import 'dart:convert';
import 'package:http/http.dart' as http;
import '../models/language.dart';
import 'settings_service.dart';

class TranslateException implements Exception {
  final String message;
  TranslateException(this.message);
  @override
  String toString() => message;
}

class DetectResult {
  final String language;
  final int confidence;
  DetectResult({required this.language, required this.confidence});
}

/// Kullanıcının kendi sunucusundaki LibreTranslate API'sine istek atar.
class TranslateService {
  final SettingsService _settings;
  TranslateService(this._settings);

  Future<String> _baseUrl() async {
    final url = await _settings.getServerUrl();
    if (url == null || url.isEmpty) {
      throw TranslateException('Sunucu adresi ayarlanmamış. Ayarlar\'dan ekleyin.');
    }
    return url;
  }

  Map<String, dynamic> _withApiKey(Map<String, dynamic> body, String? apiKey) {
    if (apiKey != null && apiKey.isNotEmpty) {
      body['api_key'] = apiKey;
    }
    return body;
  }

  String _errorFromBody(String body, int statusCode) {
    try {
      final decoded = jsonDecode(body);
      if (decoded is Map && decoded['error'] != null) {
        return decoded['error'].toString();
      }
    } catch (_) {
      // JSON değilse aşağıda genel mesaj kullanılır.
    }
    return 'Sunucu hatası (HTTP $statusCode)';
  }

  /// Sunucuya bağlanıp desteklenen dilleri getirir.
  /// Hem "bağlantı testi" hem de dil listesini doldurmak için kullanılır.
  Future<List<Language>> fetchLanguages() async {
    final base = await _baseUrl();
    final apiKey = await _settings.getApiKey();
    final uri = Uri.parse('$base/languages').replace(
      queryParameters: apiKey != null ? {'api_key': apiKey} : null,
    );

    final res = await http.get(uri).timeout(const Duration(seconds: 10));
    if (res.statusCode != 200) {
      throw TranslateException(_errorFromBody(res.body, res.statusCode));
    }
    final List<dynamic> data = jsonDecode(utf8.decode(res.bodyBytes));
    return data.map((e) => Language.fromJson(e as Map<String, dynamic>)).toList();
  }

  Future<String> translate({
    required String text,
    required String sourceLang,
    required String targetLang,
  }) async {
    if (text.trim().isEmpty) return '';
    final base = await _baseUrl();
    final apiKey = await _settings.getApiKey();

    final body = _withApiKey({
      'q': text,
      'source': sourceLang,
      'target': targetLang,
      'format': 'text',
    }, apiKey);

    final res = await http
        .post(
          Uri.parse('$base/translate'),
          headers: {'Content-Type': 'application/json'},
          body: jsonEncode(body),
        )
        .timeout(const Duration(seconds: 15));

    if (res.statusCode != 200) {
      throw TranslateException(_errorFromBody(res.body, res.statusCode));
    }
    final decoded = jsonDecode(utf8.decode(res.bodyBytes));
    return decoded['translatedText'] as String;
  }

  Future<DetectResult?> detect(String text) async {
    if (text.trim().isEmpty) return null;
    final base = await _baseUrl();
    final apiKey = await _settings.getApiKey();

    final body = _withApiKey({'q': text}, apiKey);

    final res = await http
        .post(
          Uri.parse('$base/detect'),
          headers: {'Content-Type': 'application/json'},
          body: jsonEncode(body),
        )
        .timeout(const Duration(seconds: 10));

    if (res.statusCode != 200) {
      throw TranslateException(_errorFromBody(res.body, res.statusCode));
    }
    final List<dynamic> data = jsonDecode(utf8.decode(res.bodyBytes));
    if (data.isEmpty) return null;
    final best = data.first as Map<String, dynamic>;
    return DetectResult(
      language: best['language'] as String,
      confidence: ((best['confidence'] ?? 0) as num).round(),
    );
  }
}