/**
 * Copyright 2019 Adobe. All rights reserved.
 * This file is licensed 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 REPRESENTATIONS
 * OF ANY KIND, either express or implied. See the License for the specific language
 * governing permissions and limitations under the License.
 */

import commons from './Commons';

/**
 Set of property value validation functions.
 */
class Validation {
  /**
   Ensures that the value has changed.

   @param {*} newValue
   The new value.
   @param {*} oldValue
   The existing value.

   @returns {Boolean} <code>true</code> if the values are different.
   */
  valueMustChange(newValue, oldValue) {
    // We can use exact equality here as validation functions are called after transform. Thus, the input value will be
    // converted to the same type as a stored value
    return newValue !== oldValue;
  }

  /**
   Ensures that the new value is within the enumeration. The enumeration can be given as an array of values or as a
   key/value Object. Take into consideration that enumerations are case sensitive.

   @example // Enumeration as Array
   Coral.validate.enumeration(['xs', 's', 'm', 'l']);
   @example // Enumeration as Object
   Coral.validate.enumeration({EXTRA_SMALL : 'xs', SMALL : 's', MEDIUM : 'm', LARGE : 'l'});
   @param {Object} enumeration
   Object that represents an enum.

   @returns {ValidationFunction}
   a validation function that ensures that the given value is within the enumeration.
   */
  enumeration(enumeration) {
    // Reverses the enumeration, so that we can check that the variable new value exists inside
    const enumReversed = commons.swapKeysAndValues(enumeration);

    // Returns a new function that matches the newValue, oldValue signature
    return (newValue) => typeof enumReversed[newValue] !== 'undefined';
  }
}

/**
 Signature of the function used to validate new input. It accepts a newValue and an oldValue which are used to
 determine if the newValue is valid.

 @typedef {function} ValidationFunction

 @param {*} newValue
 The new value to validate.
 @param {*} oldValue
 The existing value.

 @returns {Boolean} <code>true</code> if the validation succeeded, otherwise <code>false</code>.
 */

/**
 A property transform utility.

 @type {Validation}
 */
const validate = new Validation();

export default validate;
