import 'dart:convert';
import 'package:http/http.dart' as http;
import '../utils/constants.dart';
import '../models/user.dart';
import '../models/allarme.dart';
import '../models/sito.dart';
import '../models/statistiche.dart';

class ApiService {
  static final ApiService _instance = ApiService._internal();
  factory ApiService() => _instance;
  ApiService._internal();

  String? _authToken;

  void setAuthToken(String token) => _authToken = token;
  void clearAuthToken() => _authToken = null;

  Map<String, String> _getHeaders({bool includeAuth = true}) {
    final headers = {
      'Content-Type': 'application/json',
      'Accept': 'application/json',
    };
    if (includeAuth && _authToken != null) {
      headers['Authorization'] = 'Bearer $_authToken';
    }
    return headers;
  }

  Future<Map<String, dynamic>> _handleResponse(http.Response response) async {
    if (response.statusCode >= 200 && response.statusCode < 300) {
      return json.decode(utf8.decode(response.bodyBytes));
    } else {
      final error = json.decode(utf8.decode(response.bodyBytes));
      throw Exception(error['detail'] ?? 'Errore sconosciuto');
    }
  }

  Future<Map<String, dynamic>> login(String email, String password) async {
    final response = await http.post(
      Uri.parse('${AppConstants.apiBaseUrl}/auth/login'),
      headers: _getHeaders(includeAuth: false),
      body: json.encode({'email': email, 'password': password}),
    );
    return _handleResponse(response);
  }

  Future<User> getCurrentUser() async {
    final response = await http.get(
      Uri.parse('${AppConstants.apiBaseUrl}/auth/me'),
      headers: _getHeaders(),
    );
    final data = await _handleResponse(response);
    return User.fromJson(data);
  }

  Future<void> registerFcmToken(String fcmToken) async {
    final response = await http.post(
      Uri.parse('${AppConstants.apiBaseUrl}/auth/register-fcm-token'),
      headers: _getHeaders(),
      body: json.encode({'fcm_token': fcmToken}),
    );
    await _handleResponse(response);
  }

  Future<AllarmeListResponse> getAllarmi({
    int page = 1,
    int pageSize = 20,
    String? severita,
    String? stato,
  }) async {
    final queryParams = {
      'page': page.toString(),
      'page_size': pageSize.toString(),
      if (severita != null) 'severita': severita,
      if (stato != null) 'stato': stato,
    };

    final uri = Uri.parse('${AppConstants.apiBaseUrl}/allarmi')
        .replace(queryParameters: queryParams);

    final response = await http.get(uri, headers: _getHeaders());
    final data = await _handleResponse(response);
    return AllarmeListResponse.fromJson(data);
  }

  Future<Allarme> getAllarme(int id) async {
    final response = await http.get(
      Uri.parse('${AppConstants.apiBaseUrl}/allarmi/$id'),
      headers: _getHeaders(),
    );
    final data = await _handleResponse(response);
    return Allarme.fromJson(data);
  }

  Future<Allarme> updateAllarme(int id, {String? stato}) async {
    final body = <String, dynamic>{};
    if (stato != null) body['stato'] = stato;

    final response = await http.patch(
      Uri.parse('${AppConstants.apiBaseUrl}/allarmi/$id'),
      headers: _getHeaders(),
      body: json.encode(body),
    );
    final data = await _handleResponse(response);
    return Allarme.fromJson(data);
  }

  Future<Sito> getSito(int sitoId) async {
    final response = await http.get(
      Uri.parse('${AppConstants.apiBaseUrl}/siti/$sitoId'),
      headers: _getHeaders(),
    );
    final data = await _handleResponse(response);
    return Sito.fromJson(data);
  }

  Future<List<Sito>> getSiti({String? tipo}) async {
    final queryParams = <String, String>{};
    if (tipo != null) queryParams['tipo'] = tipo;

    final uri = Uri.parse('${AppConstants.apiBaseUrl}/siti')
        .replace(queryParameters: queryParams.isNotEmpty ? queryParams : null);

    final response = await http.get(uri, headers: _getHeaders());
    final data = await _handleResponse(response);

    final items = (data['items'] as List)
        .map((item) => Sito.fromJson(item as Map<String, dynamic>))
        .toList();

    return items;
  }

  Future<AllarmeListResponse> getAllarmiBySito(int sitoId, {int page = 1, int pageSize = 20}) async {
    final queryParams = {
      'page': page.toString(),
      'page_size': pageSize.toString(),
    };

    final uri = Uri.parse('${AppConstants.apiBaseUrl}/allarmi/sito/$sitoId')
        .replace(queryParameters: queryParams);

    final response = await http.get(uri, headers: _getHeaders());
    final data = await _handleResponse(response);
    return AllarmeListResponse.fromJson(data);
  }

  Future<Statistiche> getStatistiche() async {
    final response = await http.get(
      Uri.parse('${AppConstants.apiBaseUrl}/statistiche'),
      headers: _getHeaders(),
    );
    final data = await _handleResponse(response);
    return Statistiche.fromJson(data);
  }

  Future<AllarmiPerGiornoResponse> getAllarmiPerGiorno({int giorni = 30}) async {
    final uri = Uri.parse('${AppConstants.apiBaseUrl}/statistiche/allarmi-per-giorno')
        .replace(queryParameters: {'giorni': giorni.toString()});

    final response = await http.get(uri, headers: _getHeaders());
    final data = await _handleResponse(response);
    return AllarmiPerGiornoResponse.fromJson(data);
  }
}