<?php

namespace App\Core;

/**
 * Core Redis Client for managing connections.
 * Handles Sessions, Rate Limiting, and caching using PHP Redis extension.
 */
class RedisClient
{
    private static ?\Redis $instance = null;

    /**
     * Get the singleton Redis connection instance
     */
    public static function getInstance(): \Redis
    {
        if (self::$instance === null) {
            try {
                $redis = new \Redis();
                
                $host = getenv('REDIS_HOST') ?: '127.0.0.1';
                $port = (int)(getenv('REDIS_PORT') ?: 6379);
                $password = getenv('REDIS_PASSWORD') ?: null;
                
                // Connect with a 2 second timeout
                if (!$redis->connect($host, $port, 2.0)) {
                    throw new \RuntimeException("Could not connect to Redis server at $host:$port");
                }

                // Authenticate if password is provided
                if ($password) {
                    if (!$redis->auth($password)) {
                        throw new \RuntimeException("Redis authentication failed.");
                    }
                }

                // Set prefix for Saqel to avoid collisions
                $redis->setOption(\Redis::OPT_PREFIX, 'saqel:');

                self::$instance = $redis;
            } catch (\Exception $e) {
                // In production, fallback gracefully or throw HTTP 500
                error_log("Redis Connection Error: " . $e->getMessage());
                throw new \RuntimeException("Redis is unavailable. Please ensure the Redis server is running.");
            }
        }

        return self::$instance;
    }
    
    /**
     * Helper to close the connection explicitly
     */
    public static function close(): void
    {
        if (self::$instance !== null) {
            self::$instance->close();
            self::$instance = null;
        }
    }
}