<?php
/**
 * Banker
 *
 * A Caching library implementing psr/cache
 *
 * PHP version 5.6
 *
 * @package     Banker
 * @author      Timothy J. Warren <tim@timshomepage.net>
 * @copyright   2016  Timothy J. Warren
 * @license     http://www.opensource.org/licenses/mit-license.html  MIT License
 * @version     1.0.0
 * @link        https://git.timshomepage.net/timw4mail/banker
 */

namespace Aviat\Banker\Driver;

use Aviat\Banker\Exception\CacheException;

/**
 * Redis cache backend
 */
class MemcacheDriver extends AbstractDriver {

	/**
	 * Driver for PHP Memcache extension
	 *
	 * @param array $config
	 * @param array $options
	 * @throws CacheException
	 */
	public function __construct(array $config = [], array $options = [])
	{
		// @codeCoverageIgnoreStart
		if ( ! class_exists('Memcache'))
		{
			throw new CacheException('Memcache driver requires the PHP memcache extension');
		}
		// @codeCoverageIgnoreEnd

		$this->conn = new \Memcache();

		$method = ($config['persistent'] === TRUE) ? 'pconnect' : 'connect';

		$this->conn->$method($config['host'], $config['port']);
	}

	/**
	 * Disconnect from memcached server
	 */
	public function __destruct()
	{
		$this->conn->close();
	}

	/**
	 * See if a key currently exists in the cache
	 *
	 * @param string $key
	 * @return bool
	 */
	public function exists($key)
	{
		return $this->conn->get($key) !== FALSE;
	}

	/**
	 * Get the value for the selected cache key
	 *
	 * @param string $key
	 * @return mixed
	 */
	public function get($key)
	{
		return $this->conn->get($key);
	}

	/**
	 * Retrieve a set of values by their cache key
	 *
	 * @param string[] $keys
	 * @return array
	 */
	public function getMultiple(array $keys = [])
	{
		return $this->conn->get($keys);
	}

	/**
	 * Set a cached value
	 *
	 * @param string $key
	 * @param mixed $value
	 * @param int $expires
	 * @return DriverInterface
	 */
	public function set($key, $value, $expires = 0)
	{
		if ($this->exists($key))
		{
			$this->conn->replace($key, $value, 0, $expires);
		}
		else
		{
			$this->conn->set($key, $value, 0, $expires);
		}

		return $this;
	}

	/**
	 * Remove an item from the cache
	 *
	 * @param string $key
	 * @return boolean
	 */
	public function delete($key)
	{
		return $this->conn->delete($key);
	}

	/**
	 * Remove multiple items from the cache
	 *
	 * @param string[] $keys
	 * @return boolean
	 */
	public function deleteMultiple(array $keys = [])
	{
		// Iteratively delete each item, using a boolean
		// 'and' operation to return false if any deletion fails
		return \array_reduce($keys, function($prev, $key) {
			return $prev && $this->conn->delete($key);
		}, TRUE);
	}

	/**
	 * Empty the cache
	 *
	 * @return boolean
	 */
	public function flush()
	{
		return $this->conn->flush();
	}

	/**
	 * Set the specified key to expire at the given time
	 *
	 * @param string $key
	 * @param int $expires
	 * @return DriverInterface
	 */
	public function expiresAt($key, $expires)
	{
		$value = $this->get($key);
		$timediff = $expires - time();

		return $this->set($key, $value, $timediff);
	}
}