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

import 'dart:io';

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/discounted_price.dart';
import 'widgets/item_edit_sheet.dart';
import 'widgets/receipt_highlight_overlay.dart';
import 'widgets/store_tag.dart';
import 'widgets/tag_editor.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,
    this.ocrImageWidth,
    this.ocrImageHeight,
  });

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

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

class _ReviewScreenState extends State<ReviewScreen> {
  late List<LineItem> _items;
  late DateTime _shoppedAt;
  String? _supermarket;
  String? _customStore;
  bool _saving = false;
  final _tripName = TextEditingController();
  List<String> _tags = [];
  List<String> _tagSuggestions = [];
  String? _highlightedItemId;
  bool _showTripExtras = 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;
    }
    widget.repository
        .getUsedShopTags()
        .then((tags) {
          if (mounted) setState(() => _tagSuggestions = tags);
        })
        .catchError((_) {});
  }

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

  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;
  }

  bool get _hasReceipt {
    final path = widget.imagePath;
    return path != null && path.isNotEmpty && File(path).existsSync();
  }

  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.copyWith(
            sourceBounds: existing.sourceBounds,
            needsManualReview: false,
          );
        }
      }
      _highlightedItemId = null;
    });
  }

  void _toggleHighlight(LineItem item) {
    if (item.sourceBounds == null || !_hasReceipt) return;
    setState(() {
      _highlightedItemId = _highlightedItemId == item.id ? null : item.id;
    });
  }

  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> _openReceiptPanel() async {
    final path = widget.imagePath;
    if (path == null || path.isEmpty) return;
    final file = File(path);
    if (!file.existsSync()) return;

    final highlighted = _highlightedItemId == null
        ? null
        : _items.cast<LineItem?>().firstWhere(
            (item) => item?.id == _highlightedItemId,
            orElse: () => null,
          );

    await showModalBottomSheet<void>(
      context: context,
      isScrollControlled: true,
      showDragHandle: true,
      builder: (context) {
        return SafeArea(
          child: Padding(
            padding: const EdgeInsets.fromLTRB(16, 0, 16, 16),
            child: Column(
              mainAxisSize: MainAxisSize.min,
              crossAxisAlignment: CrossAxisAlignment.stretch,
              children: [
                Text('Receipt', style: Theme.of(context).textTheme.titleMedium),
                const SizedBox(height: 12),
                if (highlighted?.sourceBounds != null)
                  ReceiptHighlightOverlay(
                    imagePath: path,
                    bounds: highlighted!.sourceBounds!,
                    maxHeight: 360,
                  )
                else
                  GestureDetector(
                    onTap: () async {
                      await showDialog<void>(
                        context: context,
                        builder: (ctx) => Dialog(
                          insetPadding: const EdgeInsets.all(16),
                          child: InteractiveViewer(
                            child: Image.file(file, fit: BoxFit.contain),
                          ),
                        ),
                      );
                    },
                    child: ClipRRect(
                      borderRadius: BorderRadius.circular(12),
                      child: Image.file(file, fit: BoxFit.contain, height: 360),
                    ),
                  ),
              ],
            ),
          ),
        );
      },
    );
  }

  Future<void> _openOcrPanel() async {
    if (widget.rawText.isEmpty) return;
    await showModalBottomSheet<void>(
      context: context,
      isScrollControlled: true,
      showDragHandle: true,
      builder: (context) {
        return SafeArea(
          child: Padding(
            padding: const EdgeInsets.fromLTRB(16, 0, 16, 16),
            child: Column(
              mainAxisSize: MainAxisSize.min,
              crossAxisAlignment: CrossAxisAlignment.stretch,
              children: [
                Text('Raw OCR text', style: Theme.of(context).textTheme.titleMedium),
                const SizedBox(height: 12),
                ConstrainedBox(
                  constraints: BoxConstraints(
                    maxHeight: MediaQuery.sizeOf(context).height * 0.55,
                  ),
                  child: SingleChildScrollView(
                    child: SelectableText(widget.rawText),
                  ),
                ),
              ],
            ),
          ),
        );
      },
    );
  }

  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,
        name: _tripName.text,
        tags: _tags,
      );
      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!);
    }
    final flaggedCount =
        _items.where((item) => item.needsManualReview).length;
    final reviewMessage = flaggedCount > 0
        ? 'Some lines could not be parsed confidently — '
            '${flaggedCount == 1 ? '1 item is' : '$flaggedCount items are'} '
            'marked below. Check them against the receipt before saving.'
        : 'Item count or totals do not match the receipt. '
            'Check the items below before saving.';

    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(
                        reviewMessage,
                        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: Row(
                    mainAxisSize: MainAxisSize.min,
                    children: [
                      IconButton(
                        icon: Icon(
                          _showTripExtras
                              ? Icons.expand_less
                              : Icons.edit_note_outlined,
                        ),
                        tooltip: _showTripExtras
                            ? 'Hide trip name & tags'
                            : 'Trip name & tags',
                        onPressed: _saving
                            ? null
                            : () => setState(
                                () => _showTripExtras = !_showTripExtras,
                              ),
                      ),
                      const Icon(Icons.calendar_today_outlined),
                    ],
                  ),
                  title: Text(formatDate(_shoppedAt)),
                  subtitle: const Text('Shopping date'),
                  onTap: _saving ? null : _pickDate,
                ),
                if (_showTripExtras) ...[
                  const SizedBox(height: 8),
                  TextField(
                    controller: _tripName,
                    enabled: !_saving,
                    textCapitalization: TextCapitalization.sentences,
                    decoration: const InputDecoration(
                      labelText: 'Trip name',
                      hintText: 'Optional, e.g. Weekly shop',
                    ),
                  ),
                  const SizedBox(height: 12),
                  TagEditor(
                    tags: _tags,
                    suggestions: _tagSuggestions,
                    enabled: !_saving,
                    onChanged: (tags) => setState(() => _tags = tags),
                  ),
                  const SizedBox(height: 8),
                ],
              ],
            ),
          ),
          Expanded(
            child: CustomScrollView(
              slivers: [
                if (_items.isEmpty)
                  SliverFillRemaining(
                    hasScrollBody: false,
                    child: Center(
                      child: Text(
                        'No line items yet.\nAdd products for this trip.',
                        textAlign: TextAlign.center,
                        style: theme.textTheme.bodyLarge,
                      ),
                    ),
                  )
                else
                  SliverPadding(
                    padding: const EdgeInsets.fromLTRB(8, 0, 8, 8),
                    sliver: SliverList.separated(
                      itemCount: _items.length,
                      separatorBuilder: (_, _) => const SizedBox(height: 4),
                      itemBuilder: (context, index) {
                        final item = _items[index];
                        final flagged = item.needsManualReview;
                        final onReceipt = _highlightedItemId == item.id;
                        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(
                            shape: RoundedRectangleBorder(
                              borderRadius: BorderRadius.circular(12),
                              side: flagged
                                  ? BorderSide(
                                      color: theme.colorScheme.error
                                          .withValues(alpha: 0.55),
                                    )
                                  : BorderSide.none,
                            ),
                            tileColor: flagged
                                ? theme.colorScheme.errorContainer
                                    .withValues(alpha: 0.35)
                                : onReceipt
                                    ? theme.colorScheme.primaryContainer
                                        .withValues(alpha: 0.35)
                                    : null,
                            leading: item.sourceBounds != null && _hasReceipt
                                ? IconButton(
                                    icon: Icon(
                                      onReceipt
                                          ? Icons.visibility
                                          : Icons.visibility_outlined,
                                      size: 20,
                                    ),
                                    tooltip: 'Show on receipt',
                                    onPressed: _saving
                                        ? null
                                        : () => _toggleHighlight(item),
                                  )
                                : flagged
                                    ? Icon(
                                        Icons.flag_outlined,
                                        color: theme.colorScheme.error,
                                        size: 20,
                                      )
                                    : null,
                            title: Text(item.name),
                            subtitle: _itemSubtitle(item, flagged: flagged),
                            trailing: DiscountedPrice(item: item),
                            onTap: _saving ? null : () => _edit(existing: item),
                          ),
                        );
                      },
                    ),
                  ),
              ],
            ),
          ),
          if (_hasReceipt || widget.rawText.isNotEmpty)
            Padding(
              padding: const EdgeInsets.fromLTRB(16, 0, 16, 4),
              child: Row(
                children: [
                  if (_hasReceipt)
                    Expanded(
                      child: OutlinedButton.icon(
                        onPressed: _saving ? null : _openReceiptPanel,
                        icon: const Icon(Icons.receipt_long_outlined, size: 18),
                        label: const Text('Receipt'),
                      ),
                    ),
                  if (_hasReceipt && widget.rawText.isNotEmpty)
                    const SizedBox(width: 8),
                  if (widget.rawText.isNotEmpty)
                    Expanded(
                      child: OutlinedButton.icon(
                        onPressed: _saving ? null : _openOcrPanel,
                        icon: const Icon(Icons.text_snippet_outlined, size: 18),
                        label: const Text('OCR text'),
                      ),
                    ),
                ],
              ),
            ),
          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, {bool flagged = false}) {
    final parts = <String>[];
    if (flagged) parts.add('Needs review');
    if (item.quantity != null) {
      parts.add('${item.quantity} × ${formatEuro(item.unitPrice ?? 0)}');
    }
    if (parts.isEmpty) return null;
    return Text(parts.join(' · '));
  }
}