import 'package:flutter/material.dart';
import 'package:flutter_riverpod/flutter_riverpod.dart';
import '../providers/db_provider.dart';
import '../theme/app_theme.dart';
import 'package:drift/drift.dart' show Value;
import '../data/db.dart';

class BudgetScreen extends ConsumerWidget {
  const BudgetScreen({super.key});

  @override
  Widget build(BuildContext context, WidgetRef ref) {
    final groups = ref.watch(categoryGroupsProvider).valueOrNull ?? [];
    final catsByGroup = ref.watch(categoriesByGroupProvider);
    final query = ref.watch(searchQueryProvider).toLowerCase();
    final now = DateTime.now();
    final months = ['', 'Janvier', 'Février', 'Mars', 'Avril', 'Mai', 'Juin', 'Juillet', 'Août', 'Septembre', 'Octobre', 'Novembre', 'Décembre'];
    final monthLabel = '${months[now.month]} ${now.year}';

    // filter categories and groups by search query
    final filteredGroups = query.isEmpty
        ? groups
        : groups.where((g) {
            final cats = catsByGroup[g.id] ?? [];
            return cats.any((c) => c.name.toLowerCase().contains(query));
          }).toList();
    final filteredCatsByGroup = query.isEmpty
        ? catsByGroup
        : catsByGroup.map((key, value) => MapEntry(
            key,
            value.where((c) => c.name.toLowerCase().contains(query)).toList(),
          ));

    return ListView(
      padding: const EdgeInsets.fromLTRB(16, 8, 16, 90),
      children: [
        Card(
          child: Padding(
            padding: const EdgeInsets.all(20),
            child: Column(
              crossAxisAlignment: CrossAxisAlignment.start,
              children: [
                Text('Budget du mois', style: Theme.of(context).textTheme.titleMedium),
                const SizedBox(height: 4),
                Text(monthLabel, style: Theme.of(context).textTheme.bodySmall),
              ],
            ),
          ),
        ),
        const SizedBox(height: 16),
        ...filteredGroups.map((group) {
          final cats = filteredCatsByGroup[group.id] ?? [];
          if (cats.isEmpty) return const SizedBox.shrink();
          return _CategoryGroupTile(group: group, categoryIds: cats.map((c) => c.id).toList());
        }),
      ],
    );
  }
}

class _CategoryGroupTile extends ConsumerWidget {
  final CategoryGroup group;
  final List<int> categoryIds;

  const _CategoryGroupTile({required this.group, required this.categoryIds});

  @override
  Widget build(BuildContext context, WidgetRef ref) {
    final expanded = ref.watch(_expandedGroupProvider(group.id));
    final cats = ref.watch(categoriesByGroupProvider)[group.id] ?? [];

    return Column(
      crossAxisAlignment: CrossAxisAlignment.start,
      children: [
        ListTile(
          dense: true,
          contentPadding: EdgeInsets.zero,
          leading: Icon(
            expanded ? Icons.keyboard_arrow_down : Icons.keyboard_arrow_right,
            size: 18,
            color: Theme.of(context).colorScheme.onSurfaceVariant,
          ),
          title: Text(group.name,
              style: Theme.of(context)
                  .textTheme
                  .titleSmall
                  ?.copyWith(fontWeight: FontWeight.w600)),
          trailing: Text(
            formatCurrency(
              cats.fold(0.0, (s, c) => s + ref.watch(categoryRemainingProvider(c.id))),
            ),
            style: Theme.of(context).textTheme.bodySmall,
          ),
          onTap: () => ref.read(_expandedGroupProvider(group.id).notifier).toggle(),
        ),
        if (expanded)
          ...cats.map((c) => _CategoryRow(categoryId: c.id)),
        const Divider(height: 32),
      ],
    );
  }
}

class _CategoryRow extends ConsumerWidget {
  final int categoryId;

  const _CategoryRow({required this.categoryId});

  @override
  Widget build(BuildContext context, WidgetRef ref) {
    final cats = ref.watch(categoriesByGroupProvider);
    final category = cats.values
        .expand((list) => list)
        .firstWhere((c) => c.id == categoryId, orElse: () => throw StateError('missing'));

    final budgeted = ref.watch(monthlyBudgetProvider(categoryId)) ?? 0.0;
    final spent = ref.watch(categorySpentProvider(categoryId));
    final remaining = ref.watch(categoryRemainingProvider(categoryId));
    final pct = budgeted > 0 ? ((budgeted + spent) / budgeted).clamp(0.0, 1.0) : 0.0;

    void _editBudget() async {
      final month = ref.read(currentMonthProvider);
      final db = ref.read(dbProvider);
      final ctrl = TextEditingController(text: budgeted > 0 ? budgeted.toStringAsFixed(2) : '');

      final newAmount = await showDialog<double>(
        context: context,
        builder: (ctx) => AlertDialog(
          title: Text('Budget : ${category.name}'),
          content: TextField(
            controller: ctrl,
            decoration: const InputDecoration(labelText: 'Montant', hintText: '0,00'),
            keyboardType: const TextInputType.numberWithOptions(decimal: true),
            autofocus: true,
          ),
          actions: [
            FilledButton.tonal(onPressed: () => Navigator.pop(ctx), child: const Text('Annuler')),
            FilledButton(
              onPressed: () {
                final v = double.tryParse(ctrl.text.trim().replaceAll(',', '.'));
                if (v != null) Navigator.pop(ctx, v);
              },
              child: const Text('Enregistrer'),
            ),
          ],
        ),
      );
      ctrl.dispose();

      if (newAmount == null) return;
      final existing = await (db.select(db.budgets)
        ..where((b) => b.categoryId.equals(categoryId))
        ..where((b) => b.month.equals(month)))
        .get();
      if (existing.isNotEmpty) {
        await db.update(db.budgets).replace(existing.first.copyWith(budgeted: newAmount));
      } else {
        await db.into(db.budgets).insert(BudgetsCompanion.insert(
          categoryId: categoryId,
          month: month,
          budgeted: Value(newAmount),
        ));
      }
    }

    return Padding(
      padding: const EdgeInsets.only(left: 8, bottom: 12),
      child: Card(
        margin: EdgeInsets.zero,
        child: Padding(
          padding: const EdgeInsets.symmetric(horizontal: 12, vertical: 10),
          child: Column(
            crossAxisAlignment: CrossAxisAlignment.start,
            children: [
            ListTile(
              dense: true,
              contentPadding: EdgeInsets.zero,
              visualDensity: VisualDensity.compact,
              leading: Container(
                width: 36,
                height: 36,
                decoration: BoxDecoration(
                  color: Theme.of(context).colorScheme.secondaryContainer,
                  borderRadius: BorderRadius.circular(8),
                ),
                child: Icon(
                  categoryIcon(category.icon),
                  size: 18,
                  color: Theme.of(context).colorScheme.onSecondaryContainer,
                ),
              ),
              title: Text(category.name, style: Theme.of(context).textTheme.titleMedium?.copyWith(fontWeight: FontWeight.w600)),
              trailing: Text(
                formatCurrency(remaining),
                style: Theme.of(context).textTheme.bodyMedium?.copyWith(
                      fontWeight: FontWeight.w600,
                      color: remaining >= 0 ? Theme.of(context).colorScheme.primary : Theme.of(context).colorScheme.error,
                    ),
              ),
            ),
              const SizedBox(height: 4),
              ClipRRect(
                borderRadius: BorderRadius.circular(4),
                child: LinearProgressIndicator(
                  value: pct,
                  backgroundColor: Theme.of(context).colorScheme.outlineVariant,
                  valueColor: AlwaysStoppedAnimation<Color>(
                    remaining >= 0 ? Theme.of(context).colorScheme.primary : Theme.of(context).colorScheme.error,
                  ),
                  minHeight: 4,
                ),
              ),
              const SizedBox(height: 2),
              Row(
                children: [
                  GestureDetector(
                    onTap: _editBudget,
                    child: Text('Budget: ${formatCurrency(budgeted)}',
                        style: Theme.of(context).textTheme.bodySmall?.copyWith(
                              decoration: TextDecoration.underline,
                              color: Theme.of(context).colorScheme.primary,
                            )),
                  ),
                  const SizedBox(width: 12),
                  Text('Dépensé: ${formatCurrency(spent.abs())}',
                      style: Theme.of(context).textTheme.bodySmall),
                ],
              ),
            ],
          ),
        ),
      ),
    );
  }
}

class _ExpandedGroupNotifier extends StateNotifier<bool> {
  _ExpandedGroupNotifier() : super(true);

  void toggle() => state = !state;
}

final _expandedGroupProvider =
    StateNotifierProvider.family<_ExpandedGroupNotifier, bool, int>(
        (ref, id) => _ExpandedGroupNotifier());

IconData categoryIcon(String? name) {
  switch (name) {
    case 'home': return Icons.home;
    case 'bolt': return Icons.bolt;
    case 'water_drop': return Icons.water_drop;
    case 'shield': return Icons.shield;
    case 'shopping_cart': return Icons.shopping_cart;
    case 'restaurant': return Icons.restaurant;
    case 'local_gas_station': return Icons.local_gas_station;
    case 'directions_bus': return Icons.directions_bus;
    case 'tv': return Icons.tv;
    case 'celebration': return Icons.celebration;
    case 'savings': return Icons.savings;
    case 'flight': return Icons.flight;
    default: return Icons.category;
  }
}