import 'dart:convert';
import 'dart:typed_data';

import 'package:common_utils/common_utils.dart';
import 'package:pointycastle/export.dart';

import 'package:pj_supermarket_cloud/common/index.dart';

class EncryptionTool {
  // 获取base64加密后的 oauth2 APP模式客户端信息
  static String getLoginAuthorization() {
    return "Basic ${EncryptUtil.encodeBase64(Constants.oauth2AppClient)}";
  }

  /// 按 Web 端约定使用 AES-CFB、Key 同值 IV、NoPadding 加密登录密码。
  static String encryptLoginPassword(String password) {
    final keyBytes = Uint8List.fromList(utf8.encode(Constants.pwdEncKey));
    final passwordBytes = Uint8List.fromList(utf8.encode(password));
    final cipher = AESEngine()..init(true, KeyParameter(keyBytes));
    final encrypted = Uint8List(passwordBytes.length);
    var feedback = Uint8List.fromList(keyBytes);

    for (var offset = 0; offset < passwordBytes.length; offset += 16) {
      final streamBlock = Uint8List(16);
      cipher.processBlock(feedback, 0, streamBlock, 0);
      final blockLength = (passwordBytes.length - offset).clamp(0, 16).toInt();
      for (var index = 0; index < blockLength; index++) {
        encrypted[offset + index] =
            passwordBytes[offset + index] ^ streamBlock[index];
      }
      if (blockLength == 16) {
        feedback = Uint8List.fromList(
          encrypted.sublist(offset, offset + blockLength),
        );
      }
    }
    return base64Encode(encrypted);
  }
}