/// Product: photo, name, favourite, price history chart, and notes.
library;

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

import 'models/product.dart';
import 'models/purchase.dart';
import 'services/app_settings.dart';
import 'services/product_repository.dart';
import 'shop_detail_screen.dart';
import 'utils/categories.dart';
import 'utils/dates.dart';
import 'utils/money.dart';
import 'utils/supermarkets.dart';
import 'widgets/price_chart.dart';
import 'widgets/product_image.dart';
import 'widgets/store_tag.dart';

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

  final ProductRepository repository;
  final int productId;

  @override
  State<ProductDetailScreen> createState() => _ProductDetailScreenState();
}

class _ProductDetailScreenState extends State<ProductDetailScreen> {
  late Future<({Product product, List<Purchase> purchases})> _future;
  late final TextEditingController _nameController;
  late final TextEditingController _notesController;
  final ImagePicker _picker = ImagePicker();
  bool _ready = false;

  @override
  void initState() {
    super.initState();
    _nameController = TextEditingController();
    _notesController = TextEditingController();
    _future = _load();
  }

  @override
  void dispose() {
    _saveNotes();
    _nameController.dispose();
    _notesController.dispose();
    super.dispose();
  }

  Future<({Product product, List<Purchase> purchases})> _load() async {
    final product = await widget.repository.getProduct(widget.productId);
    if (product == null) {
      throw StateError('Product not found');
    }
    final purchases = await widget.repository.getPurchases(widget.productId);
    if (!_ready) {
      _nameController.text = product.name;
      _notesController.text = product.notes ?? '';
      _ready = true;
    }
    return (product: product, purchases: purchases);
  }

  void _reload() {
    setState(() => _future = _load());
  }

  Future<void> _saveName() async {
    final name = _nameController.text.trim();
    if (name.isEmpty) return;
    await widget.repository.updateProduct(id: widget.productId, name: name);
    if (mounted) _reload();
  }

  Future<void> _saveNotes() async {
    await widget.repository.updateProduct(
      id: widget.productId,
      notes: _notesController.text.trim(),
    );
  }

  Future<void> _toggleFavourite(Product product) async {
    await widget.repository.setFavourite(product.id, !product.favourite);
    if (mounted) _reload();
  }

  Future<void> _setSupermarket(String? value) async {
    if (value == null) return;
    await widget.repository.updateProduct(
      id: widget.productId,
      supermarket: value,
    );
    if (mounted) _reload();
  }

  Future<void> _pickImage(ImageSource source) async {
    final file = await _picker.pickImage(source: source, imageQuality: 85);
    if (file == null) return;
    await widget.repository.setProductImage(widget.productId, file.path);
    if (mounted) _reload();
  }

  Future<void> _chooseImageSource() async {
    final source = await showModalBottomSheet<ImageSource>(
      context: context,
      showDragHandle: true,
      builder: (context) {
        return SafeArea(
          child: Column(
            mainAxisSize: MainAxisSize.min,
            children: [
              ListTile(
                leading: const Icon(Icons.photo_camera_outlined),
                title: const Text('Take photo'),
                onTap: () => Navigator.pop(context, ImageSource.camera),
              ),
              ListTile(
                leading: const Icon(Icons.photo_library_outlined),
                title: const Text('Pick from gallery'),
                onTap: () => Navigator.pop(context, ImageSource.gallery),
              ),
            ],
          ),
        );
      },
    );
    if (source == null) return;
    await _pickImage(source);
  }

  Future<void> _pickStore() async {
    final settings = SettingsScope.maybeOf(context);
    final stores = settings?.supermarkets ?? kDefaultSupermarkets;
    final chosen = await showModalBottomSheet<String>(
      context: context,
      showDragHandle: true,
      builder: (context) {
        return SafeArea(
          child: ListView(
            shrinkWrap: true,
            children: [
              for (final store in stores)
                ListTile(
                  leading: StoreTag(name: store.name, stores: stores),
                  title: Text(store.name),
                  onTap: () => Navigator.pop(context, store.name),
                ),
            ],
          ),
        );
      },
    );
    if (chosen != null) await _setSupermarket(chosen);
  }

  Future<void> _setCategory(String? value, {bool clear = false}) async {
    await widget.repository.updateProduct(
      id: widget.productId,
      category: clear ? null : value,
      clearCategory: clear,
    );
    if (mounted) _reload();
  }

  Future<void> _pickCategory(Product product) async {
    final used = await widget.repository.getUsedCategories();
    if (!mounted) return;
    final categories = mergeCategories([
      ...used,
      if (product.category != null) product.category!,
    ]);
    final chosen = await showModalBottomSheet<String>(
      context: context,
      showDragHandle: true,
      isScrollControlled: true,
      builder: (context) {
        return SafeArea(
          child: ListView(
            shrinkWrap: true,
            children: [
              ListTile(
                leading: const Icon(Icons.clear),
                title: const Text('No category'),
                onTap: () => Navigator.pop(context, ''),
              ),
              for (final name in categories)
                ListTile(
                  leading: Icon(
                    name == product.category
                        ? Icons.check_circle
                        : Icons.category_outlined,
                  ),
                  title: Text(name),
                  onTap: () => Navigator.pop(context, name),
                ),
              ListTile(
                leading: const Icon(Icons.add),
                title: const Text('Custom category'),
                onTap: () => Navigator.pop(context, '__custom__'),
              ),
            ],
          ),
        );
      },
    );
    if (!mounted || chosen == null) return;
    if (chosen.isEmpty) {
      await _setCategory(null, clear: true);
      return;
    }
    if (chosen == '__custom__') {
      final custom = await _askCustomCategory(product.category);
      if (custom == null || !mounted) return;
      if (custom.isEmpty) {
        await _setCategory(null, clear: true);
      } else {
        await _setCategory(custom);
      }
      return;
    }
    await _setCategory(chosen);
  }

  Future<String?> _askCustomCategory(String? current) async {
    return showDialog<String>(
      context: context,
      builder: (context) => _CategoryNameDialog(initial: current),
    );
  }

  Future<void> _openShop(int shopId) async {
    await Navigator.of(context).push<void>(
      MaterialPageRoute(
        builder: (_) => ShopDetailScreen(
          repository: widget.repository,
          shopId: shopId,
        ),
      ),
    );
    if (mounted) _reload();
  }

  @override
  Widget build(BuildContext context) {
    final theme = Theme.of(context);
    final stores = SettingsScope.maybeOf(context)?.supermarkets ??
        kDefaultSupermarkets;

    return Scaffold(
      appBar: AppBar(title: const Text('Product')),
      body: FutureBuilder(
        future: _future,
        builder: (context, snapshot) {
          if (snapshot.hasError) {
            return Center(
              child: Text(
                'Could not load this product.',
                style: theme.textTheme.bodyLarge,
              ),
            );
          }
          if (!snapshot.hasData) {
            return const Center(child: CircularProgressIndicator());
          }

          final product = snapshot.data!.product;
          final purchases = snapshot.data!.purchases;

          return ListView(
            padding: const EdgeInsets.fromLTRB(16, 8, 16, 32),
            children: [
              Row(
                crossAxisAlignment: CrossAxisAlignment.start,
                children: [
                  GestureDetector(
                    onTap: _chooseImageSource,
                    child: Stack(
                      children: [
                        ProductImage(
                          name: product.name,
                          path: product.imagePath,
                          size: 88,
                        ),
                        Positioned(
                          right: 0,
                          bottom: 0,
                          child: Material(
                            color: theme.colorScheme.primary,
                            shape: const CircleBorder(),
                            child: Padding(
                              padding: const EdgeInsets.all(4),
                              child: Icon(
                                Icons.camera_alt,
                                size: 14,
                                color: theme.colorScheme.onPrimary,
                              ),
                            ),
                          ),
                        ),
                      ],
                    ),
                  ),
                  const SizedBox(width: 12),
                  Expanded(
                    child: Column(
                      crossAxisAlignment: CrossAxisAlignment.stretch,
                      children: [
                        Row(
                          children: [
                            Expanded(
                              child: TextField(
                                controller: _nameController,
                                textCapitalization: TextCapitalization.sentences,
                                decoration: const InputDecoration(
                                  labelText: 'Name',
                                  isDense: true,
                                ),
                                onSubmitted: (_) => _saveName(),
                                onEditingComplete: _saveName,
                              ),
                            ),
                            IconButton(
                              tooltip: product.favourite
                                  ? 'Remove favourite'
                                  : 'Add favourite',
                              onPressed: () => _toggleFavourite(product),
                              icon: Icon(
                                product.favourite
                                    ? Icons.star
                                    : Icons.star_outline,
                                color: product.favourite
                                    ? theme.colorScheme.primary
                                    : null,
                              ),
                            ),
                          ],
                        ),
                        const SizedBox(height: 8),
                        Align(
                          alignment: Alignment.centerLeft,
                          child: InkWell(
                            onTap: _pickStore,
                            borderRadius: BorderRadius.circular(8),
                            child: product.supermarket == null
                                ? Text(
                                    'Add supermarket',
                                    style: theme.textTheme.labelMedium?.copyWith(
                                      color: theme.colorScheme.primary,
                                    ),
                                  )
                                : StoreTag(
                                    name: product.supermarket,
                                    stores: stores,
                                  ),
                          ),
                        ),
                      ],
                    ),
                  ),
                ],
              ),
              const SizedBox(height: 24),
              Text(
                formatEuro(product.lastPrice),
                style: theme.textTheme.headlineMedium,
              ),
              Text('Price per unit', style: theme.textTheme.bodyMedium),
              const SizedBox(height: 12),
              Align(
                alignment: Alignment.centerLeft,
                child: ActionChip(
                  avatar: const Icon(Icons.category_outlined, size: 18),
                  label: Text(product.category ?? 'Add category'),
                  onPressed: () => _pickCategory(product),
                ),
              ),
              const SizedBox(height: 24),
              Text(
                'Price and purchase history',
                style: theme.textTheme.titleMedium,
              ),
              const SizedBox(height: 8),
              if (purchases.isEmpty)
                Text(
                  'Scan a receipt to start a history.',
                  style: theme.textTheme.bodyMedium,
                )
              else ...[
                PriceChart(purchases: purchases),
                const SizedBox(height: 8),
                ...purchases.map((purchase) {
                  return ListTile(
                    contentPadding: EdgeInsets.zero,
                    dense: true,
                    leading: const Icon(Icons.shopping_bag_outlined),
                    title: Text(formatEuro(purchase.unitOrLinePrice)),
                    subtitle: Text(
                      [
                        formatDate(purchase.boughtAt),
                        purchase.supermarket,
                        if (purchase.quantity != null) '${purchase.quantity}×',
                      ].join(' · '),
                    ),
                    trailing: const Icon(Icons.chevron_right),
                    onTap: () => _openShop(purchase.shopId),
                  );
                }),
              ],
              const SizedBox(height: 24),
              Text('Notes', style: theme.textTheme.titleMedium),
              const SizedBox(height: 8),
              TextField(
                controller: _notesController,
                minLines: 3,
                maxLines: 6,
                textCapitalization: TextCapitalization.sentences,
                decoration: const InputDecoration(
                  hintText: 'Add a note about this product',
                ),
                onEditingComplete: _saveNotes,
                onTapOutside: (_) => _saveNotes(),
              ),
            ],
          );
        },
      ),
    );
  }
}

class _CategoryNameDialog extends StatefulWidget {
  const _CategoryNameDialog({this.initial});

  final String? initial;

  @override
  State<_CategoryNameDialog> createState() => _CategoryNameDialogState();
}

class _CategoryNameDialogState extends State<_CategoryNameDialog> {
  late final TextEditingController _controller;

  @override
  void initState() {
    super.initState();
    _controller = TextEditingController(text: widget.initial ?? '');
  }

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

  void _save() => Navigator.pop(context, _controller.text.trim());

  @override
  Widget build(BuildContext context) {
    return AlertDialog(
      title: const Text('Category'),
      content: TextField(
        controller: _controller,
        textCapitalization: TextCapitalization.sentences,
        autofocus: true,
        decoration: const InputDecoration(labelText: 'Category'),
        onSubmitted: (_) => _save(),
      ),
      actions: [
        TextButton(
          onPressed: () => Navigator.pop(context),
          child: const Text('Cancel'),
        ),
        FilledButton(
          onPressed: _save,
          child: const Text('Save'),
        ),
      ],
    );
  }
}