import 'dart:convert';
import 'dart:io';
import 'dart:math';
import '../core/failure.dart';

enum AuthMethod { password, privateKey }

String newId() => List.generate(
  16,
  (_) => Random.secure().nextInt(256),
).map((e) => e.toRadixString(16).padLeft(2, '0')).join();

String normalizeHost(String input) {
  var host = input.trim();
  if (host.startsWith('[') && host.endsWith(']')) {
    host = host.substring(1, host.length - 1);
    if (InternetAddress.tryParse(host)?.type != InternetAddressType.IPv6) {
      throw const Failure('invalidProfile');
    }
  }
  final ip = InternetAddress.tryParse(host);
  final dns = RegExp(
    r'^(?=.{1,253}$)[a-zA-Z0-9](?:[a-zA-Z0-9-]{0,61}[a-zA-Z0-9])?(?:\.[a-zA-Z0-9](?:[a-zA-Z0-9-]{0,61}[a-zA-Z0-9])?)*$',
  );
  if (ip == null && !dns.hasMatch(host)) throw const Failure('invalidProfile');
  return host;
}

class ServerProfile {
  final String id, name, host, username;
  final int port;
  final AuthMethod auth;
  ServerProfile({
    String? id,
    required String name,
    required String host,
    required String username,
    this.port = 22,
    this.auth = AuthMethod.password,
  }) : id = id ?? newId(),
       name = name.trim(),
       host = normalizeHost(host),
       username = username.trim() {
    if (this.name.isEmpty ||
        this.name.length > 100 ||
        this.username.isEmpty ||
        this.username.length > 128 ||
        RegExp(r'[\x00-\x1f\x7f]').hasMatch(this.name + this.username) ||
        port < 1 ||
        port > 65535) {
      throw const Failure('invalidProfile');
    }
  }
  String get endpoint {
    final ip = InternetAddress.tryParse(host);
    final canonical = ip == null
        ? host.toLowerCase()
        : InternetAddress.fromRawAddress(ip.rawAddress).address;
    return ip?.type == InternetAddressType.IPv6
        ? '[$canonical]:$port'
        : '$canonical:$port';
  }

  String get identity => jsonEncode([endpoint, username]);
  Map<String, dynamic> portable() => {
    'name': name,
    'host': host,
    'username': username,
    'port': port,
  };
  Map<String, dynamic> toJson() => {...portable(), 'id': id, 'auth': auth.name};
  factory ServerProfile.fromJson(
    Map<String, dynamic> json, {
    bool portable = false,
  }) {
    if (json['name'] is! String ||
        json['host'] is! String ||
        json['username'] is! String ||
        (json.containsKey('port') && json['port'] is! int)) {
      throw const Failure('invalidProfile');
    }
    return ServerProfile(
      id: portable ? null : json['id'] as String?,
      name: json['name'],
      host: json['host'],
      username: json['username'],
      port: json['port'] ?? 22,
      auth: !portable && json['auth'] == 'privateKey'
          ? AuthMethod.privateKey
          : AuthMethod.password,
    );
  }
}