flutter_appfx/lib/util/base64Utils.dart

import 'dart:convert';
import 'dart:typed_data';
import 'package:convert/convert.dart' show hex;



/// Uint8List <--> Base64
String bytesToBase64(Uint8List data, {bool urlSafe = false}) {
  try {
    if (data.isEmpty) {
      throw ArgumentError('Input data cannot be empty');
    }

    final base64Str = base64Encode(data);

    if (urlSafe) {
      return base64Str
          .replaceAll('+', '-')
          .replaceAll('/', '_')
          .replaceAll('=', '');
    }

    return base64Str;
  } on ArgumentError catch (e) {
    rethrow;
  } catch (e) {
    throw Exception('Failed to encode Uint8List to Base64: ${e.toString()}');
  }
}

Uint8List base64ToBytes(String base64Str, {bool? urlSafe}) {
  try {
    if (base64Str.isEmpty) {
      throw ArgumentError('Base64 string cannot be empty');
    }
    // 如果未指定 urlSafe，自动检测格式
    final isUrlSafe = urlSafe ??
        (base64Str.contains('-') || base64Str.contains('_'));

    String normalizedStr = base64Str;

    if (isUrlSafe) {
      // 添加必要的填充字符
      final padding = '=' * ((4 - base64Str.length % 4) % 4);
      normalizedStr = base64Str
          .replaceAll('-', '+')
          .replaceAll('_', '/') + padding;
    }

    // 验证 Base64 字符串格式
    if (!RegExp(r'^[a-zA-Z0-9+/]*={0,2}$').hasMatch(normalizedStr)) {
      throw FormatException('Invalid Base64 string format');
    }

    return base64Decode(normalizedStr);
  } on ArgumentError catch (e) {
    rethrow;
  } on FormatException catch (e) {
    rethrow;
  } catch (e) {
    throw Exception('Failed to decode Base64 to Uint8List: ${e.toString()}');
  }
}



/// 将十六进制字符串直接转换为 Base64
///
/// [hexStr] 十六进制字符串
/// [urlSafe] 是否生成URL安全的Base64
///
/// 返回 Base64 字符串或抛出异常
String hexToBase64(String hexStr, {bool urlSafe = false}) {
  try {
    if (hexStr.isEmpty) {
      throw ArgumentError('Hex string cannot be empty');
    }

    final normalizedHex = hexStr.startsWith('0x')
        ? hexStr.substring(2)
        : hexStr;

    if (!RegExp(r'^[0-9a-fA-F]+$').hasMatch(normalizedHex)) {
      throw FormatException('Invalid hex string format');
    }

    final bytes = hex.decode(normalizedHex.padLeft(
        normalizedHex.length + normalizedHex.length % 2,
        '0'
    ));

    final base64 = base64Encode(bytes);
    return urlSafe
        ? base64.replaceAll('+', '-').replaceAll('/', '_').replaceAll('=', '')
        : base64;
  } on ArgumentError catch (e) {
    rethrow;
  } on FormatException catch (e) {
    rethrow;
  } catch (e) {
    throw Exception('Failed to convert hex to Base64: ${e.toString()}');
  }
}


/// 将 Base64 字符串转换为十六进制字符串
///
/// [base64Str] 输入的 Base64 字符串
/// [urlSafe] 输入是否是 URL 安全的 Base64 编码
/// [withPrefix] 是否添加 "0x" 前缀
///
/// 返回十六进制字符串或抛出异常
String base64ToHex(String base64Str, {
  bool urlSafe = false,
  bool withPrefix = false,
}) {
  try {
    if (base64Str.isEmpty) {
      throw ArgumentError('Base64 string cannot be empty');
    }

    String normalizedStr = base64Str;

    // 处理 URL 安全的 Base64
    if (urlSafe) {
      // 添加必要的填充字符
      final padding = '=' * ((4 - base64Str.length % 4) % 4);
      normalizedStr = base64Str
          .replaceAll('-', '+')
          .replaceAll('_', '/') + padding;
    }

    // 验证 Base64 字符串格式
    if (!RegExp(r'^[a-zA-Z0-9+/]*={0,2}$').hasMatch(normalizedStr)) {
      throw FormatException('Invalid Base64 string format');
    }

    // 解码为字节数组
    final bytes = base64Decode(normalizedStr);

    // 转换为十六进制
    final hexString = bytes.map((byte) {
      return byte.toRadixString(16).padLeft(2, '0');
    }).join('');

    return withPrefix ? '0x$hexString' : hexString;
  } on ArgumentError catch (e) {
    rethrow;
  } on FormatException catch (e) {
    rethrow;
  } catch (e) {
    throw Exception('Failed to convert Base64 to hex: ${e.toString()}');
  }
}