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

import '../products/product_provider.dart';
import 'recognition_service.dart';

/// Editable confirmation screen shown after receipt/products recognition.
/// The user can adjust quantities, units, remove items, then batch-add to pantry.
class RecognitionConfirmScreen extends ConsumerStatefulWidget {
  const RecognitionConfirmScreen({super.key, required this.items});

  final List<RecognizedItem> items;

  @override
  ConsumerState<RecognitionConfirmScreen> createState() =>
      _RecognitionConfirmScreenState();
}

class _RecognitionConfirmScreenState
    extends ConsumerState<RecognitionConfirmScreen> {
  late final List<_EditableItem> _items;
  bool _saving = false;

  static const _units = ['г', 'кг', 'мл', 'л', 'шт', 'уп'];

  @override
  void initState() {
    super.initState();
    _items = widget.items
        .map((item) => _EditableItem(
              name: item.name,
              quantity: item.quantity,
              unit: _mapUnit(item.unit),
              category: item.category,
              mappingId: item.mappingId,
              storageDays: item.storageDays,
              confidence: item.confidence,
            ))
        .toList();
  }

  String _mapUnit(String unit) {
    // Backend may return 'pcs', 'g', 'kg', etc. — normalise to display units.
    switch (unit.toLowerCase()) {
      case 'g':
        return 'г';
      case 'kg':
        return 'кг';
      case 'ml':
        return 'мл';
      case 'l':
        return 'л';
      case 'pcs':
      case 'шт':
        return 'шт';
      case 'уп':
        return 'уп';
      default:
        return unit;
    }
  }

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(
        title: Text('Найдено ${_items.length} продуктов'),
        actions: [
          if (_items.isNotEmpty)
            TextButton(
              onPressed: _saving ? null : _addAll,
              child: const Text('Добавить всё'),
            ),
        ],
      ),
      body: _items.isEmpty
          ? _EmptyState(onBack: () => Navigator.pop(context))
          : ListView.builder(
              padding: const EdgeInsets.only(bottom: 80),
              itemCount: _items.length,
              itemBuilder: (_, i) => _ItemTile(
                item: _items[i],
                units: _units,
                onDelete: () => setState(() => _items.removeAt(i)),
                onChanged: () => setState(() {}),
              ),
            ),
      floatingActionButton: _items.isEmpty
          ? null
          : FloatingActionButton.extended(
              onPressed: _saving ? null : _addAll,
              icon: _saving
                  ? const SizedBox(
                      width: 20,
                      height: 20,
                      child: CircularProgressIndicator(strokeWidth: 2),
                    )
                  : const Icon(Icons.add_shopping_cart),
              label: const Text('В запасы'),
            ),
    );
  }

  Future<void> _addAll() async {
    setState(() => _saving = true);
    try {
      for (final item in _items) {
        await ref.read(productsProvider.notifier).create(
              name: item.name,
              quantity: item.quantity,
              unit: item.unit,
              category: item.category,
              storageDays: item.storageDays,
              mappingId: item.mappingId,
            );
      }
      if (mounted) {
        ScaffoldMessenger.of(context).showSnackBar(
          SnackBar(
            content: Text('Добавлено ${_items.length} продуктов'),
          ),
        );
        // Pop back to products screen.
        int count = 0;
        Navigator.popUntil(context, (_) => count++ >= 2);
      }
    } catch (_) {
      if (mounted) {
        ScaffoldMessenger.of(context).showSnackBar(
          const SnackBar(content: Text('Не удалось добавить продукты')),
        );
      }
    } finally {
      if (mounted) setState(() => _saving = false);
    }
  }
}

// ---------------------------------------------------------------------------
// Editable item model
// ---------------------------------------------------------------------------

class _EditableItem {
  String name;
  double quantity;
  String unit;
  final String category;
  final String? mappingId;
  final int storageDays;
  final double confidence;

  _EditableItem({
    required this.name,
    required this.quantity,
    required this.unit,
    required this.category,
    this.mappingId,
    required this.storageDays,
    required this.confidence,
  });
}

// ---------------------------------------------------------------------------
// Item tile with inline editing
// ---------------------------------------------------------------------------

class _ItemTile extends StatefulWidget {
  const _ItemTile({
    required this.item,
    required this.units,
    required this.onDelete,
    required this.onChanged,
  });

  final _EditableItem item;
  final List<String> units;
  final VoidCallback onDelete;
  final VoidCallback onChanged;

  @override
  State<_ItemTile> createState() => _ItemTileState();
}

class _ItemTileState extends State<_ItemTile> {
  late final _qtyController =
      TextEditingController(text: _formatQty(widget.item.quantity));

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

  String _formatQty(double v) =>
      v == v.roundToDouble() ? v.toInt().toString() : v.toStringAsFixed(1);

  @override
  Widget build(BuildContext context) {
    final theme = Theme.of(context);
    final conf = widget.item.confidence;
    final confColor = conf >= 0.8
        ? Colors.green
        : conf >= 0.5
            ? Colors.orange
            : Colors.red;

    return Dismissible(
      key: ValueKey(widget.item.name),
      direction: DismissDirection.endToStart,
      background: Container(
        color: theme.colorScheme.error,
        alignment: Alignment.centerRight,
        padding: const EdgeInsets.only(right: 20),
        child: Icon(Icons.delete_outline, color: theme.colorScheme.onError),
      ),
      onDismissed: (_) => widget.onDelete(),
      child: Padding(
        padding: const EdgeInsets.symmetric(horizontal: 16, vertical: 8),
        child: Row(
          children: [
            Expanded(
              child: Column(
                crossAxisAlignment: CrossAxisAlignment.start,
                children: [
                  Text(widget.item.name,
                      style: theme.textTheme.bodyLarge),
                  Row(
                    children: [
                      Container(
                        width: 8,
                        height: 8,
                        decoration: BoxDecoration(
                          color: confColor,
                          shape: BoxShape.circle,
                        ),
                      ),
                      const SizedBox(width: 4),
                      Text(
                        '${(conf * 100).toInt()}% уверенность',
                        style: theme.textTheme.labelSmall
                            ?.copyWith(color: confColor),
                      ),
                    ],
                  ),
                ],
              ),
            ),
            const SizedBox(width: 8),
            SizedBox(
              width: 72,
              child: TextField(
                controller: _qtyController,
                keyboardType:
                    const TextInputType.numberWithOptions(decimal: true),
                textAlign: TextAlign.center,
                decoration: const InputDecoration(
                  isDense: true,
                  contentPadding: EdgeInsets.symmetric(vertical: 8),
                  border: OutlineInputBorder(),
                ),
                onChanged: (v) {
                  final parsed = double.tryParse(v);
                  if (parsed != null) {
                    widget.item.quantity = parsed;
                    widget.onChanged();
                  }
                },
              ),
            ),
            const SizedBox(width: 8),
            DropdownButton<String>(
              value: widget.units.contains(widget.item.unit)
                  ? widget.item.unit
                  : widget.units.last,
              underline: const SizedBox(),
              items: widget.units
                  .map((u) => DropdownMenuItem(value: u, child: Text(u)))
                  .toList(),
              onChanged: (v) {
                if (v != null) {
                  setState(() => widget.item.unit = v);
                  widget.onChanged();
                }
              },
            ),
            IconButton(
              icon: const Icon(Icons.close),
              onPressed: widget.onDelete,
            ),
          ],
        ),
      ),
    );
  }
}

// ---------------------------------------------------------------------------
// Empty state
// ---------------------------------------------------------------------------

class _EmptyState extends StatelessWidget {
  const _EmptyState({required this.onBack});

  final VoidCallback onBack;

  @override
  Widget build(BuildContext context) {
    return Center(
      child: Column(
        mainAxisSize: MainAxisSize.min,
        children: [
          const Icon(Icons.search_off, size: 64),
          const SizedBox(height: 12),
          const Text('Продукты не найдены'),
          const SizedBox(height: 16),
          FilledButton(onPressed: onBack, child: const Text('Назад')),
        ],
      ),
    );
  }
}