content: /**
   * Licensed to the Apache Software Foundation (ASF) under one
   * or more contributor license agreements.  See the NOTICE file
   * distributed with this work for additional information
   * regarding copyright ownership.  The ASF licenses this file
   * to you under the Apache License, Version 2.0 (the
   * "License"); you may not use this file except in compliance
   * with the License.  You may obtain a copy of the License at
   *
   *     http://www.apache.org/licenses/LICENSE-2.0
   *
   * Unless required by applicable law or agreed to in writing, software
   * distributed under the License is distributed on an "AS IS" BASIS,
   * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
   * See the License for the specific language governing permissions and
   * limitations under the License.
   */
  
  package org.apache.ambari.view.validation;
  
  import org.apache.ambari.view.ViewInstanceDefinition;
  
  /**
   * Interface for custom view validation.  The validator is used validate a view instance and
   * its properties.
   */
  public interface Validator {
    /**
     * Validate the given view instance definition.  Return {@code null} to indicate that
     * no validation was performed.
     *
     * @param definition  the view instance definition
     * @param mode        the validation mode
     *
     * @return the instance validation result; may be {@code null}
     */
    public ValidationResult validateInstance(ViewInstanceDefinition definition, ValidationContext mode);
  
    /**
     * Validate a property of the given view instance definition.  Return {@code null} to indicate that
     * no validation was performed.
     *
     * @param property    the property name
     * @param definition  the view instance definition
     * @param mode        the validation modes
     *
     * @return the instance validation result; may be {@code null}
     */
    public ValidationResult validateProperty(String property, ViewInstanceDefinition definition, ValidationContext mode);
  
    /**
     * The context in which a view instance validation check is performed.
     */
    public enum ValidationContext {
      PRE_CREATE,  // validation prior to creation
      PRE_UPDATE,  // validation prior to update
      EXISTING     // validation of an existing view instance
    }
  }
  