explicit EvpCipher()

in src/parquet/util/crypto.cc [54:123]
63 lines of code
22 McCabe index (conditional complexity)

  explicit EvpCipher(int cipher, int key_len, int type) {
    ctx_ = nullptr;

    if (aesGcm != cipher && aesCtr != cipher) {
      std::stringstream ss;
      ss << "Wrong cipher: " << cipher;
      throw ParquetException(ss.str());
    }

    if (16 != key_len && 24 != key_len && 32 != key_len) {
      std::stringstream ss;
      ss << "Wrong key length: " << key_len;
      throw ParquetException(ss.str());
    }

    if (encryptType != type && decryptType != type) {
      std::stringstream ss;
      ss << "Wrong cipher type: " << type;
      throw ParquetException(ss.str());
    }

    ctx_ = EVP_CIPHER_CTX_new();
    if (nullptr == ctx_) {
      throw ParquetException("Couldn't init cipher context");
    }

    if (aesGcm == cipher) {
      // Init AES-GCM with specified key length
      if (16 == key_len) {
        if (encryptType == type) {
          ENCRYPT_INIT(ctx_, EVP_aes_128_gcm());
        } else {
          DECRYPT_INIT(ctx_, EVP_aes_128_gcm());
        }
      } else if (24 == key_len) {
        if (encryptType == type) {
          ENCRYPT_INIT(ctx_, EVP_aes_192_gcm());
        } else {
          DECRYPT_INIT(ctx_, EVP_aes_192_gcm());
        }
      } else if (32 == key_len) {
        if (encryptType == type) {
          ENCRYPT_INIT(ctx_, EVP_aes_256_gcm());
        } else {
          DECRYPT_INIT(ctx_, EVP_aes_256_gcm());
        }
      }
    } else {
      // Init AES-CTR with specified key length
      if (16 == key_len) {
        if (encryptType == type) {
          ENCRYPT_INIT(ctx_, EVP_aes_128_ctr());
        } else {
          DECRYPT_INIT(ctx_, EVP_aes_128_ctr());
        }
      } else if (24 == key_len) {
        if (encryptType == type) {
          ENCRYPT_INIT(ctx_, EVP_aes_192_ctr());
        } else {
          DECRYPT_INIT(ctx_, EVP_aes_192_ctr());
        }
      } else if (32 == key_len) {
        if (encryptType == type) {
          ENCRYPT_INIT(ctx_, EVP_aes_256_ctr());
        } else {
          DECRYPT_INIT(ctx_, EVP_aes_256_ctr());
        }
      }
    }
  }