<?php

/**
 * CodeIgniter
 *
 * An open source application development framework for PHP
 *
 * This content is released under the MIT License (MIT)
 *
 * Copyright (c) 2014-2019 British Columbia Institute of Technology
 * Copyright (c) 2019-2020 CodeIgniter Foundation
 *
 * Permission is hereby granted, free of charge, to any person obtaining a copy
 * of this software and associated documentation files (the "Software"), to deal
 * in the Software without restriction, including without limitation the rights
 * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
 * copies of the Software, and to permit persons to whom the Software is
 * furnished to do so, subject to the following conditions:
 *
 * The above copyright notice and this permission notice shall be included in
 * all copies or substantial portions of the Software.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
 * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
 * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
 * THE SOFTWARE.
 *
 * @package    CodeIgniter
 * @author     CodeIgniter Dev Team
 * @copyright  2019-2020 CodeIgniter Foundation
 * @license    https://opensource.org/licenses/MIT	MIT License
 * @link       https://codeigniter.com
 * @since      Version 4.0.0
 * @filesource
 */

namespace CodeIgniter\Cache\Handlers;

use CodeIgniter\Cache\CacheInterface;
use CodeIgniter\Exceptions\CriticalError;

/**
 * Redis cache handler
 */
class RedisHandler implements CacheInterface
{

	/**
	 * Prefixed to all cache names.
	 *
	 * @var string
	 */
	protected $prefix;

	/**
	 * Default config
	 *
	 * @var array
	 */
	protected $config = [
		'host'     => '127.0.0.1',
		'password' => null,
		'port'     => 6379,
		'timeout'  => 0,
		'database' => 0,
	];

	/**
	 * Redis connection
	 *
	 * @var \Redis
	 */
	protected $redis;

	//--------------------------------------------------------------------

	/**
	 * Constructor.
	 *
	 * @param \Config\Cache $config
	 */
	public function __construct($config)
	{
		$this->prefix = $config->prefix ?: '';

		if (! empty($config))
		{
			$this->config = array_merge($this->config, $config->redis);
		}
	}

	/**
	 * Class destructor
	 *
	 * Closes the connection to Redis if present.
	 */
	public function __destruct()
	{
		if ($this->redis)
		{
			$this->redis->close();
		}
	}

	//--------------------------------------------------------------------

	/**
	 * Takes care of any handler-specific setup that must be done.
	 */
	public function initialize()
	{
		$config = $this->config;

		$this->redis = new \Redis();

		// Try to connect to Redis, if an issue occurs throw a CriticalError exception,
		// so that the CacheFactory can attempt to initiate the next cache handler.
		try
		{
			// Note:: If Redis is your primary cache choice, and it is "offline", every page load will end up been delayed by the timeout duration.
			// I feel like some sort of temporary flag should be set, to indicate that we think Redis is "offline", allowing us to bypass the timeout for a set period of time.

			if (! $this->redis->connect($config['host'], ($config['host'][0] === '/' ? 0 : $config['port']), $config['timeout']))
			{
				// Note:: I'm unsure if log_message() is necessary, however I'm not 100% comfortable removing it.
				log_message('error', 'Cache: Redis connection failed. Check your configuration.');
				throw new CriticalError('Cache: Redis connection failed. Check your configuration.');
			}

			if (isset($config['password']) && ! $this->redis->auth($config['password']))
			{
				log_message('error', 'Cache: Redis authentication failed.');
				throw new CriticalError('Cache: Redis authentication failed.');
			}

			if (isset($config['database']) && ! $this->redis->select($config['database']))
			{
				log_message('error', 'Cache: Redis select database failed.');
				throw new CriticalError('Cache: Redis select database failed.');
			}
		}
		catch (\RedisException $e)
		{
			// $this->redis->connect() can sometimes throw a RedisException.
			// We need to convert the exception into a CriticalError exception and throw it.
			throw new CriticalError('Cache: RedisException occurred with message (' . $e->getMessage() . ').');
		}
	}

	//--------------------------------------------------------------------

	/**
	 * Attempts to fetch an item from the cache store.
	 *
	 * @param string $key Cache item name
	 *
	 * @return mixed
	 */
	public function get(string $key)
	{
		$key = $this->prefix . $key;

		$data = $this->redis->hMGet($key, ['__ci_type', '__ci_value']);

		if (! isset($data['__ci_type'], $data['__ci_value']) || $data['__ci_value'] === false)
		{
			return null;
		}

		switch ($data['__ci_type'])
		{
			case 'array':
			case 'object':
				return unserialize($data['__ci_value']);
			case 'boolean':
			case 'integer':
			case 'double': // Yes, 'double' is returned and NOT 'float'
			case 'string':
			case 'NULL':
				return settype($data['__ci_value'], $data['__ci_type']) ? $data['__ci_value'] : null;
			case 'resource':
			default:
				return null;
		}
	}

	//--------------------------------------------------------------------

	/**
	 * Saves an item to the cache store.
	 *
	 * @param string  $key   Cache item name
	 * @param mixed   $value The data to save
	 * @param integer $ttl   Time To Live, in seconds (default 60)
	 *
	 * @return mixed
	 */
	public function save(string $key, $value, int $ttl = 60)
	{
		$key = $this->prefix . $key;

		switch ($data_type = gettype($value))
		{
			case 'array':
			case 'object':
				$value = serialize($value);
				break;
			case 'boolean':
			case 'integer':
			case 'double': // Yes, 'double' is returned and NOT 'float'
			case 'string':
			case 'NULL':
				break;
			case 'resource':
			default:
				return false;
		}

		if (! $this->redis->hMSet($key, ['__ci_type' => $data_type, '__ci_value' => $value]))
		{
			return false;
		}
		elseif ($ttl)
		{
			$this->redis->expireAt($key, time() + $ttl);
		}

		return true;
	}

	//--------------------------------------------------------------------

	/**
	 * Deletes a specific item from the cache store.
	 *
	 * @param string $key Cache item name
	 *
	 * @return boolean
	 */
	public function delete(string $key)
	{
		$key = $this->prefix . $key;

		return ($this->redis->del($key) === 1);
	}

	//--------------------------------------------------------------------

	/**
	 * Performs atomic incrementation of a raw stored value.
	 *
	 * @param string  $key    Cache ID
	 * @param integer $offset Step/value to increase by
	 *
	 * @return mixed
	 */
	public function increment(string $key, int $offset = 1)
	{
		$key = $this->prefix . $key;

		return $this->redis->hIncrBy($key, 'data', $offset);
	}

	//--------------------------------------------------------------------

	/**
	 * Performs atomic decrementation of a raw stored value.
	 *
	 * @param string  $key    Cache ID
	 * @param integer $offset Step/value to increase by
	 *
	 * @return mixed
	 */
	public function decrement(string $key, int $offset = 1)
	{
		$key = $this->prefix . $key;

		return $this->redis->hIncrBy($key, 'data', -$offset);
	}

	//--------------------------------------------------------------------

	/**
	 * Will delete all items in the entire cache.
	 *
	 * @return boolean
	 */
	public function clean()
	{
		return $this->redis->flushDB();
	}

	//--------------------------------------------------------------------

	/**
	 * Returns information on the entire cache.
	 *
	 * The information returned and the structure of the data
	 * varies depending on the handler.
	 *
	 * @return mixed
	 */
	public function getCacheInfo()
	{
		return $this->redis->info();
	}

	//--------------------------------------------------------------------

	/**
	 * Returns detailed information about the specific item in the cache.
	 *
	 * @param string $key Cache item name.
	 *
	 * @return mixed
	 */
	public function getMetaData(string $key)
	{
		$key = $this->prefix . $key;

		$value = $this->get($key);

		if ($value !== null)
		{
			$time = time();
			return [
				'expire' => $time + $this->redis->ttl($key),
				'mtime'  => $time,
				'data'   => $value,
			];
		}

		return null;
	}

	//--------------------------------------------------------------------

	/**
	 * Determines if the driver is supported on this system.
	 *
	 * @return boolean
	 */
	public function isSupported(): bool
	{
		return extension_loaded('redis');
	}

	//--------------------------------------------------------------------
}
