import 'dart:async';
import 'package:flutter/material.dart';
import 'package:google_fonts/google_fonts.dart';
import 'package:flutter_riverpod/flutter_riverpod.dart';
import '../../theme/app_theme.dart';
import '../../models/cycle_entry.dart';
import '../../models/user_profile.dart';
import '../../services/notification_service.dart';
import '../../providers/user_provider.dart';

class PadTrackerScreen extends ConsumerStatefulWidget {
  const PadTrackerScreen({super.key});

  @override
  ConsumerState<PadTrackerScreen> createState() => _PadTrackerScreenState();
}

class _PadTrackerScreenState extends ConsumerState<PadTrackerScreen> {
  FlowIntensity _selectedFlow = FlowIntensity.medium;
  bool _notificationScheduled = false;
  Timer? _timer;
  Duration _timeSinceLastChange = Duration.zero;
  int? _activeSupplyIndex;

  @override
  void initState() {
    super.initState();
    WidgetsBinding.instance.addPostFrameCallback((_) {
      _checkInitialPrompt();
    });
    _startTimer();
  }

  @override
  void dispose() {
    _timer?.cancel();
    super.dispose();
  }

  void _startTimer() {
    _timer = Timer.periodic(const Duration(seconds: 1), (timer) {
      if (mounted) {
        setState(() {
          _updateTimeSinceChange();
        });
      }
    });
    _updateTimeSinceChange();
  }

  void _updateTimeSinceChange() {
    final user = ref.read(userProfileProvider);
    if (user?.lastPadChangeTime != null) {
      _timeSinceLastChange = DateTime.now().difference(user!.lastPadChangeTime!);
    } else {
      _timeSinceLastChange = Duration.zero;
    }
  }

  Future<void> _checkInitialPrompt() async {
    final user = ref.read(userProfileProvider);
    if (user == null) return;

    final lastChange = user.lastPadChangeTime;
    final now = DateTime.now();
    final bool changedToday = lastChange != null && 
        lastChange.year == now.year && 
        lastChange.month == now.month && 
        lastChange.day == now.day;

    if (!changedToday) {
      await showDialog(
        context: context,
        barrierDismissible: false,
        builder: (context) => AlertDialog(
          title: Text('Track Your Change', style: GoogleFonts.outfit(fontWeight: FontWeight.bold)),
          content: Text(
            'When did you last change your pad/tampon?',
            style: GoogleFonts.outfit(),
          ),
          actions: [
            TextButton(
              onPressed: () {
                _updateLastChangeTime(DateTime.now());
                Navigator.pop(context);
              },
              child: const Text('Just Now'),
            ),
            TextButton(
              onPressed: () async {
                final time = await showTimePicker(
                  context: context,
                  initialTime: TimeOfDay.now(),
                );
                if (time != null && mounted) {
                  final now = DateTime.now();
                  final selectedDate = DateTime(now.year, now.month, now.day, time.hour, time.minute);
                  if (selectedDate.isAfter(now)) {
                     _updateLastChangeTime(now); 
                  } else {
                     _updateLastChangeTime(selectedDate);
                  }
                  Navigator.pop(context);
                }
              },
              child: const Text('Pick Time'),
            ),
             TextButton(
              onPressed: () {
                Navigator.pop(context);
              },
              child: const Text('Skip'),
            ),
          ],
        ),
      );
    }
  }

  Future<void> _updateLastChangeTime(DateTime time) async {
    final user = ref.read(userProfileProvider);
    if (user != null) {
       final updatedProfile = user.copyWith(
         lastPadChangeTime: time,
       );
       await ref.read(userProfileProvider.notifier).updateProfile(updatedProfile);
       _updateTimeSinceChange(); 
    }
  }

  SupplyItem? get _activeSupply {
    final user = ref.watch(userProfileProvider);
    if (user == null || user.padSupplies == null || user.padSupplies!.isEmpty) return null;
    if (_activeSupplyIndex == null || _activeSupplyIndex! >= user.padSupplies!.length) {
       return user.padSupplies!.first;
    }
    return user.padSupplies![_activeSupplyIndex!];
  }

  bool get _shouldShowMismatchWarning {
     final supply = _activeSupply;
     if (supply == null) return false;
     
     int flowValue = 1;
     switch (_selectedFlow) {
        case FlowIntensity.spotting: flowValue = 1; break;
        case FlowIntensity.light: flowValue = 2; break;
        case FlowIntensity.medium: flowValue = 3; break;
        case FlowIntensity.heavy: flowValue = 5; break;
     }
     
     return flowValue > supply.absorbency;
  }

  int get _recommendedHours {
    final supply = _activeSupply;
    if (supply == null) return 6; // Default

    final type = supply.type;

    if (type == PadType.menstrualCup || 
        type == PadType.menstrualDisc || 
        type == PadType.periodUnderwear) {
      return 12; 
    }

    int baseHours;
    switch (_selectedFlow) {
      case FlowIntensity.heavy:
        baseHours = (type == PadType.super_pad || type == PadType.overnight || type == PadType.tampon_super) 
            ? 4 
            : 3;
        break;
      case FlowIntensity.medium:
        baseHours = 6;
        break;
      case FlowIntensity.light:
        baseHours = 8;
        break;
      case FlowIntensity.spotting:
        baseHours = 8;
        break;
    }

    int flowValue = 1;
    switch (_selectedFlow) {
      case FlowIntensity.spotting: flowValue = 1; break;
      case FlowIntensity.light: flowValue = 2; break;
      case FlowIntensity.medium: flowValue = 3; break;
      case FlowIntensity.heavy: flowValue = 5; break;
    }

    final absorbency = supply.absorbency;
    final ratio = absorbency / flowValue;

    double adjusted = baseHours * ratio;

    int maxHours = (type == PadType.tampon_regular || type == PadType.tampon_super) 
        ? 8 
        : 12;

    if (adjusted < 1) adjusted = 1;
    if (adjusted > maxHours) adjusted = maxHours.toDouble();

    return adjusted.round();
  }

  void _showSupplyPicker() {
    showModalBottomSheet(
      context: context,
      isScrollControlled: true,
      backgroundColor: Colors.transparent,
      builder: (context) => const _SupplyManagementPopup(),
    );
  }

  @override
  Widget build(BuildContext context) {
    final remainingHours = _recommendedHours - _timeSinceLastChange.inHours;
    final isOverdue = remainingHours < 0;
    final supply = _activeSupply;
    final user = ref.watch(userProfileProvider);

    return Scaffold(
      appBar: AppBar(
        title: const Text('Pad Tracker'),
        centerTitle: true,
      ),
      body: SingleChildScrollView(
        padding: const EdgeInsets.all(20),
        child: Column(
          crossAxisAlignment: CrossAxisAlignment.start,
          children: [
            // Supply Selection at the top as requested
            _buildSectionHeader('Current Protection'),
            const SizedBox(height: 12),
            GestureDetector(
              onTap: _showSupplyPicker,
              child: Container(
                padding: const EdgeInsets.all(16),
                decoration: BoxDecoration(
                  color: Theme.of(context).cardTheme.color,
                  borderRadius: BorderRadius.circular(16),
                  border: Border.all(color: AppColors.menstrualPhase.withOpacity(0.3)),
                  boxShadow: [
                    BoxShadow(
                      color: Colors.black.withOpacity(0.05),
                      blurRadius: 10,
                      offset: const Offset(0, 4),
                    ),
                  ],
                ),
                child: Row(
                  children: [
                    Container(
                      padding: const EdgeInsets.all(10),
                      decoration: BoxDecoration(
                        color: AppColors.menstrualPhase.withOpacity(0.1),
                        shape: BoxShape.circle,
                      ),
                      child: const Icon(Icons.inventory_2_outlined, color: AppColors.menstrualPhase),
                    ),
                    const SizedBox(width: 16),
                    Expanded(
                      child: Column(
                        crossAxisAlignment: CrossAxisAlignment.start,
                        children: [
                          Text(
                            supply != null ? '${supply.brand} ${supply.type.label}' : 'No Supply Selected',
                            style: GoogleFonts.outfit(fontWeight: FontWeight.bold, fontSize: 16),
                          ),
                          if (supply != null)
                             Text(
                              'Absorbency: ${supply.absorbency}/5 • Stock: ${supply.count}',
                              style: GoogleFonts.outfit(fontSize: 12, color: AppColors.warmGray),
                            )
                          else
                            Text(
                              'Tap to manage your supplies',
                              style: GoogleFonts.outfit(fontSize: 12, color: AppColors.warmGray),
                            ),
                        ],
                      ),
                    ),
                    const Icon(Icons.edit_outlined, size: 20, color: AppColors.warmGray),
                  ],
                ),
              ),
            ),
            
            const SizedBox(height: 32),
            
            _buildSectionHeader('Current Flow Intensity'),
            const SizedBox(height: 12),
            Wrap(
              spacing: 8,
              runSpacing: 8,
              children: FlowIntensity.values.map((flow) {
                return ChoiceChip(
                  label: Text(flow.label),
                  selected: _selectedFlow == flow,
                  onSelected: (selected) {
                    if (selected) setState(() => _selectedFlow = flow);
                  },
                  selectedColor: AppColors.menstrualPhase.withOpacity(0.3),
                  labelStyle: GoogleFonts.outfit(
                     color: _selectedFlow == flow ? AppColors.navyBlue : AppColors.charcoal,
                     fontWeight: _selectedFlow == flow ? FontWeight.w600 : FontWeight.w400,
                  ),
                );
              }).toList(),
            ),
            const SizedBox(height: 48),

            // Recommendation Card / Timer
            Center(
              child: Container(
                width: double.infinity,
                padding: const EdgeInsets.all(24),
                decoration: BoxDecoration(
                  color: isOverdue ? AppColors.rose.withOpacity(0.15) : AppColors.sageGreen.withOpacity(0.15),
                  borderRadius: BorderRadius.circular(20),
                  border: Border.all(
                    color: isOverdue ? AppColors.rose.withOpacity(0.3) : AppColors.sageGreen.withOpacity(0.3)
                  ),
                ),
                child: Column(
                  children: [
                    Icon(
                      isOverdue ? Icons.warning_amber_rounded : Icons.timer_outlined, 
                      size: 48, 
                      color: isOverdue ? AppColors.rose : AppColors.sageGreen
                    ),
                    const SizedBox(height: 16),
                    Text(
                      isOverdue ? 'Change Overdue!' : 'Next Change In:',
                      style: GoogleFonts.outfit(
                        fontSize: 16,
                        color: AppColors.warmGray,
                      ),
                    ),
                    const SizedBox(height: 8),
                    if (_timeSinceLastChange != Duration.zero) ...[
                       Text(
                        _formatRemainingTime(
                          Duration(hours: _recommendedHours) - _timeSinceLastChange,
                          user!
                        ),
                        style: GoogleFonts.outfit(
                          fontSize: 32,
                          fontWeight: FontWeight.bold,
                          color: isOverdue ? AppColors.rose : AppColors.navyBlue,
                        ),
                        textAlign: TextAlign.center,
                      ),
                       Text(
                        'Last changed: ${_formatDuration(_timeSinceLastChange, user)} ago',
                        style: GoogleFonts.outfit(fontSize: 12, color: AppColors.warmGray),
                      ),
                    ] else ...[
                       Text(
                        '~$_recommendedHours Hours',
                        style: GoogleFonts.outfit(
                          fontSize: 32,
                          fontWeight: FontWeight.bold,
                          color: AppColors.navyBlue,
                        ),
                      ),
                    ],
                  ],
                ),
              ),
            ),
            const SizedBox(height: 32),
            
            if (_shouldShowMismatchWarning)
               Container(
                margin: const EdgeInsets.only(bottom: 24),
                padding: const EdgeInsets.all(16),
                decoration: BoxDecoration(
                  color: AppColors.rose.withOpacity(0.1),
                  borderRadius: BorderRadius.circular(12),
                  border: Border.all(color: AppColors.rose.withOpacity(0.3)),
                ),
                child: Row(
                  children: [
                    const Icon(Icons.warning_amber_rounded, color: AppColors.rose),
                    const SizedBox(width: 12),
                    Expanded(
                      child: Text(
                        'Your flow is heavier than your protection capacity. Change sooner to avoid leaks!',
                        style: GoogleFonts.outfit(
                          fontSize: 14, 
                          color: AppColors.charcoal,
                          fontWeight: FontWeight.w500
                        ),
                      ),
                    ),
                  ],
                ),
               ),
            
            const SizedBox(height: 16),

            SizedBox(
              width: double.infinity,
              height: 56,
              child: ElevatedButton.icon(
                onPressed: supply == null ? null : () async {
                        final hours = _recommendedHours;
                        
                        // 1. Auto-deduct inventory
                        if (user != null && 
                            user.isAutoInventoryEnabled) {
                          
                          // Deduct from the active supply
                          final List<SupplyItem> updatedSupplies = user.padSupplies!.map((s) {
                             if (s == supply && s.count > 0) {
                               return s.copyWith(count: s.count - 1);
                             }
                             return s;
                          }).toList();

                          final updatedProfile = user.copyWith(
                            padSupplies: updatedSupplies,
                            lastInventoryUpdate: DateTime.now(),
                            lastPadChangeTime: DateTime.now(), 
                          );
                          await ref.read(userProfileProvider.notifier).updateProfile(updatedProfile);
                        } else if (user != null) {
                           final updatedProfile = user.copyWith(
                            lastPadChangeTime: DateTime.now(),
                          );
                          await ref.read(userProfileProvider.notifier).updateProfile(updatedProfile);
                        }

                        await NotificationService().scheduleNotification(
                          id: 100, 
                          title: 'Time to change!',
                          body: 'It\'s been $hours hours since you logged your protection.',
                          scheduledDate: DateTime.now().add(Duration(hours: hours)),
                        );
                        
                        setState(() {
                          _notificationScheduled = true;
                          _updateTimeSinceChange(); 
                        });
                        
                        if (mounted) {
                          ScaffoldMessenger.of(context).showSnackBar(
                            const SnackBar(content: Text('Logged! Timer reset & Inventory updated.')),
                          );
                        }
                      },
                icon: Icon(_notificationScheduled ? Icons.check : Icons.restart_alt),
                label: Text(
                  'Changed / Remind Me',
                  style: GoogleFonts.outfit(fontSize: 18, fontWeight: FontWeight.w600),
                ),
                style: ElevatedButton.styleFrom(
                  backgroundColor: AppColors.menstrualPhase,
                  foregroundColor: Colors.white,
                  disabledBackgroundColor: AppColors.warmGray.withOpacity(0.2),
                ),
              ),
            ),
          ],
        ),
      ),
    );
  }

  String _formatDuration(Duration d, UserProfile user) {
    final hours = d.inHours;
    final minutes = d.inMinutes % 60;
    final seconds = d.inSeconds % 60;
    
    final bool showMins = user.showPadTimerMinutes;
    final bool showSecs = user.showPadTimerSeconds && showMins; // Enforce minutes must be shown to show seconds
    
    List<String> parts = [];
    if (hours > 0) parts.add('${hours}h');
    if (showMins) parts.add('${minutes}m');
    if (showSecs) parts.add('${seconds}s');
    
    if (parts.isEmpty) {
      if (hours == 0 && minutes == 0 && seconds == 0) return 'Just now';
      return '${d.inMinutes}m'; // Fallback
    }
    return parts.join(' ');
  }

  String _formatRemainingTime(Duration remaining, UserProfile user) {
    final isOverdue = remaining.isNegative;
    final absRemaining = remaining.abs();
    
    final hours = absRemaining.inHours;
    final minutes = absRemaining.inMinutes % 60;
    final seconds = absRemaining.inSeconds % 60;
    
    final bool showMins = user.showPadTimerMinutes;
    final bool showSecs = user.showPadTimerSeconds && showMins; // Enforce minutes must be shown to show seconds
    
    List<String> parts = [];
    if (hours > 0) parts.add('${hours}h');
    if (showMins) {
      parts.add('${minutes}m');
    }
    if (showSecs) {
      parts.add('${seconds}s');
    }
    
    if (parts.isEmpty) {
      return isOverdue ? 'Overdue' : 'Change Now';
    }
    
    String timeStr = parts.join(' ');
    return isOverdue ? '$timeStr overdue' : timeStr;
  }

  Widget _buildSectionHeader(String title) {
    return Text(
      title,
      style: GoogleFonts.outfit(
        fontSize: 18,
        fontWeight: FontWeight.w600,
        color: AppColors.navyBlue,
      ),
    );
  }
}

class _SupplyManagementPopup extends ConsumerStatefulWidget {
  const _SupplyManagementPopup();

  @override
  ConsumerState<_SupplyManagementPopup> createState() => _SupplyManagementPopupState();
}

class _SupplyManagementPopupState extends ConsumerState<_SupplyManagementPopup> {
  final _brandController = TextEditingController();
  PadType _selectedType = PadType.regular;
  int _absorbency = 3;
  int _count = 20;

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

  void _addSupply() async {
    final brand = _brandController.text.trim();
    if (brand.isEmpty) return;

    final user = ref.read(userProfileProvider);
    if (user == null) return;

    final newSupply = SupplyItem(
      brand: brand,
      type: _selectedType,
      absorbency: _absorbency,
      count: _count,
    );

    final List<SupplyItem> updatedSupplies = <SupplyItem>[...(user.padSupplies ?? []), newSupply];
    final updatedProfile = user.copyWith(padSupplies: updatedSupplies);
    
    await ref.read(userProfileProvider.notifier).updateProfile(updatedProfile);
    _brandController.clear();
    setState(() {
      _count = 20;
      _absorbency = 3;
    });
  }

  @override
  Widget build(BuildContext context) {
    final user = ref.watch(userProfileProvider);
    final supplies = user?.padSupplies ?? [];

    return Container(
      padding: EdgeInsets.only(
        bottom: MediaQuery.of(context).viewInsets.bottom,
        top: 20,
        left: 20,
        right: 20,
      ),
      decoration: BoxDecoration(
        color: Theme.of(context).scaffoldBackgroundColor,
        borderRadius: const BorderRadius.vertical(top: Radius.circular(24)),
      ),
      child: Column(
        mainAxisSize: MainAxisSize.min,
        crossAxisAlignment: CrossAxisAlignment.start,
        children: [
          Row(
            mainAxisAlignment: MainAxisAlignment.spaceBetween,
            children: [
              Text(
                'Manage Supplies',
                style: GoogleFonts.outfit(fontSize: 20, fontWeight: FontWeight.bold),
              ),
              IconButton(
                icon: const Icon(Icons.close),
                onPressed: () => Navigator.pop(context),
              ),
            ],
          ),
          const Divider(),
          const SizedBox(height: 16),
          
          if (supplies.isNotEmpty) ...[
            Text('Current Stock', style: GoogleFonts.outfit(fontWeight: FontWeight.w600, color: AppColors.navyBlue)),
            const SizedBox(height: 12),
            SizedBox(
              height: 120,
              child: ListView.builder(
                scrollDirection: Axis.horizontal,
                itemCount: supplies.length,
                itemBuilder: (context, index) {
                  final item = supplies[index];
                  return Container(
                    width: 160,
                    margin: const EdgeInsets.only(right: 12),
                    padding: const EdgeInsets.all(12),
                    decoration: BoxDecoration(
                      color: AppColors.warmCream.withOpacity(0.3),
                      borderRadius: BorderRadius.circular(16),
                      border: Border.all(color: AppColors.warmGray.withOpacity(0.2)),
                    ),
                    child: Column(
                      crossAxisAlignment: CrossAxisAlignment.start,
                      children: [
                        Row(
                          mainAxisAlignment: MainAxisAlignment.spaceBetween,
                          children: [
                            Expanded(
                              child: Text(item.brand, style: GoogleFonts.outfit(fontWeight: FontWeight.bold, fontSize: 13), overflow: TextOverflow.ellipsis),
                            ),
                            GestureDetector(
                               onTap: () async {
                                 final updatedSupplies = List<SupplyItem>.from(supplies)..removeAt(index);
                                 await ref.read(userProfileProvider.notifier).updateProfile(user!.copyWith(padSupplies: updatedSupplies));
                               },
                               child: const Icon(Icons.delete_outline, size: 16, color: Colors.red),
                            ),
                          ],
                        ),
                        Text(item.type.label, style: GoogleFonts.outfit(fontSize: 11, color: AppColors.warmGray)),
                        const Spacer(),
                        Row(
                          mainAxisAlignment: MainAxisAlignment.spaceBetween,
                          children: [
                             Text('Qty: ${item.count}', style: GoogleFonts.outfit(fontSize: 12, fontWeight: FontWeight.w600)),
                             Text('Abs: ${item.absorbency}', style: GoogleFonts.outfit(fontSize: 11, color: AppColors.menstrualPhase)),
                          ],
                        ),
                      ],
                    ),
                  );
                },
              ),
            ),
            const SizedBox(height: 24),
          ],

          Text('Add New Pack', style: GoogleFonts.outfit(fontWeight: FontWeight.w600, color: AppColors.navyBlue)),
          const SizedBox(height: 12),
          TextField(
            controller: _brandController,
            decoration: InputDecoration(
              hintText: 'Brand Name (e.g. Always)',
              filled: true,
              fillColor: AppColors.warmCream.withOpacity(0.2),
              border: OutlineInputBorder(borderRadius: BorderRadius.circular(12), borderSide: BorderSide.none),
              contentPadding: const EdgeInsets.symmetric(horizontal: 16, vertical: 12),
            ),
          ),
          const SizedBox(height: 12),
          Row(
            children: [
              Expanded(
                child: DropdownButtonFormField<PadType>(
                  value: _selectedType,
                  decoration: InputDecoration(
                    contentPadding: const EdgeInsets.symmetric(horizontal: 12),
                    border: OutlineInputBorder(borderRadius: BorderRadius.circular(12)),
                  ),
                  items: PadType.values.map((t) => DropdownMenuItem(value: t, child: Text(t.label, style: const TextStyle(fontSize: 13)))).toList(),
                  onChanged: (val) => setState(() => _selectedType = val!),
                ),
              ),
              const SizedBox(width: 12),
              Container(
                width: 100,
                padding: const EdgeInsets.symmetric(horizontal: 8),
                decoration: BoxDecoration(
                  border: Border.all(color: Colors.grey),
                  borderRadius: BorderRadius.circular(12),
                ),
                child: Row(
                  children: [
                    IconButton(icon: const Icon(Icons.remove, size: 16), onPressed: () => setState(() => _count = (_count > 0 ? _count - 1 : 0))),
                    Text('$_count', style: const TextStyle(fontWeight: FontWeight.bold)),
                    IconButton(icon: const Icon(Icons.add, size: 16), onPressed: () => setState(() => _count++)),
                  ],
                ),
              ),
            ],
          ),
          const SizedBox(height: 16),
          Text('Absorbency: $_absorbency/5', style: GoogleFonts.outfit(fontSize: 13, color: AppColors.warmGray)),
          Slider(
            value: _absorbency.toDouble(),
            min: 1, max: 5, divisions: 4,
            activeColor: AppColors.menstrualPhase,
            onChanged: (val) => setState(() => _absorbency = val.round()),
          ),
          const SizedBox(height: 16),
          SizedBox(
            width: double.infinity,
            height: 50,
            child: ElevatedButton(
              onPressed: _addSupply,
              style: ElevatedButton.styleFrom(backgroundColor: AppColors.navyBlue, foregroundColor: Colors.white),
              child: const Text('Add to Inventory'),
            ),
          ),
          const SizedBox(height: 24),
        ],
      ),
    );
  }
}