPickerSheet> createState() => _StationPickerSheetState();
}

class _StationPickerSheetState extends State<_StationPickerSheet> {
  static const _debounceTag = 'rmv_station_search';

  final TextEditingController _controller = TextEditingController();
  final RmvRepository _repo = RmvRepository();
  List<StopLocation>? _results;
  bool _loading = false;
  Object? _error;
  String _query = '';

  @override
  void dispose() {
    Debouncer.cancel(_debounceTag);
    _controller.dispose();
    super.dispose();
  }

  void _onChanged(String value) {
    final trimmed = value.trim();
    setState(() => _query = trimmed);
    if (trimmed.length < 2) {
      setState(() {
        _results = null;
        _error = null;
        _loading = false;
      });
      Debouncer.cancel(_debounceTag);
      return;
    }
    Debouncer.debounce(_debounceTag, const Duration(milliseconds: 300), () {
      _runSearch(trimmed);
    });
  }

  Future<void> _runSearch(String q) async {
    setState(() {
      _loading = true;
      _error = null;
    });
    try {
      final results = await _repo.searchStops(q, max: 25);
      if (!mounted || _query != q) return;
      setState(() {
        _results = results;
        _loading = false;
      });
    } catch (e) {
      if (!mounted || _query != q) return;
      setState(() {
        _error = e;
        _loading = false;
      });
    }
  }

  @override
  Widget build(BuildContext context) {
    final settings = context.read<SettingsCubit>();
    final favorites =
        settings.val().rmvSettings.favoriteStations;
    final recents = settings.val().rmvSettings.recentStations;
    final viewInsets = MediaQuery.of(context).viewInsets;

    return Padding(
      padding: EdgeInsets.only(bottom: viewInsets.bottom),
      child: Column(
        mainAxisSize: MainAxisSize.min,
        children: [
          Padding(
            padding: const EdgeInsets.fromLTRB(16, 4, 16, 8),
            child: Text(
              widget.title,
              style: Theme.of(context).textTheme.titleLarge,
            ),
          ),
          Padding(
            padding: const EdgeInsets.symmetric(horizontal: 16),
            child: TextField(
              controller: _controller,
              autofocus: true,
              onChanged: _onChanged,
              decoration: InputDecoration(
                hintText: 'Station suchen…',
                prefixIcon: const Icon(Icons.search),
                suffixIcon: _query.isEmpty
                    ? null
                    : IconButton(
                        icon: const Icon(Icons.clear),
                        onPressed: () {
                          _controller.clear();
                          _onChanged('');
                        },
                      ),
                border: OutlineInputBorder(
                  borderRadius: BorderRadius.circular(8),
                ),
              ),
            ),
          ),
          const SizedBox(height: 8),
          ConstrainedBox(
            constraints: BoxConstraints(
              maxHeight: MediaQuery.of(context).size.height * 0.6,
              minHeight: 200,
            ),
            child: _body(favorites, recents),
          ),
        ],
      ),
    );
  }

  Widget _body(List<StopLocation> favorites, List<StopLocation> recents) {
    if (_loading) {
      return const Center(child: AppProgressIndicator.medium());
    }
    final err = _error;
    if (err != null) {
      return Padding(
        padding: const EdgeInsets.all(16),
        child: Text(
          errorToUserMessage(err),
          style: TextStyle(color: Theme.of(context).colorScheme.error),
        ),
      );
    }
    final results = _results;
    if (results != null) {
      if (results.isEmpty) {
        return Center(
          child: Padding(
            padding: const EdgeInsets.all(16),
            child: Text(
              'Keine Station für "$_query" gefunden.',
              style: Theme.of(context).textTheme.bodyMedium,
            ),
          ),
        );
      }
      return ListView(
        children: results
            .map((s) => _tile(s, leadingIcon: Icons.directions_transit))
            .toList(),
      );
    }
    // Empty query → favorites + recents.
    final widgets = <Widget>[];
    if (favorites.isNotEmpty) {
      widgets.add(_sectionHeader('Favoriten'));
      widgets.addAll(
        favorites.map((s) => _tile(s, leadingIcon: Icons.star)),
      );
    }
    if (recents.isNotEmpty) {
      widgets.add(_sectionHeader('Zuletzt verwendet'));
      widgets.addAll(
        recents.map((s) => _tile(s, leadingIcon: Icons.history)),
      );
    }
    if (widgets.isEmpty) {
      return Center(
        child: Padding(
          padding: const EdgeInsets.all(16),
          child: Text(
            'Tippe oben einen Stationsnamen ein, um die RMV-Datenbank zu durchsuchen.',
            style: Theme.of(context).textTheme.bodyMedium,
            textAlign: TextAlign.center,
          ),
        ),
      );
    }
    return ListView(children: widgets);
  }

  Widget _sectionHeader(String text) => Padding(
    padding: const EdgeInsets.fromLTRB(16, 12, 16, 4),
    child: Text(
      text,
      style: Theme.of(context).textTheme.labelLarge?.copyWith(
        color: Theme.of(context).colorScheme.secondary,
      ),
    ),
  );

  Widget _tile(StopLocation stop, {required IconData leadingIcon}) => ListTile(
    leading: CenteredLeading(Icon(leadingIcon)),
    title: Text(stop.name),
    subtitle: stop.description == null ? null : Text(stop.description!),
    onTap: () {
      RmvFavoritesController(context.read<SettingsCubit>()).addRecent(stop);
      Navigator.of(context).pop(stop);
    },
  );
}