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

import 'package:household_keeper/features/home/domain/daily_plan_models.dart';
import 'package:household_keeper/features/home/presentation/daily_plan_providers.dart';
import 'package:household_keeper/features/home/presentation/daily_plan_task_row.dart';
import 'package:household_keeper/features/home/presentation/progress_card.dart';
import 'package:household_keeper/features/tasks/presentation/task_providers.dart';
import 'package:household_keeper/l10n/app_localizations.dart';

/// Warm coral/terracotta color for overdue section header.
const _overdueColor = Color(0xFFE07A5F);

/// The app's primary screen: daily plan showing what's due today,
/// overdue tasks, and a preview of tomorrow.
///
/// Replaces the former placeholder with a full daily workflow:
/// see what's due, check it off, feel progress.
class HomeScreen extends ConsumerStatefulWidget {
  const HomeScreen({super.key});

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

class _HomeScreenState extends ConsumerState<HomeScreen> {
  /// Task IDs currently animating out after completion.
  final Set<int> _completingTaskIds = {};

  void _onTaskCompleted(int taskId) {
    setState(() {
      _completingTaskIds.add(taskId);
    });
    ref.read(taskActionsProvider.notifier).completeTask(taskId);
  }

  @override
  Widget build(BuildContext context) {
    final l10n = AppLocalizations.of(context);
    final theme = Theme.of(context);
    final dailyPlan = ref.watch(dailyPlanProvider);

    return dailyPlan.when(
      loading: () => const Center(child: CircularProgressIndicator()),
      error: (error, _) => Center(child: Text(error.toString())),
      data: (state) {
        // Clean up completing IDs that are no longer in the data
        _completingTaskIds.removeWhere((id) =>
            !state.overdueTasks.any((t) => t.task.id == id) &&
            !state.todayTasks.any((t) => t.task.id == id));

        return _buildDailyPlan(context, state, l10n, theme);
      },
    );
  }

  Widget _buildDailyPlan(
    BuildContext context,
    DailyPlanState state,
    AppLocalizations l10n,
    ThemeData theme,
  ) {
    // Case a: No tasks at all (user hasn't created any rooms/tasks)
    if (state.totalTodayCount == 0 &&
        state.tomorrowTasks.isEmpty &&
        state.completedTodayCount == 0) {
      return _buildNoTasksState(l10n, theme);
    }

    // Case b: All clear -- there WERE tasks today but all are done
    if (state.overdueTasks.isEmpty &&
        state.todayTasks.isEmpty &&
        state.completedTodayCount > 0 &&
        state.tomorrowTasks.isEmpty) {
      return _buildAllClearState(state, l10n, theme);
    }

    // Case c: Nothing today, but stuff tomorrow -- show celebration + tomorrow
    if (state.overdueTasks.isEmpty &&
        state.todayTasks.isEmpty &&
        state.completedTodayCount == 0 &&
        state.tomorrowTasks.isNotEmpty) {
      return _buildAllClearWithTomorrow(state, l10n, theme);
    }

    // Case b extended: all clear with tomorrow tasks
    if (state.overdueTasks.isEmpty &&
        state.todayTasks.isEmpty &&
        state.completedTodayCount > 0 &&
        state.tomorrowTasks.isNotEmpty) {
      return _buildAllClearWithTomorrow(state, l10n, theme);
    }

    // Case d: Normal state -- tasks exist
    return _buildNormalState(state, l10n, theme);
  }

  /// No tasks at all -- first-run empty state.
  Widget _buildNoTasksState(AppLocalizations l10n, ThemeData theme) {
    return Center(
      child: Padding(
        padding: const EdgeInsets.symmetric(horizontal: 32),
        child: Column(
          mainAxisSize: MainAxisSize.min,
          children: [
            Icon(
              Icons.checklist_rounded,
              size: 80,
              color: theme.colorScheme.onSurface.withValues(alpha: 0.4),
            ),
            const SizedBox(height: 24),
            Text(
              l10n.dailyPlanNoTasks,
              style: theme.textTheme.headlineSmall,
              textAlign: TextAlign.center,
            ),
            const SizedBox(height: 8),
            Text(
              l10n.homeEmptyMessage,
              style: theme.textTheme.bodyLarge?.copyWith(
                color: theme.colorScheme.onSurface.withValues(alpha: 0.6),
              ),
              textAlign: TextAlign.center,
            ),
            const SizedBox(height: 24),
            FilledButton.tonal(
              onPressed: () => context.go('/rooms'),
              child: Text(l10n.homeEmptyAction),
            ),
          ],
        ),
      ),
    );
  }

  /// All tasks done, no tomorrow tasks -- celebration state.
  Widget _buildAllClearState(
    DailyPlanState state,
    AppLocalizations l10n,
    ThemeData theme,
  ) {
    return Center(
      child: Padding(
        padding: const EdgeInsets.symmetric(horizontal: 32),
        child: Column(
          mainAxisSize: MainAxisSize.min,
          children: [
            ProgressCard(
              completed: state.completedTodayCount,
              total: state.totalTodayCount,
            ),
            const SizedBox(height: 16),
            Icon(
              Icons.celebration_outlined,
              size: 80,
              color: theme.colorScheme.onSurface.withValues(alpha: 0.4),
            ),
            const SizedBox(height: 24),
            Text(
              l10n.dailyPlanAllClearTitle,
              style: theme.textTheme.headlineSmall,
              textAlign: TextAlign.center,
            ),
            const SizedBox(height: 8),
            Text(
              l10n.dailyPlanAllClearMessage,
              style: theme.textTheme.bodyLarge?.copyWith(
                color: theme.colorScheme.onSurface.withValues(alpha: 0.6),
              ),
              textAlign: TextAlign.center,
            ),
          ],
        ),
      ),
    );
  }

  /// All clear for today but tomorrow tasks exist.
  Widget _buildAllClearWithTomorrow(
    DailyPlanState state,
    AppLocalizations l10n,
    ThemeData theme,
  ) {
    return ListView(
      children: [
        ProgressCard(
          completed: state.completedTodayCount,
          total: state.totalTodayCount,
        ),
        const SizedBox(height: 16),
        Center(
          child: Column(
            children: [
              Icon(
                Icons.celebration_outlined,
                size: 80,
                color: theme.colorScheme.onSurface.withValues(alpha: 0.4),
              ),
              const SizedBox(height: 24),
              Text(
                l10n.dailyPlanAllClearTitle,
                style: theme.textTheme.headlineSmall,
                textAlign: TextAlign.center,
              ),
              const SizedBox(height: 8),
              Text(
                l10n.dailyPlanAllClearMessage,
                style: theme.textTheme.bodyLarge?.copyWith(
                  color: theme.colorScheme.onSurface.withValues(alpha: 0.6),
                ),
                textAlign: TextAlign.center,
              ),
            ],
          ),
        ),
        const SizedBox(height: 16),
        _buildTomorrowSection(state, l10n, theme),
      ],
    );
  }

  /// Normal state with overdue/today/tomorrow sections.
  Widget _buildNormalState(
    DailyPlanState state,
    AppLocalizations l10n,
    ThemeData theme,
  ) {
    return ListView(
      children: [
        ProgressCard(
          completed: state.completedTodayCount,
          total: state.totalTodayCount,
        ),
        // Overdue section (conditional)
        if (state.overdueTasks.isNotEmpty) ...[
          _buildSectionHeader(
            l10n.dailyPlanSectionOverdue,
            theme,
            color: _overdueColor,
          ),
          ...state.overdueTasks.map(
            (tw) => _buildAnimatedTaskRow(tw, showCheckbox: true),
          ),
        ],
        // Today section
        _buildSectionHeader(
          l10n.dailyPlanSectionToday,
          theme,
          color: theme.colorScheme.primary,
        ),
        if (state.todayTasks.isEmpty)
          Padding(
            padding: const EdgeInsets.symmetric(horizontal: 16, vertical: 8),
            child: Text(
              l10n.dailyPlanAllClearMessage,
              style: theme.textTheme.bodyMedium?.copyWith(
                color: theme.colorScheme.onSurfaceVariant,
              ),
            ),
          )
        else
          ...state.todayTasks.map(
            (tw) => _buildAnimatedTaskRow(tw, showCheckbox: true),
          ),
        // Tomorrow section (conditional, collapsed)
        if (state.tomorrowTasks.isNotEmpty)
          _buildTomorrowSection(state, l10n, theme),
      ],
    );
  }

  Widget _buildSectionHeader(
    String title,
    ThemeData theme, {
    required Color color,
  }) {
    return Padding(
      padding: const EdgeInsets.symmetric(horizontal: 16, vertical: 8),
      child: Text(
        title,
        style: theme.textTheme.titleMedium?.copyWith(color: color),
      ),
    );
  }

  Widget _buildAnimatedTaskRow(
    TaskWithRoom tw, {
    required bool showCheckbox,
  }) {
    final isCompleting = _completingTaskIds.contains(tw.task.id);

    if (isCompleting) {
      return _CompletingTaskRow(
        key: ValueKey('completing-${tw.task.id}'),
        taskWithRoom: tw,
      );
    }

    return DailyPlanTaskRow(
      key: ValueKey('task-${tw.task.id}'),
      taskWithRoom: tw,
      showCheckbox: showCheckbox,
      onCompleted: () => _onTaskCompleted(tw.task.id),
    );
  }

  Widget _buildTomorrowSection(
    DailyPlanState state,
    AppLocalizations l10n,
    ThemeData theme,
  ) {
    return ExpansionTile(
      initiallyExpanded: false,
      title: Text(
        l10n.dailyPlanUpcomingCount(state.tomorrowTasks.length),
        style: theme.textTheme.titleMedium,
      ),
      children: state.tomorrowTasks
          .map(
            (tw) => DailyPlanTaskRow(
              key: ValueKey('tomorrow-${tw.task.id}'),
              taskWithRoom: tw,
              showCheckbox: false,
            ),
          )
          .toList(),
    );
  }
}

/// A task row that animates to zero height on completion.
class _CompletingTaskRow extends StatefulWidget {
  const _CompletingTaskRow({
    super.key,
    required this.taskWithRoom,
  });

  final TaskWithRoom taskWithRoom;

  @override
  State<_CompletingTaskRow> createState() => _CompletingTaskRowState();
}

class _CompletingTaskRowState extends State<_CompletingTaskRow>
    with SingleTickerProviderStateMixin {
  late final AnimationController _controller;
  late final Animation<double> _sizeAnimation;
  late final Animation<Offset> _slideAnimation;

  @override
  void initState() {
    super.initState();
    _controller = AnimationController(
      duration: const Duration(milliseconds: 300),
      vsync: this,
    );
    _sizeAnimation = Tween<double>(begin: 1.0, end: 0.0).animate(
      CurvedAnimation(parent: _controller, curve: Curves.easeInOut),
    );
    _slideAnimation = Tween<Offset>(
      begin: Offset.zero,
      end: const Offset(1.0, 0.0),
    ).animate(
      CurvedAnimation(parent: _controller, curve: Curves.easeInOut),
    );
    _controller.forward();
  }

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

  @override
  Widget build(BuildContext context) {
    return SizeTransition(
      sizeFactor: _sizeAnimation,
      child: SlideTransition(
        position: _slideAnimation,
        child: DailyPlanTaskRow(
          taskWithRoom: widget.taskWithRoom,
          showCheckbox: true,
        ),
      ),
    );
  }
}