<?php

/**
 * Caching System
 *
 * Licensed under The MIT License
 * Redistribution of these files must retain the above copyright notice.
 *
 * @copyright Copyright 2007-2014, Josh Sherman
 * @license   http://www.opensource.org/licenses/mit-license.html
 * @link      http://picklesphp.com
 * @package   Pickles
 */

namespace Pickles;

/**
 * Cache Class
 *
 * Wrapper class for Memcache() to allow for better error handling when the
 * Memcached server is unavailable. Designed around the syntax for Memcached()
 * to allow for an easier transistion to the aforementioned in the future. I
 * don't entirely remember specifics, but the reason for not using Memcached()
 * was due to an unexplainable bug in the version in the repository for Ubuntu
 * 10.04 LTS. Memcached() does support more of the memcached protocol and will
 * eventually be what Pickles uses. Keys are forced to be uppercase for
 * consistencies sake as I've been burned by the case sensitivity due to typos
 * in my code.
 *
 * Requires php5-memcache
 *
 * @link http://us.php.net/manual/en/book.memcache.php
 * @link http://packages.ubuntu.com/lucid/php5-memcache
 * @link http://www.memcached.org/
 */
class Cache extends Object
{
    /**
     * Namespace (prefix)
     *
     * @access private
     * @var    string
     */
    private $namespace = '';

    /**
     * Servers
     *
     * @access private
     * @var    integer
     */
    private $servers = 0;

    /**
     * Connection resource to Memcached
     *
     * @access private
     * @var    object
     */
    private $connection = null;

    /**
     * Constructor
     *
     * Sets up our connection variables.
     *
     * @param string $hostname optional hostname to connect to
     * @param string $database optional port to use
     */
    public function __construct()
    {
        parent::__construct();

        // @todo Shouldn't need the isset() but Travis is failing some tests
        if (isset($this->config['pickles']['cache']) && $this->config['pickles']['cache'])
        {
            $datasources = $this->config['pickles']['cache'];

            if (!is_array($datasources))
            {
                $datasources = [$datasources];
            }

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

            foreach ($datasources as $name)
            {
                if (isset($this->config['datasources'][$name]))
                {
                    $datasource = $this->config['datasources'][$name];

                    $this->connection->addServer($datasource['hostname'], $datasource['port']);
                    $this->servers++;

                    if (isset($datasource['namespace']))
                    {
                        $this->namespace = $datasource['namespace'];
                    }
                }
            }
        }

        if ($this->namespace != '')
        {
            $this->namespace .= '-';
        }
    }

    /**
     * Destructor
     *
     * Closes the connection when the object dies.
     */
    public function __destruct()
    {
        if ($this->servers)
        {
            $this->connection->close();
        }
    }

    /**
     * Get Instance
     *
     * Let's the parent class do all the work.
     *
     * @static
     * @param  string $class name of the class to instantiate
     * @return object self::$instance instance of the Cache class
     */
    public static function getInstance($class = 'Cache')
    {
        return parent::getInstance($class);
    }

    /**
     * Get Key
     *
     * Gets the value of the key(s) and returns it.
     *
     * @param  mixed $keys key(s) to retrieve
     * @return mixed value(s) of the requested key(s), false if not set
     */
    public function get($keys)
    {
        if (is_array($keys))
        {
            foreach ($keys as $index => $key)
            {
                $keys[$index] = strtoupper($this->namespace . $key);
            }
        }
        else
        {
            $keys = strtoupper($this->namespace . $keys);
        }

        return $this->connection->get($keys);
    }

    /**
     * Set Key
     *
     * Sets key to the specified value. I've found that compression can lead to
     * issues with integers and can slow down the storage and retrieval of data
     * (defeats the purpose of caching if you ask me) and isn't supported. I've
     * also been burned by data inadvertantly being cached for infinity, but
     * have had great success caching data for a full day, hence defaulting the
     * expiration to a full day.
     *
     * @param  string  $key key to set
     * @param  mixed   $value value to set
     * @param  integer $expiration optional expiration, defaults to 1 day
     * @return boolean status of writing the data to the key
     */
    public function set($key, $value, $expire = Time::DAY)
    {
        $key = strtoupper($key);

        return $this->connection->set(strtoupper($this->namespace . $key), $value, 0, $expire);
    }

    /**
     * Delete Key
     *
     * Deletes the specified key(s).
     *
     * @param  mixed $keys key(s) to delete
     * @return boolean status of deleting the key
     */
    public function delete($keys)
    {
        if (!is_array($keys))
        {
            $keys = [$keys];
        }

        // Memcache() doesn't let you pass an array to delete all records the same way you can with get()
        foreach ($keys as $key)
        {
            $this->connection->delete(strtoupper($this->namespace . $key));
        }

        return true;
    }

    /**
     * Increment Key
     *
     * Increments the value of an existing key.
     *
     * @param  string $key key to increment
     * @return boolean status of incrementing the key
     * @todo   Check if it's set as Memcache() doesn't and won't inc if it doesn't exist
     */
    public function increment($key)
    {
        return $this->connection->increment(strtoupper($this->namespace . $key));
    }
}