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

namespace yii\mutex;

use PDO;
use yii\base\InvalidConfigException;

/**
 * OracleMutex implements mutex "lock" mechanism via Oracle locks.
 *
 * Application configuration example:
 *
 * ```
 * [
 *     'components' => [
 *         'db' => [
 *             'class' => 'yii\db\Connection',
 *             'dsn' => 'oci:dbname=LOCAL_XE',
 *              ...
 *         ]
 *         'mutex' => [
 *             'class' => 'yii\mutex\OracleMutex',
 *             'lockMode' => 'NL_MODE',
 *             'releaseOnCommit' => true,
 *              ...
 *         ],
 *     ],
 * ]
 * ```
 *
 * @see http://docs.oracle.com/cd/B19306_01/appdev.102/b14258/d_lock.htm
 * @see Mutex
 *
 * @author Alexander Zlakomanov <zlakomanoff@gmail.com>
 * @since 2.0.10
 */
class OracleMutex extends DbMutex
{
    /** available lock modes */
    const MODE_X = 'X_MODE';
    const MODE_NL = 'NL_MODE';
    const MODE_S = 'S_MODE';
    const MODE_SX = 'SX_MODE';
    const MODE_SS = 'SS_MODE';
    const MODE_SSX = 'SSX_MODE';

    /**
     * @var string lock mode to be used.
     * @see http://docs.oracle.com/cd/B19306_01/appdev.102/b14258/d_lock.htm#CHDBCFDI
     */
    public $lockMode = self::MODE_X;
    /**
     * @var bool whether to release lock on commit.
     */
    public $releaseOnCommit = false;


    /**
     * Initializes Oracle specific mutex component implementation.
     * @throws InvalidConfigException if [[db]] is not Oracle connection.
     */
    public function init()
    {
        parent::init();
        if (strpos($this->db->driverName, 'oci') !== 0 && strpos($this->db->driverName, 'odbc') !== 0) {
            throw new InvalidConfigException('In order to use OracleMutex connection must be configured to use Oracle database.');
        }
    }

    /**
     * Acquires lock by given name.
     * @see http://docs.oracle.com/cd/B19306_01/appdev.102/b14258/d_lock.htm
     * @param string $name of the lock to be acquired.
     * @param int $timeout to wait for lock to become released.
     * @return bool acquiring result.
     */
    protected function acquireLock($name, $timeout = 0)
    {
        $lockStatus = null;

        /** clean vars before using */
        $releaseOnCommit = $this->releaseOnCommit ? 'TRUE' : 'FALSE';
        $timeout = abs((int)$timeout);

        /** inside pl/sql scopes pdo binding not working correctly :(  */
        $this->db->createCommand(
                'DECLARE
    handle VARCHAR2(128);
BEGIN
    DBMS_LOCK.ALLOCATE_UNIQUE(:name, handle);
    :lockStatus := DBMS_LOCK.REQUEST(handle, DBMS_LOCK.' . $this->lockMode . ', ' . $timeout . ', ' . $releaseOnCommit . ');
END;',
                [':name' => $name]
            )
            ->bindParam(':lockStatus', $lockStatus, PDO::PARAM_INT, 1)
            ->execute();

        return ($lockStatus === 0 || $lockStatus === '0');
    }

    /**
     * Releases lock by given name.
     * @param string $name of the lock to be released.
     * @return bool release result.
     * @see http://docs.oracle.com/cd/B19306_01/appdev.102/b14258/d_lock.htm
     */
    protected function releaseLock($name)
    {
        $releaseStatus = null;
        $this->db->createCommand(
                'DECLARE
    handle VARCHAR2(128);
BEGIN
    DBMS_LOCK.ALLOCATE_UNIQUE(:name, handle);
    :result := DBMS_LOCK.RELEASE(handle);
END;',
                [':name' => $name]
            )
            ->bindParam(':result', $releaseStatus, PDO::PARAM_INT, 1)
            ->execute();

        return ($releaseStatus === 0 || $releaseStatus === '0');
    }
}
