import 'package:flutter/material.dart';
import 'package:intl/intl.dart';
import 'package:shared_preferences/shared_preferences.dart';
import '../services/google_calendar_service.dart';

class CalendarScreen extends StatefulWidget {
  const CalendarScreen({super.key});

  @override
  State<CalendarScreen> createState() => _CalendarScreenState();
}

class _CalendarScreenState extends State<CalendarScreen> {
  final GoogleCalendarService _calendarService = GoogleCalendarService();
  bool _isLoading = false;
  List<CalendarEvent> _events = [];
  String? _errorMessage;
  String _bulletColor = 'Blue';

  @override
  void initState() {
    super.initState();
    _loadBulletColor();
    _loadEvents();
  }

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

  Future<void> _loadBulletColor() async {
    final prefs = await SharedPreferences.getInstance();
    setState(() {
      _bulletColor = prefs.getString('bulletColor') ?? 'Blue';
    });
  }

  Color _getAccentColor() {
    switch (_bulletColor.toLowerCase()) {
      case 'blue':
        return Colors.blue;
      case 'green':
        return Colors.green;
      case 'yellow':
        return Colors.yellow;
      case 'purple':
        return Colors.purple;
      case 'cyan':
        return Colors.cyan;
      case 'teal':
        return Colors.teal;
      case 'indigo':
        return Colors.indigo;
      case 'pink':
        return Colors.pink;
      case 'lime':
        return Colors.lime;
      case 'mint':
        return Colors.greenAccent;
      case 'orange':
        return Colors.orange;
      case 'violet':
        return Colors.deepPurpleAccent;
      case 'amber':
        return Colors.amber;
      case 'brown':
        return Colors.brown;
      case 'grey':
        return Colors.grey;
      default:
        return Colors.blue;
    }
  }

  bool _isValidEvent(CalendarEvent event) {
    // Filter out events that are just single names or too short
    if (event.summary == null || event.summary!.trim().isEmpty) {
      return false;
    }

    final summary = event.summary!.trim();

    // Exclude if it's just a single word (likely just a name)
    if (!summary.contains(' ') && summary.length < 15) {
      return false;
    }

    return true;
  }

  Future<void> _loadEvents() async {
    setState(() {
      _isLoading = true;
      _errorMessage = null;
    });

    try {
      final events = await _calendarService.getEvents(
        startDate: DateTime.now(),
        endDate: DateTime.now().add(const Duration(days: 365)),
      );

      // Get today's date at midnight for comparison
      final now = DateTime.now();
      final today = DateTime(now.year, now.month, now.day);

      // Filter: valid events AND events from today onwards
      final filteredEvents = events.where((event) {
        if (!_isValidEvent(event)) return false;

        // Only include events that are today or in the future
        if (event.startTime != null) {
          final eventDate = DateTime(
            event.startTime!.year,
            event.startTime!.month,
            event.startTime!.day,
          );
          return eventDate.isAtSameMomentAs(today) || eventDate.isAfter(today);
        }
        return false;
      }).toList();

      filteredEvents.sort((a, b) {
        if (a.startTime == null) return 1;
        if (b.startTime == null) return -1;
        return a.startTime!.compareTo(b.startTime!);
      });

      setState(() {
        _events = filteredEvents;
      });
    } catch (e) {
      setState(() {
        _errorMessage = 'Error loading events: $e';
      });
    } finally {
      setState(() => _isLoading = false);
    }
  }

  @override
  Widget build(BuildContext context) {
    final accentColor = _getAccentColor();

    if (_isLoading && _events.isEmpty) {
      return Scaffold(
        body: Center(
          child: CircularProgressIndicator(color: accentColor),
        ),
      );
    }

    if (_errorMessage != null && _events.isEmpty) {
      return Scaffold(
        body: Center(
          child: Column(
            mainAxisAlignment: MainAxisAlignment.center,
            children: [
              Icon(Icons.error_outline, size: 64, color: accentColor),
              const SizedBox(height: 24),
              Padding(
                padding: const EdgeInsets.symmetric(horizontal: 32),
                child: Text(
                  _errorMessage!,
                  textAlign: TextAlign.center,
                  style: const TextStyle(fontSize: 16),
                ),
              ),
              const SizedBox(height: 16),
              ElevatedButton.icon(
                onPressed: _loadEvents,
                icon: const Icon(Icons.refresh),
                label: const Text('Retry'),
                style: ElevatedButton.styleFrom(
                  backgroundColor: accentColor,
                  foregroundColor: Colors.white,
                ),
              ),
            ],
          ),
        ),
      );
    }

    return Scaffold(
      backgroundColor: Colors.white,
      body: RefreshIndicator(
        onRefresh: _loadEvents,
        color: accentColor,
        child: _events.isEmpty
            ? ListView(
                children: [
                  SizedBox(height: MediaQuery.of(context).size.height * 0.3),
                  Center(
                    child: Column(
                      mainAxisAlignment: MainAxisAlignment.center,
                      children: [
                        Icon(Icons.event_available, size: 64, color: Colors.grey[400]),
                        const SizedBox(height: 16),
                        const Text(
                          'No upcoming events',
                          style: TextStyle(fontSize: 16, color: Colors.grey),
                        ),
                        const SizedBox(height: 8),
                        Text(
                          'Pull down to refresh',
                          style: TextStyle(fontSize: 14, color: Colors.grey[400]),
                        ),
                      ],
                    ),
                  ),
                ],
              )
            : ListView.builder(
                itemCount: _events.length,
                padding: const EdgeInsets.all(8),
                itemBuilder: (context, index) {
                  final event = _events[index];
                  return _buildEventCard(event, accentColor);
                },
              ),
      ),
    );
  }

  Widget _buildEventCard(CalendarEvent event, Color accentColor) {
    final startTime = event.startTime;
    final isAllDay = event.isAllDay;

    String timeText;
    if (isAllDay) {
      timeText = 'All day';
    } else if (startTime != null) {
      timeText = DateFormat('HH:mm').format(startTime.toLocal());
    } else {
      timeText = '';
    }

    // Format the date for display
    String dateText = '';
    bool isToday = false;
    if (startTime != null) {
      final now = DateTime.now();
      final today = DateTime(now.year, now.month, now.day);
      final eventDay = DateTime(startTime.year, startTime.month, startTime.day);
      final difference = eventDay.difference(today).inDays;

      if (difference == 0) {
        dateText = 'Today';
        isToday = true;
      } else if (difference == 1) {
        dateText = 'Tomorrow';
      } else {
        dateText = DateFormat('EEEE, MMMM d').format(startTime);
      }
    }

    return Container(
      margin: const EdgeInsets.symmetric(vertical: 6, horizontal: 16),
      decoration: BoxDecoration(
        color: Colors.white,
        borderRadius: BorderRadius.circular(12),
        boxShadow: [
          BoxShadow(
            color: Colors.black.withValues(alpha: 0.05),
            blurRadius: 4,
            offset: const Offset(0, 2),
          ),
        ],
      ),
      child: Material(
        color: Colors.transparent,
        child: InkWell(
          onTap: () => _showEventDetails(event, accentColor),
          borderRadius: BorderRadius.circular(12),
          child: Column(
            crossAxisAlignment: CrossAxisAlignment.start,
            children: [
              // Date header
              Container(
                width: double.infinity,
                padding: const EdgeInsets.symmetric(horizontal: 16, vertical: 12),
                decoration: BoxDecoration(
                  color: isToday
                      ? accentColor.withValues(alpha: 0.15)
                      : Colors.grey[50],
                  borderRadius: const BorderRadius.only(
                    topLeft: Radius.circular(12),
                    topRight: Radius.circular(12),
                  ),
                ),
                child: Row(
                  children: [
                    Container(
                      width: 4,
                      height: 16,
                      decoration: BoxDecoration(
                        color: accentColor,
                        borderRadius: BorderRadius.circular(2),
                      ),
                    ),
                    const SizedBox(width: 8),
                    Text(
                      dateText,
                      style: TextStyle(
                        fontSize: 14,
                        fontWeight: FontWeight.bold,
                        color: isToday ? accentColor : Colors.black87,
                      ),
                    ),
                    if (isToday) ...[
                      const SizedBox(width: 8),
                      Container(
                        padding: const EdgeInsets.symmetric(horizontal: 6, vertical: 2),
                        decoration: BoxDecoration(
                          color: accentColor,
                          borderRadius: BorderRadius.circular(8),
                        ),
                        child: const Text(
                          'NOW',
                          style: TextStyle(
                            fontSize: 10,
                            fontWeight: FontWeight.bold,
                            color: Colors.white,
                          ),
                        ),
                      ),
                    ],
                  ],
                ),
              ),
              // Time and title
              Padding(
                padding: const EdgeInsets.all(16),
                child: Row(
                  crossAxisAlignment: CrossAxisAlignment.center,
                  children: [
                    // Time indicator with accent color
                    Container(
                      width: 60,
                      height: 60,
                      decoration: BoxDecoration(
                        color: accentColor.withValues(alpha: 0.1),
                        borderRadius: BorderRadius.circular(12),
                      ),
                      child: Center(
                        child: Text(
                          timeText,
                          textAlign: TextAlign.center,
                          style: TextStyle(
                            fontSize: isAllDay ? 12 : 14,
                            fontWeight: FontWeight.bold,
                            color: accentColor,
                          ),
                        ),
                      ),
                    ),
                    const SizedBox(width: 16),
                    // Title
                    Expanded(
                      child: Text(
                        event.summary ?? 'Untitled Event',
                        style: const TextStyle(
                          fontSize: 15,
                          fontWeight: FontWeight.w600,
                          color: Colors.black87,
                        ),
                        maxLines: 2,
                        overflow: TextOverflow.ellipsis,
                      ),
                    ),
                    const SizedBox(width: 8),
                    // Arrow icon
                    Icon(
                      Icons.arrow_forward_ios,
                      size: 16,
                      color: Colors.grey[400],
                    ),
                  ],
                ),
              ),
            ],
          ),
        ),
      ),
    );
  }

  void _showEventDetails(CalendarEvent event, Color accentColor) {
    final startTime = event.startTime;
    final endTime = event.endTime;
    final isAllDay = event.isAllDay;

    showDialog(
      context: context,
      builder: (context) => Dialog(
        shape: RoundedRectangleBorder(borderRadius: BorderRadius.circular(16)),
        child: Container(
          constraints: const BoxConstraints(maxWidth: 400),
          padding: const EdgeInsets.all(24),
          child: Column(
            mainAxisSize: MainAxisSize.min,
            crossAxisAlignment: CrossAxisAlignment.start,
            children: [
              Row(
                children: [
                  Container(
                    width: 4,
                    height: 24,
                    decoration: BoxDecoration(
                      color: accentColor,
                      borderRadius: BorderRadius.circular(2),
                    ),
                  ),
                  const SizedBox(width: 12),
                  Expanded(
                    child: Text(
                      event.summary ?? 'Event Details',
                      style: const TextStyle(
                        fontSize: 20,
                        fontWeight: FontWeight.bold,
                        color: Colors.black87,
                      ),
                    ),
                  ),
                ],
              ),
              const SizedBox(height: 24),
              if (startTime != null) ...[
                _buildDetailRow(
                  icon: Icons.calendar_today,
                  label: 'Date',
                  value: DateFormat('EEEE, MMMM d, y').format(startTime),
                  accentColor: accentColor,
                ),
                const SizedBox(height: 16),
              ],
              if (!isAllDay && startTime != null && endTime != null) ...[
                _buildDetailRow(
                  icon: Icons.access_time,
                  label: 'Time',
                  value:
                      '${DateFormat('HH:mm').format(startTime.toLocal())} - ${DateFormat('HH:mm').format(endTime.toLocal())}',
                  accentColor: accentColor,
                ),
                const SizedBox(height: 16),
              ],
              if (isAllDay) ...[
                _buildDetailRow(
                  icon: Icons.access_time,
                  label: 'Duration',
                  value: 'All day event',
                  accentColor: accentColor,
                ),
                const SizedBox(height: 16),
              ],
              if (event.location != null && event.location!.isNotEmpty) ...[
                _buildDetailRow(
                  icon: Icons.location_on,
                  label: 'Location',
                  value: event.location!,
                  accentColor: accentColor,
                ),
                const SizedBox(height: 16),
              ],
              if (event.description != null && event.description!.isNotEmpty) ...[
                _buildDetailRow(
                  icon: Icons.notes,
                  label: 'Notes',
                  value: event.description!,
                  accentColor: accentColor,
                ),
                const SizedBox(height: 16),
              ],
              const SizedBox(height: 8),
              SizedBox(
                width: double.infinity,
                child: ElevatedButton(
                  onPressed: () => Navigator.pop(context),
                  style: ElevatedButton.styleFrom(
                    backgroundColor: accentColor,
                    foregroundColor: Colors.white,
                    padding: const EdgeInsets.symmetric(vertical: 14),
                    shape: RoundedRectangleBorder(
                      borderRadius: BorderRadius.circular(12),
                    ),
                  ),
                  child: const Text(
                    'Close',
                    style: TextStyle(fontWeight: FontWeight.w600),
                  ),
                ),
              ),
            ],
          ),
        ),
      ),
    );
  }

  Widget _buildDetailRow({
    required IconData icon,
    required String label,
    required String value,
    required Color accentColor,
  }) {
    return Row(
      crossAxisAlignment: CrossAxisAlignment.start,
      children: [
        Container(
          padding: const EdgeInsets.all(8),
          decoration: BoxDecoration(
            color: accentColor.withValues(alpha: 0.1),
            borderRadius: BorderRadius.circular(8),
          ),
          child: Icon(icon, size: 20, color: accentColor),
        ),
        const SizedBox(width: 12),
        Expanded(
          child: Column(
            crossAxisAlignment: CrossAxisAlignment.start,
            children: [
              Text(
                label,
                style: TextStyle(
                  fontSize: 12,
                  fontWeight: FontWeight.w600,
                  color: Colors.grey[600],
                ),
              ),
              const SizedBox(height: 4),
              Text(
                value,
                style: const TextStyle(
                  fontSize: 14,
                  color: Colors.black87,
                ),
              ),
            ],
          ),
        ),
      ],
    );
  }
}