/// Editable list of parsed receipt lines before they are saved as a shop trip.
library;

import 'package:flutter/material.dart';

import 'models/line_item.dart';
import 'services/app_settings.dart';
import 'services/product_repository.dart';
import 'utils/dates.dart';
import 'utils/money.dart';
import 'utils/supermarkets.dart';
import 'widgets/item_edit_sheet.dart';
import 'widgets/store_tag.dart';

class ReviewScreen extends StatefulWidget {
  const ReviewScreen({
    super.key,
    required this.items,
    required this.rawText,
    required this.repository,
    this.imagePath,
    this.supermarketNames = kSupermarkets,
    this.needsReview = false,
    this.detectedStore,
  });

  final List<LineItem> items;
  final String rawText;
  final ProductRepository repository;
  final String? imagePath;
  final List<String> supermarketNames;
  final bool needsReview;
  final String? detectedStore;

  @override
  State<ReviewScreen> createState() => _ReviewScreenState();
}

class _ReviewScreenState extends State<ReviewScreen> {
  late List<LineItem> _items;
  late DateTime _shoppedAt;
  String? _supermarket;
  String? _customStore;
  bool _saving = false;

  @override
  void initState() {
    super.initState();
    _items = List<LineItem>.from(widget.items);
    _shoppedAt = DateTime.now();
    final detected = detectSupermarket(
      widget.rawText,
      names: widget.supermarketNames,
    );
    if (detected != null) {
      _supermarket = detected;
    } else if (widget.detectedStore != null) {
      _supermarket = widget.detectedStore;
    }
  }

  String? get _resolvedSupermarket {
    if (_supermarket == null) return null;
    if (_supermarket == kOtherSupermarket) {
      final custom = _customStore?.trim();
      if (custom == null || custom.isEmpty) return null;
      return custom;
    }
    return _supermarket;
  }

  Future<void> _edit({LineItem? existing}) async {
    final result = await showItemEditSheet(context, item: existing);
    if (result == null || !mounted) return;

    setState(() {
      if (existing == null) {
        _items.add(result);
      } else {
        final index = _items.indexWhere((item) => item.id == existing.id);
        if (index >= 0) {
          _items[index] = result;
        }
      }
    });
  }

  Future<void> _pickDate() async {
    final picked = await showDatePicker(
      context: context,
      initialDate: _shoppedAt,
      firstDate: DateTime(2018),
      lastDate: DateTime.now().add(const Duration(days: 1)),
    );
    if (picked == null || !mounted) return;
    setState(() => _shoppedAt = picked);
  }

  Future<void> _confirm() async {
    final supermarket = _resolvedSupermarket;
    if (supermarket == null) {
      ScaffoldMessenger.of(context)
          .showSnackBar(const SnackBar(content: Text('Select a supermarket.')));
      return;
    }
    if (_items.isEmpty) {
      ScaffoldMessenger.of(context).showSnackBar(
        const SnackBar(content: Text('Add at least one product.')),
      );
      return;
    }

    setState(() => _saving = true);
    try {
      await widget.repository.saveShop(
        supermarket: supermarket,
        shoppedAt: _shoppedAt,
        items: _items,
        receiptImagePath: widget.imagePath,
      );
      if (!mounted) return;
      Navigator.of(context).pop(true);
    } catch (_) {
      if (!mounted) return;
      setState(() => _saving = false);
      ScaffoldMessenger.of(context).showSnackBar(
        const SnackBar(content: Text('Could not save this shopping trip.')),
      );
    }
  }

  @override
  Widget build(BuildContext context) {
    final theme = Theme.of(context);
    final total = _items.fold<double>(0, (sum, item) => sum + item.price);
    final settings = SettingsScope.maybeOf(context);
    final stores = settings?.supermarkets ?? kDefaultSupermarkets;
    final names = [
      ...{...widget.supermarketNames, ...stores.map((s) => s.name)},
    ];
    if (_supermarket != null && !names.contains(_supermarket)) {
      names.add(_supermarket!);
    }

    return Scaffold(
      appBar: AppBar(
        title: Text(
          widget.rawText.isEmpty && widget.imagePath == null
              ? 'New trip'
              : 'Review items',
        ),
      ),
      body: Column(
        children: [
          Padding(
            padding: const EdgeInsets.fromLTRB(16, 8, 16, 0),
            child: Column(
              crossAxisAlignment: CrossAxisAlignment.stretch,
              children: [
                if (widget.needsReview) ...[
                  Material(
                    color: theme.colorScheme.errorContainer,
                    borderRadius: BorderRadius.circular(12),
                    child: Padding(
                      padding: const EdgeInsets.all(12),
                      child: Text(
                        'Parsed totals do not match the receipt. Check the items before saving.',
                        style: theme.textTheme.bodyMedium?.copyWith(
                          color: theme.colorScheme.onErrorContainer,
                        ),
                      ),
                    ),
                  ),
                  const SizedBox(height: 12),
                ],
                DropdownButtonFormField<String>(
                  key: ValueKey(_supermarket),
                  initialValue: _supermarket,
                  hint: const Text('Select supermarket'),
                  decoration: const InputDecoration(labelText: 'Supermarket'),
                  items: [
                    for (final store in names)
                      DropdownMenuItem(
                        value: store,
                        child: StoreTag(
                          name: store,
                          stores: stores,
                          compact: true,
                        ),
                      ),
                  ],
                  onChanged: _saving
                      ? null
                      : (value) => setState(() => _supermarket = value),
                ),
                if (_supermarket == kOtherSupermarket) ...[
                  const SizedBox(height: 12),
                  TextField(
                    enabled: !_saving,
                    textCapitalization: TextCapitalization.words,
                    decoration: const InputDecoration(labelText: 'Store name'),
                    onChanged: (value) => _customStore = value,
                  ),
                ],
                const SizedBox(height: 8),
                ListTile(
                  contentPadding: EdgeInsets.zero,
                  leading: const Icon(Icons.calendar_today_outlined),
                  title: Text(formatDate(_shoppedAt)),
                  subtitle: const Text('Shopping date'),
                  onTap: _saving ? null : _pickDate,
                ),
              ],
            ),
          ),
          Expanded(
            child: _items.isEmpty
                ? Center(
                    child: Text(
                      'No line items yet.\nAdd products for this trip.',
                      textAlign: TextAlign.center,
                      style: theme.textTheme.bodyLarge,
                    ),
                  )
                : ListView.separated(
                    padding: const EdgeInsets.fromLTRB(8, 8, 8, 8),
                    itemCount: _items.length,
                    separatorBuilder: (_, _) => const SizedBox(height: 4),
                    itemBuilder: (context, index) {
                      final item = _items[index];
                      return Dismissible(
                        key: ValueKey(item.id),
                        direction: DismissDirection.endToStart,
                        background: Container(
                          alignment: Alignment.centerRight,
                          padding: const EdgeInsets.only(right: 20),
                          decoration: BoxDecoration(
                            color: theme.colorScheme.errorContainer,
                            borderRadius: BorderRadius.circular(12),
                          ),
                          child: Icon(
                            Icons.delete_outline,
                            color: theme.colorScheme.onErrorContainer,
                          ),
                        ),
                        onDismissed: (_) {
                          setState(() {
                            _items.removeWhere((row) => row.id == item.id);
                          });
                        },
                        child: ListTile(
                          title: Text(item.name),
                          subtitle: _itemSubtitle(item),
                          trailing: Text(
                            formatEuro(item.price),
                            style: theme.textTheme.titleMedium,
                          ),
                          onTap: _saving ? null : () => _edit(existing: item),
                        ),
                      );
                    },
                  ),
          ),
          if (widget.rawText.isNotEmpty)
            ExpansionTile(
              title: const Text('Raw OCR text'),
              children: [
                ConstrainedBox(
                  constraints: const BoxConstraints(maxHeight: 180),
                  child: SingleChildScrollView(
                    padding: const EdgeInsets.fromLTRB(16, 0, 16, 16),
                    child: SelectableText(widget.rawText),
                  ),
                ),
              ],
            ),
          SafeArea(
            child: Padding(
              padding: const EdgeInsets.fromLTRB(16, 8, 16, 16),
              child: Column(
                crossAxisAlignment: CrossAxisAlignment.stretch,
                children: [
                  OutlinedButton.icon(
                    onPressed: _saving ? null : () => _edit(),
                    icon: const Icon(Icons.add),
                    label: const Text('Add item'),
                  ),
                  const SizedBox(height: 8),
                  FilledButton(
                    onPressed: _saving ? null : _confirm,
                    child: Text(
                      _saving ? 'Saving…' : 'Save trip · ${formatEuro(total)}',
                    ),
                  ),
                ],
              ),
            ),
          ),
        ],
      ),
    );
  }

  Widget? _itemSubtitle(LineItem item) {
    final parts = [
      if (item.quantity != null)
        '${item.quantity} × ${formatEuro(item.unitPrice ?? 0)}',
      if (item.discount != 0) 'Discount ${formatEuro(item.discount.abs())}',
    ];
    if (parts.isEmpty) return null;
    return Text(parts.join(' · '));
  }
}