<?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\base\InvalidConfigException;
use yii\db\ActiveRecord;

/**
 * CUniqueValidator validates that the attribute value is unique in the corresponding database table.
 *
 * @author Qiang Xue <qiang.xue@gmail.com>
 * @since 2.0
 */
class UniqueValidator extends Validator
{
	/**
	 * @var string the ActiveRecord class name or alias of the class
	 * that should be used to look for the attribute value being validated.
	 * Defaults to null, meaning using the ActiveRecord class of the attribute being validated.
	 * @see attributeName
	 */
	public $className;
	/**
	 * @var string the ActiveRecord class attribute name that should be
	 * used to look for the attribute value being validated. Defaults to null,
	 * meaning using the name of the attribute being validated.
	 */
	public $attributeName;

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

	/**
	 * Validates the attribute of the object.
	 * If there is any error, the error message is added to the object.
	 * @param \yii\db\ActiveRecord $object the object being validated
	 * @param string $attribute the attribute being validated
	 * @throws InvalidConfigException if table doesn't have column specified
	 */
	public function validateAttribute($object, $attribute)
	{
		$value = $object->$attribute;

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

		/** @var $className \yii\db\ActiveRecord */
		$className = $this->className === null ? get_class($object) : Yii::import($this->className);
		$attributeName = $this->attributeName === null ? $attribute : $this->attributeName;

		$table = $className::getTableSchema();
		if (($column = $table->getColumn($attributeName)) === null) {
			throw new InvalidConfigException("Table '{$table->name}' does not have a column named '$attributeName'.");
		}

		$query = $className::find();
		$query->where(array($column->name => $value));

		if (!$object instanceof ActiveRecord || $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()
			$query->limit(2);
			$objects = $query->all();

			$n = count($objects);
			if ($n === 1) {
				if ($column->isPrimaryKey) {
					// 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
					$exists = array_shift($objects)->getPrimaryKey() != $object->getOldPrimaryKey();
				}
			} else {
				$exists = $n > 1;
			}
		}

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