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

class TractionPage extends StatefulWidget {
  const TractionPage({
    super.key,
    this.selectionMode = false,
    this.onSelect,
    this.selectedKeys = const {},
  });

  final bool selectionMode;
  final ValueChanged<LocoSummary>? onSelect;
  final Set<String> selectedKeys;

  @override
  State<TractionPage> createState() => _TractionPageState();
}

class _TractionPageState extends State<TractionPage> {
  final _classController = TextEditingController();
  final _classFocusNode = FocusNode();
  final _numberController = TextEditingController();
  final _nameController = TextEditingController();
  bool _mileageFirst = true;
  bool _initialised = false;
  bool _showAdvancedFilters = false;
  String? _selectedClass;
  late Set<String> _selectedKeys;

  final Map<String, TextEditingController> _dynamicControllers = {};
  final Map<String, String?> _enumSelections = {};

  @override
  void initState() {
    super.initState();
    _classController.addListener(_onClassTextChanged);
  }

  @override
  void didChangeDependencies() {
    super.didChangeDependencies();
    if (!_initialised) {
      _initialised = true;
      _selectedKeys = {...widget.selectedKeys};
      WidgetsBinding.instance.addPostFrameCallback((_) {
        final data = context.read<DataService>();
        data.fetchClassList();
        data.fetchEventFields();
        _refreshTraction();
      });
    }
  }

  @override
  void dispose() {
    _classController.removeListener(_onClassTextChanged);
    _classController.dispose();
    _classFocusNode.dispose();
    _numberController.dispose();
    _nameController.dispose();
    for (final controller in _dynamicControllers.values) {
      controller.dispose();
    }
    super.dispose();
  }

  bool get _hasFilters {
    final dynamicFieldsUsed =
        _dynamicControllers.values.any(
          (controller) => controller.text.trim().isNotEmpty,
        ) ||
        _enumSelections.values.any(
          (value) => (value ?? '').toString().trim().isNotEmpty,
        );

    return [
          _selectedClass,
          _classController.text,
          _numberController.text,
          _nameController.text,
        ].any((value) => (value ?? '').toString().trim().isNotEmpty) ||
        dynamicFieldsUsed;
  }

  Future<void> _refreshTraction({bool append = false}) async {
    final data = context.read<DataService>();
    final filters = <String, dynamic>{};
    final name = _nameController.text.trim();
    if (name.isNotEmpty) filters['name'] = name;
    _dynamicControllers.forEach((key, controller) {
      final value = controller.text.trim();
      if (value.isNotEmpty) filters[key] = value;
    });
    _enumSelections.forEach((key, value) {
      if (value != null && value.toString().trim().isNotEmpty) {
        filters[key] = value;
      }
    });
    final hadOnly = !_hasFilters;
    await data.fetchTraction(
      hadOnly: hadOnly,
      locoClass: _selectedClass ?? _classController.text.trim(),
      locoNumber: _numberController.text.trim(),
      offset: append ? data.traction.length : 0,
      append: append,
      filters: filters,
      mileageFirst: _mileageFirst,
    );
  }

  void _clearFilters() {
    for (final controller in [
      _classController,
      _numberController,
      _nameController,
    ]) {
      controller.clear();
    }
    for (final controller in _dynamicControllers.values) {
      controller.clear();
    }
    _enumSelections.clear();
    setState(() {
      _selectedClass = null;
      _mileageFirst = true;
    });
    _refreshTraction();
  }

  void _onClassTextChanged() {
    if (_selectedClass != null &&
        _classController.text.trim() != (_selectedClass ?? '')) {
      setState(() {
        _selectedClass = null;
      });
    }
  }

  List<EventField> _activeEventFields(List<EventField> fields) {
    return fields
        .where(
          (field) => ![
            'class',
            'number',
            'name',
            'build date',
            'build_date',
          ].contains(field.name.toLowerCase()),
        )
        .toList();
  }

  void _ensureControllersForFields(List<EventField> fields) {
    for (final field in fields) {
      if (field.enumValues != null) {
        _enumSelections.putIfAbsent(field.name, () => null);
      } else {
        _dynamicControllers.putIfAbsent(
          field.name,
          () => TextEditingController(),
        );
      }
    }
  }

  @override
  Widget build(BuildContext context) {
    final data = context.watch<DataService>();
    final traction = data.traction;
    final classOptions = data.locoClasses;
    final isMobile = MediaQuery.of(context).size.width < 700;
    _ensureControllersForFields(data.eventFields);
    final extraFields = _activeEventFields(data.eventFields);

    final listView = RefreshIndicator(
      onRefresh: _refreshTraction,
      child: ListView(
        padding: const EdgeInsets.all(16),
        physics: const AlwaysScrollableScrollPhysics(),
        children: [
          Row(
            crossAxisAlignment: CrossAxisAlignment.start,
            children: [
              Expanded(
                child: Column(
                  crossAxisAlignment: CrossAxisAlignment.start,
                  children: [
                    Text(
                      'Fleet',
                      style: Theme.of(context).textTheme.labelMedium,
                    ),
                    const SizedBox(height: 2),
                    Text(
                      'Traction',
                      style: Theme.of(context).textTheme.headlineSmall,
                    ),
                  ],
                ),
              ),
              Row(
                mainAxisSize: MainAxisSize.min,
                children: [
                  IconButton(
                    tooltip: 'Refresh',
                    onPressed: _refreshTraction,
                    icon: const Icon(Icons.refresh),
                  ),
                  const SizedBox(width: 8),
                  FilledButton.icon(
                    onPressed: () async {
                      final createdClass = await context.push<String>(
                        '/traction/new',
                      );
                      if (createdClass != null && createdClass.isNotEmpty) {
                        _classController.text = createdClass;
                        _selectedClass = createdClass;
                        if (mounted) {
                          _refreshTraction();
                        }
                      } else if (mounted && createdClass == '') {
                        _refreshTraction();
                      }
                    },
                    icon: const Icon(Icons.add),
                    label: const Text('New Traction'),
                  ),
                ],
              ),
            ],
          ),
          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(
                        onPressed: _clearFilters,
                        child: const Text('Clear'),
                      ),
                    ],
                  ),
                  const SizedBox(height: 8),
                  Wrap(
                    spacing: 12,
                    runSpacing: 12,
                    children: [
                      SizedBox(
                        width: isMobile ? double.infinity : 240,
                        child: RawAutocomplete<String>(
                          textEditingController: _classController,
                          focusNode: _classFocusNode,
                          optionsBuilder: (TextEditingValue textEditingValue) {
                            final query = textEditingValue.text.toLowerCase();
                            if (query.isEmpty) {
                              return classOptions;
                            }
                            return classOptions.where(
                              (c) => c.toLowerCase().contains(query),
                            );
                          },
                          fieldViewBuilder:
                              (
                                context,
                                controller,
                                focusNode,
                                onFieldSubmitted,
                              ) {
                                return TextField(
                                  controller: controller,
                                  focusNode: focusNode,
                                  decoration: const InputDecoration(
                                    labelText: 'Class',
                                    border: OutlineInputBorder(),
                                  ),
                                  onSubmitted: (_) => _refreshTraction(),
                                );
                              },
                          optionsViewBuilder: (context, onSelected, options) {
                            final optionList = options.toList();
                            if (optionList.isEmpty) {
                              return const SizedBox.shrink();
                            }
                            final maxWidth = isMobile
                                ? MediaQuery.of(context).size.width - 64
                                : 240.0;
                            return Align(
                              alignment: Alignment.topLeft,
                              child: Material(
                                elevation: 4,
                                child: ConstrainedBox(
                                  constraints: BoxConstraints(
                                    maxWidth: maxWidth,
                                    maxHeight: 240,
                                  ),
                                  child: ListView.builder(
                                    padding: EdgeInsets.zero,
                                    shrinkWrap: true,
                                    itemCount: optionList.length,
                                    itemBuilder: (context, index) {
                                      final option = optionList[index];
                                      return ListTile(
                                        title: Text(option),
                                        onTap: () => onSelected(option),
                                      );
                                    },
                                  ),
                                ),
                              ),
                            );
                          },
                          onSelected: (String selection) {
                            setState(() {
                              _selectedClass = selection;
                              _classController.text = selection;
                            });
                            _refreshTraction();
                          },
                        ),
                      ),
                      SizedBox(
                        width: isMobile ? double.infinity : 220,
                        child: TextField(
                          controller: _numberController,
                          decoration: const InputDecoration(
                            labelText: 'Number',
                            border: OutlineInputBorder(),
                          ),
                          onSubmitted: (_) => _refreshTraction(),
                        ),
                      ),
                      SizedBox(
                        width: isMobile ? double.infinity : 220,
                        child: TextField(
                          controller: _nameController,
                          decoration: const InputDecoration(
                            labelText: 'Name',
                            border: OutlineInputBorder(),
                          ),
                          onSubmitted: (_) => _refreshTraction(),
                        ),
                      ),
                      FilterChip(
                        label: Text(
                          _mileageFirst ? 'Mileage first' : 'Number order',
                        ),
                        selected: _mileageFirst,
                        onSelected: (v) {
                          setState(() => _mileageFirst = v);
                          _refreshTraction();
                        },
                      ),
                      TextButton.icon(
                        onPressed: () => setState(
                          () => _showAdvancedFilters = !_showAdvancedFilters,
                        ),
                        icon: Icon(
                          _showAdvancedFilters
                              ? Icons.expand_less
                              : Icons.expand_more,
                        ),
                        label: Text(
                          _showAdvancedFilters
                              ? 'Hide filters'
                              : 'More filters',
                        ),
                      ),
                      ElevatedButton.icon(
                        onPressed: _refreshTraction,
                        icon: const Icon(Icons.search),
                        label: const Text('Search'),
                      ),
                    ],
                  ),
                  AnimatedCrossFade(
                    crossFadeState: _showAdvancedFilters
                        ? CrossFadeState.showFirst
                        : CrossFadeState.showSecond,
                    duration: const Duration(milliseconds: 200),
                    firstChild: Padding(
                      padding: const EdgeInsets.only(top: 12.0),
                      child: data.isEventFieldsLoading
                          ? const Center(
                              child: Padding(
                                padding: EdgeInsets.all(8.0),
                                child: CircularProgressIndicator(
                                  strokeWidth: 2,
                                ),
                              ),
                            )
                          : extraFields.isEmpty
                          ? const Text('No extra filters available right now.')
                          : Wrap(
                              spacing: 12,
                              runSpacing: 12,
                              children: extraFields
                                  .map(
                                    (field) => _buildFilterInput(
                                      context,
                                      field,
                                      isMobile,
                                    ),
                                  )
                                  .toList(),
                            ),
                    ),
                    secondChild: const SizedBox.shrink(),
                  ),
                ],
              ),
            ),
          ),
          const SizedBox(height: 12),
          if (data.isTractionLoading && traction.isEmpty)
            const Center(
              child: Padding(
                padding: EdgeInsets.symmetric(vertical: 24.0),
                child: CircularProgressIndicator(),
              ),
            )
          else if (traction.isEmpty)
            Card(
              child: Padding(
                padding: const EdgeInsets.all(16.0),
                child: Column(
                  crossAxisAlignment: CrossAxisAlignment.start,
                  children: [
                    Text(
                      'No traction found',
                      style: Theme.of(context).textTheme.titleMedium?.copyWith(
                        fontWeight: FontWeight.w700,
                      ),
                    ),
                    const SizedBox(height: 8),
                    const Text('Try relaxing the filters or sync again.'),
                  ],
                ),
              ),
            )
          else
            Column(
              children: [
                ...traction.map((loco) => _buildTractionCard(context, loco)),
                if (data.tractionHasMore || data.isTractionLoading)
                  Padding(
                    padding: const EdgeInsets.only(top: 8.0),
                    child: OutlinedButton.icon(
                      onPressed: data.isTractionLoading
                          ? null
                          : () => _refreshTraction(append: true),
                      icon: data.isTractionLoading
                          ? const SizedBox(
                              height: 14,
                              width: 14,
                              child: CircularProgressIndicator(strokeWidth: 2),
                            )
                          : const Icon(Icons.expand_more),
                      label: Text(
                        data.isTractionLoading ? 'Loading...' : 'Load more',
                      ),
                    ),
                  ),
              ],
            ),
        ],
      ),
    );

    if (widget.selectionMode) {
      return Scaffold(
        appBar: AppBar(
          leadingWidth: 140,
          leading: Padding(
            padding: const EdgeInsets.only(left: 8.0),
            child: TextButton.icon(
              onPressed: () => Navigator.of(context).pop(),
              icon: const Icon(Icons.arrow_back),
              label: const Text('Back'),
              style: TextButton.styleFrom(
                padding: const EdgeInsets.symmetric(
                  horizontal: 12,
                  vertical: 10,
                ),
                foregroundColor: Theme.of(context).colorScheme.onSurface,
              ),
            ),
          ),
          title: null,
        ),
        body: listView,
      );
    }

    return listView;
  }

  Widget _buildTractionCard(BuildContext context, LocoSummary loco) {
    final keyVal = '${loco.locoClass}-${loco.number}';
    final isSelected = _selectedKeys.contains(keyVal);
    final status = loco.status ?? 'Unknown';
    final operatorName = loco.operator ?? '';
    final domain = loco.domain ?? '';
    final hasMileageOrTrips = _hasMileageOrTrips(loco);
    final statusColors = _statusChipColors(context, status);
    return Card(
      child: Padding(
        padding: const EdgeInsets.all(12.0),
        child: Column(
          crossAxisAlignment: CrossAxisAlignment.start,
          children: [
            Row(
              mainAxisAlignment: MainAxisAlignment.spaceBetween,
              children: [
                Column(
                  crossAxisAlignment: CrossAxisAlignment.start,
                  children: [
                    Row(
                      children: [
                        Text(
                          loco.number,
                          style: Theme.of(context).textTheme.headlineSmall
                              ?.copyWith(fontWeight: FontWeight.w800),
                        ),
                        if (hasMileageOrTrips)
                          Padding(
                            padding: const EdgeInsets.only(left: 6.0),
                            child: Icon(
                              Icons.check_circle,
                              size: 18,
                              color: Colors.green.shade600,
                            ),
                          ),
                      ],
                    ),
                    Text(
                      loco.locoClass,
                      style: Theme.of(context).textTheme.labelMedium,
                    ),
                    if ((loco.name ?? '').isNotEmpty)
                      Padding(
                        padding: const EdgeInsets.only(top: 2.0),
                        child: Text(
                          loco.name ?? '',
                          style: Theme.of(context).textTheme.bodyMedium
                              ?.copyWith(fontStyle: FontStyle.italic),
                        ),
                      ),
                  ],
                ),
                Chip(
                  label: Text(status),
                  backgroundColor: statusColors.$1,
                  labelStyle: TextStyle(color: statusColors.$2),
                ),
              ],
            ),
            const SizedBox(height: 8),
            Row(
              children: [
                TextButton.icon(
                  onPressed: () => _showLocoInfo(loco),
                  icon: const Icon(Icons.info_outline),
                  label: const Text('Details'),
                ),
                const SizedBox(width: 8),
                TextButton.icon(
                  onPressed: () => _openTimeline(loco),
                  icon: const Icon(Icons.timeline),
                  label: const Text('Timeline'),
                ),
                const Spacer(),
                if (widget.selectionMode)
                  TextButton.icon(
                    onPressed: () {
                      if (widget.onSelect != null) {
                        widget.onSelect!(loco);
                      }
                      setState(() {
                        if (isSelected) {
                          _selectedKeys.remove(keyVal);
                        } else {
                          _selectedKeys.add(keyVal);
                        }
                      });
                    },
                    icon: Icon(
                      isSelected
                          ? Icons.remove_circle_outline
                          : Icons.add_circle_outline,
                    ),
                    label: Text(isSelected ? 'Remove' : 'Add to entry'),
                  ),
              ],
            ),
            Wrap(
              spacing: 8,
              runSpacing: 4,
              children: [
                _statPill(
                  context,
                  label: 'Miles',
                  value: _formatNumber(loco.mileage),
                ),
                _statPill(
                  context,
                  label: 'Trips',
                  value: (loco.trips ?? loco.journeys ?? 0).toString(),
                ),
                if (operatorName.isNotEmpty)
                  _statPill(context, label: 'Operator', value: operatorName),
                if (domain.isNotEmpty)
                  _statPill(context, label: 'Domain', value: domain),
              ],
            ),
          ],
        ),
      ),
    );
  }

  Widget _statPill(
    BuildContext context, {
    required String label,
    required String value,
  }) {
    return Container(
      padding: const EdgeInsets.symmetric(horizontal: 10, vertical: 6),
      decoration: BoxDecoration(
        color: Theme.of(context).colorScheme.surfaceContainerHighest,
        borderRadius: BorderRadius.circular(10),
      ),
      child: Row(
        mainAxisSize: MainAxisSize.min,
        children: [
          Text('$label: ', style: Theme.of(context).textTheme.labelSmall),
          Text(
            value,
            style: Theme.of(
              context,
            ).textTheme.labelSmall?.copyWith(fontWeight: FontWeight.w700),
          ),
        ],
      ),
    );
  }

  (Color, Color) _statusChipColors(BuildContext context, String status) {
    final scheme = Theme.of(context).colorScheme;
    final isDark = scheme.brightness == Brightness.dark;
    Color blend(
      Color base, {
      double bgOpacity = 0.18,
      double fgOpacity = 0.82,
    }) {
      final bg = Color.alphaBlend(
        base.withOpacity(isDark ? bgOpacity + 0.07 : bgOpacity),
        scheme.surface,
      );
      final fg = Color.alphaBlend(
        base.withOpacity(isDark ? fgOpacity : fgOpacity * 0.8),
        scheme.onSurface,
      );
      return Color.lerp(bg, fg, 0.0) ?? bg;
    }

    Color background;
    Color foreground;
    final key = status.toLowerCase();

    if (key.contains('scrap')) {
      background = blend(Colors.red);
      foreground = Colors.red.shade200.withOpacity(isDark ? 0.85 : 0.9);
    } else if (key.contains('active')) {
      background = blend(scheme.primary);
      foreground = scheme.primary.withOpacity(isDark ? 0.9 : 0.8);
    } else if (key.contains('withdrawn')) {
      background = blend(Colors.amber);
      foreground = Colors.amber.shade800.withOpacity(isDark ? 0.9 : 0.8);
    } else if (key.contains('stored') || key.contains('unknown')) {
      background = blend(Colors.grey);
      foreground = Colors.grey.shade700.withOpacity(isDark ? 0.85 : 0.75);
    } else {
      background = scheme.surfaceContainerHighest;
      foreground = scheme.onSurface;
    }
    return (background, foreground);
  }

  void _openTimeline(LocoSummary loco) {
    final label = '${loco.locoClass} ${loco.number}'.trim();
    context.push(
      '/traction/${loco.id}/timeline',
      extra: {'label': label},
    );
  }

  Future<void> _showLocoInfo(LocoSummary loco) async {
    await showModalBottomSheet(
      context: context,
      isScrollControlled: true,
      builder: (ctx) {
        return DraggableScrollableSheet(
          expand: false,
          maxChildSize: 0.9,
          initialChildSize: 0.65,
          builder: (_, controller) {
            return Padding(
              padding: const EdgeInsets.all(16.0),
              child: Column(
                crossAxisAlignment: CrossAxisAlignment.start,
                children: [
                  Row(
                    children: [
                      IconButton(
                        icon: const Icon(Icons.close),
                        onPressed: () => Navigator.of(ctx).pop(),
                      ),
                      const SizedBox(width: 8),
                      Column(
                        crossAxisAlignment: CrossAxisAlignment.start,
                        children: [
                          Row(
                            children: [
                              Text(
                                loco.number,
                                style: Theme.of(context).textTheme.titleLarge
                                    ?.copyWith(fontWeight: FontWeight.w800),
                              ),
                              if (_hasMileageOrTrips(loco))
                                Padding(
                                  padding: const EdgeInsets.only(left: 6.0),
                                  child: Icon(
                                    Icons.check_circle,
                                    size: 18,
                                    color: Colors.green.shade600,
                                  ),
                                ),
                            ],
                          ),
                          Text(
                            loco.locoClass,
                            style: Theme.of(context).textTheme.labelMedium,
                          ),
                        ],
                      ),
                    ],
                  ),
                  if ((loco.name ?? '').isNotEmpty)
                    Padding(
                      padding: const EdgeInsets.only(left: 52.0, bottom: 12),
                      child: Text(
                        loco.name ?? '',
                        style: Theme.of(context).textTheme.bodyMedium,
                      ),
                    ),
                  const SizedBox(height: 4),
                  Expanded(
                    child: ListView(
                      controller: controller,
                      children: [
                        _detailRow('Status', loco.status ?? 'Unknown'),
                        _detailRow('Operator', loco.operator ?? ''),
                        _detailRow('Domain', loco.domain ?? ''),
                        _detailRow('Owner', loco.owner ?? ''),
                        _detailRow('Livery', loco.livery ?? ''),
                        _detailRow('Location', loco.location ?? ''),
                        _detailRow('Mileage', _formatNumber(loco.mileage ?? 0)),
                        _detailRow(
                          'Trips',
                          (loco.trips ?? loco.journeys ?? 0).toString(),
                        ),
                        _detailRow('EVN', loco.evn ?? ''),
                        if (loco.notes != null && loco.notes!.isNotEmpty)
                          _detailRow('Notes', loco.notes!),
                      ],
                    ),
                  ),
                ],
              ),
            );
          },
        );
      },
    );
  }

  Widget _detailRow(String label, String value) {
    if (value.isEmpty) return const SizedBox.shrink();
    return Padding(
      padding: const EdgeInsets.symmetric(vertical: 6.0),
      child: Row(
        children: [
          SizedBox(
            width: 110,
            child: Text(
              label,
              style: Theme.of(
                context,
              ).textTheme.labelMedium?.copyWith(fontWeight: FontWeight.w600),
            ),
          ),
          Expanded(
            child: Text(value, style: Theme.of(context).textTheme.bodyMedium),
          ),
        ],
      ),
    );
  }

  String _formatNumber(double? value) {
    if (value == null) return '0';
    return value.toStringAsFixed(1);
  }

  bool _hasMileageOrTrips(LocoSummary loco) {
    final mileage = loco.mileage ?? 0;
    final trips = loco.trips ?? loco.journeys ?? 0;
    return mileage > 0 || trips > 0;
  }

  Widget _buildFilterInput(
    BuildContext context,
    EventField field,
    bool isMobile,
  ) {
    final width = isMobile ? double.infinity : 220.0;
    if (field.enumValues != null && field.enumValues!.isNotEmpty) {
      final options = field.enumValues!
          .map((e) => e.toString())
          .toSet()
          .toList();
      final currentValue = _enumSelections[field.name];
      final safeValue = options.contains(currentValue) ? currentValue : null;
      return SizedBox(
        width: width,
        child: DropdownButtonFormField<String?>(
          value: safeValue,
          decoration: InputDecoration(
            labelText: field.display,
            border: const OutlineInputBorder(),
          ),
          items: [
            const DropdownMenuItem(value: null, child: Text('Any')),
            ...options.map(
              (value) => DropdownMenuItem(value: value, child: Text(value)),
            ),
          ],
          onChanged: (val) {
            setState(() {
              _enumSelections[field.name] = val;
            });
            _refreshTraction();
          },
        ),
      );
    }

    final controller =
        _dynamicControllers[field.name] ?? TextEditingController();
    _dynamicControllers[field.name] = controller;
    TextInputType? inputType;
    if (field.type != null) {
      final type = field.type!.toLowerCase();
      if (type.contains('int') ||
          type.contains('num') ||
          type.contains('double')) {
        inputType = const TextInputType.numberWithOptions(decimal: true);
      }
    }

    return SizedBox(
      width: width,
      child: TextField(
        controller: controller,
        keyboardType: inputType,
        decoration: InputDecoration(
          labelText: field.display,
          border: const OutlineInputBorder(),
        ),
        onSubmitted: (_) => _refreshTraction(),
      ),
    );
  }
}