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

import '../../core/cache/cached.dart';
import '../../core/utils/json.dart';
import '../../core/widgets/async_value_view.dart';
import '../../core/widgets/empty_state.dart';
import '../../core/widgets/stale_banner.dart';
import 'data/goals_api.dart';
import 'goal_card.dart';
import 'goal_edit_dialog.dart';
import 'providers.dart';

/// Цели: the goal list, each card carrying its server-computed progress.
class GoalsPage extends ConsumerStatefulWidget {
  const GoalsPage({super.key});

  @override
  ConsumerState<GoalsPage> createState() => _GoalsPageState();
}

class _GoalsPageState extends ConsumerState<GoalsPage> {
  bool _showArchived = false;

  void _snack(String message) =>
      ScaffoldMessenger.of(context)
          .showSnackBar(SnackBar(content: Text(message)));

  Future<void> _create() async {
    final goal = await showDialog<Goal>(
      context: context,
      builder: (_) => const GoalEditDialog(),
    );
    if (goal == null) return;
    try {
      await ref.read(goalsApiProvider).create(goal);
      if (!mounted) return;
      invalidateGoals(ref);
    } catch (e) {
      if (mounted) _snack(apiErrorMessage(e));
    }
  }

  Future<void> _edit(Goal goal) async {
    final updated = await showDialog<Goal>(
      context: context,
      builder: (_) => GoalEditDialog(initial: goal),
    );
    if (updated == null) return;
    try {
      await ref.read(goalsApiProvider).patch(goal.id, updated.toJson());
      if (!mounted) return;
      invalidateGoals(ref);
    } catch (e) {
      if (mounted) _snack(apiErrorMessage(e));
    }
  }

  Future<void> _delete(Goal goal) async {
    final confirmed = await showDialog<bool>(
      context: context,
      builder: (ctx) => AlertDialog(
        title: const Text('Удалить цель?'),
        content: Text('«${goal.name}» будет удалена безвозвратно.'),
        actions: [
          TextButton(
            onPressed: () => Navigator.of(ctx).pop(false),
            child: const Text('Отмена'),
          ),
          FilledButton(
            onPressed: () => Navigator.of(ctx).pop(true),
            child: const Text('Удалить'),
          ),
        ],
      ),
    );
    if (confirmed != true) return;
    try {
      await ref.read(goalsApiProvider).delete(goal.id);
      if (!mounted) return;
      invalidateGoals(ref);
    } catch (e) {
      if (mounted) _snack(apiErrorMessage(e));
    }
  }

  @override
  Widget build(BuildContext context) {
    final goals = ref.watch(goalsProvider);
    // Every card's own progress fetch counts toward the one banner too — a fresh list with a
    // stale progress card is still an offline dashboard, just not a visibly empty one.
    final goalIds = [
      for (final g in goals.valueOrNull?.data ?? const <Goal>[]) g.id,
    ];
    final stale = oldestFetch([
      goals.valueOrNull?.fetchedAt,
      for (final id in goalIds)
        ref.watch(goalProgressProvider(id)).valueOrNull?.fetchedAt,
    ]);

    return Scaffold(
      appBar: AppBar(
        title: const Text('Цели'),
        actions: [
          IconButton(
            tooltip: _showArchived ? 'Скрыть архив' : 'Показать архив',
            icon: Icon(
              _showArchived ? Icons.inventory_2 : Icons.inventory_2_outlined,
            ),
            onPressed: () => setState(() => _showArchived = !_showArchived),
          ),
          IconButton(
            tooltip: 'Обновить',
            icon: const Icon(Icons.refresh),
            onPressed: () => invalidateGoals(ref),
          ),
        ],
      ),
      floatingActionButton: FloatingActionButton.extended(
        onPressed: _create,
        icon: const Icon(Icons.add),
        label: const Text('Новая цель'),
      ),
      body: RefreshIndicator(
        onRefresh: () async => invalidateGoals(ref),
        child: AsyncValueView(
          value: goals,
          onRetry: () => ref.invalidate(goalsProvider),
          data: (cached) {
            final all = cached.data;
            final rows = _showArchived
                ? all
                : all.where((g) => !g.archived).toList();
            if (rows.isEmpty) {
              return ListView(
                padding: const EdgeInsets.all(16),
                children: [
                  if (stale != null) StaleBanner(fetchedAt: stale),
                  const SizedBox(height: 48),
                  EmptyState(
                    icon: Icons.flag_outlined,
                    message: all.isEmpty
                        ? 'Целей пока нет.\nЦель — это сумма и (необязательно) дата; '
                              'прогноз считает сервер по доходности или по взносам.'
                        : 'Все цели в архиве — включите показ архива.',
                  ),
                ],
              );
            }
            return ListView(
              padding: const EdgeInsets.fromLTRB(16, 16, 16, 88),
              children: [
                if (stale != null) StaleBanner(fetchedAt: stale),
                for (final g in rows)
                  Padding(
                    padding: const EdgeInsets.only(bottom: 12),
                    child: GoalCard(
                      goal: g,
                      onEdit: () => _edit(g),
                      onDelete: () => _delete(g),
                    ),
                  ),
              ],
            );
          },
        ),
      ),
    );
  }
}