import 'package:flutter/material.dart';
import 'package:flutter_riverpod/flutter_riverpod.dart';
import '../../core/theme/app_theme.dart';
import '../../models/timetable.dart';
import '../../providers/timetable_provider.dart';

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

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

    return Scaffold(
      appBar: AppBar(
        title: const Text('Weekly Timetable'),
      ),
      body: RefreshIndicator(
        onRefresh: () async {
          ref.invalidate(timetableProvider);
          await ref.read(timetableProvider.future);
        },
        child: timetableAsync.when(
          loading: () => const Center(child: CircularProgressIndicator()),
          error: (err, _) => Center(
            child: Padding(
              padding: const EdgeInsets.all(24),
              child: Column(
                mainAxisAlignment: MainAxisAlignment.center,
                children: [
                  const Icon(Icons.error_outline_rounded, size: 48, color: AppTheme.errorColor),
                  const SizedBox(height: 12),
                  const Text('Failed to load timetable',
                      style: TextStyle(fontSize: 16, fontWeight: FontWeight.bold)),
                  const SizedBox(height: 8),
                  Text(err.toString(),
                      textAlign: TextAlign.center,
                      style: const TextStyle(color: AppTheme.textSecondary, fontSize: 13)),
                  const SizedBox(height: 16),
                  ElevatedButton(
                    onPressed: () => ref.refresh(timetableProvider),
                    child: const Text('Retry'),
                  ),
                ],
              ),
            ),
          ),
          data: (slots) {
            if (slots.isEmpty) {
              return const Center(
                child: Padding(
                  padding: EdgeInsets.all(32),
                  child: Column(
                    mainAxisAlignment: MainAxisAlignment.center,
                    children: [
                      Icon(Icons.calendar_month_outlined, size: 60, color: AppTheme.textMuted),
                      SizedBox(height: 12),
                      Text(
                        'No timetable slots scheduled',
                        style: TextStyle(fontSize: 16, fontWeight: FontWeight.w600),
                      ),
                      SizedBox(height: 6),
                      Text(
                        'Your class schedule has not been published yet.',
                        textAlign: TextAlign.center,
                        style: TextStyle(color: AppTheme.textSecondary, fontSize: 13),
                      ),
                    ],
                  ),
                ),
              );
            }

            // Group slots by Day or Date
            final Map<String, List<TimetableSlot>> grouped = {};
            for (final slot in slots) {
              final key = slot.day.isNotEmpty
                  ? slot.day
                  : (slot.date.isNotEmpty ? slot.date : 'Scheduled Classes');
              grouped.putIfAbsent(key, () => []).add(slot);
            }

            return ListView(
              padding: const EdgeInsets.all(16),
              children: grouped.entries.map((entry) {
                return Column(
                  crossAxisAlignment: CrossAxisAlignment.start,
                  children: [
                    Padding(
                      padding: const EdgeInsets.symmetric(vertical: 8, horizontal: 4),
                      child: Text(
                        entry.key.toUpperCase(),
                        style: const TextStyle(
                          fontSize: 13,
                          fontWeight: FontWeight.bold,
                          color: AppTheme.primaryColor,
                          letterSpacing: 0.5,
                        ),
                      ),
                    ),
                    ...entry.value.map((slot) => _buildSlotCard(slot)),
                    const SizedBox(height: 12),
                  ],
                );
              }).toList(),
            );
          },
        ),
      ),
    );
  }

  Widget _buildSlotCard(TimetableSlot slot) {
    return Card(
      child: Padding(
        padding: const EdgeInsets.all(14),
        child: Row(
          crossAxisAlignment: CrossAxisAlignment.start,
          children: [
            Container(
              padding: const EdgeInsets.symmetric(horizontal: 10, vertical: 8),
              decoration: BoxDecoration(
                color: AppTheme.primaryColor.withOpacity(0.08),
                borderRadius: BorderRadius.circular(8),
              ),
              child: Column(
                children: [
                  Text(
                    slot.startTime,
                    style: const TextStyle(
                      fontSize: 12,
                      fontWeight: FontWeight.bold,
                      color: AppTheme.primaryDark,
                    ),
                  ),
                  const Text('to', style: TextStyle(fontSize: 10, color: AppTheme.textSecondary)),
                  Text(
                    slot.endTime,
                    style: const TextStyle(
                      fontSize: 12,
                      fontWeight: FontWeight.bold,
                      color: AppTheme.primaryDark,
                    ),
                  ),
                ],
              ),
            ),
            const SizedBox(width: 14),
            Expanded(
              child: Column(
                crossAxisAlignment: CrossAxisAlignment.start,
                children: [
                  Text(
                    slot.subject?.name ?? 'Lecture Session',
                    style: const TextStyle(
                      fontSize: 15,
                      fontWeight: FontWeight.bold,
                      color: AppTheme.textPrimary,
                    ),
                  ),
                  const SizedBox(height: 6),
                  if (slot.faculty?.name != null)
                    Row(
                      children: [
                        const Icon(Icons.person_outline, size: 14, color: AppTheme.textSecondary),
                        const SizedBox(width: 4),
                        Text(
                          slot.faculty!.name,
                          style: const TextStyle(fontSize: 12, color: AppTheme.textSecondary),
                        ),
                      ],
                    ),
                  if (slot.room?.name != null) ...[
                    const SizedBox(height: 3),
                    Row(
                      children: [
                        const Icon(Icons.meeting_room_outlined,
                            size: 14, color: AppTheme.textSecondary),
                        const SizedBox(width: 4),
                        Text(
                          slot.room!.name,
                          style: const TextStyle(fontSize: 12, color: AppTheme.textSecondary),
                        ),
                      ],
                    ),
                  ],
                ],
              ),
            ),
          ],
        ),
      ),
    );
  }
}