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

namespace yii\validators;

use Yii;
use yii\db\ActiveRecordInterface;

/**
 * UniqueValidator validates that the attribute value is unique in the specified database table.
 *
 * UniqueValidator checks if the value being validated is unique in the table column specified by
 * the ActiveRecord class [[targetClass]] and the attribute [[targetAttribute]].
 *
 * The followings are examples of validation rules using this validator:
 *
 * ```php
 * // a1 needs to be unique
 * ['a1', 'unique']
 * // a1 needs to be unique, but column a2 will be used to check the uniqueness of the a1 value
 * ['a1', 'unique', 'targetAttribute' => 'a2']
 * // a1 and a2 need to unique together, and they both will receive error message
 * [['a1', 'a2'], 'unique', 'targetAttribute' => ['a1', 'a2']]
 * // a1 and a2 need to unique together, only a1 will receive error message
 * ['a1', 'unique', 'targetAttribute' => ['a1', 'a2']]
 * // a1 needs to be unique by checking the uniqueness of both a2 and a3 (using a1 value)
 * ['a1', 'unique', 'targetAttribute' => ['a2', 'a1' => 'a3']]
 * ```
 *
 * @author Qiang Xue <qiang.xue@gmail.com>
 * @since 2.0
 */
class UniqueValidator extends Validator
{
	/**
	 * @var string the name of the ActiveRecord class that should be used to validate the uniqueness
	 * of the current attribute value. It not set, it will use the ActiveRecord class of the attribute being validated.
	 * @see targetAttribute
	 */
	public $targetClass;
	/**
	 * @var string|array the name of the ActiveRecord attribute that should be used to
	 * validate the uniqueness of the current attribute value. If not set, it will use the name
	 * of the attribute currently being validated. You may use an array to validate the uniqueness
	 * of multiple columns at the same time. The array values are the attributes that will be
	 * used to validate the uniqueness, while the array keys are the attributes whose values are to be validated.
	 * If the key and the value are the same, you can just specify the value.
	 */
	public $targetAttribute;

	/**
	 * @inheritdoc
	 */
	public function init()
	{
		parent::init();
		if ($this->message === null) {
			$this->message = Yii::t('yii', '{attribute} "{value}" has already been taken.');
		}
	}

	/**
	 * @inheritdoc
	 */
	public function validateAttribute($object, $attribute)
	{
		/** @var ActiveRecordInterface $targetClass */
		$targetClass = $this->targetClass === null ? get_class($object) : $this->targetClass;
		$targetAttribute = $this->targetAttribute === null ? $attribute : $this->targetAttribute;

		if (is_array($targetAttribute)) {
			$params = [];
			foreach ($targetAttribute as $k => $v) {
				$params[$v] = is_integer($k) ? $object->$v : $object->$k;
			}
		} else {
			$params = [$targetAttribute => $object->$attribute];
		}

		foreach ($params as $value) {
			if (is_array($value)) {
				$this->addError($object, $attribute, Yii::t('yii', '{attribute} is invalid.'));
				return;
			}
		}

		$query = $targetClass::find();
		$query->where($params);

		if (!$object instanceof ActiveRecordInterface || $object->getIsNewRecord()) {
			// if current $object isn't in the database yet then it's OK just to call exists()
			$exists = $query->exists();
		} else {
			// if current $object is in the database already we can't use exists()
			/** @var ActiveRecordInterface[] $objects */
			$objects = $query->limit(2)->all();
			$n = count($objects);
			if ($n === 1) {
				$keys = array_keys($params);
				$pks = (array) $targetClass::primaryKey();
				sort($keys);
				sort($pks);
				if ($keys === $pks) {
					// primary key is modified and not unique
					$exists = $object->getOldPrimaryKey() != $object->getPrimaryKey();
				} else {
					// non-primary key, need to exclude the current record based on PK
					$exists = $objects[0]->getPrimaryKey() != $object->getOldPrimaryKey();
				}
			} else {
				$exists = $n > 1;
			}
		}

		if ($exists) {
			$this->addError($object, $attribute, $this->message);
		}
	}
}