/// One shopping trip: receipt photo, supermarket, products and costs.
library;

import 'dart:io';

import 'package:flutter/material.dart';

import 'models/line_item.dart';
import 'models/shop.dart';
import 'product_detail_screen.dart';
import 'services/product_repository.dart';
import 'services/receipt_capture.dart';
import 'utils/dates.dart';
import 'utils/money.dart';
import 'widgets/confirm_dialog.dart';
import 'widgets/item_edit_sheet.dart';
import 'widgets/name_dialog.dart';
import 'widgets/tag_editor.dart';

class ShopDetailScreen extends StatefulWidget {
  const ShopDetailScreen({
    super.key,
    required this.repository,
    required this.shopId,
  });

  final ProductRepository repository;
  final int shopId;

  @override
  State<ShopDetailScreen> createState() => _ShopDetailScreenState();
}

class _ShopDetailScreenState extends State<ShopDetailScreen> {
  Shop? _shop;
  List<ShopItem>? _items;
  Object? _error;
  bool _editing = false;
  List<String> _tagSuggestions = [];
  int _loadToken = 0;
  bool _addingReceipt = false;

  @override
  void initState() {
    super.initState();
    widget.repository.addListener(_load);
    _load();
    widget.repository
        .getUsedShopTags()
        .then((tags) {
          if (mounted) setState(() => _tagSuggestions = tags);
        })
        .catchError((_) {});
  }

  @override
  void dispose() {
    widget.repository.removeListener(_load);
    super.dispose();
  }

  Future<void> _load() async {
    final token = ++_loadToken;
    try {
      final shop = await widget.repository.getShop(widget.shopId);
      if (shop == null) throw StateError('Shop not found');
      final items = await widget.repository.getShopItems(widget.shopId);
      if (!mounted || token != _loadToken) return;
      setState(() {
        _shop = shop;
        _items = items;
        _error = null;
      });
    } catch (error) {
      if (!mounted || token != _loadToken) return;
      setState(() => _error = error);
    }
  }

  Future<void> _openReceipt(File file) async {
    await showDialog<void>(
      context: context,
      builder: (context) {
        return Dialog(
          insetPadding: const EdgeInsets.all(16),
          child: InteractiveViewer(
            child: Image.file(file, fit: BoxFit.contain),
          ),
        );
      },
    );
  }

  Future<void> _openProduct(int productId) async {
    await Navigator.of(context).push<void>(
      MaterialPageRoute(
        builder: (_) => ProductDetailScreen(
          repository: widget.repository,
          productId: productId,
        ),
      ),
    );
  }

  Future<void> _addItem() async {
    final shop = _shop;
    if (shop == null) return;
    final result = await showItemEditSheet(context);
    if (result == null || !mounted) return;

    final pendingId = -DateTime.now().microsecondsSinceEpoch;
    final pending = ShopItem(
      id: pendingId,
      shopId: shop.id,
      name: result.name,
      price: result.price,
      quantity: result.quantity,
      unitPrice: result.unitPrice,
    );
    setState(() {
      _items = [...?_items, pending];
      _shop = Shop(
        id: shop.id,
        supermarket: shop.supermarket,
        shoppedAt: shop.shoppedAt,
        total: roundMoney(shop.total + result.price),
        itemCount: shop.itemCount + 1,
        name: shop.name,
        receiptImagePath: shop.receiptImagePath,
        tags: shop.tags,
      );
    });

    try {
      final saved = await widget.repository.addShopItem(
        shopId: shop.id,
        item: result,
      );
      if (!mounted) return;
      setState(() {
        _items = [
          for (final entry in _items ?? const <ShopItem>[])
            if (entry.id == pendingId) saved else entry,
        ];
      });
    } catch (_) {
      if (!mounted) return;
      ScaffoldMessenger.of(context).showSnackBar(
        const SnackBar(content: Text('Could not add this product.')),
      );
      _load();
    }
  }

  Future<void> _addFromReceipt() async {
    final shop = _shop;
    if (shop == null || _addingReceipt) return;
    setState(() => _addingReceipt = true);
    try {
      final captured = await captureAndParseReceipt(context);
      if (captured == null || !mounted) return;

      var added = 0;
      for (final item in captured.items) {
        await widget.repository.addShopItem(shopId: shop.id, item: item);
        added++;
      }
      if (!mounted) return;
      await _load();
      if (!mounted) return;
      ScaffoldMessenger.of(context).showSnackBar(
        SnackBar(
          content: Text(
            added == 1
                ? 'Added 1 item from receipt.'
                : 'Added $added items from receipt.',
          ),
        ),
      );
    } catch (_) {
      if (!mounted) return;
      ScaffoldMessenger.of(context).showSnackBar(
        const SnackBar(content: Text('Could not add items from this receipt.')),
      );
      _load();
    } finally {
      if (mounted) setState(() => _addingReceipt = false);
    }
  }

  Future<void> _editItem(ShopItem item) async {
    final result = await showItemEditSheet(
      context,
      item: LineItem(
        id: '${item.id}',
        name: item.name,
        price: item.price,
        quantity: item.quantity,
        unitPrice: item.unitPrice,
      ),
    );
    if (result == null || !mounted) return;
    await widget.repository.updateShopItem(
      id: item.id,
      name: result.name,
      price: result.price,
      quantity: result.quantity,
      unitPrice: result.unitPrice,
      clearQuantity: result.quantity == null,
    );
    if (mounted) _load();
  }

  Future<void> _removeItem(ShopItem item) async {
    final confirmed = await confirmAction(
      context,
      title: 'Remove item?',
      message:
          '"${item.name}" will be removed from this trip. The product stays in your catalog.',
      confirmLabel: 'Remove',
    );
    if (!confirmed || !mounted) return;

    final isLastItem = (_items?.length ?? 0) == 1;
    final shop = _shop;

    setState(() {
      _items = [
        for (final entry in _items ?? const <ShopItem>[])
          if (entry.id != item.id) entry,
      ];
      if (shop != null) {
        _shop = Shop(
          id: shop.id,
          supermarket: shop.supermarket,
          shoppedAt: shop.shoppedAt,
          total: roundMoney(shop.total - item.price),
          itemCount: shop.itemCount - 1,
          name: shop.name,
          receiptImagePath: shop.receiptImagePath,
          tags: shop.tags,
        );
      }
    });
    try {
      await widget.repository.deleteShopItem(item.id);
      if (!mounted || !isLastItem || shop == null) return;
      await _confirmRemoveEmptyTrip(shop);
    } catch (_) {
      if (mounted) _load();
    }
  }

  Future<void> _confirmRemoveEmptyTrip(Shop shop) async {
    final removeTrip = await confirmAction(
      context,
      title: 'Remove trip?',
      message:
          'This trip has no products left. Remove it from your shop log? '
          'Products from this trip stay in your catalog.',
      confirmLabel: 'Remove trip',
    );
    if (!mounted) return;
    if (!removeTrip) return;

    try {
      await widget.repository.deleteShop(shop.id);
      if (mounted) Navigator.of(context).pop();
    } catch (_) {
      if (!mounted) return;
      ScaffoldMessenger.of(context).showSnackBar(
        const SnackBar(content: Text('Could not remove this trip.')),
      );
      _load();
    }
  }

  Future<void> _editName(Shop shop) async {
    final name = await showNameDialog(
      context,
      title: 'Trip name',
      label: 'Name',
      initial: shop.name,
      allowEmpty: true,
    );
    if (name == null || !mounted) return;
    await widget.repository.updateShop(
      id: shop.id,
      name: name,
      clearName: name.isEmpty,
    );
    if (mounted) _load();
  }

  Future<void> _editDate(Shop shop) async {
    final picked = await showDatePicker(
      context: context,
      initialDate: shop.shoppedAt,
      firstDate: DateTime(2018),
      lastDate: DateTime.now().add(const Duration(days: 1)),
    );
    if (picked == null || !mounted) return;
    await widget.repository.updateShop(
      id: shop.id,
      shoppedAt: DateTime(picked.year, picked.month, picked.day),
    );
    if (mounted) _load();
  }

  Future<void> _setTags(Shop shop, List<String> tags) async {
    await widget.repository.updateShop(id: shop.id, tags: tags);
    if (mounted) _load();
  }

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

  @override
  Widget build(BuildContext context) {
    final theme = Theme.of(context);

    return Scaffold(
      appBar: AppBar(
        title: const Text('Shopping trip'),
        actions: [
          IconButton(
            tooltip: _editing ? 'Done' : 'Edit',
            onPressed: () => setState(() => _editing = !_editing),
            icon: Icon(_editing ? Icons.check : Icons.edit_outlined),
          ),
        ],
      ),
      floatingActionButtonLocation: FloatingActionButtonLocation.centerFloat,
      floatingActionButton: _editing
          ? Padding(
              padding: const EdgeInsets.symmetric(horizontal: 16),
              child: Row(
                children: [
                  Expanded(
                    child: FilledButton.tonalIcon(
                      onPressed: _addingReceipt ? null : _addFromReceipt,
                      icon: _addingReceipt
                          ? const SizedBox(
                              width: 18,
                              height: 18,
                              child: CircularProgressIndicator(strokeWidth: 2),
                            )
                          : const Icon(Icons.receipt_long_outlined),
                      label: const Text('Add receipt'),
                      style: FilledButton.styleFrom(
                        minimumSize: const Size.fromHeight(52),
                      ),
                    ),
                  ),
                  const SizedBox(width: 12),
                  Expanded(
                    child: FilledButton.icon(
                      onPressed: _addingReceipt ? null : _addItem,
                      icon: const Icon(Icons.add),
                      label: const Text('Add product'),
                      style: FilledButton.styleFrom(
                        minimumSize: const Size.fromHeight(52),
                      ),
                    ),
                  ),
                ],
              ),
            )
          : null,
      body: Builder(
        builder: (context) {
          if (_error != null) {
            return Center(
              child: Text(
                'Could not load this trip.',
                style: theme.textTheme.bodyLarge,
              ),
            );
          }
          final shop = _shop;
          final items = _items;
          if (shop == null || items == null) {
            return const Center(child: CircularProgressIndicator());
          }

          final receipt = shop.receiptImagePath;
          final receiptFile = receipt == null ? null : File(receipt);
          final hasReceipt = receiptFile != null && receiptFile.existsSync();

          return ListView(
            padding: const EdgeInsets.fromLTRB(16, 8, 16, 96),
            children: [
              if (_editing)
                ListTile(
                  contentPadding: EdgeInsets.zero,
                  title: Text(
                    shop.name?.isNotEmpty == true
                        ? shop.name!
                        : 'Add a trip name',
                  ),
                  subtitle: const Text('Optional name for this shop log'),
                  trailing: const Icon(Icons.edit_outlined),
                  onTap: () => _editName(shop),
                )
              else
                Text(shop.displayName, style: theme.textTheme.headlineMedium),
              if (_editing || (shop.name != null && shop.name!.isNotEmpty)) ...[
                const SizedBox(height: 4),
                Text(shop.supermarket, style: theme.textTheme.titleMedium),
              ],
              const SizedBox(height: 4),
              if (_editing)
                ListTile(
                  contentPadding: EdgeInsets.zero,
                  title: Text(formatDate(shop.shoppedAt)),
                  subtitle: const Text('Trip date'),
                  trailing: const Icon(Icons.calendar_today_outlined),
                  onTap: () => _editDate(shop),
                )
              else
                Text(
                  formatDate(shop.shoppedAt),
                  style: theme.textTheme.bodyLarge,
                ),
              if (_editing) ...[
                const SizedBox(height: 16),
                TagEditor(
                  tags: shop.tags,
                  suggestions: _tagSuggestions,
                  onChanged: (tags) => _setTags(shop, tags),
                ),
              ] else if (shop.tags.isNotEmpty) ...[
                const SizedBox(height: 12),
                TagChips(tags: shop.tags),
              ],
              if (hasReceipt) ...[
                const SizedBox(height: 16),
                GestureDetector(
                  onTap: () => _openReceipt(receiptFile),
                  child: ClipRRect(
                    borderRadius: BorderRadius.circular(16),
                    child: Image.file(
                      receiptFile,
                      height: 180,
                      width: double.infinity,
                      fit: BoxFit.cover,
                      cacheWidth: 900,
                    ),
                  ),
                ),
              ],
              const SizedBox(height: 24),
              Text('Products', style: theme.textTheme.titleMedium),
              const SizedBox(height: 8),
              if (items.isEmpty)
                Text(
                  'No items on this trip.',
                  style: theme.textTheme.bodyLarge,
                ),
              for (final item in items)
                ListTile(
                  contentPadding: EdgeInsets.zero,
                  title: Text(item.name),
                  subtitle: _itemSubtitle(item),
                  trailing: _editing
                      ? Row(
                          mainAxisSize: MainAxisSize.min,
                          children: [
                            IconButton(
                              tooltip: 'Edit',
                              visualDensity: VisualDensity.compact,
                              onPressed: () => _editItem(item),
                              icon: const Icon(Icons.edit_outlined),
                            ),
                            IconButton(
                              tooltip: 'Remove',
                              visualDensity: VisualDensity.compact,
                              onPressed: () => _removeItem(item),
                              icon: const Icon(Icons.delete_outline),
                            ),
                          ],
                        )
                      : Text(
                          formatEuro(item.price),
                          style: theme.textTheme.titleMedium,
                        ),
                  onTap: _editing || item.productId == null
                      ? null
                      : () => _openProduct(item.productId!),
                ),
              const Divider(),
              ListTile(
                contentPadding: EdgeInsets.zero,
                title: Text('Total', style: theme.textTheme.titleMedium),
                trailing: Text(
                  formatEuro(shop.total),
                  style: theme.textTheme.titleLarge,
                ),
              ),
            ],
          );
        },
      ),
    );
  }
}