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

import '../../../core/router/app_router.dart';
import '../../../core/widgets/app_drawer.dart';
import '../../../l10n/generated/app_localizations.dart';
import '../../household/data/household_providers.dart';
import '../../household/domain/household.dart';
import '../../plants/data/plants_provider.dart';
import '../application/due_tasks_provider.dart';
import '../domain/due_task.dart';

/// Start-Screen der App: die Tages-Checkliste.
/// Push-Erinnerungen führen später direkt hierher.
class TodayScreen extends ConsumerWidget {
  const TodayScreen({super.key});

  @override
  Widget build(BuildContext context, WidgetRef ref) {
    final l10n = AppLocalizations.of(context);
    final tasks = ref.watch(dueTasksProvider);

    final Widget body;
    if (ref.watch(dueTasksLoadingProvider)) {
      body = const Center(child: CircularProgressIndicator());
    } else if (tasks.isEmpty) {
      body = const _AllDoneView();
    } else {
      body = _TaskListView(tasks: tasks);
    }

    final canEdit = ref.watch(myRoleProvider) == HouseholdRole.member;

    return Scaffold(
      appBar: AppBar(title: Text(l10n.todayTitle)),
      drawer: const AppDrawer(),
      floatingActionButton: canEdit
          ? FloatingActionButton.extended(
              onPressed: () => context.push(AppRoutes.plantAdd),
              icon: const Icon(Icons.add),
              label: Text(l10n.addPlant),
            )
          : null,
      body: body,
    );
  }
}

class _TaskListView extends ConsumerWidget {
  const _TaskListView({required this.tasks});

  final List<DueTask> tasks;

  @override
  Widget build(BuildContext context, WidgetRef ref) {
    final l10n = AppLocalizations.of(context);
    final theme = Theme.of(context);

    // Zwischenüberschriften nur, wenn Aufgaben aus mehreren Haushalten da
    // sind – im Normalfall (ein Haushalt) bleibt die Liste wie gewohnt.
    final householdIds = {for (final task in tasks) task.householdId};
    final showHouseholdHeaders = householdIds.length > 1;

    final children = <Widget>[
      Padding(
        padding: const EdgeInsets.symmetric(vertical: 8),
        child: Text(
          l10n.todayOpenTasks(tasks.length),
          style: theme.textTheme.titleMedium,
        ),
      ),
    ];
    String? currentHouseholdId;
    for (final task in tasks) {
      if (showHouseholdHeaders && task.householdId != currentHouseholdId) {
        currentHouseholdId = task.householdId;
        children.add(Padding(
          padding: const EdgeInsets.only(top: 12, bottom: 4),
          child: Row(
            children: [
              Icon(Icons.home_outlined,
                  size: 18, color: theme.colorScheme.primary),
              const SizedBox(width: 6),
              Expanded(
                child: Text(
                  task.householdName,
                  style: theme.textTheme.titleSmall
                      ?.copyWith(color: theme.colorScheme.primary),
                  overflow: TextOverflow.ellipsis,
                ),
              ),
            ],
          ),
        ));
      }
      children.add(_TaskCard(task: task));
    }

    return ListView(
      padding: const EdgeInsets.fromLTRB(16, 8, 16, 96),
      children: children,
    );
  }
}

class _TaskCard extends ConsumerWidget {
  const _TaskCard({required this.task});

  final DueTask task;

  @override
  Widget build(BuildContext context, WidgetRef ref) {
    final l10n = AppLocalizations.of(context);
    final theme = Theme.of(context);
    final today = DateTime.now();
    final overdueDays =
        task.overdueDays(DateTime(today.year, today.month, today.day));

    final title = switch (task.type) {
      CareTaskType.watering => l10n.taskWaterTitle(task.plant.nickname),
      CareTaskType.fertilizing => l10n.taskFertilizeTitle(task.plant.nickname),
    };
    final icon = switch (task.type) {
      CareTaskType.watering => Icons.water_drop,
      CareTaskType.fertilizing => Icons.compost,
    };

    return Card(
      margin: const EdgeInsets.symmetric(vertical: 6),
      child: Padding(
        padding: const EdgeInsets.all(16),
        child: Row(
          children: [
            Icon(icon, size: 32, color: theme.colorScheme.primary),
            const SizedBox(width: 16),
            Expanded(
              child: Column(
                crossAxisAlignment: CrossAxisAlignment.start,
                children: [
                  Text(title, style: theme.textTheme.titleMedium),
                  const SizedBox(height: 4),
                  Text(
                    overdueDays > 0
                        ? l10n.taskOverdue(overdueDays)
                        : l10n.taskDueToday,
                    style: theme.textTheme.bodyMedium?.copyWith(
                      color: overdueDays > 0
                          ? theme.colorScheme.error
                          : theme.colorScheme.onSurfaceVariant,
                    ),
                  ),
                ],
              ),
            ),
            const SizedBox(width: 12),
            FilledButton.icon(
              onPressed: () {
                ref.read(plantRepositoryProvider).confirmTask(
                    task.householdId, task.plant.id, task.type);
                ScaffoldMessenger.of(context)
                  ..hideCurrentSnackBar()
                  ..showSnackBar(
                    SnackBar(
                      content:
                          Text(l10n.taskDoneConfirmation(task.plant.nickname)),
                    ),
                  );
              },
              icon: const Icon(Icons.check),
              label: Text(l10n.taskDone),
            ),
          ],
        ),
      ),
    );
  }
}

class _AllDoneView extends ConsumerWidget {
  const _AllDoneView();

  @override
  Widget build(BuildContext context, WidgetRef ref) {
    final l10n = AppLocalizations.of(context);
    final theme = Theme.of(context);
    final nextDue = ref.watch(nextDueDateProvider);
    final locale = Localizations.localeOf(context).toString();

    return Center(
      child: Padding(
        padding: const EdgeInsets.all(32),
        child: Column(
          mainAxisAlignment: MainAxisAlignment.center,
          children: [
            Icon(
              Icons.check_circle,
              size: 72,
              color: theme.colorScheme.primary,
            ),
            const SizedBox(height: 16),
            Text(
              l10n.todayAllDone,
              style: theme.textTheme.headlineSmall,
              textAlign: TextAlign.center,
            ),
            const SizedBox(height: 8),
            Text(
              nextDue != null
                  ? l10n.todayNextTask(
                      DateFormat('EEEE, d. MMMM', locale).format(nextDue))
                  : l10n.todayEmptyHint,
              style: theme.textTheme.bodyLarge,
              textAlign: TextAlign.center,
            ),
          ],
        ),
      ),
    );
  }
}