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

import '../../../../core/utils/date_time_utils.dart';
import '../../domain/entities/exercise_entry.dart';
import '../controllers/exercise_controller.dart';
import '../widgets/log_exercise_dialog.dart';

/// Resistance-training log for lean mass preservation during GLP-1 therapy.
///
/// The screen pairs a weekly strength-workout frequency card (sessions
/// completed vs. the recommended three per week) with the full working-set
/// log, grouped by day, plus an interactive "log exercise" dialog.
class ExerciseScreen extends ConsumerWidget {
  const ExerciseScreen({super.key});

  @override
  Widget build(BuildContext context, WidgetRef ref) {
    final state = ref.watch(exerciseControllerProvider);

    ref.listen(exerciseControllerProvider, (previous, next) {
      if (next.errorMessage != null &&
          next.errorMessage != previous?.errorMessage) {
        ScaffoldMessenger.of(context).showSnackBar(
          SnackBar(
            content: Text(next.errorMessage!),
            backgroundColor: Theme.of(context).colorScheme.error,
          ),
        );
        ref.read(exerciseControllerProvider.notifier).clearError();
      }
    });

    return Scaffold(
      appBar: AppBar(title: const Text('Exercise Log')),
      body: ListView(
        padding: const EdgeInsets.fromLTRB(16, 16, 16, 88),
        children: [
          _WeeklyFrequencyCard(
            sessionsThisWeek: state.weeklyWorkoutCount,
            targetSessions: ExerciseController.recommendedWeeklySessions,
          ),
          const SizedBox(height: 16),
          Text(
            'Working Sets',
            style: Theme.of(context)
                .textTheme
                .titleMedium
                ?.copyWith(fontWeight: FontWeight.bold),
          ),
          const SizedBox(height: 8),
          if (state.entries.isEmpty)
            const _EmptyLogHint()
          else
            ..._buildDayGroups(context, state),
        ],
      ),
      floatingActionButton: FloatingActionButton.extended(
        onPressed: () => _showLogDialog(context),
        icon: const Icon(Icons.add),
        label: const Text('Log Exercise'),
      ),
    );
  }

  /// Groups the log by calendar day (newest day first, newest set first).
  List<Widget> _buildDayGroups(BuildContext context, ExerciseState state) {
    final byDay = <DateTime, List<ExerciseEntry>>{};
    for (final entry in state.entries) {
      byDay.putIfAbsent(startOfDay(entry.timestamp), () => []).add(entry);
    }
    final days = byDay.keys.toList()..sort((a, b) => b.compareTo(a));

    return [
      for (final day in days) ...[
        Padding(
          padding: const EdgeInsets.only(top: 8, bottom: 4),
          child: Text(
            formatMonthDay(day),
            style: Theme.of(context)
                .textTheme
                .labelLarge
                ?.copyWith(color: Theme.of(context).colorScheme.primary),
          ),
        ),
        for (final entry in byDay[day]!) _ExerciseTile(entry: entry),
      ],
    ];
  }

  Future<void> _showLogDialog(BuildContext context) {
    return showDialog<void>(
      context: context,
      builder: (context) => const LogExerciseDialog(),
    );
  }
}

/// Card surfacing weekly strength-workout frequency against the lean-mass
/// preservation recommendation (three resistance sessions per week).
class _WeeklyFrequencyCard extends StatelessWidget {
  const _WeeklyFrequencyCard({
    required this.sessionsThisWeek,
    required this.targetSessions,
  });

  final int sessionsThisWeek;
  final int targetSessions;

  @override
  Widget build(BuildContext context) {
    final theme = Theme.of(context);
    final progress =
        (sessionsThisWeek / targetSessions).clamp(0.0, 1.0).toDouble();
    final goalMet = sessionsThisWeek >= targetSessions;

    return Card(
      child: Padding(
        padding: const EdgeInsets.all(16),
        child: Column(
          crossAxisAlignment: CrossAxisAlignment.start,
          children: [
            Row(
              children: [
                Icon(
                  Icons.fitness_center,
                  color: goalMet
                      ? Colors.green.shade700
                      : theme.colorScheme.primary,
                ),
                const SizedBox(width: 8),
                Expanded(
                  child: Text(
                    'Weekly Strength Frequency',
                    style: theme.textTheme.titleSmall
                        ?.copyWith(fontWeight: FontWeight.bold),
                  ),
                ),
                if (goalMet)
                  Chip(
                    visualDensity: VisualDensity.compact,
                    backgroundColor: Colors.green.shade100,
                    label: Text(
                      'Goal met',
                      style: TextStyle(
                        fontSize: 12,
                        fontWeight: FontWeight.bold,
                        color: Colors.green.shade800,
                      ),
                    ),
                  ),
              ],
            ),
            const SizedBox(height: 12),
            Text(
              '$sessionsThisWeek of $targetSessions sessions this week',
              style: theme.textTheme.titleMedium
                  ?.copyWith(fontWeight: FontWeight.w600),
            ),
            const SizedBox(height: 8),
            ClipRRect(
              borderRadius: BorderRadius.circular(4),
              child: LinearProgressIndicator(
                value: progress,
                minHeight: 8,
                backgroundColor: theme.colorScheme.surfaceContainerHighest,
              ),
            ),
            const SizedBox(height: 8),
            Text(
              'Resistance training preserves lean mass and offsets '
              'GLP-1-driven muscle loss — aim for $targetSessions full-body '
              'or split sessions per week.',
              style: theme.textTheme.bodySmall
                  ?.copyWith(color: theme.colorScheme.outline),
            ),
          ],
        ),
      ),
    );
  }
}

/// One logged working-set row with a swipe-to-delete affordance.
class _ExerciseTile extends ConsumerWidget {
  const _ExerciseTile({required this.entry});

  final ExerciseEntry entry;

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

    return Dismissible(
      key: ValueKey(entry.id),
      direction: DismissDirection.endToStart,
      background: Container(
        alignment: Alignment.centerRight,
        padding: const EdgeInsets.only(right: 16),
        color: theme.colorScheme.errorContainer,
        child: Icon(Icons.delete_outline, color: theme.colorScheme.error),
      ),
      onDismissed: (_) => ref
          .read(exerciseControllerProvider.notifier)
          .deleteEntry(entry.id),
      child: Card(
        margin: const EdgeInsets.symmetric(vertical: 4),
        child: ListTile(
          leading: CircleAvatar(
            backgroundColor: theme.colorScheme.secondaryContainer,
            child: Icon(
              Icons.fitness_center,
              size: 20,
              color: theme.colorScheme.onSecondaryContainer,
            ),
          ),
          title: Text(
            entry.exerciseName,
            style: const TextStyle(fontWeight: FontWeight.w600),
          ),
          subtitle: Text(
            '${entry.muscleGroup.displayName} · ${entry.volumeLabel}',
          ),
          trailing: Text(
            formatDateTime(entry.timestamp),
            style: theme.textTheme.labelSmall
                ?.copyWith(color: theme.colorScheme.outline),
          ),
        ),
      ),
    );
  }
}

/// Placeholder shown while the log has no entries.
class _EmptyLogHint extends StatelessWidget {
  const _EmptyLogHint();

  @override
  Widget build(BuildContext context) {
    final theme = Theme.of(context);
    return Padding(
      padding: const EdgeInsets.symmetric(vertical: 32),
      child: Column(
        children: [
          Icon(Icons.fitness_center_outlined,
              size: 40, color: theme.colorScheme.outline),
          const SizedBox(height: 8),
          Text(
            'No sessions logged yet.\nTap "Log Exercise" to record your '
            'first working set.',
            textAlign: TextAlign.center,
            style: theme.textTheme.bodySmall
                ?.copyWith(fontStyle: FontStyle.italic),
          ),
        ],
      ),
    );
  }
}