<?php

namespace XcVm\Core\Cache;

use XcVm\Infrastructure\Redis\RedisManager;

/**
 * \Redis Cache Driver
 *
 * \Redis-based cache driver implementing CacheInterface.
 * Wraps the phpredis extension with serialization and TTL support.
 *
 * ServiceContainer Registration:
 *
 *   $container->set('redis', function($c) {
 *       $settings = $c->get('settings');
 *       $config   = $c->get('config');
 *       return new RedisCache(
 *           $config['hostname'],
 *           6379,
 *           $settings['redis_password']
 *       );
 *   });
 *
 * Raw \Redis Access:
 *
 *   During migration, legacy code may need raw \Redis:
 *     $rawRedis = $redisCache->getConnection();
 *     $rawRedis->multi();
 *     $rawRedis->zAdd('LIVE', $timestamp, $uuid);
 *     $rawRedis->exec();
 *
 * @see CacheInterface
 * @see RedisManager::ensureConnected()
 *
 * @package XC_VM_Core_Cache
 * @author  Divarion_D <https://github.com/Divarion-D>
 * @copyright 2025-2026 Vateron Media
 * @link    https://github.com/Vateron-Media/XC_VM
 * @license AGPL-3.0 https://www.gnu.org/licenses/agpl-3.0.html
 */

class RedisCache implements CacheInterface {
	/** @var \Redis|null phpredis connection */
	protected $redis = null;

	/** @var string \Redis host */
	protected $host;

	/** @var int \Redis port */
	protected $port;

	/** @var string|null \Redis password */
	protected $password;

	/** @var bool Whether connection is established */
	protected $connected = false;

	/** @var string Key prefix to avoid collisions */
	protected $prefix = '';

	/**
	 * @param string $host \Redis host
	 * @param int $port \Redis port
	 * @param string|null $password \Redis AUTH password
	 * @param string $prefix Optional key prefix
	 */
	public function __construct(string $host = '127.0.0.1', int $port = 6379, ?string $password = null, string $prefix = '') {
		$this->host = $host;
		$this->port = $port;
		$this->password = $password;
		$this->prefix = $prefix;
	}

	/**
	 * Establish \Redis connection (lazy — called on first operation)
	 *
	 * @return bool
	 */
	public function connect() {
		if ($this->connected && $this->redis !== null) {
			return true;
		}

		try {
			$this->redis = new \Redis();
			$this->redis->connect($this->host, $this->port);

			if ($this->password) {
				$this->redis->auth($this->password);
			}

			// Use igbinary serializer if available for consistency with FileCache
			if (defined('Redis::SERIALIZER_IGBINARY')) {
				$this->redis->setOption(\Redis::OPT_SERIALIZER, \Redis::SERIALIZER_IGBINARY);
			}

			$this->connected = true;
			return true;
		} catch (\Exception $e) {
			$this->redis = null;
			$this->connected = false;
			return false;
		}
	}

	/**
	 * {@inheritdoc}
	 */
	public function get($key, $maxAge = null) {
		if (!$this->ensureConnected()) {
			return false;
		}

		$prefixedKey = $this->prefix . $key;
		$data = $this->redis->get($prefixedKey);

		if ($data === false) {
			return false;
		}

		// maxAge is handled by \Redis TTL, not by us
		// But if caller wants to check age, we can't — \Redis doesn't store creation time
		// For file-based TTL compat, we ignore maxAge here (\Redis uses its own TTL)

		return $data;
	}

	/**
	 * {@inheritdoc}
	 */
	public function set($key, $data, $ttl = 0) {
		if (!$this->ensureConnected()) {
			return false;
		}

		$prefixedKey = $this->prefix . $key;

		if ($ttl > 0) {
			return $this->redis->setex($prefixedKey, $ttl, $data);
		}

		return $this->redis->set($prefixedKey, $data);
	}

	/**
	 * {@inheritdoc}
	 */
	public function delete($key) {
		if (!$this->ensureConnected()) {
			return false;
		}

		$prefixedKey = $this->prefix . $key;
		$this->redis->del($prefixedKey);

		return true;
	}

	/**
	 * {@inheritdoc}
	 */
	public function has($key, $maxAge = null) {
		if (!$this->ensureConnected()) {
			return false;
		}

		$prefixedKey = $this->prefix . $key;

		return (bool) $this->redis->exists($prefixedKey);
	}

	/**
	 * {@inheritdoc}
	 *
	 * WARNING: Flushes the ENTIRE \Redis database. Use with caution.
	 */
	public function flush() {
		if (!$this->ensureConnected()) {
			return false;
		}

		return $this->redis->flushDB();
	}

	// ───────────────────────────────────────────────────────────
	//  Raw \Redis Access (for migration period)
	// ───────────────────────────────────────────────────────────

	/**
	 * Get the raw phpredis connection
	 *
	 * Allows legacy code to use \Redis-specific operations (sorted sets,
	 * pipelines, pub/sub, etc.) that don't fit the CacheInterface.
	 *
	 * @return \Redis|null
	 */
	public function getConnection() {
		$this->ensureConnected();
		return $this->redis;
	}

	/**
	 * Check if connection is alive
	 *
	 * @return bool
	 */
	public function isConnected() {
		if (!$this->connected || !$this->redis) {
			return false;
		}

		try {
			return $this->redis->ping() !== false;
		} catch (\Exception $e) {
			$this->connected = false;
			return false;
		}
	}

	/**
	 * Close connection
	 */
	public function disconnect() {
		if ($this->redis) {
			try {
				$this->redis->close();
			} catch (\Exception $e) {
				// ignore
			}
		}

		$this->redis = null;
		$this->connected = false;
	}

	/**
	 * Ensure connection is active, reconnect if needed
	 *
	 * @return bool
	 */
	protected function ensureConnected() {
		if ($this->connected && $this->redis !== null) {
			return true;
		}

		return $this->connect();
	}

	/**
	 * Disconnect from \Redis when the instance is destroyed.
	 */
	public function __destruct() {
		$this->disconnect();
	}
}