import 'package:flutter/material.dart';
import 'package:go_router/go_router.dart';
import '../../core/theme/app_theme.dart';
import '../../core/widgets/step_indicator.dart';
import '../../data/models/models.dart';
import '../../data/services/order_service.dart';

class SlotsScreen extends StatefulWidget {
  final int orderId;
  const SlotsScreen({super.key, required this.orderId});

  @override
  State<SlotsScreen> createState() => _SlotsScreenState();
}

class _SlotsScreenState extends State<SlotsScreen> {
  final _service = MockOrderService();
  Order? _order;
  List<StorageSlot> _slots = [];
  final Set<int> _selectedSlotIds = {};
  bool _loading = true;

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

  Future<void> _load() async {
    final results = await Future.wait([
      _service.getOrderDetail(widget.orderId),
      _service.getAvailableSlots(),
    ]);
    if (mounted) {
      setState(() {
        _order = results[0] as Order;
        _slots = results[1] as List<StorageSlot>;
        _loading = false;
      });
    }
  }

  bool get _needsFreezer => _order?.segments
          .expand((s) => s.items)
          .any((i) => i.type == ItemType.frozen && i.isCompleted) ??
      false;

  bool get _needsFridge => _order?.segments
          .expand((s) => s.items)
          .any((i) => i.type == ItemType.cold && i.isCompleted) ??
      false;

  List<StorageSlot> get _relevantSlots {
    return _slots.where((s) {
      if (s.type == StorageSlotType.cell) return true;
      if (s.type == StorageSlotType.freezer && _needsFreezer) return true;
      if (s.type == StorageSlotType.fridge && _needsFridge) return true;
      return false;
    }).toList();
  }

  Future<void> _confirmSlots() async {
    if (_selectedSlotIds.isEmpty) return;
    await _service.assignSlots(widget.orderId, _selectedSlotIds.toList());
    if (mounted) context.push('/orders/${widget.orderId}/handoff');
  }

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(
        title: Text(_order?.orderNumber ?? ''),
        leading: IconButton(icon: const Icon(Icons.arrow_back), onPressed: () => context.pop()),
      ),
      body: _loading
          ? const Center(child: CircularProgressIndicator())
          : Column(
              children: [
                const StepIndicator(currentStep: BatchStep.slots),
                Padding(
                  padding: const EdgeInsets.all(16),
                  child: Column(
                    crossAxisAlignment: CrossAxisAlignment.start,
                    children: [
                      const Text('Оберіть ячейки для зберігання',
                          style: TextStyle(fontSize: 16, fontWeight: FontWeight.bold)),
                      const SizedBox(height: 4),
                      Text(
                        'Обрано: ${_selectedSlotIds.length}',
                        style: const TextStyle(color: AppColors.textSecondary),
                      ),
                    ],
                  ),
                ),
                Expanded(
                  child: ListView(
                    padding: const EdgeInsets.symmetric(horizontal: 16),
                    children: [
                      _buildSlotGroup('Ячейки', StorageSlotType.cell),
                      if (_needsFreezer) _buildSlotGroup('Морозилка', StorageSlotType.freezer),
                      if (_needsFridge) _buildSlotGroup('Холодильник', StorageSlotType.fridge),
                    ],
                  ),
                ),
                SafeArea(
                  child: Padding(
                    padding: const EdgeInsets.all(16),
                    child: ElevatedButton(
                      onPressed: _selectedSlotIds.isEmpty ? null : _confirmSlots,
                      child: const Text('Далі: Видача'),
                    ),
                  ),
                ),
              ],
            ),
    );
  }

  Widget _buildSlotGroup(String title, StorageSlotType type) {
    final slots = _relevantSlots.where((s) => s.type == type).toList();
    if (slots.isEmpty) return const SizedBox.shrink();

    return Column(
      crossAxisAlignment: CrossAxisAlignment.start,
      children: [
        Padding(
          padding: const EdgeInsets.symmetric(vertical: 8),
          child: Text(title, style: const TextStyle(fontSize: 14, fontWeight: FontWeight.w600, color: AppColors.textSecondary)),
        ),
        GridView.builder(
          shrinkWrap: true,
          physics: const NeverScrollableScrollPhysics(),
          gridDelegate: const SliverGridDelegateWithFixedCrossAxisCount(
            crossAxisCount: 3,
            crossAxisSpacing: 8,
            mainAxisSpacing: 8,
            childAspectRatio: 1.5,
          ),
          itemCount: slots.length,
          itemBuilder: (context, i) {
            final slot = slots[i];
            final selected = _selectedSlotIds.contains(slot.id);
            return InkWell(
              borderRadius: BorderRadius.circular(10),
              onTap: () => setState(() {
                if (selected) {
                  _selectedSlotIds.remove(slot.id);
                } else {
                  _selectedSlotIds.add(slot.id);
                }
              }),
              child: AnimatedContainer(
                duration: const Duration(milliseconds: 150),
                decoration: BoxDecoration(
                  color: selected ? AppColors.primary : Colors.white,
                  borderRadius: BorderRadius.circular(10),
                  border: Border.all(
                    color: selected ? AppColors.primary : AppColors.divider,
                    width: 2,
                  ),
                ),
                child: Center(
                  child: Column(
                    mainAxisAlignment: MainAxisAlignment.center,
                    children: [
                      Icon(
                        type == StorageSlotType.cell
                            ? Icons.inbox
                            : type == StorageSlotType.freezer
                                ? Icons.ac_unit
                                : Icons.kitchen,
                        color: selected ? Colors.white : AppColors.primary,
                        size: 20,
                      ),
                      const SizedBox(height: 2),
                      Text(
                        slot.name,
                        style: TextStyle(
                          fontSize: 11,
                          fontWeight: FontWeight.w600,
                          color: selected ? Colors.white : AppColors.textPrimary,
                        ),
                        textAlign: TextAlign.center,
                      ),
                    ],
                  ),
                ),
              ),
            );
          },
        ),
        const SizedBox(height: 8),
      ],
    );
  }
}