import 'package:flutter/material.dart';
import 'package:mileograph_flutter/services/dataService.dart';
import 'package:provider/provider.dart';

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

  @override
  State<LegsPage> createState() => _LegsPageState();
}

class _LegsPageState extends State<LegsPage> {
  int _sortDirection = 0;
  DateTime? _startDate;
  DateTime? _endDate;
  bool _initialised = false;

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

  Future<void> _refreshLegs() async {
    final data = context.read<DataService>();
    await data.fetchLegs(
      sortDirection: _sortDirection,
      dateRangeStart: _formatDate(_startDate),
      dateRangeEnd: _formatDate(_endDate),
    );
  }

  Future<void> _loadMore() async {
    final data = context.read<DataService>();
    await data.fetchLegs(
      sortDirection: _sortDirection,
      dateRangeStart: _formatDate(_startDate),
      dateRangeEnd: _formatDate(_endDate),
      offset: data.legs.length,
      append: true,
    );
  }

  double _pageMileage(List legs) {
    return legs.fold<double>(
      0,
      (prev, leg) => prev + (leg.mileage as double? ?? 0),
    );
  }

  Future<void> _pickDate({required bool start}) async {
    final initial = start
        ? _startDate ?? DateTime.now()
        : _endDate ?? _startDate ?? DateTime.now();
    final picked = await showDatePicker(
      context: context,
      initialDate: initial,
      firstDate: DateTime(1970),
      lastDate: DateTime.now().add(const Duration(days: 365)),
    );
    if (picked != null) {
      setState(() {
        if (start) {
          _startDate = picked;
          if (_endDate != null && _endDate!.isBefore(picked)) {
            _endDate = picked;
          }
        } else {
          _endDate = picked;
        }
      });
      await _refreshLegs();
    }
  }

  void _clearFilters() {
    setState(() {
      _startDate = null;
      _endDate = null;
      _sortDirection = 0;
    });
    _refreshLegs();
  }

  @override
  Widget build(BuildContext context) {
    final data = context.watch<DataService>();
    final legs = data.legs;
    final pageMileage = _pageMileage(legs);

    return RefreshIndicator(
      onRefresh: _refreshLegs,
      child: ListView(
        padding: const EdgeInsets.all(16),
        physics: const AlwaysScrollableScrollPhysics(),
        children: [
          Row(
            mainAxisAlignment: MainAxisAlignment.spaceBetween,
            children: [
              Column(
                crossAxisAlignment: CrossAxisAlignment.start,
                children: [
                  Text('Logbook',
                      style: Theme.of(context).textTheme.labelMedium),
                  const SizedBox(height: 2),
                  Text('Entries',
                      style: Theme.of(context).textTheme.headlineSmall),
                ],
              ),
              Card(
                child: Padding(
                  padding:
                      const EdgeInsets.symmetric(horizontal: 12, vertical: 8),
                  child: Column(
                    crossAxisAlignment: CrossAxisAlignment.end,
                    children: [
                      Text('Page mileage',
                          style: Theme.of(context).textTheme.labelSmall),
                      Text('${pageMileage.toStringAsFixed(1)} mi',
                          style: Theme.of(context)
                              .textTheme
                              .titleMedium
                              ?.copyWith(fontWeight: FontWeight.w700)),
                    ],
                  ),
                ),
              ),
            ],
          ),
          const SizedBox(height: 12),
          Card(
            child: Padding(
              padding: const EdgeInsets.all(12),
              child: Column(
                crossAxisAlignment: CrossAxisAlignment.stretch,
                children: [
                  Row(
                    mainAxisAlignment: MainAxisAlignment.spaceBetween,
                    children: [
                      Text('Filters',
                          style: Theme.of(context).textTheme.titleMedium),
                      TextButton.icon(
                        onPressed: _clearFilters,
                        icon: const Icon(Icons.refresh),
                        label: const Text('Clear'),
                      ),
                    ],
                  ),
                  const SizedBox(height: 8),
                  Wrap(
                    spacing: 12,
                    runSpacing: 12,
                    crossAxisAlignment: WrapCrossAlignment.center,
                    children: [
                      SegmentedButton<int>(
                        segments: const [
                          ButtonSegment(
                            value: 0,
                            icon: Icon(Icons.south),
                            label: Text('Newest first'),
                          ),
                          ButtonSegment(
                            value: 1,
                            icon: Icon(Icons.north),
                            label: Text('Oldest first'),
                          ),
                        ],
                        selected: {_sortDirection},
                        onSelectionChanged: (selection) {
                          setState(() => _sortDirection = selection.first);
                          _refreshLegs();
                        },
                      ),
                      FilledButton.tonalIcon(
                        onPressed: () => _pickDate(start: true),
                        icon: const Icon(Icons.calendar_month),
                        label: Text(
                          _startDate == null
                              ? 'Start date'
                              : _formatDate(_startDate!)!,
                        ),
                      ),
                      FilledButton.tonalIcon(
                        onPressed: () => _pickDate(start: false),
                        icon: const Icon(Icons.event),
                        label: Text(
                          _endDate == null
                              ? 'End date'
                              : _formatDate(_endDate!)!,
                        ),
                      ),
                    ],
                  ),
                ],
              ),
            ),
          ),
          const SizedBox(height: 12),
          if (data.isLegsLoading && legs.isEmpty)
            const Center(
              child: Padding(
                padding: EdgeInsets.symmetric(vertical: 24.0),
                child: CircularProgressIndicator(),
              ),
            )
          else if (legs.isEmpty)
            Card(
              child: Padding(
                padding: const EdgeInsets.all(16.0),
                child: Column(
                  crossAxisAlignment: CrossAxisAlignment.start,
                  children: [
                    Text(
                      'No entries found',
                      style: Theme.of(context)
                          .textTheme
                          .titleMedium
                          ?.copyWith(fontWeight: FontWeight.w700),
                    ),
                    const SizedBox(height: 8),
                    const Text('Adjust the filters or add a new leg.'),
                  ],
                ),
              ),
            )
          else
            Column(
              children: [
                ...legs.map((leg) => Card(
                      child: ListTile(
                        leading: const Icon(Icons.train),
                        title: Text('${leg.start} → ${leg.end}'),
                        subtitle: Column(
                          crossAxisAlignment: CrossAxisAlignment.start,
                          children: [
                            Text(_formatDateTime(leg.beginTime)),
                            if (leg.headcode.isNotEmpty)
                              Text('Headcode: ${leg.headcode}'),
                            if (leg.route.isNotEmpty)
                              Text(
                                leg.route,
                                maxLines: 1,
                                overflow: TextOverflow.ellipsis,
                              ),
                          ],
                        ),
                        trailing: Column(
                          mainAxisAlignment: MainAxisAlignment.center,
                          children: [
                            Text('${leg.mileage.toStringAsFixed(1)} mi'),
                            Text(
                              leg.network,
                              style: Theme.of(context).textTheme.labelSmall,
                            ),
                          ],
                        ),
                        isThreeLine: true,
                      ),
                    )),
                const SizedBox(height: 8),
                if (data.legsHasMore || data.isLegsLoading)
                  Align(
                    alignment: Alignment.center,
                    child: OutlinedButton.icon(
                      onPressed:
                          data.isLegsLoading ? null : () => _loadMore(),
                      icon: data.isLegsLoading
                          ? const SizedBox(
                              height: 14,
                              width: 14,
                              child: CircularProgressIndicator(strokeWidth: 2),
                            )
                          : const Icon(Icons.expand_more),
                      label: Text(
                        data.isLegsLoading ? 'Loading...' : 'Load more',
                      ),
                    ),
                  ),
              ],
            ),
        ],
      ),
    );
  }

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

  String _formatDateTime(DateTime date) {
    final dateStr = _formatDate(date) ?? '';
    final timeStr =
        '${date.hour.toString().padLeft(2, '0')}:${date.minute.toString().padLeft(2, '0')}';
    return '$dateStr · $timeStr';
  }
}