package cn.home1.oss.lib.common.crypto;
   
   import static java.nio.charset.StandardCharsets.UTF_8;
   import static javax.crypto.Cipher.ENCRYPT_MODE;
   
   import lombok.Getter;
   import lombok.SneakyThrows;
   
   import java.nio.ByteBuffer;
  import java.nio.charset.Charset;
  import java.security.Provider;
  
  import javax.crypto.Cipher;
  
  import cn.home1.oss.lib.common.CodecUtils;
  
  /**
   * Created by zhanghaolun on 16/11/17.
   */
  public class AesEncryptor implements EncodeEncryptor {
  
    @Getter
    private final Charset charset;
    private final Provider provider;
    private final AesCbcKey key;
  
    public AesEncryptor(final Provider provider, final KeyExpression keyExpression) {
      this.charset = UTF_8;
      this.provider = provider;
      this.key = new AesCbcKey(keyExpression);
    }
  
    @Override
    public String encrypt(final String plainText) {
      return this.encryptBytes( //
        RandomString.RandomStrings.RANDOM_BASE62.generate(this.key.getCbcIvLength()), //
        plainText.getBytes(this.charset) //
      );
    }
  
    @Override
    public String encrypt(final String plainText, final Integer maxAge) {
      throw new UnsupportedOperationException();
    }
  
    public String encryptBytes(final String random, final byte[] plainBytes) {
      final byte[] randomBytes = random.getBytes(this.charset);
      final int nopadLength = randomBytes.length + plainBytes.length;
      // ... + pad: 使用自定义的填充方式对明文进行补位填充
      final byte[] padBytes = Pkcs7Encoder.PKCS7_UTF8_BLOCK32.encode(nopadLength);
  
      // 获得最终的字节流, 未加密
      // random + plain + pad
      final ByteBuffer unencrypted = ByteBuffer.allocate(nopadLength + padBytes.length);
      unencrypted.put(randomBytes);
      unencrypted.put(plainBytes);
      unencrypted.put(padBytes);
      try {
        // 加密
        final byte[] encrypted = this.encryptCipher().doFinal(unencrypted.array());
        // 使用BASE64对加密后的字符串进行编码
        return CodecUtils.encodeBase64(encrypted);
      } catch (final Exception cause) {
        throw new AesException(AesException.AesError.ENCRYPT_AES_ERROR, cause);
      } finally {
        unencrypted.clear();
      }
    }
  
    @SneakyThrows
    Cipher encryptCipher() { // arg1: "BC" 指定使用 bouncycastle provider, 不指定则使用jre
      final Cipher cipher = Cipher.getInstance(CryptoConstants.AES_CBC_NOPADDING, this.provider);// 设置加密模式为AES的CBC模式
      cipher.init(ENCRYPT_MODE, this.key.getKeySpec(), this.key.getCbcIv());
      return cipher;
    }
  }