import 'package:flutter/material.dart';
import '/domain/services/api_service.dart';
import 'package:http/http.dart' as http;
import '/core/constants.dart';
import 'dart:convert';

class AdminBroadcastScreen extends StatefulWidget {
  const AdminBroadcastScreen({Key? key}) : super(key: key);

  @override
  State<AdminBroadcastScreen> createState() => _AdminBroadcastScreenState();
}

class _AdminBroadcastScreenState extends State<AdminBroadcastScreen> {
  final TextEditingController _messageController = TextEditingController();
  final ApiService _apiService = ApiService();
  
  bool _isLoading = false;
  bool _broadcastToAll = true;
  Set<int> _selectedUserIds = {};
  List<Map<String, dynamic>> _allUsers = [];
  bool _isLoadingUsers = false;

  @override
  void initState() {
    super.initState();
    _loadAllUsers();
  }

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

  Future<void> _loadAllUsers() async {
    setState(() => _isLoadingUsers = true);
    try {
      final token = await _apiService.getAccessToken();
      final response = await http.get(
        Uri.parse('${AppConstants.baseUrl}/users/all'),
        headers: {
          'Authorization': 'Bearer $token',
          'Content-Type': 'application/json',
        },
      );

      if (response.statusCode == 200) {
        final List<dynamic> data = jsonDecode(utf8.decode(response.bodyBytes));
        setState(() {
          _allUsers = data.map((user) {
            return {
              'id': user['id'],
              'username': user['username'],
              'name': user['name'],
            };
          }).toList();
        });
      } else {
        _showErrorDialog('Не удалось загрузить список пользователей');
      }
    } catch (e) {
      _showErrorDialog('Ошибка при загрузке пользователей: $e');
    } finally {
      setState(() => _isLoadingUsers = false);
    }
  }

  Future<void> _sendBroadcast() async {
    final message = _messageController.text.trim();
    
    if (message.isEmpty) {
      _showErrorDialog('Введите текст сообщения');
      return;
    }

    if (!_broadcastToAll && _selectedUserIds.isEmpty) {
      _showErrorDialog('Выберите хотя бы одного пользователя');
      return;
    }

    setState(() => _isLoading = true);

    try {
      final token = await _apiService.getAccessToken();
      
      final payload = {
        'content': message,
        if (!_broadcastToAll) 'user_ids': _selectedUserIds.toList(),
      };

      final response = await http.post(
        Uri.parse('${AppConstants.baseUrl}/admin/broadcast'),
        headers: {
          'Authorization': 'Bearer $token',
          'Content-Type': 'application/json',
        },
        body: jsonEncode(payload),
      );

      if (response.statusCode == 200) {
        final data = jsonDecode(utf8.decode(response.bodyBytes));
        _messageController.clear();
        setState(() => _selectedUserIds.clear());
        
        _showSuccessDialog(data['message'] ?? 'Рассылка отправлена успешно');
      } else {
        final errorData = jsonDecode(utf8.decode(response.bodyBytes));
        _showErrorDialog(
          errorData['detail'] ?? 'Не удалось отправить рассылку',
        );
      }
    } catch (e) {
      _showErrorDialog('Ошибка при отправке рассылки: $e');
    } finally {
      setState(() => _isLoading = false);
    }
  }

  void _showErrorDialog(String message) {
    showDialog(
      context: context,
      builder: (ctx) => AlertDialog(
        title: const Text('Ошибка'),
        content: Text(message),
        actions: [
          TextButton(
            onPressed: () => Navigator.pop(ctx),
            child: const Text('OK'),
          ),
        ],
      ),
    );
  }

  void _showSuccessDialog(String message) {
    showDialog(
      context: context,
      builder: (ctx) => AlertDialog(
        title: const Text('Успешно'),
        content: Text(message),
        actions: [
          TextButton(
            onPressed: () => Navigator.pop(ctx),
            child: const Text('OK'),
          ),
        ],
      ),
    );
  }

  @override
  Widget build(BuildContext context) {
    final colorScheme = Theme.of(context).colorScheme;

    return Scaffold(
      body: SingleChildScrollView(
        padding: const EdgeInsets.all(16),
        child: Column(
          crossAxisAlignment: CrossAxisAlignment.start,
          children: [
            // Message input section
            Text(
              'Текст сообщения',
              style: Theme.of(context).textTheme.titleMedium,
            ),
            const SizedBox(height: 8),
            TextField(
              controller: _messageController,
              decoration: InputDecoration(
                hintText: 'Введите текст для рассылки...',
                border: OutlineInputBorder(
                  borderRadius: BorderRadius.circular(12),
                ),
                filled: true,
                fillColor: colorScheme.surface,
              ),
              maxLines: 5,
              minLines: 3,
            ),
            const SizedBox(height: 24),

            // Recipient selection section
            Text(
              'Получатели',
              style: Theme.of(context).textTheme.titleMedium,
            ),
            const SizedBox(height: 12),

            // "All users" toggle
            Card(
              child: ListTile(
                title: const Text('Отправить всем'),
                leading: Radio<bool>(
                  value: true,
                  groupValue: _broadcastToAll,
                  onChanged: (value) {
                    setState(() {
                      _broadcastToAll = value ?? true;
                      if (_broadcastToAll) {
                        _selectedUserIds.clear();
                      }
                    });
                  },
                ),
              ),
            ),
            const SizedBox(height: 12),

            // "Selected users" toggle
            Card(
              child: ListTile(
                title: const Text('Отправить выбранным'),
                leading: Radio<bool>(
                  value: false,
                  groupValue: _broadcastToAll,
                  onChanged: (value) {
                    setState(() {
                      _broadcastToAll = value ?? false;
                    });
                  },
                ),
              ),
            ),
            const SizedBox(height: 16),

            // User list for selection
            if (!_broadcastToAll) ...[
              if (_isLoadingUsers)
                const Center(child: CircularProgressIndicator())
              else if (_allUsers.isEmpty)
                const Padding(
                  padding: EdgeInsets.all(16),
                  child: Text('Нет пользователей'),
                )
              else
                Card(
                  child: Column(
                    children: [
                      Padding(
                        padding: const EdgeInsets.all(12),
                        child: Row(
                          mainAxisAlignment: MainAxisAlignment.spaceBetween,
                          children: [
                            Text(
                              'Выбрано: ${_selectedUserIds.length}',
                              style: Theme.of(context).textTheme.bodyMedium,
                            ),
                            if (_selectedUserIds.isNotEmpty)
                              TextButton(
                                onPressed: () {
                                  setState(() => _selectedUserIds.clear());
                                },
                                child: const Text('Очистить'),
                              ),
                          ],
                        ),
                      ),
                      Divider(height: 0, color: colorScheme.outlineVariant),
                      SizedBox(
                        height: 250,
                        child: ListView.builder(
                          itemCount: _allUsers.length,
                          itemBuilder: (context, index) {
                            final user = _allUsers[index];
                            final userId = user['id'] as int;
                            final isSelected = _selectedUserIds.contains(userId);

                            return CheckboxListTile(
                              value: isSelected,
                              onChanged: (selected) {
                                setState(() {
                                  if (selected == true) {
                                    _selectedUserIds.add(userId);
                                  } else {
                                    _selectedUserIds.remove(userId);
                                  }
                                });
                              },
                              title: Text(user['name'] ?? 'Неизвестный'),
                              subtitle: Text('@${user['username']}'),
                            );
                          },
                        ),
                      ),
                    ],
                  ),
                ),
            ],
            const SizedBox(height: 24),

            // Send button
            SizedBox(
              width: double.infinity,
              child: FilledButton.icon(
                onPressed: _isLoading ? null : _sendBroadcast,
                icon: _isLoading
                    ? const SizedBox(
                        width: 20,
                        height: 20,
                        child: CircularProgressIndicator(strokeWidth: 2),
                      )
                    : const Icon(Icons.send),
                label: Text(
                  _isLoading ? 'Отправка...' : 'Отправить рассылку',
                ),
              ),
            ),
          ],
        ),
      ),
    );
  }
}