<?php

/**
 * This file is part of the CodeIgniter 4 framework.
 *
 * (c) CodeIgniter Foundation <admin@codeigniter.com>
 *
 * For the full copyright and license information, please view the LICENSE
 * file that was distributed with this source code.
 */

namespace CodeIgniter\Cache\Handlers;

use CodeIgniter\Exceptions\CriticalError;
use Config\Cache;
use Redis;
use RedisException;

/**
 * Redis cache handler
 */
class RedisHandler extends BaseHandler
{
	/**
	 * 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 Cache $config
	 */
	public function __construct(Cache $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 (isset($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)
	{
		$key  = static::validateKey($key, $this->prefix);
		$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 boolean Success or failure
	 */
	public function save(string $key, $value, int $ttl = 60)
	{
		$key = static::validateKey($key, $this->prefix);

		switch ($dataType = gettype($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' => $dataType, '__ci_value' => $value]))
		{
			return false;
		}

		if ($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 Success or failure
	 */
	public function delete(string $key)
	{
		$key = static::validateKey($key, $this->prefix);

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

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

	/**
	 * Deletes items from the cache store matching a given pattern.
	 *
	 * @param string $pattern Cache items glob-style pattern
	 *
	 * @return integer The number of deleted items
	 */
	public function deleteMatching(string $pattern)
	{
		$matchedKeys = [];
		$iterator    = null;

		do
		{
			// Scan for some keys
			$keys = $this->redis->scan($iterator, $pattern);

			// Redis may return empty results, so protect against that
			if ($keys !== false)
			{
				foreach ($keys as $key)
				{
					$matchedKeys[] = $key;
				}
			}
		}
		while ($iterator > 0);

		return $this->redis->del($matchedKeys);
	}

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

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

		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 integer
	 */
	public function decrement(string $key, int $offset = 1)
	{
		$key = static::validateKey($key, $this->prefix);

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

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

	/**
	 * Will delete all items in the entire cache.
	 *
	 * @return boolean Success or failure
	 */
	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 array
	 */
	public function getCacheInfo()
	{
		return $this->redis->info();
	}

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

	/**
	 * Returns detailed information about the specific item in the cache.
	 *
	 * @param string $key Cache item name.
	 *
	 * @return array|null
	 *   Returns null if the item does not exist, otherwise array<string, mixed>
	 *   with at least the 'expire' key for absolute epoch expiry (or null).
	 */
	public function getMetaData(string $key)
	{
		$key   = static::validateKey($key, $this->prefix);
		$value = $this->get($key);

		if ($value !== null)
		{
			$time = time();
			$ttl  = $this->redis->ttl($key);

			return [
				'expire' => $ttl > 0 ? time() + $ttl : null,
				'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');
	}
}