<?php
/**
 * @link http://www.yiiframework.com/
 * @copyright Copyright (c) 2008 Yii Software LLC
 * @license http://www.yiiframework.com/license/
 */

namespace yii\behaviors;

use Yii;
use Closure;
use yii\base\Behavior;
use yii\base\Event;

/**
 * AttributeBehavior automatically assigns a specified value to one or multiple attributes of an ActiveRecord object when certain events happen.
 *
 * To use AttributeBehavior, configure the [[attributes]] property which should specify the list of attributes
 * that need to be updated and the corresponding events that should trigger the update. For example,
 * Then configure the [[value]] property with a PHP callable whose return value will be used to assign to the current
 * attribute(s). For example,
 *
 * ~~~
 * use yii\behaviors\AttributeBehavior;
 *
 * public function behaviors()
 * {
 *     return [
 *         'attributeStamp' => [
 *             'class' => AttributeBehavior::className(),
 *             'attributes' => [
 *                 ActiveRecord::EVENT_BEFORE_INSERT => 'attribute1',
 *                 ActiveRecord::EVENT_BEFORE_UPDATE => 'attribute2',
 *             ],
 *             'value' => function ($event) {
 *                 return 'some value';
 *             },
 *         ],
 *     ];
 * }
 * ~~~
 *
 * @author Luciano Baraglia <luciano.baraglia@gmail.com>
 * @author Qiang Xue <qiang.xue@gmail.com>
 * @since 2.0
 */
class AttributeBehavior extends Behavior
{
	/**
	 * @var array list of attributes that are to be automatically filled with the value specified via [[value]].
	 * The array keys are the ActiveRecord events upon which the attributes are to be updated,
	 * and the array values are the corresponding attribute(s) to be updated. You can use a string to represent
	 * a single attribute, or an array to represent a list of attributes. For example,
	 *
	 * ```php
	 * [
	 *     ActiveRecord::EVENT_BEFORE_INSERT => ['attribute1', 'attribute2'],
	 *     ActiveRecord::EVENT_BEFORE_UPDATE => 'attribute2',
	 * ]
	 * ```
	 */
	public $attributes = [];
	/**
	 * @var mixed the value that will be assigned to the current attributes. This can be an anonymous function
	 * or an arbitrary value. If the former, the return value of the function will be assigned to the attributes.
	 * The signature of the function should be as follows,
	 *
	 * ```php
	 * function ($event) {
	 *     // return value will be assigned to the attribute
	 * }
	 * ```
	 */
	public $value;


	/**
	 * @inheritdoc
	 */
	public function events()
	{
		return array_fill_keys(array_keys($this->attributes), 'evaluateAttributes');
	}

	/**
	 * Evaluates the attribute value and assigns it to the current attributes.
	 * @param $event
	 */
	public function evaluateAttributes($event)
	{
		if (!empty($this->attributes[$event->name])) {
			$attributes = (array)$this->attributes[$event->name];
			$value = $this->getValue($event);
			foreach ($attributes as $attribute) {
				$this->owner->$attribute = $value;
			}
		}
	}

	/**
	 * Returns the value of the current attributes.
	 * This method is called by [[evaluateAttributes()]]. Its return value will be assigned
	 * to the attributes corresponding to the triggering event.
	 * @param Event $event the event that triggers the current attribute updating.
	 * @return mixed the attribute value
	 */
	protected function getValue($event)
	{
		return $this->value instanceof Closure ? call_user_func($this->value, $event) : $this->value;
	}
}
