/// Dashboard of catalog, trips, lists, and this month's spend.
library;

import 'package:flutter/material.dart';

import 'models/app_overview.dart';
import 'models/shop.dart';
import 'services/app_settings.dart';
import 'services/product_repository.dart';
import 'shop_detail_screen.dart';
import 'utils/dates.dart';
import 'utils/money.dart';
import 'widgets/profile_button.dart';
import 'widgets/settings_button.dart';
import 'widgets/store_tag.dart';

class HomeScreen extends StatefulWidget {
  const HomeScreen({
    super.key,
    required this.repository,
    required this.onOpenProducts,
    required this.onOpenLists,
    required this.onOpenShopLog,
    required this.onOpenAdd,
  });

  final ProductRepository repository;
  final VoidCallback onOpenProducts;
  final VoidCallback onOpenLists;
  final VoidCallback onOpenShopLog;
  final VoidCallback onOpenAdd;

  @override
  State<HomeScreen> createState() => _HomeScreenState();
}

class _HomeScreenState extends State<HomeScreen> {
  AppOverview? _overview;
  Object? _error;
  int _loadToken = 0;

  @override
  void initState() {
    super.initState();
    widget.repository.addListener(_load);
    _load();
  }

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

  Future<void> _load() async {
    final token = ++_loadToken;
    try {
      final overview = await widget.repository.getOverview();
      if (!mounted || token != _loadToken) return;
      setState(() {
        _overview = overview;
        _error = null;
      });
    } catch (error) {
      if (!mounted || token != _loadToken) return;
      setState(() => _error = error);
    }
  }

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

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

    return Scaffold(
      appBar: AppBar(
        title: const Text('Home'),
        actions: const [ProfileButton(), SettingsButton()],
      ),
      body: _error != null && _overview == null
          ? Center(
              child: Text(
                'Could not load an overview.',
                style: theme.textTheme.bodyLarge,
              ),
            )
          : _overview == null
          ? const Center(child: CircularProgressIndicator())
          : _HomeBody(
              overview: _overview!,
              onOpenProducts: widget.onOpenProducts,
              onOpenLists: widget.onOpenLists,
              onOpenShopLog: widget.onOpenShopLog,
              onOpenAdd: widget.onOpenAdd,
              onOpenShop: _openShop,
            ),
    );
  }
}

class _HomeBody extends StatelessWidget {
  const _HomeBody({
    required this.overview,
    required this.onOpenProducts,
    required this.onOpenLists,
    required this.onOpenShopLog,
    required this.onOpenAdd,
    required this.onOpenShop,
  });

  final AppOverview overview;
  final VoidCallback onOpenProducts;
  final VoidCallback onOpenLists;
  final VoidCallback onOpenShopLog;
  final VoidCallback onOpenAdd;
  final ValueChanged<Shop> onOpenShop;

  @override
  Widget build(BuildContext context) {
    final theme = Theme.of(context);
    final stores = SettingsScope.maybeOf(context)?.supermarkets ?? const [];
    final empty =
        overview.productCount == 0 &&
        overview.tripCount == 0 &&
        overview.listCount == 0;

    return ListView(
      padding: const EdgeInsets.fromLTRB(16, 8, 16, 24),
      children: [
        Text('Overview', style: theme.textTheme.titleMedium),
        const SizedBox(height: 8),
        if (empty)
          Card(
            child: Padding(
              padding: const EdgeInsets.all(20),
              child: Column(
                children: [
                  Text(
                    'Nothing logged yet.',
                    style: theme.textTheme.titleMedium,
                  ),
                  const SizedBox(height: 8),
                  Text(
                    'Scan a receipt or add a trip to see products, lists, and spending here.',
                    textAlign: TextAlign.center,
                    style: theme.textTheme.bodyMedium,
                  ),
                  const SizedBox(height: 16),
                  FilledButton.icon(
                    onPressed: onOpenAdd,
                    icon: const Icon(Icons.add),
                    label: const Text('Add a trip'),
                  ),
                ],
              ),
            ),
          )
        else ...[
          Row(
            children: [
              Expanded(
                child: _StatCard(
                  icon: Icons.receipt_long_outlined,
                  label: formatMonthYear(DateTime.now()),
                  value: formatEuro(overview.monthTotal),
                  detail: overview.monthTripCount == 0
                      ? 'No trips yet'
                      : overview.monthTripCount == 1
                      ? '1 trip'
                      : '${overview.monthTripCount} trips',
                  onTap: onOpenShopLog,
                ),
              ),
              const SizedBox(width: 8),
              Expanded(
                child: _StatCard(
                  icon: Icons.inventory_2_outlined,
                  label: 'Products',
                  value: '${overview.productCount}',
                  detail: overview.favouriteCount == 0
                      ? 'No favourites'
                      : overview.favouriteCount == 1
                      ? '1 favourite'
                      : '${overview.favouriteCount} favourites',
                  onTap: onOpenProducts,
                ),
              ),
            ],
          ),
          const SizedBox(height: 8),
          _StatCard(
            icon: Icons.checklist_outlined,
            label: 'Shopping lists',
            value: '${overview.listCount}',
            detail: overview.listCount == 1 ? '1 list' : 'Open your lists',
            onTap: onOpenLists,
          ),
        ],
        if (overview.recentShops.isNotEmpty) ...[
          const SizedBox(height: 24),
          Text('Recent trips', style: theme.textTheme.titleMedium),
          const SizedBox(height: 8),
          for (final shop in overview.recentShops)
            Padding(
              padding: const EdgeInsets.only(bottom: 4),
              child: ListTile(
                contentPadding: const EdgeInsets.symmetric(horizontal: 8),
                title: shop.name == null || shop.name!.isEmpty
                    ? StoreTag(name: shop.supermarket, stores: stores)
                    : Text(shop.name!),
                subtitle: Text(
                  [
                    formatDate(shop.shoppedAt),
                    formatEuro(shop.total),
                  ].join(' · '),
                ),
                trailing: const Icon(Icons.chevron_right),
                onTap: () => onOpenShop(shop),
              ),
            ),
        ],
      ],
    );
  }
}

class _StatCard extends StatelessWidget {
  const _StatCard({
    required this.icon,
    required this.label,
    required this.value,
    required this.detail,
    required this.onTap,
  });

  final IconData icon;
  final String label;
  final String value;
  final String detail;
  final VoidCallback onTap;

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

    return Card(
      child: InkWell(
        onTap: onTap,
        borderRadius: BorderRadius.circular(16),
        child: Padding(
          padding: const EdgeInsets.fromLTRB(16, 16, 16, 14),
          child: Column(
            crossAxisAlignment: CrossAxisAlignment.start,
            children: [
              Icon(icon, color: scheme.primary),
              const SizedBox(height: 12),
              Text(label, style: theme.textTheme.bodyMedium),
              const SizedBox(height: 4),
              Text(value, style: theme.textTheme.titleLarge),
              const SizedBox(height: 2),
              Text(detail, style: theme.textTheme.bodyMedium),
            ],
          ),
        ),
      ),
    );
  }
}