import 'dart:convert';
import 'package:http/http.dart' as http;
import 'package:shared_preferences/shared_preferences.dart';

/// Модель файла из Gitea Contents API
class GiteaFile {
  final String name;
  final String path;
  final String type; // 'file' | 'dir'
  final String? sha;
  final String? content; // base64 encoded
  final int? size;
  final String? downloadUrl;

  GiteaFile({
    required this.name,
    required this.path,
    required this.type,
    this.sha,
    this.content,
    this.size,
    this.downloadUrl,
  });

  factory GiteaFile.fromJson(Map<String, dynamic> json) {
    return GiteaFile(
      name: json['name'] ?? '',
      path: json['path'] ?? '',
      type: json['type'] ?? 'file',
      sha: json['sha'],
      content: json['content'],
      size: json['size'],
      downloadUrl: json['download_url'],
    );
  }

  /// Декодирует base64 content (Gitea возвращает base64 с переносами)
  String? get decodedContent {
    if (content == null || content!.isEmpty) return null;
    try {
      final clean = content!.replaceAll('\n', '');
      return utf8.decode(base64Decode(clean));
    } catch (e) {
      return null;
    }
  }
}

/// Сервис прямой синхронизации с Gitea REST API
/// Используется в мобильном приложении вместо Obsidian Git plugin
class GiteaSyncService {
  static final GiteaSyncService _instance = GiteaSyncService._internal();
  factory GiteaSyncService() => _instance;
  GiteaSyncService._internal();

  String? _baseUrl;
  String? _token;
  String? _owner;
  String? _repo;

  static const String _prefsBaseUrlKey = 'gitea_base_url';
  static const String _prefsTokenKey = 'gitea_token';
  static const String _prefsOwnerKey = 'gitea_owner';
  static const String _prefsRepoKey = 'gitea_repo';

  /// Инициализация из SharedPreferences
  Future<void> initialize() async {
    final prefs = await SharedPreferences.getInstance();
    _baseUrl = prefs.getString(_prefsBaseUrlKey);
    _token = prefs.getString(_prefsTokenKey);
    _owner = prefs.getString(_prefsOwnerKey);
    _repo = prefs.getString(_prefsRepoKey);
  }

  /// Настройка подключения
  Future<void> configure({
    required String baseUrl,
    required String token,
    required String owner,
    required String repo,
  }) async {
    _baseUrl = baseUrl.replaceAll(RegExp(r'/+$'), '');
    _token = token;
    _owner = owner;
    _repo = repo;

    final prefs = await SharedPreferences.getInstance();
    await prefs.setString(_prefsBaseUrlKey, _baseUrl!);
    await prefs.setString(_prefsTokenKey, _token!);
    await prefs.setString(_prefsOwnerKey, _owner!);
    await prefs.setString(_prefsRepoKey, _repo!);
  }

  bool get isConfigured =>
      _baseUrl != null && _token != null && _owner != null && _repo != null;

  // ==================== AUTH / TEST ====================

  /// Проверка соединения и валидности токена
  Future<bool> testConnection() async {
    if (!isConfigured) return false;
    try {
      final response = await _get('/api/v1/user');
      return response.statusCode == 200;
    } catch (e) {
      return false;
    }
  }

  /// Получить информацию о текущем пользователе
  Future<Map<String, dynamic>?> getCurrentUser() async {
    final response = await _get('/api/v1/user');
    if (response.statusCode == 200) {
      return jsonDecode(response.body) as Map<String, dynamic>;
    }
    return null;
  }

  // ==================== REPOSITORY CONTENTS ====================

  /// Получить список файлов в директории репозитория
  Future<List<GiteaFile>> listFiles({
    String path = '',
    String branch = 'main',
  }) async {
    final response = await _get(
      '/api/v1/repos/$_owner/$_repo/contents/$path?ref=$branch',
    );

    if (response.statusCode != 200) {
      throw Exception(
          'Failed to list files: ${response.statusCode} ${response.body}');
    }

    final List<dynamic> data = jsonDecode(response.body);
    return data
        .map((e) => GiteaFile.fromJson(e as Map<String, dynamic>))
        .toList();
  }

  /// Получить содержимое одного файла
  Future<GiteaFile> getFile({
    required String path,
    String branch = 'main',
  }) async {
    final response = await _get(
      '/api/v1/repos/$_owner/$_repo/contents/$path?ref=$branch',
    );

    if (response.statusCode != 200) {
      throw Exception(
          'Failed to get file: ${response.statusCode} ${response.body}');
    }

    final data = jsonDecode(response.body) as Map<String, dynamic>;
    return GiteaFile.fromJson(data);
  }

  /// Обновить/создать файл в репозитории
  Future<void> updateFile({
    required String path,
    required String content,
    required String commitMessage,
    String branch = 'main',
    String? authorName,
    String? authorEmail,
  }) async {
    // Получаем текущий sha если файл существует
    String? currentSha;
    try {
      final existing = await getFile(path: path, branch: branch);
      currentSha = existing.sha;
    } catch (_) {
      // файл не существует — создаём новый
    }

    final body = <String, dynamic>{
      'content': base64Encode(utf8.encode(content)),
      'message': commitMessage,
      'branch': branch,
    };

    if (currentSha != null) {
      body['sha'] = currentSha;
    }

    if (authorName != null && authorEmail != null) {
      body['author'] = {
        'name': authorName,
        'email': authorEmail,
      };
    }

    final response = await _put(
      '/api/v1/repos/$_owner/$_repo/contents/$path',
      body: body,
    );

    if (response.statusCode != 200 && response.statusCode != 201) {
      throw Exception(
          'Failed to update file: ${response.statusCode} ${response.body}');
    }
  }

  /// Удалить файл из репозитория
  Future<void> deleteFile({
    required String path,
    required String commitMessage,
    String branch = 'main',
  }) async {
    final existing = await getFile(path: path, branch: branch);

    final response = await _delete(
      '/api/v1/repos/$_owner/$_repo/contents/$path',
      body: {
        'message': commitMessage,
        'sha': existing.sha,
        'branch': branch,
      },
    );

    if (response.statusCode != 200 && response.statusCode != 204) {
      throw Exception(
          'Failed to delete file: ${response.statusCode} ${response.body}');
    }
  }

  // ==================== GIT OPERATIONS ====================

  /// Получить дерево файлов (рекурсивно)
  Future<List<GiteaFile>> getTree({
    String branch = 'main',
    bool recursive = true,
  }) async {
    final response = await _get(
      '/api/v1/repos/$_owner/$_repo/git/trees/$branch?recursive=${recursive ? 1 : 0}',
    );

    if (response.statusCode != 200) {
      throw Exception('Failed to get tree: ${response.statusCode}');
    }

    final data = jsonDecode(response.body) as Map<String, dynamic>;
    final List<dynamic> tree = data['tree'] ?? [];

    return tree
        .where((e) => e['type'] == 'blob')
        .map((e) => GiteaFile(
              name: e['path'].toString().split('/').last,
              path: e['path'] ?? '',
              type: 'file',
              sha: e['sha'],
              size: e['size'],
            ))
        .toList();
  }

  /// Получить последний коммит ветки
  Future<Map<String, dynamic>?> getLatestCommit(
      {String branch = 'main'}) async {
    final response = await _get(
      '/api/v1/repos/$_owner/$_repo/commits?sha=$branch&limit=1',
    );

    if (response.statusCode == 200) {
      final List<dynamic> data = jsonDecode(response.body);
      if (data.isNotEmpty) return data.first as Map<String, dynamic>;
    }
    return null;
  }

  /// Получить историю коммитов
  Future<List<Map<String, dynamic>>> getCommits({
    String branch = 'main',
    int page = 1,
    int limit = 30,
  }) async {
    final response = await _get(
      '/api/v1/repos/$_owner/$_repo/commits?sha=$branch&page=$page&limit=$limit',
    );

    if (response.statusCode == 200) {
      final List<dynamic> data = jsonDecode(response.body);
      return data.cast<Map<String, dynamic>>();
    }
    return [];
  }

  // ==================== HELPERS ====================

  Map<String, String> _getHeaders() {
    return {
      'Content-Type': 'application/json',
      'Authorization': 'token $_token',
    };
  }

  Future<http.Response> _get(String path) async {
    final uri = Uri.parse('$_baseUrl$path');
    return http.get(uri, headers: _getHeaders());
  }

  Future<http.Response> _put(String path,
      {required Map<String, dynamic> body}) async {
    final uri = Uri.parse('$_baseUrl$path');
    return http.put(
      uri,
      headers: _getHeaders(),
      body: jsonEncode(body),
    );
  }

  Future<http.Response> _delete(String path,
      {required Map<String, dynamic> body}) async {
    final uri = Uri.parse('$_baseUrl$path');
    final request = http.Request('DELETE', uri)
      ..headers.addAll(_getHeaders())
      ..body = jsonEncode(body);
    return http.Client().send(request).then((r) => http.Response.fromStream(r));
  }
}