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

import '../../core/region/geo.dart';
import '../../core/region/region_config.dart';
import '../../core/region/region_repository.dart';
import '../../l10n/app_localizations.dart';
import 'comune.dart';
import 'comuni_repository.dart';
import 'coordinate_input.dart';

/// What the user picked out of search.
class SearchResult {
  const SearchResult({required this.point, required this.label});

  final GeoPoint point;

  /// How to name it if it gets saved as a place.
  final String label;
}

/// One field that takes either a municipality name or coordinates.
///
/// Two separate searches would make the user decide up front which kind of
/// thing they are looking for, which they should not have to: a string either
/// parses as coordinates or it does not, and the answer is obvious from the
/// text itself.
class SearchScreen extends ConsumerStatefulWidget {
  const SearchScreen({super.key});

  @override
  ConsumerState<SearchScreen> createState() => _SearchScreenState();
}

class _SearchScreenState extends ConsumerState<SearchScreen> {
  final TextEditingController _controller = TextEditingController();
  String _query = '';

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

  @override
  Widget build(BuildContext context) {
    final l10n = AppLocalizations.of(context);
    final index = ref.watch(comuneIndexProvider);
    final region = ref.watch(regionConfigProvider).value;

    final coordinates = parseCoordinates(_query);
    final matches = switch (index) {
      AsyncData(:final value) => value.search(_query),
      _ => const <Comune>[],
    };

    return Scaffold(
      appBar: AppBar(
        title: TextField(
          controller: _controller,
          autofocus: true,
          textInputAction: TextInputAction.search,
          decoration: InputDecoration(
            hintText: l10n.searchHint,
            border: InputBorder.none,
          ),
          onChanged: (value) => setState(() => _query = value),
        ),
        actions: [
          if (_query.isNotEmpty)
            IconButton(
              icon: const Icon(Icons.clear),
              onPressed: () {
                _controller.clear();
                setState(() => _query = '');
              },
            ),
        ],
      ),
      body: switch (index) {
        AsyncError(:final error) => Center(
          child: Padding(
            padding: const EdgeInsets.all(24),
            child: Text('${l10n.dataUnavailable}\n$error'),
          ),
        ),
        AsyncData() => _results(
          context,
          coordinates: coordinates,
          matches: matches,
          region: region,
        ),
        _ => Center(child: Text(l10n.loading)),
      },
    );
  }

  Widget _results(
    BuildContext context, {
    required GeoPoint? coordinates,
    required List<Comune> matches,
    required RegionConfig? region,
  }) {
    final l10n = AppLocalizations.of(context);
    final theme = Theme.of(context);

    if (_query.trim().isEmpty) {
      return Padding(
        padding: const EdgeInsets.all(24),
        child: Text(l10n.searchHelp, style: theme.textTheme.bodyMedium),
      );
    }

    final outsideRegion =
        coordinates != null &&
        region != null &&
        !region.bounds.contains(coordinates);

    return ListView(
      children: [
        if (coordinates != null)
          ListTile(
            leading: const Icon(Icons.my_location),
            title: Text(l10n.searchCoordinatesResult),
            subtitle: Text(
              '${coordinates.latitude.toStringAsFixed(4)}, '
              '${coordinates.longitude.toStringAsFixed(4)}'
              // Saying so beats letting them travel to an empty map.
              '${outsideRegion ? '\n${l10n.searchOutsideRegion}' : ''}',
              style: outsideRegion
                  ? TextStyle(color: theme.colorScheme.error)
                  : null,
            ),
            onTap: () => Navigator.of(context).pop(
              SearchResult(
                point: coordinates,
                label:
                    '${coordinates.latitude.toStringAsFixed(4)}, '
                    '${coordinates.longitude.toStringAsFixed(4)}',
              ),
            ),
          ),

        if (coordinates != null && matches.isNotEmpty) const Divider(),

        if (matches.isNotEmpty)
          Padding(
            padding: const EdgeInsets.fromLTRB(16, 12, 16, 4),
            child: Text(
              l10n.searchComuniCount(matches.length),
              style: theme.textTheme.labelMedium?.copyWith(
                color: theme.colorScheme.primary,
              ),
            ),
          ),

        for (final comune in matches)
          ListTile(
            leading: const Icon(Icons.location_city),
            title: Text(comune.name),
            subtitle: Text(comune.province),
            onTap: () =>
                Navigator.of(context)
                    .pop(SearchResult(point: comune.point, label: comune.name)),
          ),

        if (matches.isEmpty && coordinates == null)
          Padding(
            padding: const EdgeInsets.all(24),
            child: Column(
              crossAxisAlignment: CrossAxisAlignment.start,
              children: [
                Text(l10n.searchNoResults, style: theme.textTheme.titleSmall),
                const SizedBox(height: 8),
                Text(l10n.searchHelp, style: theme.textTheme.bodySmall),
              ],
            ),
          ),
      ],
    );
  }
}