import 'package:flutter/material.dart';
import 'package:provider/provider.dart';
import 'package:flutter_datetime_picker_plus/flutter_datetime_picker_plus.dart';
import '../models/supplement.dart';
import '../providers/supplement_provider.dart';

class AddSupplementScreen extends StatefulWidget {
  final Supplement? supplement;

  const AddSupplementScreen({super.key, this.supplement});

  @override
  State<AddSupplementScreen> createState() => _AddSupplementScreenState();
}

class _AddSupplementScreenState extends State<AddSupplementScreen> {
  final _formKey = GlobalKey<FormState>();
  final _nameController = TextEditingController();
  final _dosageAmountController = TextEditingController();
  final _numberOfUnitsController = TextEditingController();
  final _notesController = TextEditingController();
  
  String _selectedUnit = 'mg';
  String _selectedUnitType = 'capsules';
  int _frequencyPerDay = 1;
  List<String> _reminderTimes = ['08:00'];

  final List<String> _units = ['mg', 'g', 'μg', 'IU', 'ml'];
  final List<String> _unitTypes = ['capsules', 'tablets', 'softgels', 'drops', 'ml', 'scoops', 'gummies'];

  @override
  void initState() {
    super.initState();
    if (widget.supplement != null) {
      _initializeWithExistingSupplement();
    } else {
      _numberOfUnitsController.text = '1'; // Default to 1 unit
    }
  }

  void _initializeWithExistingSupplement() {
    final supplement = widget.supplement!;
    _nameController.text = supplement.name;
    _dosageAmountController.text = supplement.dosageAmount.toString();
    _numberOfUnitsController.text = supplement.numberOfUnits.toString();
    _notesController.text = supplement.notes ?? '';
    _selectedUnit = supplement.unit;
    _selectedUnitType = supplement.unitType;
    _frequencyPerDay = supplement.frequencyPerDay;
    _reminderTimes = List.from(supplement.reminderTimes);
  }

  @override
  Widget build(BuildContext context) {
    final isEditing = widget.supplement != null;

    return Scaffold(
      appBar: AppBar(
        title: Text(isEditing ? 'Edit Supplement' : 'Add Supplement'),
        backgroundColor: Theme.of(context).colorScheme.inversePrimary,
      ),
      body: Form(
        key: _formKey,
        child: SingleChildScrollView(
          padding: const EdgeInsets.all(16),
          child: Column(
            crossAxisAlignment: CrossAxisAlignment.start,
            children: [
              // Name field
              TextFormField(
                controller: _nameController,
                decoration: const InputDecoration(
                  labelText: 'Supplement Name *',
                  border: OutlineInputBorder(),
                  hintText: 'e.g., Vitamin D3',
                ),
                validator: (value) {
                  if (value == null || value.trim().isEmpty) {
                    return 'Please enter a supplement name';
                  }
                  return null;
                },
              ),
              const SizedBox(height: 16),

              // Dosage amount per unit
              Row(
                children: [
                  Expanded(
                    flex: 2,
                    child: TextFormField(
                      controller: _dosageAmountController,
                      keyboardType: TextInputType.number,
                      decoration: const InputDecoration(
                        labelText: 'Amount per unit *',
                        border: OutlineInputBorder(),
                        hintText: '187',
                      ),
                      validator: (value) {
                        if (value == null || value.trim().isEmpty) {
                          return 'Please enter amount per unit';
                        }
                        if (double.tryParse(value) == null) {
                          return 'Please enter a valid number';
                        }
                        return null;
                      },
                    ),
                  ),
                  const SizedBox(width: 12),
                  Expanded(
                    flex: 1,
                    child: DropdownButtonFormField<String>(
                      value: _selectedUnit,
                      decoration: const InputDecoration(
                        labelText: 'Unit',
                        border: OutlineInputBorder(),
                      ),
                      items: _units.map((unit) {
                        return DropdownMenuItem(
                          value: unit,
                          child: Text(unit),
                        );
                      }).toList(),
                      onChanged: (value) {
                        setState(() {
                          _selectedUnit = value!;
                        });
                      },
                    ),
                  ),
                ],
              ),
              const SizedBox(height: 16),

              // Number of units to take
              Row(
                children: [
                  Expanded(
                    flex: 2,
                    child: TextFormField(
                      controller: _numberOfUnitsController,
                      keyboardType: TextInputType.number,
                      decoration: const InputDecoration(
                        labelText: 'Number to take *',
                        border: OutlineInputBorder(),
                        hintText: '2',
                      ),
                      validator: (value) {
                        if (value == null || value.trim().isEmpty) {
                          return 'Please enter number to take';
                        }
                        if (int.tryParse(value) == null || int.parse(value) < 1) {
                          return 'Please enter a valid number (1 or more)';
                        }
                        return null;
                      },
                    ),
                  ),
                  const SizedBox(width: 12),
                  Expanded(
                    flex: 1,
                    child: DropdownButtonFormField<String>(
                      value: _selectedUnitType,
                      decoration: const InputDecoration(
                        labelText: 'Type',
                        border: OutlineInputBorder(),
                      ),
                      items: _unitTypes.map((type) {
                        return DropdownMenuItem(
                          value: type,
                          child: Text(type),
                        );
                      }).toList(),
                      onChanged: (value) {
                        setState(() {
                          _selectedUnitType = value!;
                        });
                      },
                    ),
                  ),
                ],
              ),
              const SizedBox(height: 8),
              Text(
                'Total per intake: ${_dosageAmountController.text.isNotEmpty && _numberOfUnitsController.text.isNotEmpty ? (double.tryParse(_dosageAmountController.text) ?? 0) * (int.tryParse(_numberOfUnitsController.text) ?? 0) : 0} $_selectedUnit',
                style: TextStyle(
                  fontSize: 12,
                  color: Theme.of(context).colorScheme.onSurfaceVariant,
                  fontStyle: FontStyle.italic,
                ),
              ),
              const SizedBox(height: 16),

              // Frequency per day
              Row(
                children: [
                  const Text('Frequency per day: '),
                  const SizedBox(width: 8),
                  DropdownButton<int>(
                    value: _frequencyPerDay,
                    items: List.generate(6, (index) => index + 1).map((freq) {
                      return DropdownMenuItem(
                        value: freq,
                        child: Text('$freq time${freq > 1 ? 's' : ''}'),
                      );
                    }).toList(),
                    onChanged: (value) {
                      setState(() {
                        _frequencyPerDay = value!;
                        _adjustReminderTimes();
                      });
                    },
                  ),
                ],
              ),
              const SizedBox(height: 16),

              // Reminder times
              const Text(
                'Reminder Times',
                style: TextStyle(fontSize: 16, fontWeight: FontWeight.bold),
              ),
              const SizedBox(height: 8),
              ..._reminderTimes.asMap().entries.map((entry) {
                final index = entry.key;
                final time = entry.value;
                return Padding(
                  padding: const EdgeInsets.only(bottom: 8),
                  child: Row(
                    children: [
                      Expanded(
                        child: InkWell(
                          onTap: () => _selectTime(index),
                          child: Container(
                            padding: const EdgeInsets.all(12),
                            decoration: BoxDecoration(
                              border: Border.all(color: Theme.of(context).colorScheme.outline),
                              borderRadius: BorderRadius.circular(4),
                            ),
                            child: Text(time),
                          ),
                        ),
                      ),
                      if (_reminderTimes.length > 1)
                        IconButton(
                          onPressed: () => _removeReminderTime(index),
                          icon: const Icon(Icons.remove_circle_outline),
                        ),
                    ],
                  ),
                );
              }),
              if (_reminderTimes.length < _frequencyPerDay)
                TextButton.icon(
                  onPressed: _addReminderTime,
                  icon: const Icon(Icons.add),
                  label: const Text('Add Reminder Time'),
                ),
              const SizedBox(height: 16),

              // Notes
              TextFormField(
                controller: _notesController,
                decoration: const InputDecoration(
                  labelText: 'Notes (optional)',
                  border: OutlineInputBorder(),
                  hintText: 'Take with food, before meal, etc.',
                ),
                maxLines: 3,
              ),
              const SizedBox(height: 24),

              // Save button
              SizedBox(
                width: double.infinity,
                child: ElevatedButton(
                  onPressed: _saveSupplement,
                  style: ElevatedButton.styleFrom(
                    padding: const EdgeInsets.all(16),
                  ),
                  child: Text(isEditing ? 'Update Supplement' : 'Add Supplement'),
                ),
              ),
            ],
          ),
        ),
      ),
    );
  }

  void _adjustReminderTimes() {
    if (_reminderTimes.length > _frequencyPerDay) {
      _reminderTimes = _reminderTimes.take(_frequencyPerDay).toList();
    } else if (_reminderTimes.length < _frequencyPerDay) {
      while (_reminderTimes.length < _frequencyPerDay) {
        _reminderTimes.add('08:00');
      }
    }
  }

  void _selectTime(int index) {
    DatePicker.showTimePicker(
      context,
      showTitleActions: true,
      onConfirm: (time) {
        setState(() {
          _reminderTimes[index] = '${time.hour.toString().padLeft(2, '0')}:${time.minute.toString().padLeft(2, '0')}';
        });
      },
      currentTime: DateTime.now(),
    );
  }

  void _addReminderTime() {
    if (_reminderTimes.length < _frequencyPerDay) {
      setState(() {
        _reminderTimes.add('08:00');
      });
    }
  }

  void _removeReminderTime(int index) {
    if (_reminderTimes.length > 1) {
      setState(() {
        _reminderTimes.removeAt(index);
      });
    }
  }

  void _saveSupplement() async {
    if (_formKey.currentState!.validate()) {
      final supplement = Supplement(
        id: widget.supplement?.id,
        name: _nameController.text.trim(),
        dosageAmount: double.parse(_dosageAmountController.text),
        numberOfUnits: int.parse(_numberOfUnitsController.text),
        unit: _selectedUnit,
        unitType: _selectedUnitType,
        frequencyPerDay: _frequencyPerDay,
        reminderTimes: _reminderTimes,
        notes: _notesController.text.trim().isNotEmpty ? _notesController.text.trim() : null,
        createdAt: widget.supplement?.createdAt ?? DateTime.now(),
      );

      final provider = context.read<SupplementProvider>();
      
      try {
        if (widget.supplement != null) {
          await provider.updateSupplement(supplement);
        } else {
          await provider.addSupplement(supplement);
        }

        if (mounted) {
          Navigator.of(context).pop();
          
          ScaffoldMessenger.of(context).showSnackBar(
            SnackBar(
              content: Text(widget.supplement != null 
                  ? 'Supplement updated successfully!'
                  : 'Supplement added successfully!'),
              backgroundColor: Colors.green,
            ),
          );
        }
      } catch (e) {
        if (mounted) {
          ScaffoldMessenger.of(context).showSnackBar(
            SnackBar(
              content: Text('Error: ${e.toString()}'),
              backgroundColor: Colors.red,
            ),
          );
        }
      }
    }
  }

  @override
  void dispose() {
    _nameController.dispose();
    _dosageAmountController.dispose();
    _numberOfUnitsController.dispose();
    _notesController.dispose();
    super.dispose();
  }
}