<?php
/**
 * Base Resque class.
 *
 * @package		Resque
 * @author		Chris Boulton <chris@bigcommerce.com>
 * @license		http://www.opensource.org/licenses/mit-license.php
 */
class Resque
{
	const VERSION = '1.2';

    const DEFAULT_INTERVAL = 5;

	/**
	 * @var Resque_Redis Instance of Resque_Redis that talks to redis.
	 */
	public static $redis = null;

	/**
	 * @var mixed Host/port conbination separated by a colon, or a nested
	 * array of server swith host/port pairs
	 */
	protected static $redisServer = null;

	/**
	 * @var int ID of Redis database to select.
	 */
	protected static $redisDatabase = 0;

	/**
	 * Given a host/port combination separated by a colon, set it as
	 * the redis server that Resque will talk to.
	 *
	 * @param mixed $server Host/port combination separated by a colon, or
	 *                      a nested array of servers with host/port pairs.
	 * @param int $database
	 */
	public static function setBackend($server, $database = 0)
	{
		self::$redisServer   = $server;
		self::$redisDatabase = $database;
		self::$redis         = null;
	}

	/**
	 * Return an instance of the Resque_Redis class instantiated for Resque.
	 *
	 * @return Resque_Redis Instance of Resque_Redis.
	 */
	public static function redis()
	{
		if (self::$redis !== null) {
			return self::$redis;
		}

		$server = self::$redisServer;
		if (empty($server)) {
			$server = 'localhost:6379';
		}

		self::$redis = new Resque_Redis($server, self::$redisDatabase);
		return self::$redis;
	}
	
	/**
	 * fork() helper method for php-resque that handles issues PHP socket
	 * and phpredis have with passing around sockets between child/parent
	 * processes.
	 *
	 * Will close connection to Redis before forking.
	 *
	 * @return int Return vars as per pcntl_fork()
	 */
	public static function fork()
	{
		if(!function_exists('pcntl_fork')) {
			return -1;
		}

		// Close the connection to Redis before forking.
		// This is a workaround for issues phpredis has.
		self::$redis = null;

		$pid = pcntl_fork();
		if($pid === -1) {
			throw new RuntimeException('Unable to fork child worker.');
		}

		return $pid;
	}

	/**
	 * Push a job to the end of a specific queue. If the queue does not
	 * exist, then create it as well.
	 *
	 * @param string $queue The name of the queue to add the job to.
	 * @param array $item Job description as an array to be JSON encoded.
	 */
	public static function push($queue, $item)
	{
		self::redis()->sadd('queues', $queue);
		$length = self::redis()->rpush('queue:' . $queue, json_encode($item));
		if ($length < 1) {
			return false;
		}
		return true;
	}

	/**
	 * Pop an item off the end of the specified queue, decode it and
	 * return it.
	 *
	 * @param string $queue The name of the queue to fetch an item from.
	 * @return array Decoded item from the queue.
	 */
	public static function pop($queue)
	{
        $item = self::redis()->lpop('queue:' . $queue);

		if(!$item) {
			return;
		}

		return json_decode($item, true);
	}

    /**
     * Pop an item off the end of the specified queues, using blocking list pop,
     * decode it and return it.
     *
     * @param array         $queues
     * @param int           $timeout
     * @return null|array   Decoded item from the queue.
     */
    public static function blpop(array $queues, $timeout)
    {
        $list = array();
        foreach($queues AS $queue) {
            $list[] = 'queue:' . $queue;
        }

        $item = self::redis()->blpop($list, (int)$timeout);

        if(!$item) {
            return;
        }

        /**
         * Normally the Resque_Redis class returns queue names without the prefix
         * But the blpop is a bit different. It returns the name as prefix:queue:name
         * So we need to strip off the prefix:queue: part
         */
        $queue = substr($item[0], strlen(self::redis()->getPrefix() . 'queue:'));

        return array(
            'queue'   => $queue,
            'payload' => json_decode($item[1], true)
        );
    }

	/**
	 * Return the size (number of pending jobs) of the specified queue.
	 *
	 * @param $queue name of the queue to be checked for pending jobs
	 *
	 * @return int The size of the queue.
	 */
	public static function size($queue)
	{
		return self::redis()->llen('queue:' . $queue);
	}

	/**
	 * Create a new job and save it to the specified queue.
	 *
	 * @param string $queue The name of the queue to place the job in.
	 * @param string $class The name of the class that contains the code to execute the job.
	 * @param array $args Any optional arguments that should be passed when the job is executed.
	 * @param boolean $trackStatus Set to true to be able to monitor the status of a job.
	 *
	 * @return string
	 */
	public static function enqueue($queue, $class, $args = null, $trackStatus = false)
	{
		$result = Resque_Job::create($queue, $class, $args, $trackStatus);
		if ($result) {
			Resque_Event::trigger('afterEnqueue', array(
				'class' => $class,
				'args'  => $args,
				'queue' => $queue,
			));
		}

		return $result;
	}

	/**
	 * Reserve and return the next available job in the specified queue.
	 *
	 * @param string $queue Queue to fetch next available job from.
	 * @return Resque_Job Instance of Resque_Job to be processed, false if none or error.
	 */
	public static function reserve($queue)
	{
		return Resque_Job::reserve($queue);
	}

	/**
	 * Get an array of all known queues.
	 *
	 * @return array Array of queues.
	 */
	public static function queues()
	{
		$queues = self::redis()->smembers('queues');
		if(!is_array($queues)) {
			$queues = array();
		}
		return $queues;
	}
}