code: package co.infinum.goldfinger;
  
  import java.util.ArrayList;
  import java.util.List;
  
  import androidx.annotation.NonNull;
  import androidx.annotation.Nullable;
  import androidx.fragment.app.Fragment;
  import androidx.fragment.app.FragmentActivity;
  
  class ValidateUtils {
  
      private ValidateUtils() {
      }
  
      /**
       * Return list of cipher params errors. If no errors detected, list will be empty.
       */
      @NonNull
      static List<String> validateCipherParams(@NonNull Mode mode, @Nullable String key, @Nullable String value) {
          List<String> errors = new ArrayList<>();
  
          if (mode != Mode.AUTHENTICATION) {
              if (StringUtils.isBlankOrNull(key)) {
                  errors.add("Key is required if encryption or decryption is used!");
              }
              if (StringUtils.isBlankOrNull(value)) {
                  errors.add("Value is required if encryption or decryption is used!");
              }
          }
  
          return errors;
      }
  
      /**
       * Return list of prompt params errors. If no errors detected, list will be empty.
       */
      @NonNull
      static List<String> validatePromptParams(@NonNull Mode mode, @NonNull Goldfinger.PromptParams params) {
          List<String> errors = new ArrayList<>();
  
          if (!(params.dialogOwner() instanceof Fragment) && !(params.dialogOwner() instanceof FragmentActivity)) {
              errors.add("DialogOwner must be of instance Fragment or FragmentActivity");
          }
  
          if (StringUtils.isBlankOrNull(params.title())) {
              errors.add("Title is required!");
          }
  
          if (params.deviceCredentialsAllowed() && !StringUtils.isBlankOrNull(params.negativeButtonText())) {
              errors.add("It is not possible to set NegativeButtonText while using BiometricManager.Authenticators.DEVICE_CREDENTIAL");
          }
  
          if (!params.deviceCredentialsAllowed() && StringUtils.isBlankOrNull(params.negativeButtonText())) {
              errors.add("NegativeButtonText is required!");
          }
  
          if (params.deviceCredentialsAllowed() && mode != Mode.AUTHENTICATION) {
              errors.add("DeviceCredentials are allowed only for Goldfinger#authenticate method.");
          }
  
          return errors;
      }
  }
  