<?php

namespace Blacklight\libraries;

/**
 * Class Cache.
 *
 * Class for connecting to a memcached or redis server to cache data.
 */
class Cache
{
    private const SERIALIZER_PHP = 0;
    private const SERIALIZER_IGBINARY = 1;
    private const SERIALIZER_NONE = 2;

    private const TYPE_DISABLED = 0;
    private const TYPE_MEMCACHED = 1;
    private const TYPE_REDIS = 2;
    private const TYPE_APC = 3;

    /**
     * @var \Memcached
     */
    private $server;

    /**
     * Are we connected to the cache server?
     * @var bool
     */
    private $connected = false;

    /**
     * Optional socket file location.
     * @var bool|string
     */
    private $socketFile;

    /**
     * Store data on the cache server.
     *
     *
     * @param $key
     * @param $data
     * @param $expiration
     * @return bool
     * @throws \Blacklight\libraries\CacheException
     */
    public function set($key, $data, $expiration): bool
    {
        if ($this->ping()) {
            switch (NN_CACHE_TYPE) {
                case self::TYPE_REDIS:
                case self::TYPE_MEMCACHED:
                    return $this->server->set($key, $data, $expiration);
                case self::TYPE_APC:
                    return apc_add($key, $data, $expiration);
            }
        }

        return false;
    }

    /**
     * Attempt to retrieve a value from the cache server, if not set it.
     *
     *
     * @param $key
     * @return bool|mixed|string
     * @throws \Blacklight\libraries\CacheException
     */
    public function get($key)
    {
        if ($this->ping()) {
            $data = '';
            switch (NN_CACHE_TYPE) {
                case self::TYPE_REDIS:
                case self::TYPE_MEMCACHED:
                    $data = $this->server->get($key);
                    break;
                case self::TYPE_APC:
                    $data = apc_fetch($key);
                    break;
            }

            return $data;
        }

        return false;
    }

    /**
     * Delete data tied to a key on the cache server.
     *
     *
     * @param $key
     * @return bool|string[]
     * @throws \Blacklight\libraries\CacheException
     */
    public function delete($key)
    {
        if ($this->ping()) {
            switch (NN_CACHE_TYPE) {
                case self::TYPE_REDIS:
                case self::TYPE_MEMCACHED:
                    return (bool) $this->server->delete($key);
                case self::TYPE_APC:
                    return apc_delete($key);
            }
        }

        return false;
    }

    /**
     * Flush all data from the cache server?
     *
     *
     * @throws \Blacklight\libraries\CacheException
     */
    public function flush()
    {
        if ($this->ping()) {
            switch (NN_CACHE_TYPE) {
                case self::TYPE_REDIS:
                    $this->server->flushAll();
                    break;
                case self::TYPE_MEMCACHED:
                    $this->server->flush();
                    break;
                case self::TYPE_APC:
                    apc_clear_cache('user');
                    apc_clear_cache();
                    break;
            }
        }
    }

    /**
     * Create a SHA1 hash from a string which can be used to store/retrieve data.
     *
     * @param string $string
     *
     * @return string SHA1 hash of the input string.
     */
    public function createKey($string)
    {
        return sha1($string);
    }

    /**
     * Get cache server statistics.
     *
     *
     * @return array|bool
     * @throws \Blacklight\libraries\CacheException
     */
    public function serverStatistics()
    {
        if ($this->ping()) {
            switch (NN_CACHE_TYPE) {
                case self::TYPE_REDIS:
                    return $this->server->info();
                case self::TYPE_MEMCACHED:
                    return $this->server->getStats();
                case self::TYPE_APC:
                    return apc_cache_info();
            }
        }

        return [];
    }

    /**
     * Verify the user's cache settings, try to connect to the cache server.
     *
     * @throws \Blacklight\libraries\CacheException
     */
    public function __construct()
    {
        if (! \defined('NN_CACHE_HOSTS')) {
            throw new CacheException(
                'The NN_CACHE_HOSTS is not defined! Define it in settings.php'
            );
        }

        if (! \defined('NN_CACHE_TIMEOUT')) {
            throw new CacheException(
                'The NN_CACHE_TIMEOUT is not defined! Define it in settings.php, it is the time in seconds to time out from your cache server.'
            );
        }

        $this->socketFile = false;
        if (\defined('NN_CACHE_SOCKET_FILE') && NN_CACHE_SOCKET_FILE != '') {
            $this->socketFile = true;
        }

        $serializer = false;
        if (\defined('NN_CACHE_SERIALIZER')) {
            $serializer = true;
        }

        switch (NN_CACHE_TYPE) {

            case self::TYPE_REDIS:
                if (! \extension_loaded('redis')) {
                    throw new CacheException('The redis extension is not loaded!');
                }
                $this->server = new \Redis();
                $this->connect();
                if ($serializer) {
                    $this->server->setOption(\Redis::OPT_SERIALIZER, $this->verifySerializer());
                }
                break;

            case self::TYPE_MEMCACHED:
                if (! \extension_loaded('memcached')) {
                    throw new CacheException('The memcached extension is not loaded!');
                }
                $this->server = new \Memcached();
                if ($serializer) {
                    $this->server->setOption(\Memcached::OPT_SERIALIZER, $this->verifySerializer());
                }
                $this->server->setOption(\Memcached::OPT_COMPRESSION, (defined('NN_CACHE_COMPRESSION') ? NN_CACHE_COMPRESSION : false));
                $this->connect();
                break;

            case self::TYPE_APC:
                // Faster than checking if apcu or apc is loaded.
                if (! \function_exists('apc_add')) {
                    throw new CacheException('The APCu extension is not loaded or enabled!');
                }
                $this->connect();
                break;

            case self::TYPE_DISABLED:
            default:
                break;
        }
    }

    /**
     * Destroy the connections.
     */
    public function __destruct()
    {
        switch (NN_CACHE_TYPE) {
            case self::TYPE_REDIS:
                $this->server->close();
                break;
            case self::TYPE_MEMCACHED:
                $this->server->quit();
                break;
        }
    }

    /**
     * Connect to the cache server(s).
     *
     * @throws CacheException
     */
    private function connect()
    {
        $this->connected = false;
        switch (NN_CACHE_TYPE) {
            case self::TYPE_REDIS:
                if ($this->socketFile === false) {
                    $servers = unserialize(NN_CACHE_HOSTS);
                    foreach ($servers as $server) {
                        if ($this->server->connect($server['host'], $server['port'], (float) NN_CACHE_TIMEOUT) === false) {
                            throw new CacheException('Error connecting to the Redis server!');
                        } else {
                            $this->connected = true;
                        }
                    }
                } else {
                    if ($this->server->connect(NN_CACHE_SOCKET_FILE) === false) {
                        throw new CacheException('Error connecting to the Redis server!');
                    } else {
                        $this->connected = true;
                    }
                }
                break;
            case self::TYPE_MEMCACHED:
                $params = ($this->socketFile === false ? unserialize(NN_CACHE_HOSTS) : [[NN_CACHE_SOCKET_FILE, 'port' => 0]]);
                if ($this->server->addServers($params) === false) {
                    throw new CacheException('Error connecting to the Memcached server!');
                } else {
                    $this->connected = true;
                }
                break;
            case self::TYPE_APC:
                $this->connected = true;
                break;
        }
    }

    /**
     * Check if we are still connected to the cache server, reconnect if not.
     *
     *
     * @return bool
     * @throws \Blacklight\libraries\CacheException
     */
    private function ping()
    {
        if (! $this->connected) {
            return false;
        }
        switch (NN_CACHE_TYPE) {
            case self::TYPE_REDIS:
                try {
                    return (bool) $this->server->ping();
                } catch (\RedisException $error) {
                    // nothing to see here, move along
                }
                break;
            case self::TYPE_MEMCACHED:
                $versions = $this->server->getVersion();
                if ($versions) {
                    foreach ($versions as $version) {
                        if ($version != '255.255.255') {
                            return true;
                        }
                    }
                }
                break;
            case self::TYPE_APC:
                return true;
            default:
                return false;
        }
        $this->connect();

        return $this->connected;
    }

    /**
     * Verify the user selected serializer, return the memcached or redis appropriate serializer option.
     *
     * @return int
     * @throws CacheException
     */
    private function verifySerializer()
    {
        switch (NN_CACHE_SERIALIZER) {
            case self::SERIALIZER_IGBINARY:
                if (! \extension_loaded('igbinary')) {
                    throw new CacheException('Error: The igbinary extension is not loaded!');
                }

                switch (NN_CACHE_TYPE) {
                    case self::TYPE_REDIS:
                        // If this is not defined, it means phpredis was not compiled with --enable-redis-igbinary
                        if (! \defined('\Redis::SERIALIZER_IGBINARY')) {
                            throw new CacheException('Error: phpredis was not compiled with igbinary support!');
                        }

                        return \Redis::SERIALIZER_IGBINARY;
                    case self::TYPE_MEMCACHED:
                        if (\Memcached::HAVE_IGBINARY > 0) {
                            return \Memcached::SERIALIZER_IGBINARY;
                        }
                        throw new CacheException('Error: You have not compiled Memcached with igbinary support!');
                    case self::TYPE_APC: // Ignore - set by apc.serializer setting.
                    default:
                        return null;
                }

                // no break
            case self::SERIALIZER_NONE:
                // Only redis supports this.
                if (NN_CACHE_TYPE !== self::TYPE_REDIS) {
                    throw new CacheException('Error: Disabled serialization is only available on Redis!');
                }

                return \Redis::SERIALIZER_NONE;

            case self::SERIALIZER_PHP:
            default:
                switch (NN_CACHE_TYPE) {
                    case self::TYPE_REDIS:
                        return \Redis::SERIALIZER_PHP;
                    case self::TYPE_MEMCACHED:
                        return \Memcached::SERIALIZER_PHP;
                    default:
                        return null;
                }
        }
    }
}