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

import '../../../core/api/api_error_mapper.dart';
import '../../../core/ui/async_state_views.dart';
import '../../auth/data/auth_providers.dart';
import '../data/inventory_providers.dart';
import '../domain/inventory_item.dart';

class InventoryScreen extends ConsumerWidget {
  const InventoryScreen({super.key});

  static const _locationOptions = <String>['', 'Kyl', 'Frys', 'Skafferi'];
  static const _sortOptions = <({String value, String label})>[
    (value: '', label: 'Senast tillagda'),
    (value: 'nameAsc', label: 'Namn A-O'),
    (value: 'bestBeforeAsc', label: 'Bast fore stigande'),
    (value: 'bestBeforeDesc', label: 'Bast fore fallande'),
  ];

  @override
  Widget build(BuildContext context, WidgetRef ref) {
    final location = ref.watch(inventoryLocationFilterProvider);
    final sort = ref.watch(inventorySortFilterProvider);
    final inventoryAsync = ref.watch(inventoryProvider);

    return inventoryAsync.when(
      loading: () => const LoadingStateView(label: 'Laddar inventarie...'),
      error: (e, _) => ErrorStateView(
        message: mapErrorToUserMessage(e),
        onRetry: () => ref.invalidate(inventoryProvider),
      ),
      data: (items) {
        final filterSection = Padding(
          padding: const EdgeInsets.fromLTRB(12, 12, 12, 4),
          child: Column(
            crossAxisAlignment: CrossAxisAlignment.start,
            children: [
              const Text(
                'Filter och sortering',
                style: TextStyle(fontWeight: FontWeight.w600),
              ),
              const SizedBox(height: 8),
              Wrap(
                spacing: 8,
                runSpacing: 8,
                children: _locationOptions
                    .map(
                      (option) => ChoiceChip(
                        label: Text(option.isEmpty ? 'Alla' : option),
                        selected: location == option,
                        onSelected: (_) => ref
                            .read(inventoryLocationFilterProvider.notifier)
                            .state = option,
                      ),
                    )
                    .toList(),
              ),
              const SizedBox(height: 8),
              DropdownButtonFormField<String>(
                value: sort,
                isExpanded: true,
                decoration: const InputDecoration(
                  labelText: 'Sortering',
                  border: OutlineInputBorder(),
                ),
                items: _sortOptions
                    .map(
                      (option) => DropdownMenuItem<String>(
                        value: option.value,
                        child: Text(option.label),
                      ),
                    )
                    .toList(),
                onChanged: (value) {
                  ref.read(inventorySortFilterProvider.notifier).state =
                      value ?? '';
                },
              ),
            ],
          ),
        );

        if (items.isEmpty) {
          return Stack(
            children: [
              ListView(
                padding: const EdgeInsets.only(bottom: 88),
                children: [
                  filterSection,
                  const EmptyStateView(title: 'Inventariet ar tomt.'),
                ],
              ),
              Positioned(
                right: 16,
                bottom: 16,
                child: FloatingActionButton.extended(
                  onPressed: () => context.push('/inventory/create'),
                  icon: const Icon(Icons.add),
                  label: const Text('Lägg till'),
                ),
              ),
            ],
          );
        }
        return Stack(
          children: [
            ListView.separated(
              padding: const EdgeInsets.only(bottom: 88),
              itemCount: items.length + 1,
              separatorBuilder: (_, __) => const Divider(height: 1),
              itemBuilder: (context, index) {
                if (index == 0) return filterSection;
                final item = items[index - 1];
                return _InventoryTile(item: item);
              },
            ),
            Positioned(
              right: 16,
              bottom: 16,
              child: FloatingActionButton.extended(
                onPressed: () => context.push('/inventory/create'),
                icon: const Icon(Icons.add),
                label: const Text('Lägg till'),
              ),
            ),
          ],
        );
      },
    );
  }
}

class _InventoryTile extends StatelessWidget {
  final InventoryItem item;

  const _InventoryTile({required this.item});

  @override
  Widget build(BuildContext context) {
    final subtitle = [
      '${item.quantity} ${item.unit}',
      if (item.location != null && item.location!.isNotEmpty) item.location!,
      if (item.bestBeforeDate != null) 'Bäst före: ${_formatDate(item.bestBeforeDate!)}',
    ].join(' · ');

    return ListTile(
      title: Text(item.productName),
      subtitle: Text(subtitle),
      trailing: Row(
        mainAxisSize: MainAxisSize.min,
        children: [
          if (item.opened)
            const Padding(
              padding: EdgeInsets.only(right: 4),
              child: Chip(
                label: Text('Oppnad'),
                padding: EdgeInsets.zero,
                visualDensity: VisualDensity.compact,
              ),
            ),
          Tooltip(
            message: 'Konsumera',
            child: IconButton(
              icon: const Icon(Icons.remove_circle_outline),
              onPressed: () => context.push('/inventory/${item.id}/consume'),
            ),
          ),
          Tooltip(
            message: 'Redigera',
            child: IconButton(
              icon: const Icon(Icons.edit_outlined),
              onPressed: () => context.push('/inventory/${item.id}/edit'),
            ),
          ),
          _DeleteInventoryButton(item: item),
        ],
      ),
      onTap: () => context.push('/inventory/${item.id}'),
    );
  }

  String _formatDate(String iso) {
    try {
      final dt = DateTime.parse(iso);
      return '${dt.year}-${dt.month.toString().padLeft(2, '0')}-${dt.day.toString().padLeft(2, '0')}';
    } catch (_) {
      return iso;
    }
  }
}

class _DeleteInventoryButton extends ConsumerWidget {
  final InventoryItem item;

  const _DeleteInventoryButton({required this.item});

  @override
  Widget build(BuildContext context, WidgetRef ref) {
    return Tooltip(
      message: 'Ta bort',
      child: IconButton(
        icon: const Icon(Icons.delete_outline, color: Colors.red),
        onPressed: () async {
          final confirmed = await showDialog<bool>(
            context: context,
            builder: (ctx) => AlertDialog(
              title: const Text('Ta bort inventariepost?'),
              content: Text('Vill du ta bort "${item.productName}"?'),
              actions: [
                TextButton(
                  onPressed: () => Navigator.pop(ctx, false),
                  child: const Text('Avbryt'),
                ),
                FilledButton(
                  onPressed: () => Navigator.pop(ctx, true),
                  child: const Text('Ta bort'),
                ),
              ],
            ),
          );

          if (confirmed != true) return;

          try {
            final token = await ref.read(authStateProvider.future);
            await ref
                .read(inventoryRepositoryProvider)
                .deleteInventoryItem(item.id, token: token);
            ref.invalidate(inventoryProvider);
          } catch (error) {
            if (!context.mounted) return;
            ScaffoldMessenger.of(context).showSnackBar(
              SnackBar(content: Text(mapErrorToUserMessage(error))),
            );
          }
        },
      ),
    );
  }
}